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1. 6 Tm 105 IN C 121 2 lore 6010 7 010 FF E ig r t t e m IE M oo Dad 2 a 5 nues 4 Figure 2 AXE210 Connectivity Board However due to the program memory limitations encountered with the PICAXE 18 series microcontrollers the AXE210 board is used as a PC interface only with an AXE118 board and PICAXE 20X2 microcontroller connected to assume the processing role normally undertaken by the on board 18 series microcontroller 2 8 AXE118 Connectivity Board The AXE118 board acts as an interface between the PICAXE 20X2 microcontroller and the AXE210 XBee board Connections between the XBee transmit receive and sleep I O pins the AXE210 board and the AXE118 board are made for the Base Station and Measurement Node as per Table 17 and Table 18 respectively 22 Page Function AXE118 AXE210 XBee Transmit B 4 B 7 XBee Receive 7 C 7 XBee Sleep B 2 B 6 Table 17 AXE118 AXE210 Base Station Connectivity Function AXE118 210 XBee Transmit B 4 B 7 XBee Receive C 7 C 7 XBee Sleep B 2 B 6 Table 18 AXE118 AXE210 Measurement Node Connectivity The AXE118 boards were modified by removing the Darlington driver IC and bridging the connections between the PICAXE microcontroller and the board output terminals This was necessary as Darlington driver buffered outputs were not suitable for ser
2. 46 6 0 25 E EE 48 6 1 Wireless Range Testing rc rea 48 6 1 1 Eine of 5 1 oe epi b RIEN 49 6 12 Light Urban o Rte tie tet ette teat 50 6 1 3 Heavy etre iei ita hind 51 6 1 4 Wireless Range Test 5 nnne enne nasse 52 6 2 Power Consumption Testing 52 6 3 Wireless Power Monitor Accuracy ennemis nnn nnn nnn 54 6 3 1 Voltage Accuracy 55 6 3 2 Current Accuracy 56 6 3 3 Voltage amp Current Testing 5 56 7 0 Future Worki neinei 58 EE 58 7 2 Multiple Measurement 58 7 3 5 eet ese a e o wh e et en E Rs 58 7 4 Inid ctive Charging i tret eret Senn eta ese eec op gu re teas eub ve eee 58 7 5 Carbon Emission ierit ter eite ere ete het ere erar eer 59 SO SUMMA m 60 9 0 etre 61 10 0 AppendiCes 63 7 Page i Table of Figures Figure 1 AC AC Transformer cccccccssscecssecessseceseeccssececssecesseecsseeccsaecscaeecesseccsaeeseaaeceaeecessecenaeeeeaaecenseeenas 19 Figure 2 AXE210 Connectivity Board cccccccccsssssssscsececscsesssanecsececeeseassasacseceesesenssensececessessnssenseeecess 22 Figure 3 AXE118 Connectivity
3. POWERTECH BATTERY ELIMINATOR INPUT 240 50Hz 4 mL cu E APP NO NSW23268 CAT NO 3027 9 5l 6 Figure 1 AC AC Transformer 2 6 Current Measurement A number of methods of current measurement were considered for this project The requirements for a current sensor were low susceptibility to interference and temperature drift along with the ability to measure AC current As with the voltage measurement a method of measurement which provides 19 Page galvanic isolation was also considered essential A current sensor which also requires minimal support circuitry such as signal amplification or external power was considered preferable Table 15 lists the properties of the current measurement devices considered for use in the power monitor 20 Page Joysisay 3unus 105495 19 3 3 159 4 5 0 Ayyiqudaasns queuienseaJA 01 Aqyiqudassns sasinbay nd no JaMOd sasinbay sesso 2 02 T 0 021 gt 2 08 lt 27 SOA 01 jews ON ON 2 08 Mojaq 5 2942351594 3 SPA 8 5 59 SIH 59 5 SoA 4 MO ON S A Mo ON ON S A dn oid gu his 20 SOA 8 SOA sox
4. pug 1114 1 013 0 Josuas 123433 5 jo 21 Current transformers were ultimately chosen over the other methods of current measurement due to their low susceptibility to interference from other magnetic fields such as those generated in neighbouring wires and the fact that current transformers also offer galvanic isolation An EW4008 Current Transformer Sensor Clamp was chosen for the project the ratings of which are listed below in Table 16 Specification Rating Current Range 0 100A Current Sensitivity 100mA Maximum Momentary Ratings 300A 600V Turns Ratio 1 5000 Table 16 CT Sensor Ratings Steplight 2012 Supporting circuitry required for use with the current transformer is covered in section 4 2 2 7 AXE210 Connectivity Board The AXE210 board is used to connect a PICAXE 18 series microcontroller to the XBee wireless module In addition to this the board also supports a MAX232 level converter which allows communication between the transistor to transistor logic TTL levels of the XBee module and the RS 232 logic levels required by a PC Connectivity with a PC is required for modifying settings upgrading firmware and performing wireless range testing of the XBee modules LRL oe v 46200000260 72 OPS MODULEN i Nec 010 XVIId MMM 44 115 12 008
5. 38 Figure 19 Microcontroller Variable Clock Speed 40 Figure 20 GLCD Login 5 ec a ba ce e aa nea al reu de Da eee a Tea de aas 41 Figure 21 iButton Authentication Flowchart 41 Figure 22 GLCD nace e e aa cre a aacra e aa ene aa ad ea e nba ee a e a Era 42 Figure 23 Single Phase Realtime Usage sese nennen nnne 42 Figure 24 Three Phase Realtime 42 Figure 25 Past Hour Usage Graph 43 Figure 26 Voltage Selection Flowchart osiinsa eaae 43 Fig re 27 Tariff Settings eec tte eer an bureau tre koe den a ER 44 Figure 28 Usage idee eom e ee aee nue ena ed BRE Tee 44 Figure 29 USB Logging On Off 1 eterne nnne nennen nennen terree nns 45 Figure 30 iButton Support Program Terminal 47 Figure 31 X CTU PC Interface rite recette eater eate ee E E Eve ER RR EE NE 48 Figure 32 X CTU Received Signal Strength 49 Figure 33 Line of Sight Wireless Range Test Map Google 2012 50 Figure 34 Line of Sight 1
6. Serial Data Out Transistor to Transistor Logic Transmitter Universal Asynchronous Receiver Transmitter Universal Serial Bus Wireless Local Area Network Wireless Power Monitor 10 Page 1 0 Introduction Measurement of power flow allows user to remain informed about the quantity of power that is being consumed by either an individual device or installation as a whole Along with measuring power consumption power monitoring allows the calculation of important information such as the cost of the power the times of peak usage and the power factor of specific devices With ever rising electricity costs both corporations and individuals have a vested interest in identifying where and when power is being consumed By measuring and logging power usage trends can be established and strategies implemented to reduce the quantity of consumed power or device usage plans investigated in order to limit the usage of specific devices to periods of the day when lower tariffs apply 1 1 Background Traditionally there have been two distinct methods of achieving remote power measuring and monitoring The first is by use of a data acquisition system DAQ at the location where the power measurement is required which relays data back to a user interface via a wired network typically though methods such as Profibus Fieldbus or Ethernet Wired networks are typically used for permanently installed equipment or installations and form the majority of exis
7. vasaris ZO SSA gt 9 110181 08 31108 unosa 5 2 1 p 38 Page 5 0 Software Programming amp Operation 5 1 Base Station The Base Station has the task of receiving displaying and logging the measurements taken from the Measurement Node In addition to this it provides a user interface to allow manipulation of variables and settings such as tariffs voltage and switching the USB logging on or off 5 1 1 Microcontroller Clock Speed The program has been written to allow the PICAXE microcontroller on the Base Station to operate at dual clock speeds 16MHz and 64MHz dependent upon the task being executed The clock speed is increased from the standard 8MHz to 64MHz via initialisation code that executes when the microcontroller is first powered This increase in clock speed from the standard 8MHz affects all other time related functions such as pauses and serial data rates The fastest microcontroller clock speed which supports a serial data rate of 2400bps which is rate required by the GLCD is BMHz Accordingly the default microcontroller clock speed of 64MHz is reduced to 16MHz when 2400bps serial communications are required Upon completion of the 2400bps serial communications the clock speed is returned to 64MHz Data logging is not affected by the varying microprocessor speed as all results are buffered and only written out to the USB Flash memory device when the Base Station is operating at 64MHz A
8. 16 bit Authorisation Code Figure 21 iButton Authentication Flowchart 41 Page appropriate digital input on the Base Station to gain access The flowchart shown Figure 21 displays the process of authenticating an iButton and allowing or denying access accordingly 5 1 3 Realtime Usage The realtime usage option in the main menu shown in Figure 22 allows the user to view the current present values for the RMS voltage RMS current apparent power power factor and temperature 1 3 Figure 22 GLCD Menu Any one of the three single phases can be viewed as shown in Figure 23 or the three phase measurement as shown in Figure 24 aE D IB 1111 Cur Pur Fct 24 HS 5 3H mL udi a it Figure 23 Single Phase Realtime Usage m T n In cc lm ALI IL mm mu m D ii Figure 24 Three Phase Realtime Usage 42 Page 5 1 4 Usage Graphs The Wireless Power Monitor includes a graphical display of power usage across the past hour as shown in Figure 25 or past 24 hours As the graph auto scales depending on the maximum recorded power value to provide maximum utilisation of the available GLCD d
9. 3 20X2 Microcontroller 17 2 4 08 2 Microcontroller sees 18 2 5 Voltage 4 19 2 6 Current Measurement 19 2 7 210 Connectivity Board 22 2 8 AXE118 Connectivity Board cccccccccccceesssssssaeeececeseeseeeaeceeecessesesaeaeceeecesseseaaeaeeeesessseseaeaeeeesens 22 2 9 Samsung KS108 Serial Graphic LCD 23 2 10 FGC Graphical LCD Interpreter Chip Board 24 2 11 VDrive2 USB Module 24 2 12 AXE109 iButton Module 2 2 25 2 13 i2C Real Time Clock 25 2 14 uM FPU V2x Arithmetic 0 nennen nnnm nennen nnne nnne 26 2 15 MCP1702 500 amp 300 Low Dropout Voltage 27 2 16 0518 920 c E 27 2 17 Keypad Interface ene ede 27 2 18 Pro Wireless 27 2 19 Hardware Block 29 3 0 COMMUNICATION EM 30 15 vade
10. Pos 0 0005 Figure 16 Conditioned Current Signal for PICAXE Microcontroller Input 36 Page 4 3 Base Station Schematic The final circuit diagram for the Base Station is given in Figure 17 311241 uonejs eseg ZT 314 uor4e4s 2524 4O34TUuO 559194 lIWSNUMI 7191435 ESN 1 5 8 725 281 01 3 31938 7191935 850 01 3NI SNE 945 221 01 104 1 0375 OL 104100 501915 1279 Ol 90107091 81 20142812 ET 43375 17 3M 91 9010 909 514 21 OIG ETU 13S 13003 20107204 61 10104109 PRO RF MODULE 37 Page 1 4 4 Measurement Node Schemat The final circuit diagram for the Measurement Node is given in Figure 18 LESE uosutyuac Rerusu 6 5591941 3112 15 81 1814 11 9010 9049 1743 20147519 ET 4 16 0 335 60147609 9014 99 51 13834 6 41 0 77138 03003 81 2014 249 61 101047109 1008 2 H 00104700Y 1 PRO RF MODULE 276 158 jer 9 8 00 2 6249 24 X o a 61 879 100 791535 20x2 E E
11. at maximum current 5 0 R b 0 028284 176 7780 9 Finally as the voltage input is AC waveform the burden must be divided two order to give peak to peak 5 0V output at maximum current 176 778 88 390 10 The variable burden resistor VR1 is utilised with the CT sensor which has range of 10 1000 is set to the required burden resistance of 88 40 as the closest preferred resistor values available are 820 or 1000 The variable resistor used as a burden also allows the future option of setting the resistance lower which results in greater resolution at the expense of current range and vice versa Figure 15 shows the output from the CT sensor when measuring a current of 20A As with the voltage the output from the sensor is AC and as such it experiences a zero crossing twice per cycle 35 Page Pos 0 0005 10 05 18 Oct 12 12 40 Figure 15 Current Transformer Output In the current measurement circuit shown in Figure 14 the voltage divider comprised of R1 and R2 is used to provide a 2 5V DC offset to the CT signal In the same manner as the voltage measurement circuit this is in order to bias the waveform such that it will provide only non negative values to the microcontroller s ADC and to 5 0V peak to peak signal at the maximum current of 100A Figure 16 shows the CT sensor output with and without the DC offset added CH4 and CH3 respectively
12. been created 5 3 1 Real Time Clock Support Program The RTC is able to maintain timekeeping abilities without external power as it features an on board backup battery However if the battery is depleted or removed when the RTC is not powered the time and date will be reset This will necessitate reprogramming the correct time and date into the RTC as will a change in the user s time zone A simple support program has been written to allow adjustment of the time and date for the RTC The program has been designed to allow the RTC to be programmed in situ and does not require any changes in hardware configuration The program is available in appendix 001 5 3 2 GLCD Data Store Support Program The K1 GLCD controller board contains a 16 kilobyte EEPROM module which is used to store a number of the features used to control the GLCD However only a small amount of the memory is used for this purpose In order to reduce the program size in the PICAXE microcontroller in the Base Station a secondary program was written to transfer large text strings to be stored on the GLCD EEPROM All text strings that are to be displayed by the GLCD are written into the GLCD Data Store Program The program is then loaded onto the main Base Station PICAXE microcontroller Once loaded the program automatically executes transferring all the text strings via serial output into the EEPROM on the GLCD K1 board Once the transfer has completed the main GLCD Data
13. in values of 600mV and 4 60V being displayed M Pos 0 0005 Figure 13 Conditioned Voltage Signal for PICAXE Microcontroller Input 4 2 Current Measurement Similar to voltage measurement the input waveform from the current transformer must be non negative with maximum amplitude of 5 0V peak to peak However in contrast to the voltage measurement the input current voltage does not require scaling as a suitable burden resistor is chosen to provide a 5 0V output at the maximum CT measuring current of 100A The interfacing circuit designed to allow the PICAXE microcontroller to measure current flow is shown below in Figure 14 34 Page To 5 04 GND ADC 24 gt CT Sensor Figure 14 Current Measurement Interfacing Circuit The burden resistor VR1 is required to convert the induced current in the CT sensor to a voltage suitable for the PICAXE microcontroller to read via an ADC From the CT specifications in Table 16 the maximum current rating of the CT sensor is 100A RMS so the primary peak current lp is I 100 x V2 141424 7 The secondary coil of the CT has 5000 turns so the current in the secondary Is becomes _ 141 42 0 028284A 8 5000 8 In order to utilise the full ADC range the PICAXE microcontroller for maximum resolution the burden resistor Ry should provide the ADC reference voltage of 5 0V
14. range of the Wireless Power Monitor was also tested in a light urban environment The light urban housing density was approximately 25 The distance between points displayed below in Figure 35 was again measured with GPS co ordinates entered into Google Earth 50 Page Google earth Par Figure 35 Light Urban Wireless Range Test Google 2012 10 packet loss occurred at a distance of 986m in the light urban environment with 100 packet loss occurring by 1010m As expected the wireless range was reduced in a light urban environment when compared to a line of sight scenario 6 1 3 Heavy Urban The final test of the wireless range capability of the Wireless Power Monitor was performed in a heavy urban environment A heavy urban environment equates to a typical worst case scenario whereby there are continual obstructions between the Base Station and measurement node Housing density for the heavy urban test was approximately 90 Measure the distance between two points on the ground Map Length 406 61 Meters Figure 36 Heavy Urban Wireless Range Test Map Google 2012 51 Page range heavy urban environment was reduced to less than half that of the light urban range and approximately a quarter that of the line of sight range 10 packet loss occurred at 406m with 100 packet loss by 440m 6 1 4 Wireless Range Test Summary The wireless range testing in differing environments was designe
15. simplified flowchart showing the process of switching the microprocessor clock speed to allow 2400 bps serial communications for the GLCD can be seen in Figure 19 39 Page Read XBee Data Input Set Clock Speed to 16 MHz Send Data to GLCD at 2400 bps Set Clock Speed to 64 MHz Read GLCD Status Output C Ke Status Low Figure 19 Microcontroller Variable Clock Speed Flowchart The dual clock speed allows for faster overall program execution and response while still facilitating the required low speed serial communication for the GLCD 5 1 2 Login The Base Station uses a Serial Number iButton security system to prevent unauthorised or accidental changes to settings Maxim 2010 The user must provide a valid iButton device to gain access to the settings and measurement results The login GLCD screen is shown in Figure 20 40 Page Figure 20 GLCD Login Screen Upon presentation of a valid iButton a 16 bit authorisation code is sent from the PICAXE 08M2 microcontroller to which the iButton module is attached via serial communications to the main 20X2 microcontroller The 16 bit authorisation code is used in place of a purely digital permission where high login low deny to provide extra security preventing a user from simply providing a 5V to the Check iButton Device iButton Connected Read iButton Serial Number Authorised Play Error Tone amp Serial Flash LED Play Accept Tone Send
16. via the two wire bus as opposed to each device requiring dedicated input and output pins A number of devices used in the Wireless Power Monitor have been chosen to be interfaced with the PICAXE microcontrollers via an 2 bus The real time clock RTC utilised by for time stamping the log files 30 Page calculating usage costs is interfaced with the PICAXE microcontroller by means of bus along with the 512kB EEPROM module and arithmetic co processor Each device requires a unique address to allow information passing along the bus to be read only by the correct device Table 23 lists the specific addresses and required bus speeds for the devices connected to the PICAXE microcontrollers via 2 Device Slave Address Speed RTC 1101000x i2cslow EEPROM 1010dddx i2cfast uM FPU 2 1100100x Table 23 Device Specification Table Note that the d address locations are used to specify the required memory block address required within the EEPROM module and the x denotes that either 0 or 1 may be used as the final bit of the address is ignored 3 3 IEEE 802 15 4 The XBee Pro wireless modules chosen for this project communicate using the IEEE 802 15 4 protocol IEEE Standard 802 15 4 2011 The 802 15 4 standard is set by the Institute of Electrical and Electronics Engineers IEEE and was designed to provide a standard for Low Rate Wireless Personal Area Networks LR WPANs The 802 15 4 protoco
17. 0 Packet Loss at 1 570 eene enne nnne 50 Figure 35 Light Urban Wireless Range Test Map Google 2012 51 Figure 36 Heavy Urban Wireless Range Test Map Google 2012 51 Figure 37 Standard Power Consumption esses enne 53 Figure 38 Power Consumption with Doze Function cesses nennen nennen 54 Figure 39 Fluke 287 vs Wireless Power Monitor Voltage Test sess 55 Figure 40 Fluke 287 vs Wireless Power Meter Current 56 8 Page ii List of Tables Table 1 Wireless Power Monitor 50 nenne neni nnns nnne nina nnns 11 Table 2 Wireless Power Monitor 5 12 Table 3 Wireless Power Monitor sterne 13 Table 4 Measurement Node Microcontroller Requirements eese nnn 14 Table 5 Measurement Node Microcontroller Hardware Requirement 5 14 Table 6 Base Station Microcontroller Hardware 5 100 15 Table 7 Base Station Microcontroller Hardware Requirement Totals eese 15 Table 8 PICAXE 18M2 Microcontroller Specificatio
18. 0 Series Bridges Non Line of Sight Operation Open Source Meter Inc 2011 Intro to Current Transformers OpenEnergyMonitor Accessed August 8 2012 Building Blocks http openenergymonitor org emon buildingblocks Owl 2012 Owl micro Wireless Electricty Monitor Safety and Connection Guide PICAXE Forum Accessed September 3 2012 Driving the VDrive2 http www picaxeforum co uk archive index php t 20581 html Revolution Education Ltd 2010 PICAXE Manual Microcontroller Interfacing Circuits Revolution Education Ltd 2012 PICAXE Manual I Getting Started Revolution Education Ltd 2012 PICAXE Manual I BASIC Commands Revolution Education 2004 109 08 iButton Lock Revolution Education 2011 PICAXE Connect AXE210 Revolution Education 2012 PICAXE 18M2 Update Rockwell 2012 PowerMonitor Wireless 250 Monitor User Manual Standards Australia 2000 AS 60038 2000 Standard Voltages Steplight Accessed August 10 2012 Watts Clever Wireless Energy Monitor EW4008 Current Sensor Clamp http steplight com au education monitor energy ew4008 watts clever wireless energy monitor current sensor clamp only Synergy Accessed September 10 2012 Shift and save with SmartPower http www synergy net au at home smartpower xhtml Watts Clever 2011 Wireless Energy Monitor Instruction Manual Wattson 2012 Wattson User Guide Wireless Range Maps Google Maps Accessed September 28 2012 www goo
19. 0 were considered for use in this project Wireless Module Frequency Power Output Maximum LoS Range Data Rate Mode XBee ZB 2 4 GHz 2mW 120m 250 Kbps Half Duplex XBee Pro 802 15 4 2 4 GHz 63mW 1600m 250 Kbps Half Duplex XBee Pro 900 900 MHz 100mW 9600m 10Kbps Half Duplex 433MHz RF Module 433 MHz 2mW 150m 480 bps Simplex 433MHz RF Module 433 MHz 500mW 2000m 250 Kbps Simplex Table 20 Wireless Module Comparison An additional consideration when selecting the wireless module was the legality and licensing issues associated with operating wireless transmitters The Australian Communications and Media Authority ACMA defines the limits for the equivalent isotropically radiated power EIRP output of low interference potential devices LIPDs on specific frequency bands AMCA 2012 The limits for the 433 MHz 900 MHz and 2 4 GHz frequency bands are listed in Table 21 Note that these limits are for a telecommand transmitter device as differing limits apply to other types of devices operating on these frequency bands Parameter 433 MHz Band 900 MHz Band 2 4 GHz Band Frequency Spectrum 433 05 434 79 MHz 890 960 MHz 2 4 2 4835 GHz Maximum EIRP 25mW 100mW 1000mW Table 21 AMCA LIPD Specifications Based upon insufficient maximum wireless communication distance both the 2mW 433MHz and XBee ZB wireless modules were rejected While the high power 500mW 433MHz was able t
20. 1 Wireless Range Testing Wireless range in excess of 1500m for line of sight 500m for light urban and 250m for heavy urban environments were major goals for this project The XBee wireless modules were chosen as they were rated to achieve these wireless communication distances however testing was undertaken to confirm that they were capable of meeting these requirements X CTU a software package provided by the Digi International Corporation was used to perform the range testing The Base Station was connected to a PC via a serial cable to allow communication between the XBee module and the software The range test software generates 128 bytes of data which is sent to the Base Station A loopback test is then performed between the Base Station and the Measurement Node with a 1000ms data loopback timeout When the data is sent from the Base Station it must be subsequently echoed back from the Measurement Node within 1000ms If it is not returned within this timeframe the packet is deemed to be lost The X CTU interface and the 128 bytes of generated data that were echoed can be seen in Figure 31 About PC Settings Range Test Terminal Modem Configuration Percent Start Packet Delay 100 Min msec Clear Stats Max msec Stop at 100 Stop on error Test aon Data receive timeout Loop Back 1000 msec 0123456789 lt gt ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 lt gt GABCDEFGHIJKLMNOPQRSTUVWXYZ012
21. 12 XBee Pro RF Modules Doss 2011 Wireless Energy Monitor Ecotouch 2012 Ecotouch Energy Management System Instruction Manual Energizer Holdings Inc 2012 Product Datasheet EBC 4201R9X FGC 2012 GLIC K1 Graphic LCD Interpreter Chip Fluke Corporation 2008 287 True RMS Multimeter USA Friedrich A P Lemme H 2000 The Universal Current Sensor Accessed September 8 2012 http www sensorsmag com sensors electric magnetic the universal current sensor 1029 Future Technology Devices International 2007 VDrive2 Vinculum VNC1L Module Gascon D 2008 802 15 4 vs ZigBee Accessed November 1 2012 http www sensor networks org index php page 0823123150 Horowitz Hill W 1989 The Art of Electronics 274 ed Cambridge University Press International Telecommunications Union 2002 Propagation by diffraction P 526 iSixSigma Design for Six Sigma DFSS Accessed November 1 2012 http www isixsigma com new to six sigma design for six sigma dfss Lindholm Christian Keinonen Turkka Kiljander Harri 2003 Mobile Usability How Nokia Changed the Face of the Mobile Phone New York McGraw Hil 61 Page MaxStream Inc 2005 XBee XBee PRO OEM RF Modules Product Manual V1 06 Microchip Technology Inc 2005 MCP1702 2uA Low Dropout Positive Voltage Regulator Product Brief Micromega Corporation 2005 uM FPU Floating Point Coprocessor V2 Datasheet Motorola 2007 White Paper NLoS Motorola PTP 40
22. 18 pin dual inline package DIP layout and the 20X2 has a 20 pin DIP layout resulting in the microcontrollers not being directly interchangeable Consequently a connectivity board covered in section 2 8 of this report was required to allow the microcontrollers to be interchanged Additionally as the 18M2 and 20X2 microcontrollers are based upon entirely different IC s the 1 0 connections for the attached hardware had to be altered to reflect the different pin designation along with appropriate changes to the program code Although the 20X2 microcontroller has less RAM than the 18M2 the 18M2 uses a portion of its RAM for storing general purpose variables The 20X2 has additional scratchpad memory not featured in the 18M2 which is used for general purpose variable storage The final updated pinout table for the 20X2 Base Station and Measurement node are given in Table 12 and Table 13 respectively 17 Page Functions Pin In Out ADC1 hint1 0 Designation iButton Input Notes In Out ADC2 hint2 580 1 iButton Output In Out ADC4 Comp2 B 2 XBee Sleep In Out ADCS 2 GLCD Output In Out ADC6 hpwm D 1 B 4 XBee Transmit In Out ADC10 hi2c sda hspi sdi B 5 SDA Bus 4 7k Pull Up Bus Resistor Required In Out ADC11 hserin B 6 USB Receive Hardware Serial Rx Yellow In Out hi2c scl hspi sck B 7 SCL Bus 4 7k
23. 1Hz Expandability amp 1 Open source end product allowing future adaptation or alteration of Adaptation system for specific applications 2 Spare I O available for future use Table 3 Wireless Power Monitor Outcomes 13 2 0 Hardware 2 1 Overview In order to select a microcontroller with the hardware capabilities required for the Wireless Power Monitor a list of devices which required interfacing with the microcontroller was devised Table 4 lists the 1 0 requirements for the Measurement Node Connected Device Hardware Notes Requirement Phase A Current Measurement 1x ADC Input 10 bit minimum ADC resolution Phase B Current Measurement 1x ADC Input 10 bit minimum ADC resolution Phase C Current Measurement 1x ADC Input 10 bit minimum ADC resolution Phase A Voltage Measurement 1x ADC Input 10 bit minimum ADC resolution Phase B Voltage Measurement 1x ADC Input 10 bit minimum ADC resolution Phase C Voltage Measurement 1x ADC Input 10 bit minimum ADC resolution Bus 1x SCL Line Open drain bi directional line XBee Sleep 1x Digital Output Must support serial communication Table 4 Measurement Node Microcontroller Requirements The final summary of Measurement Node hardware requirements are given in Table 5 Item Total ADC Channels 7 Digital Inputs 1 Digital Outputs 2 1x SCA Line 1x SDA Line Table 5 Measurement Node Microcontroller Hardware Requirement Totals 12 Bus Similarly the mi
24. 30 22 VC Communication BUS bes E aL MEE 30 3 3 802 15 4 31 Circuit 32 4 1 Voltage Measurement 32 4 2 Current dre eet aree opone 34 4 3 Base Station Schematic a ete er E teu 37 4 4 Measurement Node Schematic nennen nennen enne nennen nnn nnne nennen 38 5 0 Software Programming amp 39 5 ee o Et Ser cbe eb inei Ac dm EUER Et E A uot 39 5 1 1 Microcontroller Clock 5 nnns 39 RA 40 Sides Realtime eet eR eh e E dS 42 5 1 4 Usage Graphs 43 5 155 NOltage SOLU 43 516 Tarit s amp Usage 44 5 1 7 USB Flash Logging 45 5 2 Measurement Node teer a e e te ote eg eed e Pe E I RP EN rn 45 5 2 1 Microcontroller Clock 5 45 5 2 2 45 5 2 3 uM FPU V2x Arithmetic 46 5 3 Support Programs 46 5 3 1 Real Time Clock Support Program 46 5 3 2 GLCD Data Store Support Program 46 53 3 iButton Support Program
25. 3456789 GABCDEFGHIJKLMNOPQRSTUVWXY Transmit Receive 128 bytes COM3 9600 8 N 1 FLOW NONE Figure 31 X CTU Interface The software includes a received signal strength indicator RSSI which returns the signal strength in dBm of the last received data packet The value returned is between 40 dBm and 100 dBm where 100 dBm is equal to a 1 packet error rate 48 About PC Settings Range Test Terminal Modem Configuration Percent 100 0 2 msec Clear Stats Max msec E 100 lt lt lt Hide Stop on error Test Data receive timeout z 1000 msec Transmit Receive COM3 96008N 1 FLOW NONE Figure 32 X CTU Received Signal Strength Indicator Given that Wireless Power monitor does not perform any critical control which relies upon the measurements taken a packet loss of up to 1096 has been deemed acceptable A 1096 packet loss marks the absolute maximum allowable loss at which point the wireless communication link is deemed to be severed All measurements were taken on the same day with clear still air and an ambient temperature between 22 C 26 C to minimise errors introduced by environmental factors such as rain temperature and scintillation Motorola 2007 6 1 1 Line of Sight Line of sight testing was performed at an elevation of 2m above sea level with an unobstructed line of sight between the Base Station and Measurement Node GP
26. Base Station and Measurement node were selected and are given Table 9 and Table 10 respectively Functions such as the hardware serial I O and the 12 15 Page data lines that are only featured specific pins were designated these functions by necessity general I O ADC which are interchangeable were chosen arbitrarily Note that all pin functions are listed the Functions Pin column in the tables below with the red highlighted function denoting the actual pin designation Functions Pin Designation Notes SRI Out In 0 iButton Input i2c sda Touch ADC Out In B 1 SDA Bus 4 7k Pull Up Bus Resistor Required hserin Touch ADC Out In B 2 USB Rx Hardware Serial Rx pwm Touch ADC Out In B 3 GLCD Output In Out ADC Touch i2c scl B 4 SCL Bus 4 7k Pull Up Bus Resistor Required In Out ADC Touch hserout B 5 USB Tx Hardware Serial Tx In Out ADC Touch pwm B 6 XBee Sleep Out ADC Touch 7 Transmit In Out ADC Touch 0 Keypad UP 10k Pull Down Resistor Required In Out ADC Touch C 1 Keypad BACK 10k Pull Down Resistor Required DAC Touch ADC Out In C 2 Keypad DOWN 10k Pull Down Resistor Required SQR Out Serial Out C 3 iButton Output In Serial In C 4 In C 5 GLCD Status Input In Out kb clock C 6 Keypad ENTER 10k Pull Down Resistor Required In Out kb data C 7 XBee Rece
27. Board nasa asas isse suse sa sana 23 Figure 4 K1 Graphical LCD Interpreter Chip 24 Figure 5 Vinculum VDrive2 USB 25 Figure 6 te oh tr Pr 26 Figure 7 MicroMega V2x Arithmetic 5 26 Figure 8 Keypad Interface Layout sess ener nnne 27 Figure 9 XBee Pro 802 15 4 Wireless Module nnne nennen ennt nnns 28 Figure 10 Hardware Block Diagram eene nennen nennen 29 Figure 11 Voltage Measurement Interfacing 1 32 Figure 12 AC Voltage Transformer nnn enne ti ian 33 Figure 13 Conditioned Voltage Signal for PICAXE Microcontroller 34 Figure 14 Current Measurement Interfacing Circuit 35 Figure 15 Current Transformer OUEDULE ean toast ec hedera a eae 36 Figure 16 Conditioned Current Signal for PICAXE Microcontroller Input 36 Figure 17 Base Station Circuit Diagram 37 Figure 18 Measurement Node Circuit
28. Galvanic isolation 2 Low susceptibility to noise from external current sources 3 Temperature stability 4 Minimal supporting circuitry Voltage Measurement 1 Galvanic isolation 2 Low voltage AC output Communications 1 Wireless range between transmitter and receiver greater than 1500m in line of sight 500m in light urban and 250m in heavy urban environments 2 Half duplex communication between transmitter and receiver 3 Low power consumption 4 Ability to communicate between multiple nodes Microcontroller 1 Compatibility with wireless communication modules 2 Analogue to digital ADC input capabilities 3 Serial communication input and output 4 Sufficient processing power program memory and variable memory Table 2 Wireless Power Monitor Requirements Successful completion of the project will depend on the realisation of a number of outcomes regarding the operation accuracy usability and expandability of the system The complete list of required outcomes is given in Table 3 12 Property Outcome Operation 1 Minimum communication distances of 1500m 500m and 250m for line of sight light urban and heavy urban environments respectively Accuracy 1 Accurate voltage measurement minimum 5 0 2 Accurate current measurement minimum 5 0 Output 1 Simple and intuitive user interface 2 Reliable logging of measurements for recording on external media device 3 Update rate of at least once per second
29. Murdoch UNIVERSITY Murdoch Long Range Wireless Power University Monitoring System Submitted to the School of Engineering and Energy Murdoch University in partial fulfilment of the requirements for the degree of Bachelor of Engineering 2012 Ashley Jenkinson Bachelor of Engineering Department of Engineering and Energy Supervisor Dr Gareth Lee Co Supervisor Associate Professor Graeme Cole my mother father whose unwavering love and support has made this all possible 2 Page Executive Summary This thesis examines the design construction and implementation of a microcontroller based long range wireless power monitoring system suitable for both domestic and industrial use At its core the system is based on a number of PICAXE 20X2 microcontrollers and a pair of XBee Pro wireless modules which are capable of wireless communication to distances exceeding 1 5km The Long Range Wireless Power Monitoring system is capable of galvanically isolated single and three phase current and voltage measurements and is able to calculate real power apparent power and power factor The results can be displayed numerically or graphically on a Graphical Liquid Crystal Display In addition to this the system has the ability to log usage to an external USB Flash device allowing for later analysis and for the building of a usage history library The Long Range Wireless Power Monitor is equally proficient at measuring power con
30. Pull Up Bus Resistor Required hserout Out In C 0 USB Transmit Hardware Serial Tx Orange hspi sdo kb data ADC9 Out In C 1 Keypad BACK 10k Pull Down Resistor Required kb clk ADC8 Out In C 2 Keypad DOWN 10k Pull Down Resistor Required hpwm C ADC7 Out In C 3 hpwm B SRNQ Out In C 4 Keypad UP 10k Pull Down Resistor Required hpwm A pwm C 5 Out In C 5 GLCD Status Input In C 6 Keypad ENTER 10k Pull Down Resistor Required ADC3 Out In C 7 XBee Receive Table 12 20X2 Base Station Microcontroller Pinout Table Functions Pin Designation Notes In Out ADC1 hint1 0 In Out ADC2 hint2 580 1 In Out ADC4 Comp2 B 2 In Out ADC5 Comp2 B 3 In Out ADC6 hpwm D Comp1 B 4 In Out ADC10 hi2c sda hspi sdi B 5 In Out ADC11 hserin B 6 In Out hi2c scl hspi sck B 7 hserout Out In hspi sdo kb data ADC9 Out In C 1 kb clk ADC8 Out In C 2 hpwm C ADC7 Out In C 3 Phase A Current Input Temperature Sensor Phase A Voltage Input XBee Transmit 12 SDA XBee Sleep 2 SCL Phase B Current Input Phase C Current Input Phase C Voltage Input 4k7 Pull Up Resistor Required 4k7 Pull Up Bus Resistor Required 4k7 Pull Up Bus Resistor Required hpwm B SRNQ Out In C 4 hpwm A pwm C 5 Ou
31. S co ordinates were taken determine distance between the Base Station and the measurement node 10 packet loss occurred with the Base Station at co ordinates 31 54 30 12 S 115 45 19 40 E and the measurement node at 31 55 21 16 S 115 45 18 98 E The distance between these co ordinates was determined to be 1570m by use of Google Earth s ruler function as seen in Figure 33 below 49 Page Une Path Measure the distance between two points on the ground vap Length 1 571 46 Meters Ground Length 1 571 46 Heading 0 37 degrees Google earth Figure 33 Line of Sight Wireless Range Test Google 2012 At a distance of 1570m the packet loss rate was 10 with a 100 packet loss rate occurring within 1620m About PC Settings Range Test Terminal Modem Configuration Min msec Clear Stats Max msec op al 100 lt lt lt Hide stop at Stop on error Test Percent 901 ee4 su sam Data receive timeout 1000 msec Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Timeout waiting for data Transmit Receive COM3 18600 8 N 1 FLOW NONE Figure 34 Line of Sight 10 Packet Loss at 1 570m 6 1 2 Light Urban The
32. Store Program on the Base Station is overwritten by the main Base Station program Finally when the Base Station program requires a line of text to be written to the GLCD it directs the K1 board to print the text at the specific EEPROM location where it is stored A program memory saving of approximately 2200 bytes is achieved by using the EEPROM memory on the K1 board as opposed to the program memory on the PICAXE microcontroller to store the text strings As the PICAXE 20X2 microcontroller has an on board program memory space of 4096 bytes this saving is significant The GLCD Data Store Program can be found in appendix WPMOO2 5 3 3 iButton Support Program Each iButton device carries a unique 64 bit serial number upon the on board ROM The iButton support program is used to read the serial number from a device and display it on the user terminal in decimal 46 Page Figure 30 shows the serial terminal output as result of executing the program and reading the serial number from an iButton module File Edit Refresh Options Baud Rate C 300 500 1200 2400 57600 4800 9600 19200 38400 76800 Non standard 4XE027 only 4800 1 31 Input Buffer Reading iButton Serial Number iButton s Serial Number 69911635000158 Output Buffer Figure 30 iButton Support Program Terminal Output The iButton support program is available in appendix WPMOO3 47 Page 6 0 Testing 6
33. a logging of the measured and calculated parameters was achieved by use of the VDrive2 USB Flash module Finally the Wireless Power Monitor has additional I O which will allow for future expansion or adaptation to a specific application The programs for both the Base Station and the Measurement Node have been written to provide a stable platform for future users to either make additions or alterations if required 60 Page 9 0 Bibliography Australian Communication and Media Authority 1999 Accessed September 2 2012 Spectrum at 434MHz for low powered devices http www acma gov au WEB STANDARD 1001 pc PC_2633 Australian Communication and Media Authority 2011 Accessed September 2 2012 Embargo 64 www amca gov au WEB STANDARD pc PC 2572 Australian Communication and Media Authority 2012 Accessed September 2 2012 Review of the 803 960MHz Band http www acma gov au WEB STANDARD pc PC 312463 Australian Communication and Media Authority 2012 Accessed September 2 2012 Wireless LANs in the 2 4GHz band FAQs http www acma gov au WEB STANDARD pc PC_1794 rlicensing Clipsal 2003 Cent A Meter Model CM133 CMR133 User Manual Dallas Semiconductor 2001 DS1307 64 x 8 Serial Real Time Clock Dean 2010 Network Guide to Networks 5 ed Boston Cengage Learning DFROBOT Accessed October 4 2012 Real Time Clock Module http www dfrobot com wiki index php titlezReal Time Clock Module DS1307 SKU DFRO151 Digi International 20
34. ange commercially produced wireless power monitors and solution to this problem are the main topics of investigation in this project 1 2 Project Scope The Wireless Power Monitor designed in this project serves to overcome the limitations of traditional methods of remote wireless power measurement by providing a long range wireless link between the point of measurement and the user interface The completed device is deigned to be completely standalone requiring no additional infrastructure or support for its operation 1 3 Project Objectives The goal for this project is to develop a long range gt 1500m line of sight gt 500m Light Urban gt 250m heavy urban wireless power monitoring system The Wireless Power Monitor must have the ability to be deployed for use in a wide variety of applications either for power consumption measurement or for power generation measurement Examples of applications for power generation measurement include Murdoch University s renewable energy major for remotely monitoring photovoltaic PV or wind turbine power generation Further to this the Wireless Power Monitor system must be open source which will allow it to be used as a starting point for power measurement projects for students in Power Industrial Computer Systems and Renewable Energy engineering disciplines The requirements for the Wireless Power Monitor are listed in Table 2 Component Requirements Current Measurement 1
35. antity of power consumed and applicable tariff for the time of the day The default values that are pre loaded into the PICAXE microcontroller are given in Table 24 Tariff per kWh Time On Peak 20 7 7 00 21 00 Off Peak 14 0c 21 00 7 00 Table 24 Peak amp Peak Settings The default values given in Table 24 correspond to the weekend all year around tariffs and peak off peak times provided by the local power utility Synergy and are correct as of October 2012 Synergy 2012 The tariffs on peak and off peak times can be altered by the user through the tariff menu shown in Figure 27 The user defined settings are preserved in the PICAXE EEPROM until the Base Station is reset at which point they will revert back to default values Feak Of f Pe 21 E A 1 Figure 27 Tariff Settings The usage costs are determined by calculation of the power consumption multiplied by the applicable tariff dependent on whether usage occurs during peak or off peak times As shown in Figure 28 the realtime past 24 hour and total usage costs are displayed The total usage cost will accumulate until the base unit is reset Figure 28 Usage Costs 44 Page In the event that the Wireless Power Monitor is being used to measure generated power as opposed to consumed power the tariffs at which the power is sold back to the electrical utility can be entered This results in the usage costs instead being able t
36. crocontroller hardware requirements for the Base Station are listed in Table 6 14 Page Connected Device Hardware Requirement Notes USB Receive 1 Hardware Serial Input be substituted with SPI SDO Table 6 Base Station Microcontroller Hardware Requirements The final summary of microcontroller hardware requirements are given in Table 7 Item 1 1 Hardware Serial Input Hardware Serial Output 1x SCA Line 1x SDA Line Table 7 Base Station Microcontroller Hardware Requirement Totals 12 Bus Based upon the microcontroller hardware requirements the PICAXE 18M2 microcontroller was chosen for use in both the Measurement Node and the Base Station 2 2 PICAXE 18M2 Microcontroller The PICAXE 18M2 microcontroller was initially chosen for use in both the Base Station and Measurement Node as its specifications listed in Table 8 met the requirements listed in Table 5 The PICAXE 18M2 datasheet states that 2048 bytes of program memory should be sufficient for 1200 1800 lines of code which was deemed to be adequate for this project Revolution Education 2009 Feature PICAXE 18M2 Bi directional I O 13 ADC Channels 10 Program Memory bytes 2046 Expandable Memory No Processor Speed MHz 4 8 16 32 RAM bytes 512 Hardware Interrupt Pins 0 Support Yes Table 8 PICAXE 18M2 Microcontroller Specifications The pinouts for the 18M2 microcontrollers for the
37. d to give a broad cross section of the wireless range capabilities of the Wireless Power Monitor Table 25 summarises the goal and actual wireless communication distances for line of sight light urban and heavy urban conditions Environment Goal Distance m Actual Distance m Difference Goal Achieved Line of Sight 1500 1571 4 73 Yes Light Urban 500 986 97 2 Yes Heavy Urban 250 406 62 4 Yes Table 25 Wireless Range Testing Summary As expected the wireless communication range between the Base Station and the Measurement Node was reduced significantly by physical obstructions such as buildings However both the light urban and heavy urban wireless ranges were greater than expected This is likely due to geographical conditions along with solid obstructions such as buildings causing the signal to reflect diffract and scatter when it interacts with them This reflection diffraction and scattering results in multipath signal propagation which increases the overall non line of sight wireless range Dean 2010 Wireless ranges in other light urban and heavy urban environments are likely to vary from those recorded depending on specific geographical and environmental conditions While the wireless communication distances achieved for the light urban and heavy urban scenarios exceed the goal distances obstacles such as hills foliage double glazed windows or heavy rain 150mm hr may also affect total range in different locations M
38. d up and is not altered during the main program execution 5 2 2 ADC Measurement Providing that the Base Station is reachable the Measurement Node reads the voltage and current from each phase along with the temperature The current and voltage waveforms are sampled 1024 times per period and the temperature is sampled once This raw data is then passed to the arithmetic co processor in order to calculate the RMS voltage RMS current apparent power real power and power factor 45 Page 5 2 3 uM FPU V2x Arithmetic Co processor The MicroMega uM FPU V2x arithmetic co processor operates using instructions sent from a microcontroller over the 12 bus Micromega Corporation 2006 Once the raw data has been obtained from voltage current and temperature inputs it is sent along with instructions from the PICAXE microcontroller to the uM FPU for calculation The instructions are executed to make the calculations based upon the data and upon completion the uM FPU returns the results to the PICAXE microcontroller via the bus These final calculated values are lastly transmitted from the Measurement Node to the Base Station via the XBee wireless module 5 3 Support Programs A number of support programs have been written to assist in programming testing or troubleshooting individual components included in the Wireless Power Monitor Support programs for the real time clock RTC graphical liquid crystal display GLCD and iButton module have
39. e 31 Table 24 Peak amp Off Peak 5 5 enne 44 Table 25 Wireless Range Testing 52 9 Page iii Glossary AC ACMA ADC ASCII CSMA CA CT DAQ DIP DSSS EEPROM GLCD GLIC GPO 1 0 IC IEEE LIPD 05 LR WPANs NLoS PF PV PWM RAM RF RMS ROM RSSI RTC Rx SCADA SCK SCL SDA SDI SDO TTL Tx UART USB WLAN WPM Alternating Current Australian Communication and Media Authority Analogue to Digital Converter American Standard Code for Information Exchange Carrier Sense Multiple Access Collision Avoidance Current Transformer Data Acquisition System Dual Inline Package Direct Sequence Spread Spectrum Electrically Erasable Programmable Read Only Memory Graphical Liquid Crystal Display Graphical LCD Interpreter Chip General Purpose Outlet Input Output Integrated Circuit Institute of Electrical and Electronics Engineers Low Interference Potential Device Line of Sight Low Rate Wireless Personal Area Networks Non Line of Sight Power Factor Photovoltaic Pulse Width Modulation Random Access Memory Radio Frequency Root Mean Squared Read Only Memory Received Signal Strength Indicator Real Time Clock Receiver Supervisory Control And Data Acquisition Serial Clock Serial Clock Line Serial Data Line Serial Data In
40. e actual current and voltage and the current and voltage measured by the Wireless Power Monitor would then be able to be used to determine the accuracy In contrast the actual tests were performed using power from the local power utility which may be subject to harmonics may not be operating at exactly 50Hz or may have 56 Page non sinusoidal waveforms Each of these conditions will lead to an inaccuracy in results and as such the accuracy results obtained for the Wireless Power Monitor must be treated as approximations until more thorough testing is completed 57 Page 7 0 Future Work At the completion of the project the Wireless Power Monitor is capable of being deployed as a working prototype for voltage current power and power factor monitoring and logging duties However the system has the capability to be expanded or adapted either to increase functionality or to be custom fitted to a specific application 7 1 Control The Wireless Power Monitor has been designed with additional I O on both the Base Station and the Measurement Node With only minor additions to the existing PICAXE microcontroller programs the extra I O can be utilised in a number of ways including alarming switching or additional sensor input Adding high or low thresholds for voltage current power power factor or temperature into the present PICAXE microcontroller code will allow the user to trigger alarms via the unused I O Alternatively with additiona
41. e could be designed which allows SCADA monitoring and control of the Wireless Power Monitor This affords not only for a remote link between the Base Station and Measurement Node but also the possibility of a remote link between the user and the Base Station 7 4 Inductive Charging In order to extend the battery life of the Measurement Node the possibility of utilising the CTs which are employed as current measuring devices to also provide charge to the battery could be investigated The CTs have a measurement duty cycle of less than 1 and as such the remaining 99 could be used to parasitically draw power from the measurement source to charge the battery Rather than using the burden resistor which is used to provide the voltage input signal to the microcontroller from the CT a secondary burden resistor which is capable of being switched either electronically or by an electromechanical relay could be employed to provides a suitable voltage output 58 Page to charge the on board battery Only minor modification to the existing Measurement Node program would be required to facilitate this 7 5 Carbon Emission Calculation Over the past decade there has been an increasing emphasis on individuals monitoring the carbon emissions as a result of consuming electrical power from fossil fuelled generation By utilising carbon emission information supplied by the users local power utility a function could be added to the Wireless Power Monitor whic
42. gle com maps 62 Page 10 0 Appendices 001 Program 002 GLCD Data Store Program 003 iButton Serial Number Read Program 004 Wireless Power Monitor Photographs 63 Page
43. h allows information to be displayed about the total carbon emissions produced as a result of the energy that has been consumed By tracking realtime and historical usage the user will be able to view their carbon footprint and monitor any effects of a change in power usage behaviour 59 Page 8 0 Summary At the completion of the project all major objectives of the project have been met or surpassed The Wireless Power Monitor achieved all long range wireless requirements set out in the project overview The line of sight wireless range goal of 1500m was met and the measured light urban and heavy urban environment wireless ranges achieved were significantly greater than expected at 986m and 406m respectively Accuracy of both the voltage and current measurements were calculated and found to be within the 5 0 limits set at the commencement of the project Due to time constraints and a limitation on available test equipment only a preliminary study of the accuracy was performed Given a longer timeframe a more comprehensive range of tests would preferably have been undertaken across a wider range This would provide a more complete overview of the accuracy of the Wireless Power Monitor Measured current and voltage readings along with calculated apparent power power factor and temperature are capable of being displayed on the Base Stations GLCD In addition to this power usage is also able to be viewed graphically via the usage graphs Dat
44. hat for the voltage and current accuracy testing a number of assumptions and concessions are made These are discussed in section 6 3 3 of the report 6 3 1 Voltage Accuracy Testing Voltage measurements were taken and logged on both the Wireless Power Monitor and the Fluke 287 meter The results can be seen in Figure 39 Wireless Power Monitor Accuracy Test Fluke 287 True RMS Meter gt 00 gt gt 22 Wireless Power Monitor 8 9 10 11 12 13 14 15 Sample Number Figure 39 Fluke 287 vs Wireless Power Monitor Voltage Test The six sigma method was chosen to determine accuracy as it provides a 99 9999966 statistical chance of a given measurement falling within this range iSixSigma 2012 The standard deviation of the difference between the voltage measurements made by the Fluke 287 meter and the Wireless Power Monitor was calculated to be 0 5949 Thus the six sigma value is 0 5949 x 6 3 5694 14 The average voltage as measured by the Fluke 287 multimeter was 229 96V Dividing the six sigma value by the voltage 3 5694 229 96 x 100 1 552 15 And thus the voltage accuracy of the Wireless Power Monitor is 1 552 55 Page 6 3 2 Current Accuracy Testing The accuracy of the current measurements was performed in a similar manner Simultaneous measurements were taken with the Wireless Power Monitor and the Fluke 287 True RMS meter and logged as seen in Figure 40 Wireless Power M
45. ial output which is required by output devices such as the XBee module and GLCD display Further to this a number of the port pins on the PICAXE had been designated as inputs rather than outputs necessitating the removal of the Darlington driver IC The zero ohm jumpers can be seen on the AXE118 board in Figure 3 E a m m 4 z v E 2x WWW PICAXE CO Figure 3 AXE118 Connectivity Board As a response to the electrical noise which was experienced upon the ADC channels 100uF and 0 1 uF decoupling capacitors were also added to the AXE118 board used for the Measurement Node to assist in supressing this interference Revolution Education 2012 Finally the AXE118 board also contains the required hardware to allow serial communication for programming the PICAXE microcontroller 2 9 Samsung KS108 Serial Graphic LCD Module The Wireless Power Monitor requires a display for the Base Station capable of primarily presenting the measured power from the Measurement Node preferably also displaying secondary measurements such as voltage current power factor and temperature Furthermore the display was required to allow the 23 Page operator to view usage graphs power usage costs and manipulate parameters the system such as tariffs voltage and toggling the USB logging Three LCD display modules sold by Revolution Education were considered for the project and their basic spec
46. ication Communication Symbol Symbol Base Station 29 Page 3 0 Communication A number of different communication technologies and protocols are used the Wireless Power Monitor project to facilitate data exchange between the various components Serial communications are used between the PICAXE microcontrollers and a number of peripheral devices such as the GLCD display iButton module and XBee microcontroller The Real Time Clock arithmetic co processor and external EEPROM memory ICs communicate with the PICAXE microprocessor via an 1 C bus while XBee to XBee communications are achieved by use of the IEEE 802 15 4 wireless protocol 3 1 Serial Communications Serial communication is the most widely utilised method of PICAXE to peripheral communication The PICAXE 20X2 microcontroller is capable of serial communications at baud rates ranging from 600bps up to 76800bps However the serial output baud rates available are a function of the microcontroller clock speed As both the Base Station and the Measurement node are clocked at 64MHz the lowest available baud rate is 9600bps while the GLCD requires an input at a baud rate of 2400bps In order to facilitate 2400 bps serial communication for the GLCD while maintaining the faster clock speed for overall system performance the main processor clock speed is reduced to 16MHz when 2400bps communications are required The process for this is covered in greater depth in section 5 1 1 of th
47. ifications are listed in Table 19 Module Lines of Text Resolution Graphical Communication Functions AXE133Y 2 128x16 No 1 Line Serial AXE134Y 4 128x32 No 1 Line Serial LED042 8 128x64 Yes 1 Line Serial Table 19 LCD Display Comparison Revolution Education 2012 Each LCD module requires an LCD interpreter chip with a fixed instruction set to drive the display All three modules considered include the required LCD driver The LED042 Graphical LCD GLCD display was ultimately chosen due to its ability to perform graphical display functions whereas the AXE133Y and AXE134Y are capable of displaying text only 2 10 FGC K1 Graphical LCD Interpreter Chip Board GLIC Serial commands sent from the Base Station s microcontroller cannot directly drive the Samsung GLCD module For this reason a graphical LCD interpreter chip GLIC board produced by FGC is use to convert the serial commands into the instructions required to drive the GLCD display FGC 2011 The GLIC board also contains required circuitry to control screen brightness contrast and includes a 512kB EEPROM IC which has been used to store the majority of text strings that the Base Station requires to be displayed The method and reasoning for storing text strings externally to the main Base Station microcontroller are discussed further in section 5 3 2 Figure 4 FGC K1 Graphical LCD Interpreter Chip Board 2 11 VDrive2 USB Module In order to
48. implement data logging capabilities in the Wireless Power Monitor a removable storage media recording device was required The storage medium chosen for the logging duties was USB Flash due to the low device cost ready availability and the ability to be read with any modern PC The protocols required to read or write to a USB Flash drive are complicated and would consume much of the program memory of the Base Station s microcontroller For this reason a VDrive2 USB module was selected to perform the USB logging duties Future Technology Devices International 2007 The VDrive2 24 Page USB module uses an embedded USB host controller which handles all required data transfer functions making it a stand alone USB logging device Instructions are sent via serial communication from the Base Station s microcontroller to the VDrive2 to perform functions such as creating reading writing and closing files on the USB storage media The data to be logged such as the time of day and the date from the real time clock RTC power usage and temperature are all sent as a string of byte variables Figure 5 Vinculum VDrive2 USB Module A 2GB USB Flash storage device is capable of storing 2 5 years worth of data from the Measurement Node based upon a refresh rate of 1Hz 2 12 AXE109 iButton Module Board An iButton is a robust device which stores a unique 64 bit electronic serial number which is used for identification upon an on board read
49. inimum doze time for the microcontroller of 2 1 seconds with a tolerance of 5096 100 signifying that actual doze time could be between 1 05 and 4 2 seconds Revolution Education 2012 Dozing the microcontroller for these lengths of time is not a viable option in the Wireless Power Monitor as it would result in significant lag in updating and logging power usage As such the doze function was not implemented in the final program 6 3 Wireless Power Monitor Accuracy Testing The accuracy of the Wireless Power Monitor is dependent upon the accuracy of the voltage and current measurements taken at the Measurement Node In order to determine the accuracy of each a Fluke 287 True RMS meter with an accuracy of 0 02596 was used to measure current and voltage values for comparison against those of the Wireless Power Meter Fluke Corporation 2008 Both the voltage and current are measured via a 10 bit ADC input on the PICAXE microcontroller on the Wireless Power Monitor giving a total of 1024 unique voltage values Thus the maximum accuracy as a result of the 10 bit resolution of the ADC is 54 Page 0 1121 0 09766 13 Given that the accuracy from the 10 bit ADC of the microprocessor alone is approximately 4 times less than that of the Fluke 287 meter the Fluke 287 meter was be considered to be absolutely accurate and used as a reference point for the purposes of testing the voltage and current of the Wireless Power Meter Note t
50. is report The PICAXE microcontroller is capable of serial communications with either true output idle high or inverted output idle low with an output of 8 data bits no parity and 1 stop bit Revolution Education 2012 The serial communication specifications for devices used in this project are listed in Table 22 Device Serial Communication Baud Rate bps True Inverted XBee Module 9600 GLCD 2400 Button 9600 VDrive2 USB Module Table 22 Serial Communication Device Specifications Note that the VDrive2 USB module uses a dedicated universal asynchronous receiver transmitter UART hardware serial communication channel as opposed to the software serial channels employed by the other devices 3 2 Communication Bus The 2 bus is a bi directional 2 wire bus system developed by Philips Semiconductors to allow for simple effectual inter Integrated Circuit IC communications NXP 2012 The bus requires only two serial lines a serial clock line SCL and a serial data line SDA and can operate at 100kbit s or 400kbit s in Standard mode and Fast mode respectively Although the 12 bus protocol supports speeds of 1Mbit s 3 4Mbit s and 5Mbit s the PICAXE family of microcontrollers used in this project are capable of supporting only Standard and Fast modes Using the bus in place of a serial I O on the PICAXE microcontroller is advantageous as up to 8 identical devices or 144 different devices can be connected
51. isplay area the Y axis is not scaled The result is that the usage graphs are best suited to view overall trends as opposed to exact data The exact power measured is however logged out to the USB Flash device and can be viewed in the LOG csv file Past Hour Figure 25 Past Hour Usage Graph 5 1 5 Voltage Setting The voltage setting is used to provide a user defined voltage for the power measurement This is used in a situation where it may be impractical or impossible to use the AC AC voltage transformer such as a location with no access to a general purpose outlet GPO The Base Station automatically chooses between the measured voltage and the user defined voltage for the power measurement as per the flowchart below in Figure 26 Measurement Voltage gt 0 Current gt 0 Zero Voltage Use Measured Select User Voltage Defined Voltage Figure 26 Voltage Selection Flowchart If the measured voltage on a given phase is greater than zero volts it will be used in the power calculations However if the voltage measurement is zero and there is a current measurement greater 43 than on the phase being measured the user defined voltage is selected Finally a zero voltage and zero current condition will result in zero voltage value being selected 5 1 6 Tariffs amp Usage Costs The wireless power monitor is capable of calculating the cost of the power consumed based upon the qu
52. ities of the PICAXE microcontroller proved to be insufficient To address this shortcoming a MicroMega FPU V2x arithmetic co processor was added to the measurement nodes This co processor is capable of 32 bit floating point operations along with mathematic functions such as power and root operations MicroMega Coporation 2005 The co processor communicates with the PICAXE microcontroller over the 2 communication bus resulting in no additional I O being required for its implementation Figure 7 MicroMega FPU V2x Arithmetic Co Processor 26 Page 2 15 1702 500 amp 300 Low Dropout Voltage Regulators 3 cell 4 5V power supplies were initially chosen for both the Base Station and the Measurement Node However these were found to be inadequate upon addition of the uM FPU arithmetic co processor as it requires a supply voltage of 5 0V The co processor was tested at lower voltages to determine if it could be operated on the existing 4 5V supply However performance was found to be unreliable below 4 75 As a result a switch was made from a 3 cell 4 5V power supply to a 4 cell 6 0V supply An MCP1702 500 low dropout voltage regulator was added to supply a regulated 5 0V to the PICAXE and uM FPU co processor Microchip Technology 2005 A low dropout regulator was necessary as a standard regulator such as an LM7805 requires a supply voltage greater than 2 0V above its output voltage In contrast the MCP1702 regulator is capab
53. ive Table 9 18 2 Base Station Microcontroller Pinout Table Functions Pin Designation Notes SRI Out In 0 i2c sda Touch ADC Out In B 1 SDA Bus 4 7k Pull Up Bus Resistor Required hserin Touch ADC Out In B 2 Temperature Sensor 4 7k Pull Up Resistor Required pwm Touch ADC Out In B 3 Phase A Voltage Input In Out ADC Touch i2c scl B 4 SCL Bus 4 7k Pull Up Bus Resistor Required In Out ADC Touch hserout B 5 Phase A Current Input In Out ADC Touch pwm B 6 Phase B Voltage Input In Out ADC Touch B 7 XBee Transmit In Out ADC Touch 0 Phase C Voltage Input In Out ADC Touch C 1 Phase B Current Input DAC Touch ADC Out In C 2 Phase C Current Input SQR Out Serial XBee Sleep In Serial In C 4 In C 5 In Out kb clock C 6 In Out kb data C 7 XBee Receive Table 10 18 2 Measurement Node Microcontroller Pinout Table However approximately a third of the way into the project it became apparent that the 2048 bytes of program memory would not be sufficient due to a combination of large number of serial in serial out commands and text strings which consume large amounts of program memory As a result the program had reached the program capacity of 2048 bytes after only approximate
54. l hardware and modification to the Wireless Power Monitors software the unused I O can be used for conditional switching of loads based upon the measured parameters or time of day The spare could furthermore be used to monitor and log additional inputs specific to a given application 7 2 Multiple Measurement Nodes The Wireless Power Monitor has been set up with the XBee Pro modules operating in broadcast point to multi point mode Digi International 2012 In broadcast mode each XBee module sends data to all other XBee modules on the same channel The result of designing the Wireless Power Monitor around XBee modules operating in broadcast mode is that additional measurement nodes can be easily added to the existing network In addition to increasing the number of measurement nodes on the system to allow a greater number of channels to be monitored additional channels could be used to create a robust multi point wireless network which is supported by the XBee hardware This would give the major benefit of increasing the wireless range of the system as data could be passed from a measurement node which is out of range of the Base Station to another measurement node which is in range which in turn is capable of forwarding on the data to the Base Station 7 3 SCADA Monitoring XBee modules are capable of serial communication with a PC either via serial cable or wirelessly with an 802 15 4 adapter Using either method a simple PC interfac
55. l was additionally designed to set the standard for low power very low cost wireless communications XBee Pro modules using the 802 15 4 protocol were chosen due to 802 15 4s noise resistance interference resistance and low power consumption characteristics The 802 15 4 protocol uses direct sequence spread spectrum DSSS which results in less interference and enhances the signal to noise ratio SNR in the receiver Sensor Networks 2012 The transceiver also utilises carrier sense multiple access collision avoidance CSMA CA which is a process whereby the transceiver examines the medium before transmitting If an 802 15 4 transmission is occurring upon the same channel that it is attempting to transmit on the transceiver will pause for a random time and then recheck the channel sending data only when the channel is free Finally the 802 15 4 protocol was designed to work with low duty cycles allowing the transceivers to be placed into sleep mode when not transmitting or receiving resulting in low power consumption 31 Page 4 0 Circuit Design In order to determine the real power apparent power and power factor both the voltage and current are required to be measured The output of both the AC AC voltage transformer and the current transformer CT chosen for use in this project require conditioning in order to provide the PICAXE microcontroller with an input of the correct amplitude and range 4 1 Voltage Measurement In order to pr
56. le of providing a regulated 5V output from a supply as low as 625mV above the output voltage 2 16 DS18D20 A DS18B20 Maxium temperature sensor is used to provide the temperature measurement for the Wireless Power Monitor It is capable of one wire communications and offers temperature measurement with accuracy of 0 5 between 10 and 85 C Maxim 2008 2 17 Keypad Interface In order to provide the user with an interface to view and manipulate settings a simple push button keypad was used In order to consume a minimal number of microcontroller inputs only four buttons were used scroll up scroll down enter and back Figure 8 Keypad Interface Layout The use of soft keys whereby the task of the button changes depending on the function that the operator is using was also investigated Lindholm et al 2003 However the soft key option was ultimately rejected as it consumed additional program memory and required a minimum of one text display line of the GLCD to be permanently dedicated to show the soft key options which reduced the usable display area for other features 2 18 XBee Pro Wireless Module A major goal of the project was to achieve long range wireless communications between the Base Station and Measurement Node A line of sight LoS range of at least 1500m was required along with ranges of 27 Page 500m light urban environment and 250m heavy urban environment wireless modules listed in Table 2
57. ly 500 lines of code well short of the claimed 1200 1800 line capacity Revolution Education 2009 As program memory cannot be 16 Page expanded on the 18M2 microcontroller the only available option was to upgrade to processor with a larger program memory 2 3 PICAXE 20X2 Microcontroller The limitations with program memory space encountered with the PICAXE 18M2 led to their replacement in the Base Station and the Measurement Node with PICAXE 20X2 microcontrollers The 20X2 features twice the on board program memory space of the 18M2 with the ability to add up to 32 additional slots of 4096 byte program memory via connected EEPROM This provides the 20X2 with up to 64 times the program memory capacity of the 18M2 microcontroller Supplementing this the 20X2 microcontroller contains additional and ADC channels two hardware interrupts and a faster maximum processor clock speed The full list of features for the 20X2 is listed in Table 11 Feature PICAXE 20X2 Bi directional I O 15 ADC Channels 11 Program Memory bytes 4096 Expandable Memory Yes up to 32 additional slots at 4096 bytes each Processor Speed MHz 4 8 16 32 64 RAM bytes 256 Hardware Interrupt Pins 2 Support Yes Table 11 PICAXE 20X2 Microcontroller Specifications However a drawback in upgrading the 18M2 microcontroller with the 20X2 was their different form factors The 18M2 microcontroller has a
58. n the voltage divider ratio would need to provide a peak to peak value of 5 0V given by the equation below S 7 sos However AC AC transformers typically exhibit poor voltage regulation when unloaded or very lightly loaded as in the case in the project The actual measured peak to peak voltage was measured and the oscilloscope output can be seen below in Figure 12 32 Page Pos 0 0005 Figure 12 AC Voltage Transformer Output Figure 12 shows that the actual peak to peak voltage of the unloaded AC AC transformer is 33 6V This results in the equation becoming Thus a voltage divider ratio of 6 27 1 will reduce the 33 6 peak to peak transformer voltage to 5 0 peak to peak for a 230V RMS 325V peak to peak input Regardless of the observed poor regulation characteristics of the lightly loaded AC AC transformer it is still suitable for use as a voltage measurement device in this project The load presented by the voltage measurement circuit while slight is constant As a result the output voltage from the transformer while higher than the rated 9V RMS is also constant By allowing for the higher than rated voltage output with the adjusted voltage divider ratio calculated in equation 3 the effect of poor regulation becomes inconsequential The allowable tolerance in Australian mains voltage is 230V RMS 10 6 Standards Australia 2000 By including an additional 20 to the voltage divider rati
59. ns 15 Table 9 18M2 Base Station Microcontroller Pinout Table eese nennen 16 Table 10 18M2 Measurement Node Microcontroller Pinout Table 16 Table 11 PICAXE 20X2 Microcontroller Specifications 17 Table 12 20X2 Base Station Microcontroller Pinout Table eese 18 Table 13 20X2 Measurement Node Microcontroller Pinout Table 18 Table 14 PICAXE 08 2 Microcontroller Specifications 19 Table 15 Current Measurement Method Comparison nennen nnne nennen nnn nnns 21 Table 16 CT Sensor Ratings Steplight 2012 nnn nnns nnn nnn 22 Table 17 AXE118 AXE210 Base Station Connectivity enne nnns 23 Table 18 AXE118 AXE210 Measurement Node Connectivity ccccccccccesscccssscecsseceessecsseeecsaeeeesecesseeeeas 23 Table 19 LCD Display Comparison Revolution Education 2012 24 Table 20 Wireless Module 1 nennen 28 Table 21 AMCA Specifications ener nenas nnne 28 Table 22 Serial Communication Device Specifications nnne nnns 30 Table 23 Device Specification Tabl
60. o mains voltage of up to 276V RMS 390V peak to peak will be able to be read by the PICAXE microcontroller Therefore the final voltage divider ratio becomes 1 1 x 120 6 72 8 064 4 Finally to create a voltage divider ratio of 1 8 064 using R4 10k 10000 10000 9064 33 Page VR2 70 64 0 6 A variable resistor VR2 was chosen to allow the voltage measurement to be altered between range resolution by altering the voltage divider ratio Higher voltage values can be read by increasing the value of VR2 at the expense of resolution and vice versa The PICAXE microcontroller s ADC requires an input between the OV negative reference and 5 0V positive reference In order to allow analogue to digital conversion of the AC voltage waveform DC offset is applied to the signal This is achieved by use of a voltage divider comprised of R1 and R2 seen in Figure 11 using the PICAXE s 5 0V regulated supply as a reference voltage The resulting 2 5V is used to provide positive DC offset to the AC voltage signal The final scaled AC voltage signal with DC offset CH2 which is provided to the PICAXE microcontroller is shown below in Figure 13 superimposed upon the 9V RMS transformer s output CH1 Note that the maximum and minimum voltage values are actually 500mV and 4 50V respectively the oscilloscope used has a resolution of 200mV per step when set to 5 00V per division resulting
61. o achieve an acceptable wireless range its EIRP exceeded the AMCA limit and it was therefore too rejected Despite lower data throughput than other modules the XBee Pro 900 module was initially selected due to its long range capabilities However upon review it was found that the AMCA had brought spectrum embargo 64 into effect in December 2011 which applied to all new apparatus licenses for devices operating within the 803 960 MHz band AMCA 2011 The embargo prevents new licenses for devices operating within the specified frequency band from being issued and limits the renewal for existing licenses to one year Due to the existing and potential future complications of the embargo the XBee Pro 802 15 4 module was instead selected for the project Despite the maximum LoS range of the XBee Pro 802 15 4 module being less than that of the XBee Pro 900 it still exceeded the goal of 1500m and had the advantage of much higher data throughput Digi internation XBee PRO 51 a Figure 9 802 15 4 Wireless Module 28 Page The final block diagram showing hardware configuration and communication methods between the microcontroller and the peripheral devices can be seen in Figure 10 2400bps Serial 802 15 4 Protocol D 2 D 5 22 169 gt 2 9600bps Serial ADC Input Digital Input Commun
62. o be used to display the income from generation 5 1 7 USB Flash Logging The USB logging can be toggled on or off through the Settings gt USB Logging option USB logging is default off when the unit is first powered up and must be switched on to initiate logging The USB flash module will continue to log the measurements until either the user switches the USB logging option off or until the Base Station is reset Logging out of the Base Station will preserve the current on or off state of the USB logging USE Logging Figure 29 USB Logging On Off Option 5 2 Measurement Node The Measurement Node is responsible for taking current voltage and temperature measurements from the source to be monitored The Measurement Node polls the Base Station prior to performing any measurements If the Base Station is unreachable due to it being out of range or unpowered the Measurement Node enters a sleep mode and retries contacting the Base Station 1000ms later This feature is to prevent the Measurement Node from taking readings if the base station is not capable of receiving them which would unnecessarily waste battery power 5 2 1 Microcontroller Clock Speed In contrast to the Base Station no 2400bps serial communications are required on the Measurement Node Accordingly the microcontroller clock speed is set to 64MHz as part of the initialisation code that executes once at the start of the program when the microcontroller is powere
63. onitor Accuracy Test Fluke 287 True RMS Meter MNT 5 X m w pas Wireless Power Monitor 7 8 9 1C 11 12 Sample Number 14 15 16 17 18 19 Figure 40 Fluke 287 vs Wireless Power Meter Current Test The standard deviation between the Fluke 287 meter and the Wireless Power Monitor current readings was calculated to be 0 01604 Thus the six sigma is 0 01604 x 6 0 09624 16 The average current as measured by the Fluke 287 meter was 2 049A Dividing the six sigma value by the voltage 0 09624 x 4 2949 X 100 4 697 17 Thus the current accuracy of the wireless power monitor is 4 697 6 3 3 Voltage amp Current Testing Summary In both the voltage and current accuracy tests number of assumptions were made due to time and test equipment limitations Firstly the Fluke 287 meter was assumed to be 100 accurate Secondly the average of the current and voltage measured by the Fluke 287 meter was used as the reference value for the final determination of the Wireless Power Meters accuracy The assumptions made while not unreasonable result in the accuracy figures which were obtained being approximate rather than exact In order to determine absolute accuracy of the Wireless Power Monitor laboratory grade equipment is required which is capable of providing current and voltage inputs to the Wireless Power Monitor of known amplitude and frequency The difference between th
64. only memory ROM device Maxim 2010 It is capable of communication through the 1 Wire protocol requiring only a data line and a ground return It is used in this project to allow a user to log on to the Base Station to permit viewing of usage and manipulation of parameters The AXE109 iButton module board is used as an interfacing device between a PICAXE 08 2 microcontroller and the iButton reader Revolution Education 2004 A modification was made to the board for this project by removing the pull down resistor and transistor intended to provide a high power output to for a device such as a solenoid door lock A jumper wire was then used to bypass the resistor and transistor connections linking the microcontroller output to the board output The removal of the transistor allows the microcontroller s output to be used as a serial communication output permitting serial data transfer between the AXE109 s PICAXE 08 2 and the Base Station s main 20X2 microcontroller This modification was essential as serial communications were required between the AXE109 and the Base Station s 20X2 microcontroller as opposed a simple digital high low signal 2 13 i2C Real Time Clock RTC Board Functions such as time stamping logged power usage and calculating peak and off peak power usage require the implementation of an accurate timekeeping device A real time clock RTC module which is capable of 2 wire communication with the PICAXE microcont
65. otorola 2007 6 2 Power Consumption Testing Battery life of both the Base Station and the Measurement Node were taken into account as the devices do not have access to external power The Base Station and Measurement Node are both powered by four 1 5V Energizer Lithium FR6 cells Energizer 2011 These cells have a capacity of 3100mAh at a discharge rate of 250mA based upon a discharge to 1 0V To determine theoretical battery life the voltage and current draw were measured and the power consumption calculated The voltage at the Measurement Node was taken by measuring the battery supply voltage while the current was measured by placing a 1 ohm shunt resistor in series with the battery supply A shunt of 1 ohm provides a voltage drop of 1mV per mA which be viewed upon oscilloscope Figure 37 shows the current draw CH1 and the battery supply voltage CH2 The resulting power is given by the MATH function which produces a waveform based upon CH1 multiplied by CH2 52 Page Pos 0 0005 Figure 37 Standard Power Consumption The mean power usage is seen to be 565mV on the oscilliscope which corresponds to 565mW the mean current consumption is 108mA Given the 3100mAh capacity of the battery power supply the theoretical battery life is 3100 308 28 70 hours 11 In an attempt to decrease the mean power use the program was modified to force the XBee module into a low power doze mode when no data wa
66. ovide galvanic isolation between the supply and the Wireless Power Monitor an AC AC transformer is used which in addition to providing isolation also reduces the 230V AC RMS mains voltage to 9V AC RMS As the PICAXE microcontroller uses its 5 0V DC supply voltage as the analogue to digital converter ADC positive reference and OV as the negative reference the AC transformer output requires conditioning to reduce the 9V RMS waveform to a 5 0V peak to peak waveform As the PICAXE microcontroller s ADC cannot measure negative voltage DC offset is also required to bias the voltage waveform such that the lowest value is equal to or greater than the zero reference of OV The interfacing circuit designed to provide a measureable voltage from the 9V AC AC transformer for the PICAXE microcontroller is given below in Figure 11 To 5 04 2078 81 2300 Mains PICAXE GND To PICAXE ADC Figure 11 Voltage Measurement Interfacing Circuit Resistors VR2 and R4 provide a voltage divider with a variable ratio in order to reduce the voltage supplied by the AC transformer to a level which can be read by the PICAXE microcontroller s ADC The transformer has an output of 9V RMS which has a peak to peak value given by 9 x V2 x 2 25 46 1 The PICAXE microcontroller requires an analogue input voltage with a peak value no greater than the ADCs positive reference voltage This would indicate that in order to obtain maximum resolutio
67. roller via the bus was chosen for these purposes DFRobot 2012 25 Page Gnd Vcc ps Scl Ds Gy ting 2 ia 071702 MST 16 lt 27 Ri R8 R5 Bat Gnd 5 5 1 Ds SQ e U2 TES 10 Ul 9 f 3 gt D 4 e Figure 6 RTC Module The RTC module uses a DS1307 RTC IC capable of counting seconds minutes hours date month day of the week year and includes leap year compensation up to the year 2100 Dallas Semiconductor 2008 In addition to this the module contains all required ancillary hardware such as a crystal oscillator voltage regulator and backup battery A CR1225 41mAh lithium backup battery included in the RTC module is used to maintain the time and date settings when the device is not externally powered The standby time when running on battery power is a minimum of 9 years with 17 years being typical DFRobot 2012 It must be noted however a CR1225 lithium battery has a typical shelf life of approximately 10 years 2 14 uM FPU V2x Arithmetic Co Processor The PICAXE family of microcontrollers have the ability to perform only 16 bit unsigned integer mathematics Due to the more complex mathematics required to calculate and display the RMS voltage RMS current real power apparent power and power factor the on board mathematic capabil
68. s required to be transmitted or recieved Subsequently when data is required to be transmitted or received the XBee module is given an undoze command proceeded by a breif pause to allow the module to wake up In addition to this the brown out detection was disabled and the unused ADC channels were deactived in the special function register to further reduce power consumption The result as seen in Figure 38 is a decrease in mean current from 108mA to 65mA and a corresponding decrease in power consumption from 565mW to 338mW 53 Page Figure 38 Power Consumption with Doze Function With these power saving functions implemented the theoretical battery life becomes 3100 6g 47 68 hours 12 Thus the theoretical battery life has been prolonged from 28 70 hours to 47 68 hours an increase of 66 196 Testing was also performed to examine the effect of reducing the clock speed of the PICAXE microcontroller to reduce power consumption However reduced clock speed lead to reduced performance and resulted in an increase in battery life less than 0 596 Due to the low additional power saving and the degradation in performance a reduced clock speed has not been implemented into the final program The final method investigated to increase battery life was by implementing a doze instruction within the program to force the microcontroller to enter a low power mode when program execution was not necessary However the doze feature has a m
69. sumption of devices or power generation from sources such as photovoltaic cells or wind turbines In the example of power consumption usage costs are calculated from user defined tariffs Conversely for generation the income from power generated is calculated At the completion of this project the Wireless Power Monitor is capable of being deployed for use as a fully working prototype In addition to this the system provides a solid basis for future adaptation or expansion and due to its open source software can be easily modified for use in specific applications 3 Page Acknowledgements For their assistance and support throughout this project acknowledgement is given to Dr Gareth Lee Murdoch University School of Engineering and Energy Christopher Holloway Proteus EPCM Engineers Luke Morrison Rio Tinto Australia 4 Page Table of Contents i Table Of 8 5 aeea e E E 9 GIOSSANY mm 10 11 151 5 5 01 5 11 1 2 Project SCOPE nicer oca Mte rocas 20 eiue saa exec i a s eode deg 12 1 3 Project Objective S 2 2 12 2 0 14 2 1 EE 14 2 2 18M2 15 2
70. t In C 5 In C 6 ADC3 Out In C 7 XBee Receive Phase B Voltage Input Table 13 20X2 Measurement Node Microcontroller Pinout Table 18 Page implemented primarily for one off functions such as storing authorised iButton serial numbers controlling the iButton login and initialising the GLCD screen at start up As seen in Table 14 the PICAXE 08 2 has significantly less I O than the 18M2 or 20X2 microcontrollers though maintains the same program memory capacity Feature PICAXE 08M2 Bi directional I O 3 ADC Channels 3 Program Memory bytes 2048 Expandable Memory No RAM bytes 128 12 Support Yes Table 14 PICAXE 08M2 Microcontroller Specifications The PICAXE 08M2 microcontroller was not removed when the main 18M2 microcontroller was upgraded to the 20X2 Instead it was interfaced with the 20X2 and allowed to maintain its previous duties as it aided in reducing the processing load on the main processor 2 5 Voltage Measurement An AC AC transformer was chosen to perform voltage measurement duties AC AC transformers have the benefit of providing galvanic isolation as there is no physical connection between the primary and secondary coils In addition to this the AC AC transformer steps down the 230VAC RMS mains supply voltage to 9VAC which with further conditioning as discussed in section 4 1 is suitable to be utilised by the PICAXE microcontroller for voltage measurement
71. ting power measurement infrastructure The second method of remote power monitoring is by implementation of a wireless link between measurement nodes and a centralised base station Systems such as these are often used for temporary installations due to their portability and simplicity as they require no additional infrastructure to implement However the vast majority of commercially produced wireless power monitors typically have a wireless range between 30 70m making them unsuitable for large or remote installations Rockwell 2012 Clipsal 2003 Doss 2011 Ecotouch 2012 Owl 2012 Watts Clever 2011 Wattson 2012 Table 1 lists a number of commercially available wireless power monitors from various manufacturers along with their capabilities Wireless Voltage Current Power LoS Wireless Single Three Model Frequency Range Range Range m Band RMS A kW PowerMonitor Allen 250 2 4GHz Yes Yes 0 300 e Bradley 1425 1002 Clipsal Cent A Meter 30 433MHz Yes Yes 110 250 71 0 17 75 0 02 0 0005 10 2 76 eFergy E2 Classic 70 433MHz Yes Yes 90 600 2 OWL Micro 30 433MHz Yes No 100 400 71 28 4 Watts 0 1 0 008 Clever EW4008 40 433MHz Yes Yes 80 265 100 26 5 Wattson Classic 100 433MHz Yes Yes 0 250 50 max 11 5 Table 1 Wireless Power Monitor Comparison Doss 30 433MHz Yes No 200 276 11 The lack of long r

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