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Darrin Marr Marcie Webb Brad Zarikoff

Digital Input Power Meter. Darrin Marr Marcie Webb Brad Zarikoff. Background Design and operation Progress and problems encountered. Introduction. To design a Power Meter that accepts a digital input. Project Goals. Reduce the redundancy in conventional technology.

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Darrin Marr Marcie Webb Brad Zarikoff

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  1. Digital Input Power Meter Darrin Marr Marcie Webb Brad Zarikoff

  2. Background Design and operation Progress and problems encountered Introduction

  3. To design a Power Meter that accepts a digital input Project Goals • Reduce the redundancy in conventional technology • Improve on Power Measurement for Utility Industry

  4. Power Meters are typically used in substations Current and voltage transducers feed power meters You cannot connect an oscilloscope to 138 000 volts Application Overview

  5. Conventional Technology IPP tap from utility breakers (Analogue Metering) Optical Current Electronics DAC, Amplifier Current Sensor Voltage Sensor Optical Voltage Electronics DAC, Amplifier NXVCT 120V analogue signal Analogue Meter - 0.2% accuracy over 2 – 3000A range Utility owned equipment IPP owned equipment 138 kV 13.8 kV Gas Turbine Generators 225 MVA 13.8 kV, 60 Hz Stn. Service Xfmr. 475 kW load

  6. Metering with Digital Input IPP tap from utility breakers (Digital Metering) Optical Current Electronics Current Sensor Merging Unit Voltage Sensor Optical Voltage Electronics NXVCT Meter with digital input Utility owned equipment IPP owned equipment 138 kV 13.8 kV Gas Turbine Generators 225 MVA 13.8 kV, 60 Hz Stn. Service Xfmr. 475 kW load

  7. Meters

  8. NxtPhase is a company that makes Voltage and Current Transducers NxtPhase uses optics to measure the line voltage or current Optical signal is transduced to voltage and digitized Dedicated to “Digitizing the Grid” Corporate Sponsorship

  9. NxtPhase does not make Power Meters Want to interface to next generation Digital Input Power Meters and Protection Relays Need to develop a Merging Unit to IEC 60044-8 standard Keeping NxtPhase Happy

  10. Current and voltage emulation Current and voltage data merging unit Receiving and data decoding unit Data display Digital Input Power Meter

  11. Digital Input Power Meter Layout

  12. Used to generate three-phase voltage and current received from NxtPhase equipment Simulates three voltage and current signals Output at NxtPhase proprietary data and sampling rate as TDM signal Sine Wave Generator

  13. Takes TDM data of six sinusoids and packetizes them into data stream for transmission Outputs packets at 2.5Mbps at 4.8kHz sampling rate Continuous packet output (no idle) Averages samples (NxtPhase sampling rate much faster than IEC standard) Merging Unit

  14. Packetized in accordance with IEC 60044-8 standard Packet standard incorporates three-phase metering, protection, and unit data, error control (CRC) Packet Standard

  15. Merging Unit

  16. Transmission along data line to allow for remote monitoring Buffer board decodes data packet and buffers data (0.2s worth) for burst transmission National Instrument DAQ card dumps data into file on PC to be used by meter display Buffer Board

  17. Visual Basic in Excel application Retrieves voltage and current data from data file every x seconds Formats and displays current and voltage information Calculates voltage and current spectrum, power factor, and RMS values Data Display

  18. Digital Interface Meter

  19. Verification stage at present All design and implementation complete Currently testing to ensure reliable operation Visit our demo on Friday in ELW Project Status

  20. No copy of Matlab for meter display development Would have been excellent tool for data display and manipulation Now using Visual Basic in Excel Limited mathematical capabilities Slow graphing capabilities Problems Encountered

  21. Original design included fiber optic link between Merging Unit and Digital Meter Researched options available Found inexpensive development kit Lack of time forced us to abandon testing and implementation Fiber optics used to avoid EMI Problems Encountered

  22. IEC 60044-8 standard includes CRC error detection code Uses three 16-bit CRC checks Possible to have better error detection with less CRC bits required One 32-bit CRC check would have better detection capabilities Error Detection

  23. Digital input power meter currently not available commercially NxtPhase has interest because need to connect PT’s to digital meters Realizable with more time NxtPhase will be able to use Merging Unit design as step towards useable product Conclusions

  24. Questions?

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