Current and voltage synchronous measurements using NI сRIO system with sigma-delta ADC NI 92хх and S.E.A. GPS modules

Yuri Grigorievich Kononov, Mikhail Aleksandrovich Ospishchev, Vyacheslav Yuryevich Rudnev

Abstract

The article describes one of the solutions for improving the accuracy of synchronized measurement for electrical grids using sigma-delta ADC measuring systems. Key problems and their solutions are analyzed. A description is given for the developed algorithm and its implementation in FPGA on National Instruments cRIO platform. The voltage and current measurements were conducted on the NI 9225 and NI 9227 modules respectively. Synchronization is provided by the PPS signal, which is generated by a S.E.A. 9472 GPS receiver module. The essence of the proposed method consists of clocking the NI 9225 and NI 9227 modules by created in the FPGA software clock generator at the frequency of 12.8 MHz. This generator is based on the internal 200 MHz FPGA clock and synchronized to UTC by a PPS signal. The accuracy of the synchronization was experimentally confirmed by measuring the voltage via two identical measuring systems and comparing the results.

Keywords

synchronous measurements, sigma-delta ADC, time skew, PPS, FPGA

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IMEKO-TC4-2014-194.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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