Research and Design of Harmonic Measurement Instrument for High-Voltage Transmission Lines Based on Field Strength Method

Abstract

Along with the development of new energy technology, more and more power equipment such as inverters are used in power grids. The power injected into the grid by inverters contains a large number of harmonics, which seriously affects the quality of power emitted from public outlets. At present, inside the substation, voltage harmonics of high-voltage transmission lines can only be measured indirectly with the help of CVT/PT cabinets; outside the substation, the measurement of voltage harmonics of high-voltage lines is not possible due to the absence of CVT/PT cabinets installed. Therefore, a harmonic measuring instrument based on the field strength method is designed to detect the voltage harmonic content of the power grid more conveniently and accurately.The voltage harmonic signal is obtained directly through the field strength method principle, and the FFT technology is used to perform harmonic analysis on the collected grid voltage signal, and the isolation technology is used to make the measured voltage level between 10 kV and 220 kV. After the actual test, the measurement accuracy meets the B-level measurement accuracy stipulated by GB/T19862-2016 standard, which solves the problems of traditional measurement and improves the utilization of electric power transportation more.