Frequency Analysis of Measured Transient Voltage of Neutral Grounding Reactor on UHV AC Transmission Line

In this paper, the frequency of measured transient voltage of neutral grounding reactor on UHV AC transmission line (abb.: neutral reactor) is analyzed. Firstly, the measurement method of transient voltage of neutral reactor is introduced. Then the measurement results are analyzed. When the no-load transmission line is put into power system, the transient voltage of neutral reactor contains two high frequency components. The component with lower frequency is determined by the zero-sequence voltage of the transmission line, and these oscillation frequency range is between 100 Hz and 250 Hz. The component with higher frequency is determined by the inductance value of the neutral reactor, and the corresponding relationship between the transient voltage frequency and power frequency impedances of the neutral reactor is obtained. When the no-load transmission line is cut off from power system, the transient voltage of neutral reactor contains only one frequency component, which is determined by the zero-sequence voltage of the transmission line, and these oscillation frequency distribution range is below 50 Hz. The measurement results will be useful for the UHV AC insulation coordination design, computer simulation model development, voltage measurement device development or other technical fields.