The UHV AC power transmission and transformation project needs power commissioning before it is officially put into operation. Measuring the overvoltage data on site is an effective method to master the overvoltage of important equipment during power commissioning, and the accuracy of electromagnetic transient calculation can be verified  based on the measured data, so as to provide support for subsequent operation state prediction through simulation.

The voltage signals on the secondary side of the voltage transformer and the capacitor voltage divider connected to the high-voltage side of the equipment can be collected through the waveform recorder to obtain the overvoltage waveform of the tested equipment. Then the corresponding overvoltage waveform can be obtained by electromagnetic transient calculation and compared with the measured waveform to verify the accuracy of calculation. Furthermore, the calculation model is adjusted to study the influence of short-circuit faults at different locations on overvoltage at different equipment, and the statistical analysis of electromagnetic transient considering the dispersion of mechanical characteristics of circuit breaker.

The test data show that the maximum overvoltage measured during closing the no-load 500kV line is 1.621p.u.(1.0p.u.=rated voltage amplitude) , and no obvious overvoltage was measured during opening. The maximum overvoltage measured during the opening and closing of 110kV electric reactor is 1.85p.u. and 1.29p.u. respectively, for capacitor at 110kV side, it is 1.50p.u. and 1.86p.u.. The overvoltage waveform obtained by simulation is consistent with the measured waveform, which can accurately reflect the electromagnetic transient process. Further simulation results show that the maximum overvoltage that may be generated by single-phase short-circuit fault of electric reactor is 231kV, and the maximum voltage is 145kV at neutral point.

Through the comparison between the measured waveform and the simulation calculation results, the accuracy and effectiveness of the simulation calculation model and method in this paper can be verified. On this basis, the short-circuit fault analysis and statistical analysis can be further carried out, and the technical support can be provided for the state evaluation and possible fault analysis after the whole station is charged.