Application and Comparison of the Contactless Overvoltage Measurement System Based on Integrated Electro-Optic Sensors

Effective monitoring of transient overvoltage is the key to field test, fault analysis and optimal design of power system. Traditional overvoltage measurement methods need to connect primary equipment to obtain signals, which is inconvenient and has security risks. A contactless overvoltage measurement system based on integrated electro-optic sensors (IEOSs) is introduced and applied in the field. The inductive electric field on IEOS is converted into optical signals with long-distance transmission and strong anti-interference ability. After modulation by the electric field to be measured, the phase difference information is carried into the photodetector and the output voltage of three-phase coupling is obtained. The measurement system has the advantages of no electrical connection with primary equipment, no additional power supply for sensors, wide frequency band and fast response. The coupling relationship of three-phase electric field is analyzed, and the decoupling strategy of output voltage waveform based on linear transformation is given. Finally, the field test results of this measurement system are compared with the waveforms recorded by the fault recorder, which verifies the effectiveness of the decoupling strategy. It also shows that the measurement system has good high frequency response characteristics.