Reconstruction of switching overvoltage waveform measuring in a 500kV substation using electro-optical E-field sensor

Electro-optical E-field sensors show great potential for substation voltage detection due to their wide frequency bandwidth and easy maintenance. However, in substations of 500kV and below, the coupling signals of adjacent conductors cannot be ignored due to the large number of outgoing lines and compact electrical structure. The existing decoupling method often results in a high transient overvoltage amplitude, making it challenging to provide engineering application. Therefore, a new overvoltage decoupling method has been developed to consider the influence of neighboring equipment and line operating voltages. This method utilizes the sensor waveform of the line to be measured before closing to calculate the matrix of coupling coefficients of the adjacent conductors in order to isolate their influence. Measurements of voltage waveforms during breaking and closing were conducted in a 500kV substation. The decoupled waveforms were compared with voltage measured by CVT and existing decoupling methods. The results demonstrate that electro-optical sensors have a wider frequency bandwidth than CVTs. Furthermore, the background signals of adjacent conductors can reach up to 30% of the steady-state amplitude of the measured signal, causing a decoupling error exceeding 100% in traditional methods. Compared with existing decoupling methods, the proposed method more effectively eliminates the influence of coupling signals from adjacent wires, resulting in more accurate reconstruction of transient voltages.