Mechanism and Application of Arrester Block Voltage Division to Lightning Transient Voltage Monitoring in Substation Transformers

Lightning-induced overvoltage in substations is one of the main causes of insulation damage in transformers. As the complexity of power grids is continuing to increase, the existing lightning overvoltage statistical waveform may no longer meet the requirements of modern power systems. It is therefore necessary to obtain the statistical characteristics of lightning-induced overvoltage on transformers. However, the existing devices in current power systems cannot meet the requirements for monitoring of the lightning-induced overvoltages because of their limited bandwidths and sampling rates. This paper proposes a method for monitoring of lightning-induced overvoltages on substation transformers based on the principle of ZnO lightning arrester block voltage division. Consistency testing was performed on the voltage division ratio of a ZnO lightning arrester block in both the linear and nonlinear regions. The experimental results confirmed the feasibility of the proposed method and field applications using this sensor showed that long-term research will be helpful in obtaining the characteristics of lightning-induced overvoltage.