Overvoltage protection on high-frequency switching transients in large offshore wind farms

High-frequency switching overvolatges (SOV) are considered as a possible source causing component failures in existing offshore wind farms (OWFs). In order to study such overvolatges in OWFs, the main OWF components, including vacuum circuit breaker (VCB), submarine cables and transformers should be properly investigated. Firstly the parameters influencing VCB behaviors are considered, such as current chopping, the withstand capability of transient recovery voltage and the capability of high-frequency current interruption, to develop a detailed VCB model, which is capable of simulating multiple prestrikes and reignition in VCBs. Subsequently, related system element models are improved based on existing models considering frequency characteristics. Finally, this paper presents the main results of high-frequency switching overvolatges using various mitigation approaches, which are generated due to the energization of wind turbines in OWFs. The simulation results indicate the user-defined VCB model can simulate prestrikes and the proposed protection methods are effective for mitigating high-frequency switching overvoltages.