Study on high-frequency transient overvoltages protection in offshore wind farms based on RC snubbers

Based on the reflection and refraction of traveling waves and vacuum circuit breaker(VCB) characteristics, transformers interruption by VCB may produce current chopping and re-ignition that will cause severe high-frequency transient overvoltages in collection grid of offshore wind farms(OWFs). In such applications, overvoltages protection should be used. In order to study such overvoltage in OWFs, the main components, including VCB, submarine cables and transformers should be established in PSCAD/EMTDC and the interrupting transients were elucidated with equivalent circuit analysis in this paper. An overvoltage protection measure of wind turbines transformers by RC snubbers was proposed. The results show that adopting suitable RC snubbers could reduce the re-ignitions of VCB and limit the overvoltages to well-defined amplitudes, which prevents OWFs interrupting overvoltages effectively.