Study on power frequency overvoltage and wind turbine disconnection probability during non-full-phase operation

Abstract Experimental results indicate that during non-full-phase operation following a single-phase transient grounding fault, power frequency overvoltage occurs in the system. In systems with significant wind power integration, such overvoltage may lead to the disconnection of wind turbines, thereby increasing the probability of cascading failures in the power grid. To analyze the power frequency overvoltage and its impact on large-scale wind power integration during non-full-phase operation, a mathematical model of the non-full-phase operation process and an improved wind turbine disconnection probability model were established based on parameters of a typical wind power collection system. Factors such as wind turbine output power levels and transmission line lengths were studied for their influence on power frequency overvoltage and turbine disconnection. The study results show that during non-full-phase operation, higher reactive power output from wind turbines leads to larger maximum phase overvoltage and, as evaluated by using the improved turbine disconnection probability model, a higher likelihood of turbine disconnection. Additionally, excessively short or long transmission line lengths result in higher maximum phase overvoltage, further increasing the probability of turbine disconnection.