Reignition overvoltages induced by vacuum circuit breakers and its suppression in offshore wind farms

Abstract

Vacuum circuit breakers may cause severe reignition overvoltage when switching off inductive loads, which may cause damage to other equipment connected with them, especially in the offshore wind farm power collection system. In order to study this process, a 35 kV electrical system was built in a laboratory platform, and the reignition overvoltage was recorded and analyzed. The measurements were used to improve the vacuum circuit breaker model. The parameters of dielectric strength of a 40.5 kV vacuum circuit breaker model were discussed in this publication. Then, a simulation model based on the experimental system was established using PSCAD/EMTDC. The reignition breakdown voltage across vacuum circuit breakers and the voltage at the high-voltage side of the connected transformer were equal, and the reason was explained according to the theory of wave propagation. Surge arresters and RC snubber are often used for overvoltage suppression, and the different configurations of them were evaluated. Finally, the efficiency of overvoltage suppression was compared both in the time domain and energy spectral density based on the simulation results.