Study on Switching Overvoltage in Off-Shore Wind Farms

The transformers often suffer the insulation breakdown accident caused by overvoltage in some wind farms and the problem has become particularly prominent. The switching overvoltage is considered to be an important cause to insulation accident. This paper will establish a wind farm model and research on the relationship between the switching overvoltage and the length of feeder cable and the number of feeders that have been energized. First, this paper establishes two dynamic simulation systems to analyze overvoltage of step-up transformers on feeder in PSCAD. Finally, making simulation and analyzing the overvoltage of step-up transformers on feeder. The simulation results show that switching overvoltage amplitude of electrical equipment in wind farm will increase with the increasing of the feeder length both in star and radial topology; moreover, the number of energized feeders will have influence on the amplitude and steepness of switching overvoltage. The results can provide some references for the insulation design of cable system and the step-up transformer in offshore wind farm.