Mitigation techniques associating vacuum circuit breakers (VCB) were proven highly effective in reducing switching overvoltages (SOV) in wind farms. However, the structure of wind farms in modern-day power systems is not fixed to a certain topology. In this paper, the impact of changing the topology of the wind farm upon the capability of mitigation techniques in reducing SOV was investigated which is considerd the first contribution of the paper. Four wind farm topologies were selected; radial, single-sided ring, double-sided ring and star topology. Four mitigation techniques were used for each topology: the pre-insertion resistor (PIR), the RC-snubber circuit, R-L smart choke and the surge capacitor. The simulations showed the failure of the VCB to open without any suppression measure. The addition of a surge capacitor didn’t improve, while the remaining suppression measures were successful. It was noticed that PIR and R-L were optimal in radial and star topologies, which successfully reduced the SOV by an average of 52%. At the same time, R-C snubber was optimal for ring topologies that reduced SOV by an average of 70%. The presented results are not universally applicable to all wind farms, but they highlight the second contribution of the paper which is proving throught the presented investigation the dependence of the performance of SOV suppression measures upon the topology of the wind farm. The third contribution is presented in the conclusion that recommends for the selection of suppression measures in windfarms; simulations should be done to include the effect of the topology of the wind farm. |
