Transients in Wind Power Plants—Part II: Case Studies

This is the second part of a two-paper series. The first paper presented the transient modeling methodology for various components of wind power plants (WPPs). This paper presents a general methodology for transient analysis of WPPs and discusses case studies which investigate some of the most important high-frequency interactions between different components of the WPP. The focus has been on switching transients, and lighting transients have been excluded. Transient case studies conducted on a typical WPP are presented which discuss the impact of fast system surges on the performance of the circuit breaker and impact of fast surges caused by the circuit breaker on the adjacent power components. These case studies investigate the opening and closing of the collector grid vacuum circuit breaker for loaded and unloaded conditions. Simulation results provide a close match with the field measurements conducted on a laboratory prototype of a typical WPP. Differences caused by modeling assumptions or insufficient accuracy of measurement devices are highlighted. To understand the most onerous overvoltages that can be experienced in the test system, a couple of additional simulation case studies are reported. These case studies discuss the interruption of inrush current with an unloaded transformer and interruption of a small inductive current following the transformer energization.