Transmission operator perspective of Sub-Synchronous Interaction

Sub-Synchronous Interaction (SSI), in regard to wind power generation, can result from the interaction of wind power generation control systems and series capacitors. SSI occurred in South Texas in 2009, when wind generation was isolated behind a series capacitor. Three measures should be pursued to avoid SSI. Wind generation should implement control system enhancements, Transmission Service Providers (TSP) should evaluate the cost effectiveness of series compensation SSI mitigation, and both generation and transmission should implement protection systems.