Sub-synchronous control interactions between type 3 wind turbines and series compensated AC transmission systems

Recent project experience and studies have shown that Type 3 wind turbine generators with power electronic converters and controls that operate near series compensated transmission lines are susceptible to un-damped sub-synchronous oscillations. This paper presents an overview of the Sub-Synchronous Control Interaction (SSCI) phenomenon. Simulations in PSCAD/EMTDC using a Type 3 wind turbine model are used to demonstrate SSCI, and the design of an SSCI damping controller is presented to help mitigate the problem. Recommendations are provided to wind turbine manufacturers, generation developers, and system planners to appropriately predict and mitigate SSCI concerns before they severely impact project and system development.