Simulation and Verification of Sub-synchronous Oscillation from Impedance Perspective-Taking a Wind Power Base in China as an Example

Recently, numerous sub-synchronous oscillations (SSO) events have occurred in many wind farms in China, which seriously threatened the power system security and stability. It is generally believed that the LC resonance between the wind farm side and the grid side with series compensation (SC) devices is one of the conditions that cause the SSO. This paper takes a real power grid as an example, reappeared the SSO events through electromagnetic simulation, analyzed the key influence factors, and proposes a strategy from impedance perspective in the end based on reasonable assumptions, in order to suppress the SSO shortly after the oscillations happened. Firstly, make off-line impedance analysis based on the deterministic grid structure, and then give the sensitivity results of each wind farm to the SSO. Finally, cut off the wind farm based on the sensitivity orders during the SSO. The simulation results were performed to verify the validity.