Study on Risk Indicators of Sub-synchronous Oscillation in Power System with Wind Farms and Series-compensated Lines

Sub-synchronous oscillation (SSO) phenomenon of doubly fed induction generators (DFIG) connected to series compensated transmission lines is a threat to the safety and stability of the power system. Efficient method for analyzing complicated power system is in need. In this paper, sub-synchronous oscillation characteristics and influencing factors of complicated power grid with DFIG and series compensation capacitance are analyzed firstly by frequency domain impedance method, based on two simplified equivalent systems. Thus, a practical oscillation risk indicator is proposed, which comprehensively reflects the influence of series-compensation percentage and short circuit ratio. Finally, the proposed risk indicator is verified by simulation and test of a typical project.