Study on Margin Ratio Index for Evaluate The Stability of Small Signal of Multiple Renewable Energy Stations Delivery System

The long-distance and large-scale grid-connection renewable energy stations lead to the weak stability of the connecting points of the stations, which seriously restricts the safe and stable operation of the power system. Therefore, it is urgent to propose an analytical index that can accurately evaluate the stability of small signals in the multiple renewable energy stations (MRES)delivery system. Firstly, aiming at the MRES delivery system, the static voltage stability margin ratio (SVSMR) index based on the static stability limit is proposed in this paper to obtain the static stable operation area of the system. Secondly, based on single grid-connected converter accessing infinite bus system through line impedance, according to the existing analytical expression of small signal stability, the relationship between small signal stability and static stability is established through the SVSMR index, and then the small signal stable operation area of the power system integrated with MRES is obtained. Finally, time-domain simulation based on MATLAB/Simulink verifies the feasibility and effectiveness of the proposed method.