Probability Assessment of Open-Loop Mode Resonance in Grid-Connected Wind Power Systems

Since wind power generation has characteristics such as randomness, the power system stability also exhibits certain probabilistic characteristics due to the integration of wind power into the grid. Therefore, it is also extremely important to study the probabilistic assessment of closed-loop system stability that considering the randomness of wind generator output. This paper first establishes a closed-loop interconnection model with the wind turbine represented by the permanent magnet synchronous generator (PMSG) as the “feedback subsystem” and the remainder of the power system as the “feedforward sub-system”; analyzes the open-loop and closed-loop interactions between the two subsystems. At the same time, open-loop mode resonance is introduced to derive the criteria for system oscillation instability in closed-loop conditions. Then, the regional wind generator distribution characteristics and wind turbine output characteristics are numerically analyzed with the help of Weibull distribution and the wind speed power curve of the wind turbine. Characterize and obtain the probabilistic model of wind power output power; through the above relationship, the probability of subsynchronous resonance (SSR) in the power system caused by grid-connected wind power is finally evaluated, and the reliability and applicability of the evaluation results are verified with the help of cases and time domain simulations. Finally, based on the evaluation results, reasonable plans and suggestions are put forward for power system oscillation prediction and wind farm turbine operation.