Risk assessment of power imbalance for power systems with wind power integration considering governor ramp rate of conventional units

The uncertainty of wind power output leads to an increased probability of supply-demand imbalance in the power system, while wind turbines operating at constant output weaken the frequency response capability of the system, leading to a system more prone to wind power curtailment and load shedding. Most studies on risk assessment of power system focus on the adequacy of frequency response capacity, with less attention to response speed. Therefore, a risk assessment method considering the governor ramp rate of conventional units is proposed. A comprehensive risk index is devised considering wind power curtailment, load shedding, and redispatch cost of conventional units. An optimal power flow model that considers the governor ramp rate of conventional units is proposed to quantify the consequences of the stochastic system states at the assessment time. The proposed method was analysed and validated based on the IEEE reliability test system. The results show that the optimal power flow model considering the governor ramp rate of conventional units can judge the consequences of stochastic states more rigorously to prevent underestimation of the risk. The proposed method can reflect the variation of risk with wind power level and load level, providing reference for scheduling plans.