Energy Storage System Optimal Allocation Considering Flexibility Supply and Demand Uncertainty

Wind power has strong randomness, which increases the demand of the system flexibility. Using energy storage for auxiliary peak-shaving can solve the problems brought by large-scale wind power grid-connection. Considering the economy and flexibility, we propose an optimal allocation method and establish a double optimization model of energy storage auxiliary peak-shaving: The upper layer model figures out the configuration scheme of the energy storage from the economic optimization considering the uncertainty of peak-shaving demand; the underlying model aims to minimize the expected peak-shaving ability shortage considering the forced outage, the maximum/minimum outputs of units and the up/downward ramp rates in different generation output ranges. We use probabilistic production simulation based on the available capacity distribution to assess the flexibility indexes considering the operation strategy of energy storage, and return the loss of flexibility to the upper optimization model. Finally, we obtain the optimal allocation of energy storage considering both the economy and flexibility through continuous optimization and iteration. Results of the IEEE RTS-24 bus system and the IEEE 118 bus system show that the model and method can effectively quantify the influence of unit sizes and the uncertainty on the system flexibility. It also provides theoretical support for flexibility balance. © 2020, Power System Technology Press. All right reserved.