Stratified Optimization Strategy Used for Restoration With Photovoltaic-Battery Energy Storage Systems as Black-Start Resources

With the rapid growth of installed capacity of photovoltaic (PV), the PV power stations equipped with energy storage (ES) have become a new type of black-start power supply. Taking the Photovoltaic-Battery Energy Storage Systems (PV-BESS) as the black-start power source can improve the black-start ability of the regional power grid and broaden the application prospect of PV power generation. In this paper, a stratified optimization strategy for black-start of PV-BESS is proposed, which combines the key issues in the process of black-start of PV-BESS. Stratified optimization strategy is divided into data analysis layer, optimization coordination layer and scheduling control layer. The data analysis layer combines the requirements of the black-start process. Firstly, the similarity matrix ranking method is used to improve the PV power prediction method. Secondly, based on probability inclination, the PV power index is designed to evaluate the feasibility of black-start by calculating the PV lower limit power and the executable probability inclination. The optimization coordination layer is based on the state space model of blackstart of PV-BESS, combined with the control strategy of PV as the main part and ES as the auxiliary part, the optimization objectives of the maximum utilization rate of PV and tracking the ideal value of state of charge (SOC) of ES is formulated. The optimal model is solved by model predictive control, and the output power of PV and ES is controlled to complete the black-start process. The actual historical data in the power grid with a high proportion of PV sources are used as the basic data for simulation. The simulation of black-start based on MATLAB/Simulink verifies the rationality of the stratified optimization strategy, which provides a reference for the realization of black-start of PV-BESS.