Abstract
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 black-start 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.
Highlights
In recent years, several large-area blackouts have taken place in the United States, Italy, China, India, Brazil and other places [1]–[3]
The stratified optimization strategy proposed in this paper firstly evaluates the feasibility of the black-start of Photovoltaic-Battery Energy Storage Systems (PV-BESS) through data analysis layer, which can determine whether the output power of the PV-BESS can meet the power requirement of black-start load
A stratified optimization strategy suitable for the blackstart of PV-BESS is designed to make the output power of PV-BESS meet the requirements of black-start power, while the state of charge (SOC) of energy storage (ES) is kept in a reasonable range
Summary
Several large-area blackouts have taken place in the United States, Italy, China, India, Brazil and other places [1]–[3]. Optimizing coordination layer optimizes the system through MPC based black-start of PV-BESS control strategy, outputs reference values of PV cell number (Nr) and ES power (PESS). Among them: the data analysis layer is mainly based on the similarity matrix sorting method, designed a PV power prediction method suitable for black-start, and obtained the PV unit power reference value. C. FUNCTION DESIGN OF OPTIMIZATION COORDINATION LAYER In the black-start process, due to the input of high-power load and the fluctuation of PV output power, over-charging and over-discharging of ES occur, which leads to the failure of ES to continue to use. The PV-BESS needs to provide sufficient power for the load while maintaining the SOC of ES within a reasonable range until the black-start is completed For this reason, this paper designs an optimal coordination layer based on Model Predictive Control (MPC). The optimal charge/discharge power of ES and the optimal number of PV units at k+1 time are obtained by solving the optimization objective
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