Optimal two-stage dispatch method of household PV-BESS integrated generation system under time-of-use electricity price

Abstract

The Photovoltaic (PV) and Battery Energy Storage Systems (BESS) integrated generation system is favored by users, because of the policy support of PV power generation and improvement of the grid-connected electricity price mechanism. And the operating efficiency and economy of the PV-BESS integrated generation system are closely related to the day-ahead dispatch strategy. Therefore, to improve the operating efficiency of the system and user benefit, this paper proposes an optimal two-stage dispatch strategy of household PV-BESS integrated generation system under the market environment of time-of-use (TOU) price strategy and a dynamic adjust strategy to cope with the forecast error. The first stage is the battery charging stage in the TOU price valley time, and the second stage is the PV output power dispatching and battery charge–discharge power scheduling stage in the non-valley time. The strategy combines energy storage strategy with a PV optimal dispatching strategy, to make full use of the double-sided characteristics of power source and load of the battery, thus achieving peak shaving and valley filling and reducing the load difference between peak and valley of the grid. The impact of sunrise time on energy storage strategy is also considered in this study. Then, the models of the two-stage dispatch strategy and the household PV-BESS integrated generation system are established under TOU price. When the PV output power is greater than the load demand, part of the surplus power will be sold to the grid and the other part will be stored in the battery. The ratio of the selling part is defined as the grid-connected ratio, and it is taken as the decision variable, and some factors are taken as the constraint condition, such as battery charge–discharge power, power balance, etc. The objective function is the optimal user benefit, and it is solved by the particle swarm optimization (PSO). When the forecast error happens, the power exchange of battery and the electricity sent to the grid will be adjusted, and the subsequent planning needs to be re-optimized to maintain the optimal dispatch result. Finally, the rationality and effectiveness of the models and strategies are verified by taking the dispatch of the household PV-BESS integrated generation system during a dispatch day under three typical scenarios as an example, and a sensitivity analysis is carried out.