The capacity optimization of the battery energy storage system in the combined cooling, heating and power microgrid

In the microgrid, the battery energy storage system (BESS) is used in combination with renewable energy to solve the problem of renewable energy accommodation. Meanwhile, power sources with the BESS can participate in valley filling and reduce electric generation costs. However, the BESS cannot contribute sufficient capability to the microgrid and reduce costs due to its limited capabilities. To tackle this challenge, the output power model of the combined cooling, heating and power microgrid (CCHPM) with the BESS is proposed in this paper. The model takes the micro-gas turbine, the photovoltaic unit, the wind turbine, the electric refrigerator and the BESS as a whole CCHPM. Meanwhile, a capacity optimization method of the BESS is developed to select the appropriate capacity and promote renewable energy accommodation. The minimum cost of the objective function is established. The electric power balance of the CCHPM, charge state constraints of the BESS, capacity constraints and ramp-up/down constraints of the units are derived to optimize the output power of units and the capacity of the BESS. The effectiveness of the proposed method is verified by the system simulation of YALMIP and GUROBI. Compared with the traditional method, the total cost of the microgrid is decreased by 1.4%, and the microgrid’s renewable energy accommodation is enhanced by 12.2%. This capacity optimization method can enhance the applicability of BESS in CCHPM.