Equivalent modeling method of battery energy storage system in multi-time scales

The rapid development of battery energy storage technology has provided a new solution for integrating large scale renewable power generation; however, the accurate model of battery energy storage system (BESS) in multi-time scales has not been developed yet. The BESS model consists of battery model, power electronics interface model and controller model. There are still no certain math expressions about the parameters of battery model, the model of power electronics and controller are also different in different applications. Considering different applications in power system, the multi-time scales model of BESS should be established to take account of the transient, steady and dynamic state. In this paper, an equivalent modeling method of BESS was developed. First, the different equivalent circuit models of battery were summarized, according to the comparison, the thevenin equivalent circuit model was supposed as the effective model for power system application. So, taking into account the relations between the parameters such as current, internal resistance, and state of charge (SOC), the battery parameters were fitted based on experimental date. Then, the power electronics interface model including DC/AC and DC/DC converter were introduced, and the control method with different operations were proposed. Finally, the BESS model were built and verified on the platform of BESS experiment. The results show that the model can represent the multi-state characteristics of battery and has quick response.