A Decentralized Adaptive SOC Balancing Strategy in VSG-based Islanded Power System

The unbalance of the state-of-charges (SOCs) may be among paralleled energy storage systems (ESSs) is harmful for the system operation. This paper proposes an adaptive control strategy to achieve the balance of SOCs among the paralleled ESS-based virtual synchronous generators (VSGs) in a completely decentralized way. The parameters of the virtual governor are designed to change according to the local SOC taking the stability and steady-state frequency limitation into consideration. To realize the adaptive control, this paper starts with an analysis of the generalized requirements of the adaptive terms. Then linear relationships are chosen as an example to construct the adaptive controller. The IEEE 9-Bus system is used to verify that, with the proposed method, the SOC balancing can be gradually realized no matter the differences in the initial values and disturbances without the communication network.