Unified Distributed Control of Battery Storage with Various Primary Control in Power Systems

Distinct characteristics of transmission and distribution power grids typically necessitate different control algorithms, especially at the primary control level where quick responses are required. Accordingly, various droop control schemes have been developed due to specific types of power grid impedances. Therefore, controllers at higher levels often have to be redesigned whenever a different power grid is considered, hence, incurring higher cost and effort. As a way to overcome that problem, in this work, a unified secondary controller using distributed control theory is designed for different droop schemes associated with distributed battery storage in different grid conditions. The control design follows the consensus theory, originally designed for multi-agent systems, to control the frequency and voltage at the point of common coupling (PCC), synchronize energy levels, and proportionally share active and reactive powers of battery storage systems. A sufficient condition for the upper bound of communication delays between storage systems is derived to ensure system stability. Several scenarios are studied using a modified IEEE 118-bus benchmark to support the theoretical results of the proposed approach.