Stabilizer Design for Heterogeneous Types of Distributed Generators in Microgrids Operating in a Unified Control Mode

Abstract

This paper proposes a stabilizer to suppress the large transients subsequent to disconnection/reconnection of microgrids (MGs) that are controlled in a unified mode. In the unified control mode, the control system requires to operate in grid-connected mode, islanded mode, and mode transition transients with a unique control configuration. The MG is assumed to contain heterogeneous types of distributed generators (DGs) that include electronically interfaced DGs (EI-DGs) and synchronous generators (SGs). The simultaneous operation of the EI-DGs and SGs due to their different voltage and frequency control strategies makes the design of the stabilizer more challenging. A general Lyapunov function is defined considering the response delay of the primary resources. The deteriorating effects of the primary resource response delays on the mode transition transients are evaluated analytically. Furthermore, the asymptotic stability in the frequency and voltage loops are guaranteed by the proposed stabilizer that solely utilizes local information. The proposed stabilizer is designed and implemented for both EI-DGs and SGs. Finally, the effectiveness of the proposed control strategy is demonstrated using time-domain simulations on a multiresource MG. The performance of the proposed method is also compared with that of an existing method.