Distributed energy storage system‐based control strategy for hybrid DC/AC microgrids in grid‐connected mode

Abstract

This paper concentrates on the issues with the aim of providing a constant dc-link voltage and desired power sharing for a distributed energy storage system (DESS)-based hybrid microgrid under load variations. The hybrid microgrid which is consisted of PV system, lithium battery-based storage system and a grid-connected dc/ac converter are controlled by designing a controller based on the zero dynamics-based mathematical equations of all used converters. Two buck and bidirectional buck-boost dc/dc converters employed in PV and DESS systems, respectively, are responsible for damping the dc-link voltage fluctuations, and also the grid-connected converter is set to enhance the grid power quality and supply continuously the grid-connected loads. The main contributions of the proposed control technique are simplicity and providing the simultaneous stable performance for both DC and AC sides under both DC and grid-connected loads variations. Moreover, another contribution of the proposed control technique is providing accurate coordination in both steady-state and dynamic conditions. To analyze the proposed controller, the dynamic operations of the converters in various operating conditions are evaluated. In this evaluation, several curves based on their zero dynamics are achieved, and their desired operations are completely investigated in different operating conditions. Simulation results in MATLAB/SIMULINK verify the proposed controller ability at reaching the desired zero dynamics and the stable performance of the proposed hybrid microgrid.