A unified model predictive voltage and current control for microgrids with distributed fuzzy cooperative secondary control

Abstract

A microgrid formed by distributed generation (DG) units is capable of operating in islanded and grid-connected modes. Traditionally, by using model predictive control (MPC), these two operation modes can be achieved with two separate cost functions, which brings in control complexity and hence, compromises reliability. In this paper, a unified model predictive voltage and current control (UMPVIC) strategy is proposed. Specifically, the cost function is kept unified with voltage and current taken into account without altering the control architecture. A high-quality voltage is generated in islanded mode and a bidirectional power flow is achieved in grid-connected mode. In addition, by only using DGs own and neighbouring information, a secondary distributed fuzzy cooperative algorithm is developed to mitigate voltage/frequency deviations. The fuzzy controller can optimize the secondary control coefficients for further voltage quality improvement. Comprehensive tests under various scenarios demonstrate the merits of the proposed control strategy over traditional methods.