Adaptive voltage unbalance compensation based control strategy for islanded microgrid

摘要

In order to compensate voltage unbalance at the point of common coupling (PCC) for the islanded microgrid, a novel strategy based on PCC negative-sequence voltage feedforward is proposed. Through the PCC negative-sequence voltage feedforward, a virtual voltage source is added to the DG terminal at the negative-sequence. Then, the effective impedance between the distributed generation (DG) unit and the PCC can be reduced proportionally to the compensation coefficient, thereby reducing the unbalanced voltage caused by the unbalanced load. On this basis, an adaptive mechanism of the compensation coefficient is proposed to achieve compensation effort equalization among parallel DGs. Different from the widely adopted virtual impedance method, the additional unbalanced voltage droop (caused by the virtual impedance) can be avoided. In addition, the H infinity repetitive controller is designed to obtain good voltage control performance for the parallel operation. Finally, microgrid simulations are provided to demonstrate the effectiveness of the proposed control strategy. (C) 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.