A Generalized DC Electromotive Force Control Strategy for Bi-Directional Interface Converters in a Standalone Hybrid Microgrid

Aiming at the problems of poor dynamic characteristics and low power distribution accuracy of paralleled bi-directional interface converters (BICs) in hybrid AC-DC microgrids, a generalized DC electromotive force (G-DCEMF) control strategy suitable for parallel BICs is proposed in this paper. This control strategy not only enables BICs to share the active power equally under stable conditions, but also enables BICs to have the external characteristics of DC motor. When the load changes, the control strategy can suppress the fluctuation of the DC bus voltage, reduce the influence of the load change on the AC frequency, improve the dynamic response of the DC voltage, the AC frequency and the power transmission between the AC and DC subnets. Thus, this system has strong anti-interference ability. In addition, the proposed control strategy has good dynamic response under different conditions. The performance of the proposed G-DCEMF control strategy is validated by using PSCAD/EMTDC software. The results show that the proposed control strategy can realize power sharing and effectively reduce the influence of AC and DC subnet power fluctuations on the system.