Reducing distribution power loss of islanded AC microgrids using distributed electric springs with predictive control

Recently proposed electric springs (ESs), as alternatives to conventional energy storage systems, are used to regulate bus voltages of ac microgrids with few or even no battery packs. Pioneering works have demonstrated the merits of ES in reducing the infrastructure and maintenance costs of expensive battery packs while still improving the power quality, stability, and dynamic responses of microgrids. However, distribution power loss reduction of islanded ac microgrids by controlling distributed ES has never been investigated. The major novel contribution of this article is to extend the function of ES, along with emerging high-speed communication techniques, to enhance the rate of energy utilization in islanded ac microgrids. A predictive control in the power flow router calculates and feeds the optimal bus voltage references to each ES, which in turn controls the respective distribution power flow based on real-time power measurements. This allows the distributed ES to mitigate the overall distribution power loss of the islanded ac microgrid. Simulation results verified the significant power loss reductions in various structures of islanded ac microgrids with the distributed ES under the proposed predictive control. Experimental results also validate the effectiveness of the distributed ES operating under the predictive control in reducing the distribution power loss of a 3-bus and a 5-bus islanded ac microgrid.