Intra- and Inter-Phase Power Management and Control of a Residential Microgrid at the Distribution Level

A power control and management strategy for islanded residential microgrids is presented. A three-phase residential microgrid can be viewed as three separate single-phase systems. Within each phase, there are PV systems, battery storage devices, and droop controlled dispatchable units. Connections among phases are made through back-to-back converters to allow for power transfer between the phases. Hence, voltage and frequency control and power management must be carried out at intra-phase and inter-phase levels. The intra-phase power control and management system uses a modified vector control with a multi-segment (P/f) droop strategy. In the case where such a balance cannot be maintained locally, the inter-phase power can be transferred through the back-to-back converters. Both intra-phase and inter-phase power control and management scenarios have been considered. To demonstrate the effectiveness of the strategy, a detailed three-phase residential microgrid model is developed in PSCAD/EMTDC environment, including switching models of the back-to-back converters. The results have shown that the proposed strategies can effectively maintain desired voltage and frequency profiles for each phase-wise and the overall microgrid, frequency, and power balance in each phase can be effectively managed for stable operation.