Dynamic control of grid-connected microgrids for tie-line smoothing

This paper presents an interlink inverter control method for providing a constant tie-line smoothing service in a grid-connected residential microgrid (MG) to mitigate the fluctuating nature of renewable power generation and load demand. A grid power controller is designed for an MG to keep a constant grid power on typical days of the year by maintaining the charging/discharging of the battery. To achieve this objective, the MG controller sends the reference to the interlink inverter controller based on load dynamics, average PV generation and battery capacity. Moreover, a state-space model is developed from the dynamic model of the MG system, and an eigenvalue-based stability analysis is performed for different system parameters. The proposed control method is verified through extensive case studies by using real irradiance and typical residential customer load data in Queensland, Australia. In addition, a comparison with a dynamic energy management-based method that aims to achieve the same objective is presented to demonstrate the performance of the proposed control method. Results show that the proposed method provides a constant tie-line power for a grid-connected residential MG for typical days of the year.