A novel control method for preventing the PV and load fluctuations in a DC microgrid from transferring to the AC power grid

DC microgrids are gaining popularity due to the higher efficiency, reliability, lower costs and better compatibility with DC loads compared to their AC counterparts. Large-scale deployment of distributed renewable energy resources like solar in the microgrids, has to provide utilities and grid operators the capability to safely and reliably mitigate the impact of solar and loads intermittency on the main AC power grid. In this paper, a novel control method is proposed to prevent solar and load variations inside a DC microgrid from transferring to the AC power grid while the microgrid is operating in grid-tied mode. The control method works based on having multiple slack terminals with different voltage controller response times in parallel. The response times can be adjusted such that the battery converters of the microgrid absorb solar and load fluctuations while the grid-tied inverters contribute to their voltage regulation's shares smoothly according to their droop parameters. This method improves upon previously discussed methods in literature in that it does not require single slack terminal, DC bus signaling or converter mode changes.