Grid-forming Control of The Islanded Microgrid with Wind Turbines and Energy Storage Devices as Main Power Sources

The islanded microgrid taking wind turbines and energy storage devices as main power sources develops rapidly, especially in remote areas. However, this kind of islanded microgrid faces power balance problems under the conditions of load power and source power fluctuations, which can ultimately lead to a rapid drop in the microgrid frequency and even destabilization. To address these issues, this paper proposes a grid-forming control architecture for the islanded microgrid, where the grid-side converters of the wind turbines and energy storage devices adopt the grid-forming control with DC voltage as the control objective, and the machine-side converters adjust the output active power according to the DC voltage. Regarding high-frequency, low-frequency wind speed disturbances and load disturbances, a multi-timescale energy balance method for the islanded microgrid is designed based on pitch control and energy storage charging and discharging. Research results show that the functions of primary frequency regulation and resisting load fluctuations is able to be achieved in the islanded microgrid. At last, a PSCAD-based simulation model is constructed to verify the feasibility of the proposed control method and the accuracy of the theoretical analysis.