Decentralised Control of DC Microgrid Based on Virtual Admittance to Enhance DC Voltage and Grid Frequency Support

DC microgrid technology has become one of key smart grid research topics in recent years. In comparison to AC microgrids, DC microgrids are more manageable to operate in grid-connected and islanded modes, and also offering improved efficiency and better controllability. Services, such as voltages and AC system frequency support can also be potentially provided by optimally controlling the DC microgrids converter interfaces and their local distributed energy resources. These will require a good understanding of the dynamic interactions between the DC microgrid and the host AC system, and implementation of the appropriate control strategies. This paper investigates the dynamic resilience of a DC microgrid connected to an AC system under different frequency and voltage disturbances. A decentralised droop control strategy within the DC microgrid is used for fast active power control and wider system frequency support. A virtual admittance method is also utilised to enhance the local DC microgrid voltages during the AC frequency events and DC fault test scenarios. The effectiveness of the control strategy is evaluated by simulation studies in MATLAB/Simulink.