Discrete Time Distributed Secondary Control of AC Microgrid: A Digital Control Approach

Distributed control of microgrids are becoming popular due to their scalability and reliability. Most distributed controllers designed for the microgrids are in the continuous time domain and subsequently implemented on digital controllers, which work in discrete time. Due to sampling time concerns, continuous time-domain control gains may not function well for digital controllers. This paper presents a discrete-time distributed secondary control to achieve frequency restoration and average voltage control in an ac microgrid. The proposed distributed frequency control ensures frequency restoration while maintaining proportionate active power sharing. The distributed voltage and reactive power control guarantee the average microgrid voltage is restored to the reference value and achieves proportionate reactive power sharing. Simulation in MATLAB/Simulink to verify the effectiveness of the proposed control scheme. The proposed controller is implemented on a digital FPGA controller and tested the experimental setup with different loads, and the results are presented.