Simplified Distributed Secondary Control Based on Diffusion Algorithm in Isolated AC Microgrids

To achieve voltage and frequency recovery and accurate reactive power sharing in AC MGs, this paper proposes a simplified distributed secondary control strategy based on dynamic diffusion algorithm which contains only one integrator and one communicated variable in the voltage recovery and reactive power sharing regulator. Compared with traditional consensus-based secondary control method with parallel structure, the proposed control structure is simplified and the communication link burden is reduced. Furthermore, the controller's dynamic performance including convergence rate and convergence region of reactive power sharing and frequency recovery are also improved by adopting dynamic diffusion algorithm in secondary control. To verify the superiority of the proposed strategy, a three-node isolated AC MG is used to test the simplified distributed controller under load changes, communication delay comparing with consensus-based algorithm. Moreover, the proposed controller presents strong robustness under communication link failure and has plug-and-play capability.