Distributed weighted average predictive control and delay margin analysis for an islanded microgrid with time delay

The time delay is inevitable in the communication process of actual microgrids (MGs), which may lead to controller failure and even affect stability. This paper proposes a distributed weighted average prediction (WAP) control for the secondary control of islanded MGs with time delay and analyzes its delay margins. Firstly, a secondary control strategy is designed to achieve the frequency and average voltage recovery and accurate active and reactive power-sharing. Secondly, a WAP strategy is proposed to improve the delay margin of the designed MG system. Finally, the stability and delay margin of the MG system is analyzed in the frequency domain and a rigorous formula is derived to calculate the delay margin. Compared with the system without WAP control, the delay margin of the system can be increased by 15.8%. The simulation results and the experimental results based on the StarSim Modeling Tech Real-time experimental platform verify the effectiveness and feasibility of the proposed method. The results demonstrate that the proposed control strategy can improve the delay margin of the system. The proposed analysis method can obtain the expression of specific system delay margins, which can guide the parameter design.