Abstract
Frequency deviation and powers sharing error exist in a microgrid with multiple droop-controlled distributed generations. To solve the above problems, we propose an event-triggered multistage secondary control. First, to improve the synchronization accuracy, we divide secondary control into multiple stages based on frequency/voltage droop characteristics. The inputs of proportion-integration compensator for these stages are different. The corresponding stage will be activated when the value of frequency/voltage meets a certain "event" (given ranges). Then, we consider the network delay, use a discrete communication scheme to reduce the bandwidth utilization, and further avoid the oversized delay. To stabilize the interloop control with input delay, we derive the robustness criteria. Finally, simulations in RT-LAB confirm the effectiveness of the proposed control strategy.