Microgrid Power Sharing Strategy Based on Small AC Signal Injection

The droop control is applied to the control of microgrid parallel distributed generators (DGs). The power distribution can be realized without communication, but the system frequency deviates from the rated value when the load changes. PI-based secondary frequency control (PI-SFC) can eliminate this deviation, but due to the dispersion of parameters such as measurement and control between DGs and noise, it may still destroy the reasonable distribution of active power. In this regard, this paper first analyzes the influencing factors of the frequency secondary control performance and the degree of influence on the active power distribution. On this basis, a power sharing strategy based on Small AC Signal (SACS) injection is proposed. By injecting an additional SACS into each DG, the frequency is used as the global variable of the system, and the droop relationship between the SACS frequency and the rated active power compensation value is established to realize the reasonable distribution of active power between DGs. Finally, the correctness and effectiveness of the proposed strategy are verified by time domain simulation.