Improved Secondary Frequency Control and Stability Analysis of Islanded Microgrid

Because the output power of the loads and distributed generation(DG) units is uncertainty in islanded microgrid, the traditional power-frequency(p-f) droop control will lead the frequency to exceed the limit. Aiming at this problem, an improved secondary frequency control strategy without communication is proposed. According to the one-to-one correspondence between the power and the frequency of the droop curve, the power is taken as the control variable to dynamically adjust the droop coefficient. Then small signal model was set up to verify the stability of the system by the static working point, and analyzing the stability of the system when the parameters change by the root-locus method. Finally, the simulation and experiment results verify the feasibility and effectiveness of the proposed strategy.