Control strategy of sharing power in proportion for autonomous microgrid by virtual inductance

Active power-frequency (P-f) and reactive power-voltage (Q-U) droop control is widely used in microgrid. But it is unable to simultaneously share the accurate active power and reactive power for inverters with different ratings, which may result in great circulating power among inverters and cannot be solved by combining P-f, Q-U droop control and virtual impedance. We investigate the troubles occurred in power sharing for conventional droop control and propose a novel control method. In the proposed method, conventional P-f droop is reserved and Q-U droop is abandoned while virtual reactance is introduced, which are selected in reverse proportion to inverters' ratings. Stability analysis is also carried out for microgrid to which the proposed method is applied. The proposed method can simultaneously achieve active power and reactive power sharing in proportion to inverters' ratings in the absence of communication among inverters, which is confirmed by Matlab simulation. © 2016, High Voltage Engineering Editorial Department of CEPRI. All right reserved.