Abstract: In the isolated island operation mode of microgrid，the output power of distributed generation units

in the system is difficult to distribute reasonably due to the difference of output line impedance，which affects the

stability of the system. In order to realize the reasonable distribution of power according to capacity of distributed

generation in isolated island microgrid under the condition of mismatched output impedance，the influencing factors of power distribution of parallel inverter were analyzed，and an improved droop control strategy based on adaptive virtual impedance was proposed，and its feasibility was verified by convergence analysis. According to the deviation of power distribution ratio，the strategy adaptively adjusts virtual impedance and voltage phase angle to realize power distribution according to capacity. Simulation and experiment show that the improved droop control strategy can realize the rational distribution of output power of distributed generation，and overcome the influence of power distribution on bus voltage angular frequency in traditional droop control，and improve the steady-state performance of the system.

      Key words: isolated island microgrid；adaptive virtual impedance；droop control；proportional power sharing