A droop control method based on adaptive virtual impedance for parallel control of distributed generators

Traditional droop control method cannot achieve effective reactive power distribution when distributed generators are paralleled. Therefore, this paper proposes a droop control scheme based on adaptive virtual impedance to solve the problem of uneven distribution of reactive power. The proposed method calculates the impedance difference between the two distributed power sources based on the feedback of line current and voltage, and introduces the adaptive virtual impedance compensation scheme accordingly. The proposed scheme reduces the amount of data to be transmitted during communication, and the system design is simple. The simulation in this paper demonstrate that, the proposed method reduces the percentage error in reactive power distribution from 10.5% to 0.4% under load variations and from 21% to 0.1%, when there is a sudden change in the impedance of one of the lines.