A modified droop control strategy in parallel inverters system when inductance values of transmission lines are different

There are large quantities of distributed generators in micro-grid, which are all connected with PCC (Point of Common Coupling) through inverters and transmission lines. The droop control method is widely used to distribute active and reactive power among parallel inverters because its properties of low cost and high stability. In a micro-grid, the inductance values of transmission lines connecting to respective inverters are different due to the low density of distributed generators. In that situation, the reactive power cannot be equally shared even if all the inverters are using the same droop control method. With regards to this problem, a modification, called indirect amplitude control, is put forward for the droop control strategy to share reactive power equally in this paper. The feasibility of the design is validated by simulation and experiment.