Active Power Sharing Control Strategy of Photovoltaic Microgrid Based on Adaptive Droop

An error of active power distribution will occur with a traditional resistive droop control, due to the difference of the output line impedance of parallel inverters, during the operation of island photovoltaic microgrid. Aiming to this issue, a control strategy for regulating the droop coefficient automatically is proposed. The active power and reactive power output by inverters as the feedback values are lead into the droop control equation in the strategy, and the active power is employed into the reactive frequency equation; the small disturbances will be produced in reactive power, and it can be employed to compute the sharing error of the active power, the process of clearing up reactive power disturbance, which is equal to the process of regulating the droop coefficient automatically, which can greatly improve the accuracy of active power sharing. Simulation and experiment results show that, by using the proposed strategy, the precision of active power sharing can be improved and the circulating currents between inverters are suppressed.