Reactive power correction using virtual synchronous generator technique for droop controlled voltage source inverters in islanded microgrid

Abstract

This paper proposes an effective way to eliminate the reactive power-sharing errors that is compatible with droop control. The virtual synchronous generator technique was employed to estimate and compensate reactive power-sharing error. The basic idea is to inject a disturbance at active power loop for all parallel inverters from the central controller simultaneously. At the same time, the resultant signal from active power loop is processed through an integral term to fix reactive power errors. This method, in contrary to the virtual impedance method, doesn t depend on the microgrid parameters or configurations. Consequently, it supports the plug-and-play trait of modern microgrids. Moreover, stability and fast response are guaranteed using the proposed strategy. To ensure the applicability, comparisons with state of the art research are made in terms of six common scenarios. The comparison study considers the time of compensation, impact of active power change during compensation, frequency robustness, the effect of feeder impedances mismatch, the effect of local load, and the impact of having inverters with different capacities. Ultimately, the standard deviation, the approximation error, and the range are the performance indices used to have a fair comparison.