Reactive power sharing between parallel VSI into islanded microgrid based on PSO algorithm

For islanded microgrids, the power sharing and frequency restoration significantly influence MG stability and reliability. This paper proposes a control strategy based on the PSO algorithm to modify a conventional droop control method. The active power sharing between parallel connected VSI can be ensured accurately by selecting a proper value of gain of p-f droop equation at each DG controller, but this produces a small steady-state frequency deviation. On the other hand, a proper selection of the gain of the Q-V droop equation cannot ensure accurate reactive power sharing. This paper proposed a centralized control strategy to compensate steady-state voltage and frequency error and ensure reactive power sharing between DGs into islanded MG. In this paper, a PSO algorithm is adopted to calculate the parameters of the PI controller of each DG unit, thus making system operation more stable and efficient for both transient response and a steady-state period. The simulation results show the effectiveness of the proposed control strategy in terms of active and reactive power sharing and frequency restoration accuracy compared to a conventional droop method.