Reactive Power Compensation Control of PV Systems for Improved Power Transfer Capability in Weak Grid

This paper proposes a reactive power compensation control strategy to improve the power output capability of photovoltaic (PV) inverters in weak grid. The mathematical model of the PV power station under different resistance-inductance ratios of the power grid transmission line is established, and the phasor diagram is simplified. The ability of the grid to output rated power under different short circuit ratio (SCR) is discussed, and the relationship between the power factor (PF) and the minimum SCR required by the PV power plant to output rated power is obtained. Furthermore, a reactive power compensation control strategy is proposed, which can effectively compensate the output voltage, thereby improving the power output capacity of the PV power plant under the weak grid. Meanwhile, the optimal PF for the operation of the PV power plant, i.e. the optimal compensation value of the output voltage, is obtained. Finally, the effectiveness of the proposed control strategy is verified through simulation.