Research on Source-Network Coordination Voltage Control Strategy of Photovoltaic Power Plant Considering the Stability of Inverter Port Voltage

At present, the reactive power distribution method considering the reactive power adjustment capacity of the inverter in the photovoltaic (PV) power plant will lead to the output voltage of the inverter exceeding the limit. In particular, the PV inverter adopts the constant reactive power control to support the voltage at point of common coupling (PCC), which has a good effect in the steady-state operation. However, when the system is subject to transient disturbance, the PV inverter cannot flexibly support the voltage level of the system by changing the reactive power output. Therefore, this paper proposes a source-network coordination control strategy aiming at the stability of bus voltage at PCC and inverter port voltage. Firstly, the paper introduced the advantages of constant voltage control of PV inverter. Then, the voltage and reactive power control objectives of the PV Inverter in the PV power plant were calculated by considering the PCC voltage, tie lines, power collection lines, the power of transformers and the voltage loss to realize the voltage and reactive power balance control between the inverters. Finally, an actual PV power plant simulation model was built to analyse the PCC voltage under the two conditions of PV output fluctuation and system fault to verify the effectiveness of the control strategy proposed in this paper. The proposed strategy has engineering application value for the realization of closed-loop voltage control between the power grid and PV power plant and the improvement of the active response ability to the PCC voltage.