Analysis of the Impact of MW-level Grid-connected Photovoltaic Power Station on Backup Automatic Switch in Distribution Network

With the continuous improvement of grid connected photovoltaic power station capacity, the influence on the reliable operation of backup automatic switch equipment in the distribution network is also increasing. The impact of PV on the backup automatic switch is mainly due to the fact that after the bus line is de-energized, the PV will continue to supply power to the busbar, which will affect the judgment of the busbar without pressure. In this paper, according to the setting value of backup automatic switch protection commonly used in distribution network, under different load-to-source capacity ratio, the influence of PV on the reliability of the backup automatic switch action and the change of the bus voltage of the PV-connected busbar after the main supply line is de-energized are quantitatively analyzed. Through simulation verification, it is proposed that the most fundamental method to avoid the influence of PV on backup automatic switch is to disconnect the PV power station after failure or loss of system power supply, so as to prevent the occurrence of isolated islands.