Improved Differential Protection Method for the Transmission Line of Photovoltaic Station

Due to the inherent features of the thyristors and the control strategies of the converters, the fault transient features of the photovoltaic (PV) inverters are totally different from synchronous generators. This makes the conventional current differential protection not applicable for transmission lines connected to photovoltaic station. Therefore, fault transient analysis of the photovoltaic inverters and the performance of the differential protection are carried out. It showed that the conventional differential protection has a high risk of refusing action. To cope with this problem, a phase-correction differential protection method is proposed. And it revealed the effectiveness of the new proposed method.