Research on relay protection of grid- connected photovoltaic power station in the plateau

Protection of power system is an extremely important aspect as the quality and scheme of protection decides system reliability, controllability and stability. This paper concentrates on the protection of distribution system in the light of recent developments of photovoltaic generator (PV) in Qinghai. When PV is connected to the distribution system, it may have some effect on the traditional current protection and lead to the protection mal-operation. By improving the traditional protection configuration, a new protection scheme is introduced to solve the problem. According to the connected point of PV, the protected feeders are divided into different zones, with directional pilot protection configured at the upstream side of PV and the overcurrent protection retained for the whole feeder. In order to make the value setting convenient and the fault cleaning quick, the definite time or inverse-time overcurrent protection is adopted for the feeders based on different locations of PV. No matter the output power of the PV changes, the fault can be reliably cleared with this protection scheme.