Refined Operation Control and Protection of PV Power Plant Collection Lines

The existing protection of the PV power plant collection line is staged overcurrent protection at the line exit. A fault at any point on the line causes the entire line to be completely removed, bringing unnecessary power loss. This paper addresses the problem that the existing protection is not selective and proposes a new collection line protection scheme based on the Distribution line Non-Communication Protection(DNCP). After a fault occurs, the Protection Terminal Unit(PTU) on the grid-connected side of the fault point system detects an evident overcurrent corresponding to the power side of the DNCP. The PTU on the PV generation unit side of the fault point detects a voltage dip corresponding to the load side of the DNCP. After the PTU at one end operates first, the PTU at the other end accelerates the action at this end based on the detected secondary disturbance information to achieve fault zone isolation and minimal cut-off. Through the analysis of calculation cases, it is verified that the new protection scheme can realize refined operation control and protection and improve operation efficiency compared with the original protection scheme.