Strategy research of low voltage photovoltaic microgrid protection

In recent years, with rapid development of low voltage photovoltaic(PV) microgrid, control and protection technology associated with low-voltage microgrid has been the focus of research. Microgrid with its power can flow in both directions and fault current differs in the grid-connected mode and islanded mode, takes a great challenge to the traditional protection technology. To solve this problem, this paper proposes a new strategy to protect microgrid using the fault direction information, determines the switch´s fault direction through the energy function, locates the external fault, common bus fault and feeder fault using fault direction information based on stratification searching thought. For the feeder fault location, this article creates direction information matrix, switch-branch matrix and branch-switch matrix, to achieve fast feeder fault location and action through the matrix operation. The Simulation results show that, the micro-grid protection strategies propose to achieve fast fault location and isolation, effectively protect the security and stability of low voltage photovoltaic microgrid.