Study On Protection Of Distribution Network With Distributed Photovoltaic Power Generation System

Solar energy is a clean and renewable energy,uses PV(Photovoltaic power generation) to protect the environment and conserve resources.Distributed Photovoltaic Power Generating SystemParallel operation can save costs, reduce energy consumption, make the system run more reliably and then achieve a diversity of power supply.It will give PV system itself and topological structure? operation mode of the gridhas a significant impact. When PV system accessing distribution network, it results in the distribution network from a simple single power radiating supply network into a plurality of power supply electricity networks, direction of the trend is no longer a single, short-circuit current magnitude and direction will be a huge change.This will not only lead to the existing distribution network relay protection occurring tripping, malfunction, sensitivity changed and other issues, but also product isolated island of PV system.Therefore, by the study of PV systems accessed to Power Network Relay Protection and then proposing appropriate protection scheme is very necessary,which will have a very important significance to improve power supply reliability and safe operation of power.This paper analyzes the impact of PV systems connected to the distribution network for relay protection, and then analyzes the reasons for the formation of the island as well as the impact.We use PSCAD platform to build simulation models to verify the impact of PV systems accessing for protection.Finally, we propose the distribution grid protection program including PV systems,Protection scheme constitute by the PV side protection and system side protection of the distribution network.Where in the PV side protection of systems is mainly anti-islanding protection; On the basis of a conventional protection,distribution network protection of system Side is improved, we propose adaptive protection scheme.finally we verify the feasibility and advantages of adaptive current protection scheme by the simulation software.Because the basic requirements of the PV system connected to the distribution network,changed the traditional distribution network with a single power source radiation type structure,access to distribution network of the PV capacity and access location will affect the magnitude and direction of the short-circuit current, the original distribution network protection may generate phenomenon of misoperation and refusing to move, using adaptive protection scheme can increase the scope of protection, meet the best running state of the protection.