Research Of Protection On Photovoltaic Grid-Connected Power Distribution System

With the human increasing energy demand and increasing depletion of fossil fuels andthe serious pollution of the ecological environment, the photovoltaic power generation hasbeen the recognition and attention of Governments, especially photovoltaic power grid hasbecome mainstream for photovoltaic applications. However, a large number of photovoltaicpower generation grid affect the network structure of the distribution network and the size anddistribution of the short-circuit current, caused many affects on relay protection of thedistribution network, so in-depth study of the protection about photovoltaic grid powerdistribution system has very important significance.Firstly, based on the physical connection and electrical relations between the variouscomponents of photovoltaic grid system, establishes a mathematical model of the entirephotovoltaic grid system, in-depth analysis and research many aspects of he line protectionafter photovoltaic grid, such as the sensitivity, the malfunction, the scope of protection,reclosing, and provide a theoretical foundation for the research of photovoltaic griddistribution system protection.Secondly, commences the research for current instantaneous trip protection, limit currentquick break protection, directional current protection, and isolated operation protection onbilateral power supply lines to protect applicable in the power distribution system. Proposed amethod to solve the problem of protection selective and the problem of malfunction byinstalling power direction blocking element when network operation; When isolated operation,according to the fault characteristics reflected by the type of fault to determine whether thefailure, without having to consider the influence to the short-circuit current due to the PVaccess, this protection method can meet the requirements for the protection fast and selectivityon PV isolated network operation.Finally, establishes a photovoltaic grid system architecture based on multi-agenttechnology, mainly include the communication Agent, network computing model Agent,islanding detection Agent and intelligent circuit breaker Agent module. This article focuses onthe implementation process about the Intelligent the breaker Agent module, simulationanalysis shows, the protection method more reliability, sensitivity and speed of mobilitycompared with conventional protection.