Study On Distribution Network Protection For Photovoltaic Plant Distributed Access

For the shortage of fossil energy, and the more and more serious greenhouse effect caused by using fossil energy, the development and utilization of renewable energy have been obtained the self-identity of the world. Photovoltaic power generation of renewable energy power generation represented in distributed power generation technology (DG, Distributed Generation) has developed fast. According to forecasting, photovoltaic power generation in21st Century will play an important role for the world energy consumption by bearing the main energy supply. As photovoltaic distributed power large access distribution network, to the traditional distribution network protection brought certain influence. This paper studies the effect of photovoltaic power station as the representative of distributed generation on distribution network, and put forward new protection principle and algorithm for the PV power station connected to distribution network, and carries out a series of simulation validation. On the basis of the related theoretical achievements, protection device for photovoltaic power station connected to distribution network is manufactured, and displayed in the demonstration engineering.Firstly, according to the control strategy of grid-connected mode and grid-connected photovoltaic power station, analysis of the impact of photovoltaic power station access to the protection of traditional distribution network, mainly influences the protection reliability, sensitivity and selectivity.Secondly, for the ublic connection point between photovoltaic power station and network, introduces the over current protection, over/under voltage protection, over/under frequency protection, islanding protection and reverse power protection and other new protection principle;Again, for single point or a small amount of the photovoltaic power station accessed, puts forward the short current calculation method of distribution network line base on the superposition and compensation principle,according to the influence of the photovoltaic power grid connected with distribution network, carry out the simulation analysis of different capacity of PV power station, influence on the protection of distribution network connection of the photovoltaic power station,different position of PV power station, influence on the protection of distribution network connection of the photovoltaic power station, photovoltaic power plant distributed access to distribution network protection setting and allocation principle is given. Then, based on the photovoltaic power station connected to distribution network protection principle, and development for PV power plant protection intelligent terminal, the terminal after power industry electric power system automation equipment quality inspection and test center testing, the indicators meet the design requirements, the protection action is correct. At the same time the device in Nanjing, Wuxi and other grid connection of photovoltaic power station site has been applied, devices running stability, fully meet the requirements of field operation.Finally, the summary and prospect are discussed in the scope of the photovoltaic power station access protection, and prospects the future coordination, high density of photovoltaic power plant distributed power access under the automatic protection system.