| The distributed generation technology as an environmental efficient,and flexible power mode, is helpful to promote renewable energy development.With the increasing depletion of traditional fossil energy sources, photovoltaic power supply which is a kind of distributed generation gradually becomes an important source.However, large scale connected photovoltaic power parallel in distributed network access to the traditional radial distribution network from a single source network into a multiple power supply system, which will change the fault current level and direction,and thus brings the traditional distribution network protection nuisance tripping, misopreation, desensitization, reclosing failure and other problems, so the former overcurrent protection cannot hold any longer. This paper introduce the characteristics of photovoltaic power supply firstly, then introduced the principle of the distribution network of the three-current protection configuration, Relying on the company Baotou affiliated photovoltaic electricity substation access project, established a feeder with photovoltaic power supply and excluding pv power supply model, using PSCAD/EMTDC software simulation analysis. Based on these models, derived for three-phase short-circuit current value under different condition, comparison of two models of short-circuit current value, analysis on the original configuration of protection effect, According to the photovoltaic system layout pattern and main wiring design scheme selected device model, require the device meet the engineering measurement, protection and control hardware requirements. Referring to the comparison, the reasonable configuration, main transformer mothball protection device and circuit protection device.
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