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The lack of electrical power generation and the emphasis of environmental-protection consciousness have brought TPC (Taiwan Power Company) great trouble in building a large electrical generation plant. To overcome the problems of electrical power insufficiency and can’t quickly obtain enough power generation, dispersed generation is a feasible solution. Nevertheless, due to the different dispersed generation types and functions, some problems, such as protection coordination after short-circuit fault and the influence of harmonics to power supply quality, occurred in a distribution system when it is parallel with a few dispersed generations.
This thesis is mainly to investigate the influence of short circuit current, i.e., single line-to-ground fault, line-to-line fault, double-line-to-ground, and symmetrical three-phase fault, on the main system. First of all, we analogize out the calculation formula of short circuit current in the distribution systems with dispersed generations through basic circuit theory. Then we can obtain under what condition the short circuit current will be the maximum, and what relation is between the shunt position and the maximal short circuit current. Finally, we can verify the exactness by simulating those analogies through computer experiment.
As results from the simulation results, for a distribution system with two dispersed generations, the maximum short circuit current happens at symmetrical three phase fault and the fault point is adjacent to the main generator of this distribution system. The short circuit current will be smaller when the fault point is away from the main generator.
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