Research Of Calculation For Micro Power Grid Short-circuit Based On Generalized Tellegen’s Theorem

With widely expanded research of distributed generation technologies, microgrid isbecoming more and more importance. The stable operation is the main control target ofmicrogrid. However, short-circuit of Microgrid has certain influence on network surge andrelaying protection. Therefore, research of microgrid short-circuit calculation has importantsignificance to the stable operation of the microgrid. Based on the mcrogrid short-circuitcalculation, the main contents are as follows:Based on the generation principle of the distributed power supply in microgrid, andanalyzing the work principle of the commonly used distributed power supply in microgrid:photovoltaic cells, wind turbines, fuel cells, on the basis of the existing models and therequirement of short circuit calculation, establishing the concise and practical mathematicalmodel of distributed power supply.Based on the mathematical model of current injection model power flow calculation, theestablishing short circuit calculation model of current injection type of microgrid, based onthe analysis of the small perturbation theorem of generalized Tellegen’s theorem, this paperproposes a microgrid short-circuit current calculation method on the generalized Tellegen’stheorem:depending on the different types of distribuited power injected into the node,find thecorresponding corrention eqution,several iterationsuntil the results satisfy the convergencecondition.In microgrid short-circuit calculation, a fast algorithm is proposed based on generalizedTellegen’s theorem: based on distributed power in microgrid has the characteristics ofintermittent and randomness,micro power connected microgrid is equivalent to increase asmall perturbation to the network node, so calculating the variation of current fast with thesmall perturbation theorem of generalized Tellegen’s theorem, can easily calculate shortcircuit current. This microgrid short-circuit calculation method based on generalizedTellegen’s theorem not only improves the computational efficiency, but broadens theapplication scope of generalized Tellegen’s theorem.