• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.54-60
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• 2003

Feeding traction loads from the public power system may lead to some current and voltage unbalance and consequently affects the operation of its energy-supply system and other equipment connected with it. This paper introduces an analysis of the current unbalance caused by the demands of an electric railway on a public power system. And the results with compensator and without compensator are simulated, and eventually the formula about the current unbalance is suggested. The Scott-connected transformer is adopted in Korea National Railway System. So Scott-connected transformer among the various transformer connection schemes is analyzed in this paper. Also, the formulas about the unbalance and compensating current can be derived by using two parameters(M-phase and T-phase current) of secondary Scott-connected transformer. So, the practical and accurate simulation can be done through dynamic models by using scheduling of traction.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3124-3132
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• 2011

Scott transformers have widely used to convert three phases into two phases and compensate the unbalance. Theoretically, the loads of the two secondary phases are same, no unbalance appears in the PCC(point of common coupling). But Due to the uncertainty of traction load, the unbalance are generally presented at the PCC. In this paper The amount of the voltage unbalance is expressed in the ratio of the negative sequence voltages to the positive sequence voltage. We tried to compensate the unbalance using SVC(Static Var Compensator）in an unbalance traction loads state by modeling. The SVC are installed and controlled to provide different amounts of reactive power compensation.