抄録
In the single-phase AC railroad electrification, the voltage unbalance of three-phase electric power system has to be reduced. For this purpose, three-phase power is converted to two-phase power by the Scott-connected transformer, and the electric power is received from a powerful or high-tension source.
Recently, regenerative braking has come to be applied to electric rolling-stocks, but occasionally the regenerative brake increases the voltage unbalance in the three-phase electric power source with the ordinary two-phase feeding system. So, in some cases unbalance power compensation may be found more profitable than the Scott-connected transformer.
This paper describes a theoretical study and results of a test on a mini-model which uses a scalene Scott-connected transformer, switched reactors and capacitors for the purpose of reducing the voltage unbalance in the three-phase electric power source. By this method, main phase (M) and teaser transformer (T) voltages of scalene Scott-connected transformer secondary side are decided by a single load power factor, and the sum of the capacities of the reactors and the capacitors is equal to the apparent power of single-phase load.
For example in SCR switched control of the reactors/capacitors which has four steps in power running and two steps in regenerative braking, the voltage unbalance in the three-phase electric power source can be reduced satisfactorily.
