The feeding transformer for electric railways converts three-phase electric power into a pair of single-phase electric power for driving electric cars. In some case, however only a single-phase power feeding is required instead of a pair of single-phase power feeding. For example, a single-phase power feeding is suitable for car depots to prevent fluctuation of three -phase voltage. For this reason, authors have developed a small model single-phase feeding power conditioner (SFC). SFC is made of a pair of self-commutated inverters, which connect the two-phases of secondary side of feeding transformer and coupled with a DC side capacitor. Two inverters operate independently at Main-phase and Teaser in order to control reactive power. On the other hand, the power control circuit of SFC controls active power from the larger load phase circuit to the smaller one via the DC capacitor to keep the active power balanced between the Main-phase load and Teaser load. This paper describes the principle and test results of using SFC for unbalanced voltage compensation.