To resolve a problem that, in a stationary reactive power compensation device (SVC) used for the purpose of countermeasures against voltage fluctuation in the case that respective phases are positive-negative imbalance loads such as in an arc furnace and the like, in a GPT installed for ground fault protection of a secondary circuit of a TCR adjusting a reactive power by means of phase control of a thyristor, although abnormal voltage oscillation is suppressed by inserting a braking resistor to a secondary side of the GPT conventionally, a DC component caused by positive-negative imbalance of a thyristor current flows into the GPT, which may cause generation of voltage oscillation, and to suppress an oscillation voltage generated in the GPT even when the thyristor current becomes positive-negative imbalanced.

A resistor is inserted to a primary side of the GPT to suppress that the DC current flows into the GPT, and thereby, suppress abnormal voltage oscillation.