PHASE-CONTROL SWITCHING APPARATUS AND SWITCHING CONTROL METHOD FOR PHASE-CONTROL SWITCHING APPARATUS

摘要

A breaker (10) is connected between an electric power system and a transformer and is controlled to cut off or energize the transformer. A voltage measuring unit (35) measures each phase voltage between the breaker and the transformer. A residual-magnetic-flux calculating unit (50a) calculates a residual magnetic flux remaining on the transformer. A control unit (55) controls a switching timing of the breaker based on the residual magnetic flux. The residual-magnetic-flux calculating unit (50a) includes a voltage-change-rate detecting unit (52a) that detects a transformer-voltage change rate for each phase obtained by differentiating the phase voltage with respect to time, a residual-magnetic-flux detecting unit (53) that detects the residual magnetic flux based on the phase voltage, and a breaker-switching-state identifying unit (51) that detects a switching state of the breaker. The residual-magnetic--flux detecting unit (53) determines whether to recalculate the residual magnetic flux based on the transformer-voltage change rate and a predetermined threshold while the breaker-switching-state identifying unit (51) detects that the breaker is in an open state, and when it is determined to recalculate the residual magnetic flux, recalculates the residual magnetic flux.