Kabushiki Kaisha Toshiba

Hiroshi Kusuyama

Minoru Saito

Yoshimasa Sato

Tadashi Koshizuka

Koichi Futagami

Nobuyuki Takahashi

Hiroyuki Maehara

Susumu Nishiwaki

Tsuyoshi Kokumai

Tadashi Koshiduka

An overvoltage suppression device which suppresses overvoltage that occurs when breakers which turn on/off the connection between a power source bus and a power transmission line, are turned on after the breakers are turned off. The overvoltage suppression device measures the waveform of voltage on the side of the power source and the voltage on the side of the power transmission line, and extracts the waveform of a component in a predetermined frequency band on the basis of the waveform obtained by multiplying the wave shape of the voltage on the side of the power source by the waveform of the voltage on the side of the power transmission line. The breakers are turned on on the basis of a cycle wherein the waveform is peaked.

Over-voltage suppression apparatus

To suppress the magnetizing inrush current occurring when supplying power of three phases of the transformer are performed simultaneously using three single-phase circuit breakers or a non-phase segregated operation-type circuit breaker, without providing a circuit breaker with a resistor or other equipment. A magnetizing inrush current suppression method for transformer suppresses a magnetizing inrush current occurring at the start of energizing of a three-phase transformer, when a three-phase power supplyis input to a terminal of each phase by means of a three-phase circuit breaker. In the method, by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side when three-phase AC voltages are applied in a steady state to the transformer, steady-state magnetic fluxfor each phase of the transformer is calculated, and the polarity and magnitude of the residual magnetic fluxof each phase of the transformer after the circuit breakershuts off the transformer are calculated, and the three-phase circuit breaker is caused to close simultaneously in a regionin which three phases overlap, each of the three phases having the polarity of the steady-state magnetic fluxequal to the polarity of the residual magnetic fluxfor each phase of the transformer.

Magnetizing inrush current suppression device and method for transformer

A first calculation part calculates the phase-to-phase steady-state magnetic flux of the three phases of the power supply. A second calculation part calculates the phase-to-phase residual magnetic flux of the three phases in the primary windings side of the transformer when the circuit breakers interrupt the transformer. A phase detection part detects a voltage phase at which polarity and magnitude of the calculated steady-state magnetic flux and residual magnetic flux coincide. Closing control part firstly causes only the circuit breakers of the two phases to close at the detected voltage phase, and then causes the circuit breaker of the remaining one phase to close.

Magnetizing inrush current suppression device for transformer and control method of same

Growing community of inventors

Kanagawa-ken, Japan

Hiroshi Kusuyama