Magnetizing inrush current suppression device and method for transformer

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer which is installed in a non-effectively grounded system and the primary windings of which are connected in a Δ connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• integrating line-to-line voltages on the primary side or the secondary side or the tertiary side obtained when three-phase AC voltages are applied in a steady state to the transformer, to calculate the steady-state magnetic flux for each transformer phase;
• calculating the polarity and magnitude of the residual magnetic flux of each phase of the transformer after the circuit breaker shuts off the transformer;
• and
• causing the three-phase circuit breaker to close simultaneously in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux equal to the polarity of the residual magnetic flux for each phase of the transformer.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• performing an operation to open the circuit breaker at least once, and from the voltages measured by a voltage measuring device connected to a primary or secondary or tertiary terminal of the transformer at that time, measuring in advance the relation between the shutoff phase of the circuit breaker and the residual magnetic flux of the transformer;
• estimating the transformer residual magnetic flux from the relation by controlling the opening phase of the circuit breaker such that the shutoff phase is always the same when the circuit breaker shuts off the transformer;
• and
• causing, at the time of subsequent supplying power to the transformer, simultaneously closing of the three-phase circuit breaker in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux for each phase obtained when three-phase AC voltages are applied in the steady state to the transformer, which is equal to the polarity of the estimated residual magnetic flux for each phase of the transformer.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer which is installed in a non-effectively grounded system and the primary windings of which are connected in a Δ connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• performing an operation to open the circuit breaker at least once, and from the voltages measured by a voltage measuring device connected to a primary or secondary or tertiary terminal of the transformer at that time, calculating in advance the relation between the shutoff phase of the circuit breaker and the residual magnetic flux of the transformer;
• estimating the transformer residual magnetic flux from the relation by controlling the opening phase of the circuit breaker so that the shutoff phase is always the same when the circuit breaker shuts off the transformer;
• and
• causing, at the time of subsequent supplying power to the transformer, simultaneously closing of the three-phase circuit breaker in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux for each phase obtained when three-phase AC voltages are applied in the steady state to the transformer, which is equal to the polarity of the estimated residual magnetic flux for the each phase.

A magnetizing inrush current suppression device for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising:

• steady-state magnetic flux calculation means for calculating the steady-state magnetic flux for each phase of the transformer by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• residual magnetic flux calculation means for calculating the polarity and magnitude of the residual magnetic flux of each phase of the transformer after the circuit breaker shuts off the transformer;
• phase detection means for detecting and generating output of a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux equal to the polarity of the residual magnetic flux for each phase of the transformer;
• and
• closing means for causing simultaneous closing of the three-phase circuit breaker through the output of the phase detection means.

A magnetizing inrush current suppression device for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer which is installed in a non-effectively grounded system and the primary windings of which are connected in a Δ connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising:

• steady-state magnetic flux calculation means for calculating the steady-state magnetic flux for each phase of the transformer by integrating line-to-line voltages on the primary side or the secondary side or the tertiary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• residual magnetic flux calculation means for calculating the polarity and magnitude of the residual magnetic flux of each phase of the transformer after the circuit breaker shuts off the transformer;
• phase detection means for detecting and generating output of a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux equal to the polarity of the residual magnetic flux for each phase of the transformer;
• and
• closing means for causing simultaneous closing of the three-phase circuit breaker through the output of the phase detection means.

A magnetizing inrush current suppression device for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising:

• shutoff phase/residual magnetic flux relation measuring and holding means for holding the relation between the shutoff phase of the circuit breaker and the residual magnetic flux of the transformer;
• opening phase control means for controlling the opening phase of the circuit breaker such that the shutoff phase is always the same when the circuit breaker shuts off the transformer;
• output means for outputting an opening command to the circuit breaker through the output of the opening phase control means;
• phase detection means for detecting and generating output, at the time of subsequent supplying power to the transformer, of a region in which three phases of the transformer overlap, each of the three phases having the polarity of the steady-state magnetic flux for each phase obtained when three-phase AC voltages are applied in the steady state to the transformer, equal to the polarity of the residual magnetic flux for the each phase held by the shutoff phase/residual magnetic flux relation measuring and holding means;
• and
• closing means for causing simultaneous closing of the three-phase circuit breaker through the output of the phase detection means.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring phase voltages on the primary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• converting the measured phase voltages into line-to-line voltages, and integrating the line-to-line voltages to calculate the line-to-line steady-state magnetic flux;
• calculating the polarity and magnitude of each line-to-line residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing the three-phase circuit breaker to close simultaneously in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux equal to the polarity of the line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring phase voltages on the primary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• integrating the measured phase voltages to calculate the steady-state magnetic flux of each transformer terminal, and converting the steady-state magnetic flux of each transformer terminal into line-to-line steady-state magnetic flux;
• calculating the polarity and magnitude of each line-to-line residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing the three-phase circuit breaker to close simultaneously in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux equal to the polarity of the line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring line-to-line voltages on the primary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• integrating the measured line-to-line voltages to calculate each line-to-line steady-state magnetic flux of the transformer;
• calculating the polarity and magnitude of each line-to-line residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing the three-phase circuit breaker to close simultaneously in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux equal to the polarity of the line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring three-phase voltages to ground of the Δ-connected windings obtained when three-phase AC voltages are applied in a steady state to the transformer;
• integrating the measured voltages to ground to calculate each line-to-line steady-state magnetic flux of the transformer;
• calculating the polarity and magnitude of each line-to-line residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing the three-phase circuit breaker to close simultaneously in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux equal to the polarity of the line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• performing an operation to open the circuit breaker at least once, and from the voltages measured by a voltage measuring device connected to a primary or secondary or tertiary terminal of the transformer at that time, measuring in advance the relation between the shutoff phase of the circuit breaker and the residual magnetic flux of the transformer;
• estimating the transformer residual magnetic flux from the relation by controlling the opening phase of the circuit breaker such that the shutoff phase is always the same when the circuit breaker shuts off the transformer;
• and
• causing, at the time of subsequent supplying power to the transformer, simultaneously closing of the three-phase circuit breaker in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux obtained when three-phase AC voltages are applied in the steady state to the transformer, which is equal to the polarity of the estimated line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer which is installed in a non-effectively grounded system and the primary windings of which are connected in a Δ connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring phase voltages on the primary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• dividing the total of the measured phase voltages of three-phase by three to calculate a zero-phase voltage;
• subtract the zero-phase voltage from the phase voltage of each phase to calculate winding voltages of the three-phase transformer;
• integrating each of the calculated winding voltages to calculate each winding steady-state magnetic flux of the transformer
• calculating the polarity and magnitude of each winding residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing, at the time of subsequent supplying power to the transformer, simultaneously closing of the three-phase circuit breaker in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux obtained when three-phase AC voltages are applied in the steady state to the transformer, which is equal to the polarity of the estimated line-to-line residual magnetic flux.

A magnetizing inrush current suppression method for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer which is installed in a non-effectively grounded system and the primary windings of which are connected in Δ connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising the steps of:

• measuring line-to-line voltages of the Δ-connected windings obtained when three-phase AC voltages are applied in a steady state to the transformer;
• integrating the measured line-to-line voltages to calculate each winding steady-state magnetic flux of the transformer;
• calculating the polarity and magnitude of each winding residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• and
• causing, at the time of subsequent supplying power to the transformer, simultaneously closing of the three-phase circuit breaker in a region in which three phases of the transformer overlap, each of the three phases having the polarity of the winding steady-state magnetic flux obtained when three-phase AC voltages are applied in the steady state to the transformer, which is equal to the polarity of the estimated winding residual magnetic flux.

A magnetizing inrush current suppression device for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising:

• steady-state magnetic flux calculation means for calculating each line-to-line steady-state magnetic flux of the transformer by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side obtained when three-phase AC voltages are applied in a steady state to the transformer;
• residual magnetic flux calculation means for calculating the polarity and magnitude of each line-to-line residual magnetic flux of the transformer after the circuit breaker shuts off the transformer;
• phase detection means for detecting and generating output of a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux equal to the polarity of the line-to-line residual magnetic flux;
• and
• closing means for causing simultaneous closing of the three-phase circuit breaker through the output of the phase detection means.

A magnetizing inrush current suppression device for transformer, to suppress a magnetizing inrush current occurring at the start of energizing of a three-phase transformer the primary windings of which are connected in a Y connection and the secondary windings or tertiary windings of which are Δ-connected, when a three-phase power supply is input to a terminal of each phase of the transformer by means of a three-phase circuit breaker, comprising:

• means for performing an operation to open the circuit breaker at least once, and from the voltages measured at that time by a voltage measuring device connected to a primary or secondary or tertiary terminal of the transformer, measuring and holding in advance the relation between the shutoff phase of the circuit breaker and the residual magnetic flux of the transformer;
• opening phase control means for controlling the opening phase of the circuit breaker such that the shutoff phase is always the same when the circuit breaker shuts off the transformer;
• output means for outputting an opening command to the circuit breaker through the output of the opening phase control means;
• phase detection means for detecting and generating output, at the time of subsequent supplying power to the transformer, of a region in which three phases of the transformer overlap, each of the three phases having the polarity of the line-to-line steady-state magnetic flux obtained when three-phase AC voltages are applied in the steady state to the transformer, equal to the polarity of the line-to-line residual magnetic flux held in advance;
• and
• closing means for causing simultaneous closing of the three-phase circuit breaker through the output of the phase detection means.