JP2010130849A - Excitation rush current restrainer of transformer and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively restrain an excitation rush current of a transformer even when a residual magnetic flux of the transformer is not known. <P>SOLUTION: There are provided a transformer 300 and a circuit breaker 200 which connects the transformer 300 to a power supply 100 and cuts it from the power supply. When the circuit breaker 200 is closed to excite the transformer 300, the excitation rush current that occurs on the transformer is restrained. Before closing the circuit breaker 200, an AC voltage is applied to the transformer 300 for saturation of magnetic flux of an iron core of the transformer. While a voltage is applied after the circuit breaker is closed, the circuit breaker is closed assuming a timing that the magnetic flux, induced by the transformer in a normal state, almost agrees with the magnetic flux saturated as the result of application of DC voltage, as a power feeding trigger. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a transformer inrush current suppressing device and method for suppressing a magnetizing inrush current generated when a transformer is connected to a power source.

  When no-load excitation is performed by turning on the power in a state where there is residual magnetic flux in the transformer core, a large excitation inrush current flows. It is generally known that the magnitude of this magnetizing inrush current is several times the rated load current of the transformer. When such a large magnetizing inrush current flows, the system voltage fluctuates, and if the voltage fluctuation is large, the consumer may be affected.

  Conventionally, as a method of suppressing the magnetizing inrush current, a breaker with a resistor formed by connecting a making resistor and a contact in series is connected in parallel with one of the main contacts of the breaker, and the breaker with a resistor is connected to the breaker There is known a method for suppressing an inrush current that is input before the main contact (see, for example, Patent Document 1).

  As another suppression method, when a direct grounding three-phase transformer is inserted with three single-phase circuit breakers, an arbitrary one phase is introduced in advance, and then the remaining two phases are introduced. A method of suppressing the magnetizing inrush current is already known (see, for example, Non-Patent Document 1).

In addition, as shown in Patent Document 2, when introducing a three-phase transformer of ineffective grounding system with three single-phase circuit breakers, any two phases are introduced in advance, and then the remaining one phase is introduced. A method for suppressing the magnetizing inrush current is also proposed.
In addition, as shown in Patent Document 3, a three-phase collective operation type breaker in which a non-effective grounding type three-phase transformer is operated simultaneously with a single operation mechanism for opening and opening a three-phase circuit breaker. There has also been proposed a method for suppressing the magnetizing inrush current when charging by means of a generator.

JP 2002-75145 A Japanese Patent Application No. 2008-162474 JP2008-160100 IEEE Trans. Vol.16, No.2 2001 “Elimination of Transformer Inrush Currents by Controlled Switching -Part I: Theoretical Considerations”

  In the method for suppressing the inrush current by the circuit breaker with a resistor described in Patent Document 1 described above, it is necessary to add a circuit breaker with a resistor to a normal circuit breaker. In this case, it cannot be denied that the size is increased. On the other hand, as a method for efficiently and economically suppressing the magnetizing inrush current without increasing the size of the circuit breaker, the methods for suppressing the magnetizing inrush current described in Non-Patent Document 1 and Patent Document 2 are proposed. Has been.

  However, as is well known, there is a three-phase collective operation type circuit breaker in which the closing / opening operation of a three-phase circuit breaker is operated simultaneously by one operating mechanism. The operation type circuit breaker has a drawback that it cannot be applied to the excitation inrush current suppression method described in Non-Patent Document 1. As means for solving this problem, a method for suppressing the excitation inrush current described in Patent Document 3 has been proposed.

  By the way, as described in Non-Patent Document 1, Patent Document 2, and Patent Document 3 described above, the magnitude of the residual magnetic flux of the iron core when the transformer is shut off is used to suppress the magnetizing inrush current when the transformer is turned on. It is necessary to understand this. It is known that the magnitude of the residual magnetic flux of the transformer is generally obtained by integrating the transformer terminal voltage when the transformer is cut off.

  The inrush current suppression method described in Non-Patent Document 1, Patent Document 2, and Patent Document 3 can be applied to any of these methods in consideration of the magnitude of this residual magnetic flux. Is determined. Therefore, in order to suppress the magnetizing inrush current by the methods described in Non-Patent Document 1, Patent Document 2 and Patent Document 3, the residual magnetic flux measured when the transformer is shut off is then turned on. It is assumed that it is maintained until the time.

  In a normal transformer shut-off / turn-in operation, since the residual magnetic flux measured when the transformer is shut off is maintained until the next time the transformer is turned on, Non-Patent Document 1, Patent Document 2, and Patent It is possible to suppress the magnetizing inrush current by the method described in Document 3. However, it is known that when a transformer field test / inspection is performed, the residual magnetic flux measured when the transformer is cut off is not necessarily maintained until the next time the transformer is turned on.

  For example, in transformer field tests and inspections, winding resistance measurements and current transformer polarity checks may be performed. Winding resistance measurement and current transformer polarity check are generally performed by applying a DC voltage to the transformer winding. For this reason, the residual magnetic flux generated when the transformer is shut off changes or disappears under the influence of the DC voltage application, and some DC magnetic flux remains in the iron core at the end of the test / inspection.

  Therefore, when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer, non-patent literature 1 and the method described in Patent Document 3 are not necessarily applicable. Moreover, in order to measure the residual magnetic flux when the transformer is shut off, as described in Non-Patent Document 1, etc., the transformer terminal voltage before and after the shut-off is measured, and this is integrated to calculate the residual magnetic flux. As described above, it is necessary to measure the magnetic flux.

  In the measurement of residual magnetic flux, there is no problem if the transformer (VT) etc. that can measure the transformer terminal voltage is given to the substation equipment, but if the transformer (VT) etc. is not given For example, when a transformer is cut off for inspection, it is necessary to temporarily add a simple instrument transformer (VT) or the like. However, temporarily adding a simple instrument transformer (VT), etc. is limited in terms of time to stop the equipment for inspection, operational restrictions of the power company, or installation space for existing substation facilities. It is not always possible for reasons such as physical restrictions and safety restrictions. In such a case, since the residual magnetic flux of the transformer cannot be grasped, the excitation inrush current cannot be suppressed by the methods described in Non-Patent Document 1, Patent Document 2, and Patent Document 3.

  Furthermore, as described in Patent Document 3, a method has been proposed in which residual magnetic flux is controlled by controlling the cutoff phase when the transformer is shut off, and measurement of the transformer terminal voltage is not required. When the primary side capacity of the transformer is large, the behavior of the magnetic flux at the time of interruption becomes random, and it becomes difficult to control the residual magnetic flux. Even in such a case, since the residual magnetic flux of the transformer cannot be grasped, the inrush current cannot be suppressed by the methods described in Non-Patent Document 1, Patent Document 2, and Patent Document 3.

  The object of the present invention is made in view of the above-described conventional technology, and is a field test involving application of a DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. The object is to provide a method and a magnetizing inrush current suppressing device that suppress the magnetizing inrush current when the transformer is turned on without adding equipment such as a circuit breaker with a resistor even when inspection is performed.

  Another object of the present invention is to provide a magnetizing inrush current at the time of turning on the transformer without adding equipment such as a breaker with a resistor even when the residual magnetic flux cannot be grasped when the transformer is cut off. And a magnetizing inrush current suppressing device.

In order to achieve the above object, the present invention provides a circuit comprising a transformer and a circuit breaker for turning on and off the power supply of the transformer, and for cutting off the transformer to excite the transformer. In the method of suppressing the excitation inrush current generated in the transformer when the transformer is turned on, a DC voltage is applied to the transformer before turning on the circuit breaker. Then, when the magnetic flux of the iron core of the transformer is saturated, the magnetic flux induced in the steady state in the transformer in the applied state after turning on the circuit breaker and the magnetic flux saturated as a result of applying the DC voltage substantially coincide with each other The circuit breaker is turned on with the function as an electrical turn-on target.
Moreover, the magnetizing inrush current suppression apparatus which implement | achieves such a method is also 1 aspect of this invention.

  According to the present invention, before applying the circuit breaker, by applying a DC voltage to the transformer and saturating the magnetic flux of the iron core of the transformer, the effect can be obtained even when the residual magnetic flux of the transformer is unknown. Therefore, it is possible to suppress the magnetizing inrush current of the transformer.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a transformer inrush current suppressing device and method for a transformer according to the present invention will be described with reference to the drawings.

(First embodiment)
(Constitution)
FIG. 1 is a block diagram showing a connection relationship between a magnetizing inrush current suppressing device for a transformer, a transformer, and a circuit breaker according to the first embodiment of the present invention. In FIG. 1, 100 is a power source, 200 is a circuit breaker, and 300 is a single-phase transformer that is turned on or off by the circuit breaker 200.

  Next, the connection relationship between the magnetizing inrush current suppressing device 600 and the main circuit will be described. 400 is a power supply voltage measuring device composed of a voltage transformer (VT) or the like for measuring the power supply voltage, and 600 is an excitation for outputting a closing command with a closing phase controlled to the main contact of the circuit breaker 200. This is an inrush current suppressing device.

  In the magnetizing inrush current suppressing device 600, reference numeral 601 denotes power supply voltage measuring means for taking in and measuring the power supply voltage output from the power supply voltage measuring device 400 such as VT. Reference numeral 602 denotes a closing phase setting unit which has a function of setting and holding a desired phase to be controlled by the closing phase control unit 603.

  Reference numeral 603 denotes a making phase control means. The making-up phase control means 603 performs control to electrically turn on the circuit breaker at a desired making-up phase of the power supply voltage. The closing phase control means 603 has a function of referring to the output of the voltage measuring means 601 and controlling the closing phase so that the circuit breaker 200 is electrically turned on at a desired closing phase of this voltage. 604 is a closing command output means having a function of receiving a signal output from the closing phase control means 603 and outputting a closing command (breaker closing command signal) to an operating mechanism that drives the main contact of the breaker 200. ing.

  The making phase control means 603 and the making command output means 604 in the present embodiment constitute the making control means of the present invention. Here, the closing phase control means 603 and the closing command output means 604 take into consideration the circuit breaker state quantity, that is, at least one of the circuit breaker open / close state and the operating speed, and the circuit breaker is turned on at a target phase. To control.

  Reference numeral 605 denotes a DC voltage application means, which has a function of applying a DC voltage between the terminals of the transformer 300 via the connection 606. The direct current application means 605 applies direct current to the iron core of the transformer 300 for a time sufficient for the iron core to be magnetically saturated.

  In the present embodiment, the DC voltage application unit 605 is configured in the same unit as the magnetizing inrush current suppression device 600, but may be configured as a separate unit. In the present embodiment, a single-phase circuit including a single-phase circuit breaker and a single-phase transformer has been described. However, the same system can be applied to a three-phase circuit including a three-phase circuit breaker and a three-phase transformer. Needless to say. In addition, the circuit breaker in the three-phase circuit may be either a phase operation type circuit breaker or a three-phase collective operation type circuit breaker.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 1st Embodiment is demonstrated below.

  In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core. In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied. Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 2 is a flowchart of the excitation inrush current suppression method according to the present embodiment, assuming the state of the transformer based on the above assumption (a state in which any DC magnetic flux remains in the transformer core or a case where the residual magnetic flux cannot be grasped) as an initial state. Show.

Step 1 : Apply a DC voltage across the transformer terminals.
A DC voltage from the DC voltage applying means 605 is applied between the terminals of the single-phase transformer 300 via the connection 606.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core is saturated. The DC voltage application time is a unique condition for each transformer.

Step 3 : Set the circuit breaker closing phase.
For example, as shown in FIG. 1, when the DC voltage is applied so that the iron core magnetic flux of the single-phase transformer 300 becomes about + 100% DC magnetic flux, The electrical closing phase of the circuit breaker is set to about 180 ° as the timing at which the magnetic flux induced in the steady state substantially coincides with the DC magnetic flux saturated as a result of applying the DC voltage. The closing phase of the circuit breaker 200 may be set each time, or a phase preset in the closing phase setting means 602 may be used. Further, it may be automatically set in conjunction with the DC voltage application means 605.

Step 4 : The circuit breaker is phase-controlled using the input phase set in Step 3 as the electrical input timing.
A timing chart of the phase control input of the transformer is shown in FIG. The circuit breaker is electrically turned on at the timing of “+ 100% DC magnetic flux = magnetic flux induced in a steady state by the power supply voltage”, that is, at a phase of 180 ° of the power supply voltage.

  By the above procedure, the transformer 300 can be turned on by suppressing the magnetizing inrush current by turning on the phase control. That is, in this embodiment, when the phase control of the transformer is turned on, the magnetic flux of the transformer core is always set to 100%, so that the magnitude of the residual magnetic flux of the iron core can be accurately grasped.

  As a result, it is possible to easily grasp the timing when the DC magnetic flux before being turned on and the magnetic flux induced in the steady state by the power supply voltage are equal, and the target phase of the power supply voltage is set so that the circuit breaker is turned on at that time. Turn on the circuit breaker. As a result, as shown in FIG. 3, the magnetic flux induced in the transformer core after turning on the circuit breaker is not accompanied by a transient phenomenon, so that the inrush current can be effectively suppressed.

  In the present embodiment, the circuit breaker timing is not necessarily the same as the magnetic flux induced in the steady state in the transformer in the state of power application after the circuit breaker is turned on and the magnetic flux saturated as a result of DC voltage application. It is not limited to. Even if the two substantially match, the excitation inrush current can be significantly suppressed. Similarly, the magnetic flux in the transformer core due to the application of the DC voltage need not be completely saturated, and may be almost saturated. Even in such a case, the magnetic flux induced in the steady state in the transformer in the applied state after the circuit breaker is turned on can be brought close to the magnetic flux induced in the transformer core as a result of applying the DC voltage, and the circuit breaker is in that phase. By turning on, the magnetizing inrush current can be suppressed.

(effect)
As is apparent from the above description, the transformer inrush current suppressing device and method according to the first embodiment have the following effects.

  In other words, even when field tests and inspections involving the application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer, are performed, apply a + 100% DC magnetic flux once. Thus, the magnetic flux of the transformer core can always be equal to the magnetic flux induced in the steady state. Therefore, without adding equipment such as a breaker with a resistor, or installing a voltage transformer (VT) for measuring the voltage at the transformer terminal, the circuit breaker will be turned on at an appropriate closing phase. By controlling so that the magnetizing inrush current when the transformer is turned on can be suppressed.

(Second Embodiment)
(Constitution)
FIG. 4 is a block diagram showing a connection relationship between the transformer inrush current suppressing device, the three-phase transformer, and the three-phase circuit breaker in the second embodiment of the present invention.

  In FIG. 4, reference numeral 110 denotes a power system bus (also referred to as a power supply bus), and 210 U to V are phase-operating circuit breakers in which main contacts of the phases are individually operated. Reference numeral 310 denotes a three-phase transformer that is turned on or off from the power supply bus 110 by each phase operation type circuit breaker 210. The primary winding 311 is Y-connected, and the secondary winding 312 and the tertiary winding 313 are Δ Connected.

  A configuration in which a three-phase transformer having a connection other than that shown in FIG. 4 is applied, such as a three-phase transformer in which the primary winding 311 and the secondary winding 312 are Y-connected and the tertiary winding 313 is Δ-connected. good. Further, although a direct grounding transformer is used in FIG. 4, a non-grounding transformer or a non-effective grounding transformer (resistance grounding transformer) may be applied.

  That is, the transformer in the present embodiment is installed in an effective ground system or an ineffective ground system, and each phase has two windings or three windings. In the case of two windings, the secondary winding is Δ-connected. In the case of 3 windings, the secondary winding or tertiary winding is Δ-connected, the primary winding is connected to Y-connection, and when installed in an effective grounding system, the neutral point of Y-connection Is grounded and installed in an ineffective grounding system, a three-phase transformer in which the neutral point of the Y connection is grounded via an element that is not grounded or has an impedance can be used.

Next, the connection relationship between the magnetizing inrush current suppressing device 610 and the main circuit will be described.
Reference numeral 410 denotes a power supply voltage measuring device composed of a voltage transformer (VT) or the like for measuring each phase (U, V, W) voltage of the power supply bus 110, and 610 denotes each phase operation type circuit breaker 210. This is a magnetizing inrush current suppressing device that outputs a closing command in which the closing phase is controlled individually for each phase with respect to the main contact.

  In the magnetizing inrush current suppressing device 610, reference numeral 611 denotes power supply voltage measuring means for taking in and measuring the power supply voltage of each phase (U, V, W phase) output from the power supply voltage measuring device 410 such as VT. Reference numeral 613 denotes a making phase control means. The making-up phase control means 613 performs control to electrically turn on the circuit breaker at a desired making-up phase of the power supply voltage. The closing phase control means 613 refers to the output of the voltage measuring means 611, and has a function of controlling the closing phase so that the circuit breakers 210U to 210W are electrically turned on individually for each phase in the desired closing phase of this voltage. I have.

  Reference numeral 614 denotes a closing command output means that has a function of receiving an output signal from the closing phase control means 613 and outputting a closing instruction for each phase individually to an operating mechanism that drives the main contact of the circuit breaker 210. Reference numeral 612 denotes a closing phase setting unit which has a function of setting and holding a desired phase to be controlled by the closing phase control unit 613.

  Reference numeral 615 denotes DC voltage application means, which has a function of applying a DC voltage between two terminals of the secondary winding 312 or the tertiary winding 313 which is the Δ connection of the three-phase transformer 310 via the connection 616. ing. In the example of FIG. 4, a DC voltage applying unit 615 is connected between the uv terminals of the secondary winding 312. Note that the DC voltage applying means 615 may be connected between the v-w terminals, the wu terminals, or the tertiary winding of the secondary winding 312. In the present embodiment, the DC voltage application unit 615 is configured in the same unit as the magnetizing inrush current suppression device 610, but may be configured as a separate unit.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 2nd Embodiment is demonstrated below. In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core.

  In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied. Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 5 shows a flowchart of the method for suppressing the inrush current according to the present embodiment, assuming the state of the transformer based on the above assumption (a state in which any DC magnetic flux remains in the transformer core or a case where the residual magnetic flux cannot be grasped) as an initial state. Show.

Step 1 : A DC voltage is applied between the terminals of the Δ connection of the three-phase transformer.
A DC voltage from DC voltage applying means 615 is applied between terminals of Δ connection of three-phase transformer 310 via connection 616.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core (corresponding phase core between the DC voltage application terminals) is saturated. The DC voltage application time is a unique condition for each transformer. In the example of FIG. 4, the DC voltage from the DC voltage applying unit 615 is applied between the u−v terminals of the secondary winding 312. In this case, as shown in FIG. 6, the DC magnetic flux 1010u of the U-phase iron core of the three-phase transformer 310 is about + 100%, and the DC magnetic flux 1010v of the V-phase iron core and the DC magnetic flux 1010w of the W-phase iron core are each about -50%. become.

Step 3 : Set the input phase of the 3-phase circuit breaker individually for each phase.
The closed first phase is a phase corresponding to the DC voltage application terminal, that is, a phase in which the iron core is saturated. The remaining two phases are a closed second phase and a closed third phase that are input after a preset time.

  For example, as shown in FIG. 4, when a DC voltage is applied between the u and v terminals of the secondary winding 312, the DC magnetic flux 1010u of the U-phase core of the three-phase transformer 310 is about Since the DC magnetic flux 1010v of the V-phase iron core and the DC magnetic flux 1010w of the W-phase iron core are each about -50%, the U-phase of the three-phase transformer is in the applied state after turning on the U-phase circuit breaker 210U. As the timing at which the magnetic flux induced in the steady state and the DC magnetic flux of the U phase saturated as a result of DC voltage application substantially coincide, the electrical application phase of the U-phase circuit breaker 210U is set to 180 °. The remaining two phases, that is, the electrical input phases of the V-phase circuit breaker 210V and the W-phase circuit breaker 210W are set to phases corresponding to 0 ° (or 180 °) of the U-phase voltage.

  The closing phase of the circuit breaker may be set each time, or a phase preset in the closing phase setting means 612 may be used. Further, it may be automatically set in conjunction with the DC voltage applying means 615. In short, the remaining two phases only have to be electrically charged at the phase voltage zero point of the closed first phase previously input after a preset time.

Step 4 : The three-phase circuit breaker 210 is phase-controlled individually for each phase using the input phase set in Step 3 as the electrical input timing.
The timing chart for turning on the phase control of the first closed phase is the same as the timing chart for turning on the phase control of the transformer in FIG. As shown in FIG. 4, when a DC voltage is applied between the uv terminals of the secondary winding 312, the U-phase circuit breaker 210 U is “steady state with + 100% DC magnetic flux of U phase = U phase power supply voltage. It is electrically supplied at the timing of the “induced U-phase magnetic flux”, that is, at a phase of 180 ° of the U-phase power supply voltage.

  An example of the closing timing of the first closed phase and the remaining two phases is shown in FIG. In the example of FIG. 7, the U phase is a closed first phase and is electrically turned on at a phase of 180 ° (timing A in FIG. 7). Subsequently, after one cycle, the remaining two phases, that is, the V phase and the W phase are electrically turned on at the timing of 180 ° of the U phase (timing B in FIG. 7).

  In this case, if only the U phase is seen, as in the first embodiment, it is possible to easily grasp the timing when the DC magnetic flux before being applied and the magnetic flux induced in the steady state by the power supply voltage are equal. The circuit breaker is turned on at the target phase of the power supply voltage so that the circuit breaker is turned on. As a result, since the U-phase magnetic flux induced in the U-phase iron core of the transformer is not accompanied by a transient phenomenon as in FIG. 3, it is possible to effectively suppress the U-phase excitation inrush current of the transformer.

  On the other hand, for the remaining two phases, ie, the V phase and the W phase, the DC magnetic flux 1010v of the V-phase core and the DC magnetic flux 1010w of the W-phase core are about −50% in a state where the U-phase transformer core is magnetically saturated. Therefore, the circuit breaker can be turned on at an appropriate timing while suppressing the magnetizing inrush current.

In particular, after the U phase, which is the first phase, is applied, the remaining two-phase V and W DC fluxes are rapidly suppressed due to the homogenization phenomenon of the iron core magnetic flux, and after one or a few cycles The V-phase and W-phase DC magnetic fluxes are negligible. In this case, as shown in FIG. 7, by turning on the V phase and the W phase at the timing of 180 ° of the U phase, which is the first input phase, the remaining V phase and W phase excitation inrush currents of the transformer It is possible to effectively suppress this.
The concept of suppressing the magnetizing inrush current of the three-phase transformer described above is described in detail, for example, in Non-Patent Document 1, and detailed description thereof is omitted here.

(effect)
As is apparent from the above description, the transformer inrush current suppressing device and method according to the second embodiment have the following effects.

  Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on.

  In particular, according to the present embodiment, the phase control of each phase operation type circuit breaker 210U to W can suppress the magnetizing inrush current, and the three phase transformer 310 can be turned on. When the method is applied, it is possible to provide an optimal excitation inrush current suppression method. In addition, according to the present embodiment, since the iron core is saturated by applying a DC voltage between the terminals of the secondary winding or the Δ winding of the tertiary winding, the grounding method of the Y connection on the primary side (directly) Regardless of the grounding, non-grounding method, or non-effective grounding method (resistance grounding method), a similar phase control throwing method can be applied.

(Third embodiment)
(Constitution)
FIG. 8 is a block diagram showing a connection relationship between the transformer inrush current suppression device, the three-phase transformer, and the three-phase circuit breaker according to the third embodiment of the present invention. Since the configuration of the third embodiment is the same as the configuration of the second embodiment except for the following points, detailed description is omitted.

  In FIG. 8, 220 is a three-phase batch operation type circuit breaker in which the main contacts of each phase are batch operated. Reference numeral 320 denotes a three-phase transformer that is turned on or off from the power supply bus 110 by a three-phase collective operation type circuit breaker 220. The primary winding 321 is Y-connected, and the secondary winding 322 and the tertiary winding 323 are Δ is connected. Zn is an impedance for grounding the neutral point of the primary winding 321.

  In addition, each phase operation circuit breaker may be applied instead of the three-phase collective operation type breaker 220, and each phase operation circuit breaker may be turned on or off simultaneously for three phases. Further, a configuration in which a three-phase transformer having a connection other than that shown in FIG. 8 is applied, such as a three-phase transformer in which the primary winding 321 and the secondary winding 322 are Y-connected and the tertiary winding 323 is Δ-connected. good. Moreover, although the non-effective grounding transformer (resistance grounding transformer) is used in FIG. 8, it is good also as a structure which applied a direct grounding transformer and a non-grounding transformer.

  The connection relationship between the magnetizing inrush current suppressing device 620 and the main circuit is the second embodiment except that, when the circuit breaker is a three-phase collective operation type circuit breaker 220, a closing command is output in a three-phase package. Is the same. Further, the configuration of the magnetizing inrush current suppressing device 620 is such that the closing command output means 624 receives the output signal of the closing phase control means 623 and issues a closing command in a three-phase manner to the operation mechanism that drives the main contact of the circuit breaker 220. The second embodiment is the same as the second embodiment except that a function for outputting is provided.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 3rd Embodiment is demonstrated below. In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core. In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied.

  Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 9 is a flowchart of the method for suppressing the inrush current according to the present embodiment, assuming that the state of the transformer based on the above assumption (a state in which some DC magnetic flux remains in the transformer core or the case where the residual magnetic flux cannot be grasped) is an initial state. Show.

Step 1 : A DC voltage is applied between the terminals of the Δ connection of the three-phase transformer.
A DC voltage from the DC voltage applying means 625 is applied between the terminals of the Δ connection of the three-phase transformer 320 via the connection 626.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core (corresponding phase core between the DC voltage application terminals) is saturated. The DC voltage application time is a unique condition for each transformer. In the example of FIG. 8, the DC voltage from the DC voltage applying means 625 is applied between the u−v terminals of the secondary winding 322. In this case, the same DC magnetic flux as in the second embodiment remains. That is, as in FIG. 6, the DC magnetic flux of the U-phase iron core of the three-phase transformer 320 is about + 100%, and the DC magnetic flux of the V-phase iron core and the DC magnetic flux of the W-phase iron core are each about -50%.

Step 3 : Set the input phase of the three-phase circuit breaker in three phases.
The phase having the maximum DC magnetic flux is a phase corresponding to the DC voltage application terminals, that is, a phase in which the iron core is saturated (this phase is referred to as X phase). Therefore, a three-phase circuit breaker is simultaneously turned on with an X-phase voltage zero point that transitions from the same polarity as the X-phase magnetic flux saturated as a result of DC voltage application to the opposite polarity as an electrical turn-on target.

  For example, as shown in FIG. 8, when a DC voltage is applied between the uv terminals of the secondary winding 322, the DC magnetic flux of the U-phase iron core of the three-phase transformer 320 is about + 100% as in FIG. Thus, the DC magnetic flux of the V-phase iron core and the DC magnetic flux of the W-phase iron core are each about -50%. Therefore, as shown in FIG. 10, 180 ° (timing C in FIG. 10) of the U-phase voltage at which the voltage transitions from positive polarity to negative polarity is set as the electrical input phase. The closing phase of the circuit breaker may be set each time, or a phase preset in the closing phase setting means 622 may be used. Further, it may be automatically set in conjunction with the DC voltage applying means 625.

Step 4 : The three-phase batch operation type circuit breaker 220 is phase-controlled in a three-phase batch with the closing phase set in Step 3 as an electrical closing timing. The timing chart for turning on phase control is the same as the timing chart for turning on phase control of the transformer of FIG. With the above procedure, the three-phase transformer 320 can be turned on by suppressing the magnetizing inrush current by turning on the phase control of the three-phase batch operation type circuit breaker 220.

(effect)
As is apparent from the above description, the transformer inrush current suppression device and method in the third embodiment have the following effects.

  Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on. In particular, this embodiment can provide an optimum excitation inrush current suppression method when a three-phase collective operation type circuit breaker is applied.

  In addition, according to the present embodiment, since the iron core is saturated by applying a DC voltage between the terminals of the secondary winding or the Δ winding of the tertiary winding, the grounding method of the Y connection on the primary side (directly) Regardless of the grounding, non-grounding method, or non-effective grounding method (resistance grounding method), a similar phase control throwing method can be applied.

(Fourth embodiment)
(Constitution)
FIG. 11: is a block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 3rd Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker.

  In FIG. 11, reference numeral 110 denotes a power system bus (also referred to as a power supply bus), and 210U to V are each phase operation type circuit breakers in which the main contacts of each phase are individually operated. Reference numeral 330 denotes a three-phase transformer which is turned on or off from the power supply bus 110 by each phase operation type circuit breaker 210. The primary winding 331 is Y-connected, and the secondary winding 332 and the tertiary winding 333 are Δ Connected. The three-phase transformer 330 is a direct grounding transformer in which the neutral point of the Y connection of the primary winding 331 is directly grounded.

  In addition, a direct grounding type three-phase transformer with a connection other than that shown in FIG. 11 is applied, such as a three-phase transformer in which the primary winding 331 and the secondary winding 332 are Y-connected and the tertiary winding 333 is Δ-connected. It is good also as the structure which carried out. Since the connection relationship between the magnetizing inrush current suppressing device 630 and the main circuit is the same as that of the second embodiment, detailed description thereof is omitted. Further, the configuration of the magnetizing inrush current suppressing device 630 is the same as that of the second embodiment except for the connection of the DC voltage applying means 635, and thus detailed description thereof is omitted.

  The DC voltage applying means 635 applies a DC voltage between any one of the three phases of the primary winding 331 that is the Y connection of the three-phase transformer 330 and the ground terminal via the connection 636. It has a function to do. In the example of FIG. 4, a DC voltage application unit 635 is connected between the U-phase terminal of the primary winding 331 and the neutral point (ground) terminal. The DC voltage applying means 635 may be connected between the V phase terminal and the neutral point (ground) terminal of the primary winding 331 and between the W phase terminal and the neutral point (ground) terminal. In the present embodiment, the DC voltage application unit 635 is configured in the same unit as the magnetizing inrush current suppression device 630, but may be configured as a separate unit.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 4th Embodiment is demonstrated below. In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core.

  In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied. Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 12 is a flowchart of the excitation inrush current suppression method according to the present embodiment, assuming the state of the transformer based on the above premise (a state in which some DC magnetic flux remains in the transformer core or the case where the residual magnetic flux cannot be grasped) as an initial state. Show.

Step 1 : A DC voltage is applied between the Y-connection terminal of the three-phase transformer and the ground.
A DC voltage from the DC voltage applying means 635 is applied between the terminal of any one of the three phases of the Y connection of the three-phase transformer 330 and the ground terminal via the connection 636.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core (phase core corresponding to the DC voltage application terminal) is saturated. The DC voltage application time is a unique condition for each transformer. In the example of FIG. 11, the DC voltage from the DC voltage applying unit 635 is applied between the U-phase terminal of the primary winding 331 and the neutral point (ground) terminal. In this case, as shown in FIG. 13, the DC magnetic flux 1030U of the U-phase iron core of the three-phase transformer 330 is about + 100%, and the DC magnetic flux 1030V of the V-phase iron core and the DC magnetic flux 1030W of the W-phase iron core are each about -50%. become.

Step 3 : Set the input phase of the 3-phase circuit breaker individually for each phase.
The closed first phase is a phase corresponding to the DC voltage application terminal, that is, a phase in which the iron core is saturated. The remaining two phases are a closed second phase and a closed third phase that are input after a preset time.

  For example, as shown in FIG. 11, when a DC voltage is applied between the U-phase terminal and the neutral point (ground) terminal of the primary winding 331, the U-phase iron of the three-phase transformer 330 as shown in FIG. The DC magnetic flux 1030U of the core is about + 100%, and the DC magnetic flux 1030V of the V-phase iron core and the DC magnetic flux 1030W of the W-phase iron core are each about -50%. As the timing at which the magnetic flux induced in the steady state in the U phase of the three-phase transformer substantially coincides with the DC magnetic flux of the U phase saturated as a result of applying the DC voltage, the electrical application phase of the U phase breaker 210U is 180 °. Set to. The remaining two phases, that is, the electrical input phases of the V-phase circuit breaker 210V and the W-phase circuit breaker 210W are set to phases corresponding to 0 ° (or 180 °) of the U-phase voltage.

  Note that the closing phase of the circuit breaker may be set each time, or a phase preset in the closing phase setting means 632 may be used. Further, it may be set automatically in conjunction with the DC voltage applying means 635.

Step 4 : The three-phase circuit breaker 210 is phase-controlled individually for each phase using the input phase set in Step 3 as the electrical input timing.
The timing chart for turning on the phase control of the first closed phase is the same as the timing chart for turning on the phase control of the transformer in FIG. As shown in FIG. 11, when a DC voltage is applied between the U-phase terminal of the primary winding 331 and the neutral point (ground) terminal, the U-phase circuit breaker 210U indicates that “+ 100% DC magnetic flux of U phase = U The phase-phase power supply voltage is electrically applied at the timing of the “U-phase magnetic flux induced in a steady state by the phase power supply voltage”, that is, at a phase of 180 ° of the U-phase power supply voltage.

The closing timings of the first closed phase and the remaining two phases are the same as the timing shown in FIG.
As shown in FIG. 7, the U phase is a closed first phase, and is electrically turned on at a phase of 180 ° (timing A in FIG. 7). Subsequently, after one cycle, the remaining two phases, that is, the V phase and the W phase are electrically turned on at the timing of 180 ° of the U phase (timing B in FIG. 7).

  With the above procedure, the three-phase transformer 330 can be turned on while suppressing the magnetizing inrush current by turning on the phase control of each phase operation type breaker 210U-W.

(effect)
As is clear from the above description, the transformer inrush current suppressing device and method in the fourth embodiment have the following effects.

  Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on. In particular, this embodiment is effective when it is not possible to apply a DC voltage to the Δ connection for convenience of equipment, and in the case of applying each phase operation type circuit breaker to a direct grounding three-phase transformer. Thus, it is possible to provide an optimal excitation inrush current suppression method.

(Fifth embodiment)
(Constitution)
FIG. 14: is a block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 3rd Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. Since the configuration of the fifth embodiment is the same as the configuration of the fourth embodiment except for the following points, detailed description is omitted.

  In FIG. 14, 220 is a three-phase batch operation type circuit breaker in which the main contacts of each phase are batch operated. Reference numeral 330 denotes a three-phase transformer that is turned on or off by the three-phase collective operation type circuit breaker 220. The primary winding 331 is Y-connected, and the secondary winding 332 and the tertiary winding 333 are Δ is connected. The three-phase transformer 330 is a direct grounding transformer in which the neutral point of the Y connection of the primary winding 331 is directly grounded.

  In addition, each phase operation circuit breaker may be applied instead of the three-phase collective operation type breaker 220, and each phase operation circuit breaker may be turned on or off simultaneously for three phases. In addition, a direct-phase three-phase transformer with a connection other than that shown in FIG. 14, such as a three-phase transformer in which the primary winding 331 and the secondary winding 332 are Y-connected and the tertiary winding 333 is Δ-connected, is applied. It is good also as the structure which carried out.

  The connection relationship between the magnetizing inrush current suppression device 640 and the main circuit is the same as that of the fourth embodiment, except that a closing command is output in a three-phase batch when the circuit breaker is a three-phase batch operation type circuit breaker 220. Is the same. In addition, the configuration of the magnetizing inrush current suppressing device 640 is such that the closing command output means 644 receives the output signal of the closing phase control means 643 and issues a closing command in three phases to the operating mechanism that drives the main contact of the circuit breaker 220. It is the same as that of 4th Embodiment except having the function to output.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 5th Embodiment is demonstrated below. In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core.

  In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied. Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 15 is a flowchart of the excitation inrush current suppression method according to the present embodiment, assuming the state of the transformer based on the above assumption (a state in which any DC magnetic flux remains in the transformer core or a case where the residual magnetic flux cannot be grasped) as an initial state. Show.

Step 1 : A DC voltage is applied between the Y-connection terminal of the three-phase transformer and the ground.
A DC voltage from the DC voltage applying means 645 is applied between the terminal of any one of the three phases of the Y connection of the three-phase transformer 330 and the ground terminal via the connection 646.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core (phase core corresponding to the DC voltage application terminal) is saturated. The DC voltage application time is a unique condition for each transformer. In the example of FIG. 14, the DC voltage from the DC voltage applying means 645 is applied between the U-phase terminal of the primary winding 331 and the neutral point (ground) terminal.

  In this case, as in the fourth embodiment, as shown in FIG. 13, the DC magnetic flux 1030U of the U-phase iron core of the three-phase transformer 330 is about + 100%, and the DC magnetic flux 1030V of the V-phase iron core and the direct current of the W-phase iron core. Each of the magnetic fluxes 1030W is about -50%.

Step 3 : Set the input phase of the three-phase circuit breaker in three phases.
The phase with the maximum DC magnetic flux is the phase corresponding to the DC voltage application terminal, that is, the phase in which the iron core is saturated (this phase is defined as the X phase). Therefore, a three-phase circuit breaker is simultaneously turned on with an X-phase voltage zero point that transitions from the same polarity as the X-phase magnetic flux saturated as a result of DC voltage application to the opposite polarity as an electrical turn-on target. For example, as shown in FIG. 14, when a DC voltage is applied between the U-phase terminal and the neutral point (ground) terminal of the primary winding 331, as shown in FIG. The DC magnetic flux of the U-phase iron core of the three-phase transformer 330 is about + 100%, and the DC magnetic flux of the V-phase iron core and the DC magnetic flux of the W-phase iron core are each about -50%. Therefore, as in the third embodiment, as shown in FIG. 10, the electrical phase is set to 180 ° (timing C in FIG. 10) of the U-phase voltage at which the voltage changes from positive polarity to negative polarity.

  The closing phase of the circuit breaker may be set each time, or a phase preset in the closing phase setting means 642 may be used. Further, it may be set automatically in conjunction with the DC voltage application means 645.

Step 4 : The three-phase batch operation type circuit breaker 220 is phase-controlled in a three-phase batch with the closing phase set in Step 3 as an electrical closing timing. The timing chart for turning on phase control is the same as the timing chart for turning on phase control of the transformer of FIG.

  With the above procedure, the three-phase transformer 330 can be turned on by suppressing the magnetizing inrush current by turning on the phase control of the three-phase batch operation type circuit breaker 220.

(effect)
As is clear from the above description, the transformer inrush current suppressing device and method in the fifth embodiment have the following effects. Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on.

  In particular, this embodiment is effective when a DC voltage cannot be applied to the Δ connection for convenience of equipment, and when a three-phase collective operation type circuit breaker is applied to a direct grounding three-phase transformer. In addition, it is possible to provide an optimal excitation inrush current suppression method.

(Sixth embodiment)
(Constitution)
FIG. 16: is a block diagram which shows the connection relationship of the magnetizing inrush current suppression apparatus of a transformer in 3rd Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker.

  In FIG. 16, 110 is a power system bus (also referred to as a power supply bus), and 220 is a three-phase batch operation type circuit breaker in which the main contacts of each phase are batch operated. Reference numeral 350 denotes a three-phase transformer that is turned on or off to the power supply bus 110 by the three-phase collective operation type circuit breaker 220. The primary winding 351 is Y-connected, and the secondary winding 352 and the tertiary winding 353 are Δ is connected. Zn is an impedance for grounding the neutral point of the primary winding 351. The three-phase transformer 350 is an ineffective grounding transformer in which the neutral point of the Y connection of the primary winding 351 is grounded via an impedance.

  In addition, non-effective grounding type three-phase transformers other than those shown in FIG. 16 such as a three-phase transformer in which the primary winding 351 and the secondary winding 352 are Y-connected and the tertiary winding 353 is Δ-connected. An applied configuration may be used. Moreover, it is good also as a structure which applied the non-grounding type | system | group 3 phase transformer.

  Since the connection relationship between the magnetizing inrush current suppressing device 650 and the main circuit is the same as that of the third embodiment, detailed description thereof is omitted. Further, the configuration of the magnetizing inrush current suppressing device 650 is the same as that of the third embodiment except for the connection of the DC voltage applying means 655, and thus detailed description thereof is omitted.

  The DC voltage application means 655 has a function of applying a DC voltage between terminals of any two phases of the three phases of the primary winding 351 that is the Y connection of the three-phase transformer 350 via the connection 656. ing. In the example of FIG. 16, a DC voltage application unit 655 is connected between the U-phase terminal and the V-phase terminal of the primary winding 351. The DC voltage application means 655 may be connected between the V-phase terminal and the W-phase terminal of the primary winding 351 and between the W-phase terminal and the U-phase terminal. In the present embodiment, the DC voltage application unit 655 is configured in the same unit as the magnetizing inrush current suppression device 650, but may be configured as a separate unit.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 6th Embodiment is demonstrated below. In this embodiment, for example, the transformer was cut off by conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. When the residual magnetic flux generated sometimes changes or disappears and the test / inspection ends, some DC magnetic flux remains in the transformer core.

  In addition, a case where some DC magnetic flux remains in the transformer core due to some other physical influence is applied. Furthermore, when the residual magnetic flux changes or disappears as a result of some physical influence on the transformer, and the residual magnetic flux cannot be grasped as a result, it is also applied as a similar case.

  FIG. 17 is a flowchart of the excitation inrush current suppression method according to the present embodiment, assuming that the state of the transformer based on the above premise (a state in which some DC magnetic flux remains in the transformer core or a case where the residual magnetic flux cannot be grasped) is an initial state. Show.

Step 1 : A DC voltage is applied between the Y connection terminals of the three-phase transformer.
A DC voltage from the DC voltage applying means 655 is applied between terminals of any two phases of the three phases of the Y connection of the three-phase transformer 350 via the connection 656.

Step 2 : Has the applied time elapsed until the transformer core is saturated?
The DC voltage is applied for a time sufficient to consider that the transformer core (phase core corresponding to the DC voltage application terminal) is saturated. The DC voltage application time is a unique condition for each transformer. In the example of FIG. 16, the DC voltage from the DC voltage applying unit 655 is applied between the U-phase terminal and the V-phase terminal of the primary winding 351. In this case, as shown in FIG. 18, the DC magnetic flux 1050U of the U-phase iron core of the three-phase transformer 330 is about + 100%, the DC magnetic flux 1050V of the V-phase iron core is about −100%, and the DC magnetic flux 1050W of the W-phase iron core. Becomes about 0%.

Step 3 : Set the input phase of the three-phase circuit breaker in three phases.
The phase with the maximum absolute value of the DC magnetic flux is the two phases corresponding to the DC voltage application terminals, that is, the two phases in which the iron core is saturated to the positive polarity and the negative polarity, respectively. Here, a phase having a positive magnetic flux is selected, and this is designated as an X phase. Therefore, a three-phase circuit breaker is simultaneously turned on with an X-phase voltage zero point that transitions from the same polarity as the X-phase magnetic flux saturated as a result of DC voltage application to the opposite polarity as an electrical turn-on target.

  For example, as shown in FIG. 16, when a DC voltage is applied between the U-phase terminal and the V-phase terminal of the primary winding 351, the DC magnetic flux of the U-phase iron core of the three-phase transformer 330 as shown in FIG. 1050U is about + 100%, the DC magnetic flux 1050V of the V-phase core is about -100%, and the DC magnetic flux 1050W of the W-phase core is about 0%. Accordingly, when a phase in which the DC magnetic flux is positive is selected, as shown in FIG. 19, the 180 ° U-phase voltage (timing D in FIG. 19) at which the voltage transitions from positive polarity to negative polarity is electrically applied. Set to.

  The closing phase of the circuit breaker may be set each time, or a phase preset in the closing phase setting means 652 may be used. Further, it may be set automatically in conjunction with the DC voltage application means 655.

Step 4 : The three-phase batch operation type circuit breaker 220 is phase-controlled in a three-phase batch with the closing phase set in Step 3 as an electrical closing timing. The timing chart for turning on phase control is the same as the timing chart for turning on phase control of the transformer of FIG.

  With the above procedure, the three-phase transformer 350 can be turned on while suppressing the magnetizing inrush current by turning on the phase control of the three-phase batch operation type circuit breaker 220. In the present embodiment, the case where the DC magnetic flux is selected as the positive polarity phase has been described in setting the input phase of the three-phase circuit breaker. However, the negative polarity phase may be selected. The case of selecting a negative magnetic flux will be described below by taking the case of FIGS. 16 and 18 as an example.

  In FIG. 18, the DC magnetic flux 1050U of the U-phase iron core of the three-phase transformer 330 is about + 100%, the DC magnetic flux 1050V of the V-phase iron core is about −100%, and the DC magnetic flux 1050W of the W-phase iron core is about 0%. . Therefore, when selecting a phase in which the DC magnetic flux has a negative polarity, as shown in FIG. 19, as shown in FIG. Set to phase. If the three-phase batch operation type circuit breaker 220 is phase-controlled at the 0 ° timing of the V phase, the three-phase transformer 350 can be turned on while suppressing the magnetizing inrush current.

(effect)
As is clear from the above description, the transformer inrush current suppressing device and method in the sixth embodiment have the following effects.

  Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on. In particular, the present embodiment is effective when a DC voltage cannot be applied to the Δ connection for convenience of equipment, and in a three-phase transformer of a non-grounding system or a non-effective grounding system (resistance grounding system) When a batch operation type circuit breaker is applied, an optimum excitation inrush current suppression method can be provided.

(Seventh embodiment)
(Constitution)
Since the structure of 7th Embodiment of this invention is the same as 6th Embodiment, description is abbreviate | omitted.

(Function)
The effect | action of the magnetizing inrush current suppression apparatus of the transformer in 7th Embodiment is demonstrated below. The flowchart of the magnetizing inrush current suppression method of the seventh embodiment is the same as that of the sixth embodiment (see FIG. 17) except for step 3 “set the three-phase circuit breaker closing phase in a three-phase batch” (see FIG. 17). Only 3 will be described in detail below.

Step 3 : Set the input phase of the three-phase circuit breaker in three phases.
The peak voltage timing (90 ° or 270 °) of the phase corresponding to the terminal to which no DC voltage is applied (this phase is assumed to be the X phase) is a candidate for the input phase. In general, the phase having the minimum absolute value of the DC magnetic flux is selected as the X phase.

  Of the two X-phase peak voltages, the remaining two phases, in which a DC voltage is applied to saturate the iron core, are induced in a steady state in each phase of the three-phase transformer in the applied state after the circuit breaker is turned on. The X-phase peak voltage that coincides with the period in which the polarity of the magnetic flux and the polarity of the DC magnetic flux of the relevant phase saturated as a result of DC voltage application are the same polarity is set as the final input phase, and this timing is electrically As an input target, a three-phase circuit breaker is simultaneously input.

  For example, as shown in FIG. 17, when a DC voltage is applied between the U-phase terminal and the V-phase terminal of the primary winding 351, the DC magnetic flux of the U-phase iron core of the three-phase transformer 330 as shown in FIG. 1050U is about + 100%, the DC magnetic flux 1050V of the V-phase core is about -100%, and the DC magnetic flux 1050W of the W-phase core is about 0%. Therefore, the timing (90 ° or 270 °) of the peak voltage of the W phase to which no DC voltage is applied is a candidate for the input phase.

  Next, the remaining two-phase state in which a DC voltage is applied to saturate the iron core is considered. As shown in FIG. 20, the polarity of the magnetic flux induced in the steady state in the U phase of the three-phase transformer in the applied state after the circuit breaker is turned on, and the DC magnetic flux of the U phase saturated as a result of applying the DC voltage (+ 100% ) Is a period a. On the other hand, the polarity of the magnetic flux induced in the steady state in the V phase of the three-phase transformer in the applied state after turning on the circuit breaker and the polarity of the DC magnetic flux (−100%) of the V phase saturated as a result of applying the DC voltage are The period having the same polarity is the period b.

  Accordingly, the timing of the W-phase peak voltage in the period in which the period a and the period b overlap becomes the final input phase. From the above, the input timing F of FIG. 20, that is, the W-phase voltage of 270 ° is set as the electrical input phase.

  With the above procedure, the three-phase transformer 350 can be turned on while suppressing the magnetizing inrush current by turning on the phase control of the three-phase batch operation type circuit breaker 220.

(effect)
As is apparent from the above description, the transformer inrush current suppressing device and method according to the seventh embodiment have the following effects.

  Add equipment such as a breaker with a resistor even when conducting on-site tests and inspections involving application of DC voltage to the transformer winding, such as measuring the winding resistance of the transformer and checking the polarity of the current transformer. In addition, it is possible to suppress the magnetizing inrush current when the transformer is turned on. In particular, the present embodiment is effective when a DC voltage cannot be applied to the Δ connection for convenience of equipment, and in a three-phase transformer of a non-grounding system or a non-effective grounding system (resistance grounding system) When a batch operation type circuit breaker is applied, an optimum excitation inrush current suppression method can be provided.

(Modification 1)
In the sixth embodiment and the seventh embodiment, the case where the circuit breaker is a three-phase collective operation type circuit breaker has been described. When the three-phase transformer is a non-grounded or non-effective grounding (resistive grounding) three-phase transformer, and the circuit breaker is a phase-operated circuit breaker, and each circuit breaker is turned on individually However, the magnetizing inrush current at the time of turning on the transformer can be suppressed by a method similar to that of the third embodiment. In this case, the method described in Patent Document 2 may be adopted as a method for setting the input phase and a method for controlling the input phase.

  According to this modification, it is effective when a DC voltage cannot be applied to the Δ connection due to facilities, and each phase of the non-grounding system or non-effective grounding system (resistance grounding system) When an operation type circuit breaker is applied, an optimum excitation inrush current suppression method can be provided.

(Modification 2)
Similarly, when the state of the residual magnetic flux of the transformer is unknown, by applying the methods of the first to seventh embodiments and the first modification, the equipment such as a breaker with a resistor is provided. It is clear that the magnetizing inrush current at the time of turning on the transformer can be suppressed without adding.

  Therefore, according to the present embodiment, there are reasons such as time restrictions for equipment stoppage for inspection, operational restrictions of electric power companies, physical restrictions such as installation space for existing substations, and safety restrictions. Therefore, even if it is impossible to add a voltage transformer (VT) etc. and the residual magnetic flux of the transformer cannot be grasped, it is possible to transform without adding equipment such as a breaker with a resistor. The magnetizing inrush current when the device is turned on can be suppressed.

  Further, according to this modification, even in a system in which the residual magnetic flux cannot be controlled by the breaker control of the transformer, the magnetizing inrush current at the time of turning on the transformer is reduced without adding equipment such as a breaker with a resistor. Can be suppressed.

The block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 1st Embodiment of this invention, a transformer, and a circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 1st Embodiment of this invention. Timing chart of transformer phase control input. The block diagram which shows the connection relationship of the magnetizing inrush current suppression apparatus of a transformer in 2nd Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 2nd Embodiment of this invention. The relationship between the DC voltage application terminal and DC magnetic flux in 2nd Embodiment of this invention. The timing chart of phase control injection | throwing-in of each phase operation type circuit breaker in a three-phase transformer. The block diagram which shows the connection relationship of the magnetizing inrush current suppression apparatus of a transformer in 3rd Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 3rd Embodiment of this invention. The timing chart of the phase control injection | throwing-in of the three-phase collective operation type circuit breaker with respect to the DC magnetic flux of the three-phase transformer in 3rd Embodiment of this invention. The block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 4th Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 4th Embodiment of this invention. The connection diagram which shows the relationship between the DC voltage application terminal and DC magnetic flux in 4th Embodiment of this invention. The block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 5th Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 5th Embodiment of this invention. The block diagram which shows the connection relation of the magnetizing inrush current suppression apparatus of a transformer in 6th Embodiment of this invention, a three-phase transformer, and a three-phase circuit breaker. The flowchart of the magnetizing inrush current suppression method of the transformer in 6th Embodiment of this invention. The connection diagram which shows the relationship between the DC voltage application terminal and DC magnetic flux in 6th Embodiment of this invention. The timing chart of the phase control injection | throwing-in of the three-phase collective operation type circuit breaker with respect to the DC magnetic flux of the three-phase transformer in 6th Embodiment of this invention. The timing chart of the phase control injection | throwing-in of the three-phase collective operation type circuit breaker with respect to the DC magnetic flux of the three-phase transformer in 7th Embodiment of this invention.

Explanation of symbols

200, 210, 220 ... Circuit breakers 300, 310, 320, 330, 350 ... Transformers 311, 321, 331, 351 ... Primary windings 312, 322, 332, 352 ... Secondary windings 313, 323, 333, 353 ... tertiary winding 400, 410 ... instrument transformer 600, 610, 620, 630, 640, 650 ... magnetizing inrush current suppression device 601, 611, 621, 631, 641, 651 ... voltage measuring means 602, 612, 622, 632, 642, 652 ... closing phase setting means 603, 613, 623, 633, 643, 653 ... closing phase control means 605, 615, 624, 634, 644, 654 ... DC voltage applying means

Claims (15)

An excitation generated in the transformer when the circuit breaker is turned on to energize the transformer. In the method of suppressing the magnetizing inrush current of the transformer that suppresses the inrush current,
Before turning on the circuit breaker, a DC voltage is applied to the transformer to saturate the magnetic flux in the iron core of the transformer,
The circuit breaker is turned on with an electrical application target of the timing at which the magnetic flux induced in a steady state in the transformer in the applied state after the circuit breaker is turned on and the magnetic flux saturated as a result of applying the DC voltage substantially coincide. A method for suppressing the magnetizing inrush current of a transformer. A primary winding connected to the Y connection, a three-phase transformer having a △ -connected secondary winding or tertiary winding, and the three-phase transformer is turned on and off from the three-phase power supply And a three-phase circuit breaker that suppresses excitation inrush current generated in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer. In the excitation inrush current suppression method of
Before turning on the three-phase circuit breaker, a DC voltage is applied between two terminals of the Δ connection of the three-phase transformer, and a specific phase of the three-phase transformer corresponding to the DC voltage application terminal of the Δ connection Saturate the magnetic flux of the iron core,
The timing at which the magnetic flux induced in a steady state in the specific phase in which the iron core is saturated in the applied state after turning on the three-phase circuit breaker and the magnetic flux in the specific phase saturated as a result of DC voltage application substantially coincide with each other. A method for suppressing the magnetizing inrush current of a transformer, characterized in that the three-phase circuit breaker is turned on as a proper turn-on target. The three-phase circuit breaker is a phase operation type circuit breaker,
The specific phase with the iron core saturated is defined as a closed first phase, and is induced in the closed first phase of the three-phase transformer in a steady state in the applied state after turning on the breaker of the closed first phase. With the timing when the magnetic flux and the magnetic flux of the closed first phase saturated as a result of DC voltage application substantially coincide with each other as an electrical application target, the closed first phase of the three-phase circuit breaker is applied,
The remaining two phases are electrically turned on at a phase voltage zero point of the first phase of the first closed pole that has been previously turned on after a preset time, and the inrush current suppression of the transformer according to claim 2 Method.   Three-phase circuit breakers are simultaneously turned on, with the voltage zero point at which the phase voltage of the specific phase that has saturated the iron core transitions from the same polarity to the opposite polarity as the magnetic flux of the relevant phase saturated as a result of DC voltage application as an electrical turn-on target The method according to claim 2, wherein the magnetizing inrush current is suppressed. A three-phase circuit comprising a three-phase transformer having a primary winding connected to a Y connection, and a three-phase circuit breaker for turning on and off the three-phase power supply of the three-phase transformer. In the method for suppressing the excitation inrush current of the transformer, the excitation inrush current generated in the three-phase transformer is suppressed when the three-phase circuit breaker is turned on to excite the three-phase transformer.
Before turning on the three-phase circuit breaker, a DC voltage is applied between any one of the three phases of the Y connection, which is the primary winding of the three-phase transformer, and the ground terminal, Saturate the magnetic flux of the iron core of the specific phase of the three-phase transformer corresponding to the DC voltage application terminal of this Y connection,
The magnetic flux induced in the steady state in the specific phase in which the iron core selected when the DC voltage is applied in the applied state after the three-phase circuit breaker is turned on and the magnetic flux in the specific phase saturated as a result of the DC voltage application are approximately A method for suppressing a magnetizing inrush current of a transformer, wherein the three-phase circuit breaker is turned on with the coincidence timing as an electrical turn-on target. The three-phase circuit breaker is a phase operation type circuit breaker,
The specific phase in which the iron core selected at the time of applying the DC voltage is saturated is a closed first phase, and the closed first phase of the three-phase transformer is in an applied state after the circuit breaker of the closed first phase is turned on. The closed first phase of the three-phase circuit breaker is set to an electrical input target at which the magnetic flux induced in a steady state at approximately the same time as the magnetic flux of the closed first phase saturated as a result of applying a DC voltage. ,
6. The inrush current suppression of a transformer according to claim 5, wherein the remaining two phases are electrically turned on after a preset time at the phase voltage zero point of the closed first phase that was previously turned on. Method.   The voltage zero point at which the phase voltage of the specific phase that has saturated the iron core selected when the DC voltage is applied transitions from the same polarity to the opposite polarity as the magnetic flux of the phase that is saturated as a result of the DC voltage application is 3 6. The method according to claim 5, wherein the phase breakers are turned on simultaneously. A three-phase transformer in which a primary winding is connected to a Y-connection, and a neutral point of the Y-connection is grounded via an element that is not grounded or has an impedance; Occurs in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer in a three-phase circuit comprising a three-phase circuit breaker that cuts off from a three-phase power source. In the transformer inrush current suppression method for suppressing the transformer inrush current,
Before turning on the three-phase circuit breaker, a DC voltage is applied between terminals of any two of the three phases of the Y connection, which is the primary winding of the three-phase transformer, Saturate the magnetic flux of a specific two-phase iron core of the three-phase transformer corresponding to the DC voltage application terminal,
Magnetic flux of the phase in which any one of the two specific phases obtained by saturating the iron core selected at the time of application of the DC voltage in the applied state after the three-phase circuit breaker is applied is saturated as a result of application of the DC voltage. A method for suppressing the inrush current of a transformer, wherein a three-phase circuit breaker is simultaneously turned on, with a voltage zero point transitioning from the same polarity to the opposite polarity as an electrical target. A three-phase transformer in which a primary winding is connected to a Y-connection, and a neutral point of the Y-connection is grounded via an element that is not grounded or has an impedance; Occurs in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer in a three-phase circuit comprising a three-phase circuit breaker that cuts off from a three-phase power source. In the transformer inrush current suppression method for suppressing the transformer inrush current,
Before turning on the three-phase circuit breaker, a DC voltage is applied between terminals of any two of the three phases of the Y connection, which is the primary winding of the three-phase transformer, Saturate the magnetic flux of a specific two-phase iron core of the three-phase transformer corresponding to the DC voltage application terminal,
In the specific two phases in which the iron core selected at the time of applying the DC voltage is saturated, the polarity of the magnetic flux induced in the steady state in each phase of the three-phase transformer in the applied state after turning on the circuit breaker, and the DC voltage It is a period in which the polarity of the magnetic flux of the phase saturated as a result of application is the same polarity,
In addition, the three-phase circuit breaker is simultaneously turned on, with the timing at which the remaining one-phase phase voltage, which was not selected when the DC voltage is applied to the three-phase transformer applied, being a peak, is an electrical turn-on target. Method for suppressing magnetizing inrush current of transformer.   The method according to claim 4, 7, 8, or 9, wherein the three-phase circuit breaker is a three-phase collective operation type circuit breaker. An excitation generated in the transformer when the circuit breaker is turned on to energize the transformer. In the transformer inrush current suppression device of the transformer that suppresses the inrush current,
DC voltage application means for saturating the magnetic flux of the iron core of the transformer before turning on the circuit breaker;
A circuit breaker closing control means for inputting a power supply voltage, a circuit breaker state quantity, and a circuit breaker closing command signal, and performing control to electrically turn on the circuit breaker at a desired power supply voltage applying phase. When,
As the desired closing phase, a closing phase setting for setting a timing at which the magnetic flux induced in the steady state in the transformer in the applied state after turning on the circuit breaker and the magnetic flux saturated as a result of applying the DC voltage substantially coincide with each other. Means,
An apparatus for suppressing an inrush current of a transformer, comprising: A primary winding connected to the Y connection, a three-phase transformer having a △ -connected secondary winding or tertiary winding, and the three-phase transformer is turned on and off from the three-phase power supply And a three-phase circuit breaker that suppresses excitation inrush current generated in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer. In the inrush current suppression device of
Before turning on the three-phase circuit breaker, a DC voltage is applied between two terminals of the Δ connection of the three-phase transformer, and a specific phase of the three-phase transformer corresponding to the DC voltage application terminal of the Δ connection DC voltage application means for saturating the magnetic flux of the iron core of
A circuit breaker closing control means for inputting a power supply voltage, a circuit breaker state quantity, and a circuit breaker closing command signal, and performing control to electrically turn on the circuit breaker at a desired power supply voltage applying phase. When,
As the desired input phase, a magnetic flux induced in a steady state in the specific phase in which the iron core is saturated in the applied state after the three-phase circuit breaker is input, and a magnetic flux in the specific phase that is saturated as a result of applying the DC voltage Closing phase setting means for setting the timing at which substantially matches,
An apparatus for suppressing an inrush current of a transformer, comprising: A three-phase circuit comprising a three-phase transformer having a primary winding connected to a Y connection, and a three-phase circuit breaker for turning on and off the three-phase power supply of the three-phase transformer. In the transformer inrush current suppression device for a transformer, which suppresses the magnetizing inrush current generated in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer,
Before turning on the three-phase circuit breaker, a DC voltage is applied between any one of the three phases of the Y connection, which is the primary winding of the three-phase transformer, and the ground terminal, DC voltage application means for saturating the magnetic flux of the iron core of the specific phase of the three-phase transformer corresponding to the DC voltage application terminal of the Y connection;
A circuit breaker closing control means for inputting a power supply voltage, a circuit breaker state quantity, and a circuit breaker closing command signal, and performing control to electrically turn on the circuit breaker at a desired power supply voltage applying phase. When,
As the desired input phase, a magnetic flux induced in a steady state in the specific phase in which the iron core is saturated in the applied state after the three-phase circuit breaker is input, and a magnetic flux in the specific phase that is saturated as a result of applying the DC voltage Closing phase setting means for setting the timing at which substantially matches,
An apparatus for suppressing an inrush current of a transformer, comprising: A three-phase transformer in which a primary winding is connected to a Y-connection, and a neutral point of the Y-connection is grounded via an element that is not grounded or has an impedance; Occurs in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer in a three-phase circuit comprising a three-phase circuit breaker that cuts off from a three-phase power source. In the transformer inrush current suppression device for the transformer that suppresses the magnetizing inrush current,
Before turning on the three-phase circuit breaker, a DC voltage is applied between terminals of any two of the three phases of the Y connection, which is the primary winding of the three-phase transformer, DC voltage application means for saturating the magnetic flux of a specific two-phase iron core of the three-phase transformer corresponding to a DC voltage application terminal;
A circuit breaker that performs control to input a power supply voltage, a circuit breaker state quantity, and a circuit breaker closing command signal to electrically turn on a three-phase circuit breaker simultaneously at a desired application phase of the power supply voltage. Input control means,
As the desired input phase, the phase voltage of any one of the two specific phases obtained by saturating the iron core selected at the time of applying the DC voltage in the applied state after applying the three-phase circuit breaker is the DC voltage applied The input phase setting means for setting a voltage zero point for transition from the same polarity to the opposite polarity as the magnetic flux of the phase saturated as a result,
An apparatus for suppressing an inrush current of a transformer, comprising: A three-phase transformer in which a primary winding is connected to a Y-connection, and a neutral point of the Y-connection is grounded via an element that is not grounded or has an impedance; Occurs in the three-phase transformer when the three-phase circuit breaker is turned on to excite the three-phase transformer in a three-phase circuit comprising a three-phase circuit breaker that cuts off from a three-phase power source. In the transformer inrush current suppression device for the transformer that suppresses the magnetizing inrush current,
Before turning on the three-phase circuit breaker, a DC voltage is applied between terminals of any two of the three phases of the Y connection, which is the primary winding of the three-phase transformer, DC voltage application means for saturating the magnetic flux of a specific two-phase iron core of the three-phase transformer corresponding to a DC voltage application terminal;
A circuit breaker that performs control to input a power supply voltage, a circuit breaker state quantity, and a circuit breaker closing command signal to electrically turn on a three-phase circuit breaker simultaneously at a desired application phase of the power supply voltage. Input control means,
As the desired input phase, in the specific two phases in which the iron core selected at the time of applying the DC voltage is saturated, it is induced in a steady state in each phase of the three-phase transformer in an applied state after the circuit breaker is turned on. The remaining one-phase phase, which is a period in which the polarity of the magnetic flux and the polarity of the magnetic flux of the phase saturated as a result of applying the DC voltage are the same polarity, and which is not selected when the DC voltage is applied to the three-phase transformer An input phase setting means for setting the timing when the voltage reaches a peak,
An apparatus for suppressing an inrush current of a transformer, comprising:

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