JP7138585B2 - On-load tap-changers, on-load tap-changing transformers and voltage regulators - Google Patents

Description

TECHNICAL FIELD The present invention relates to an on-load tap changer, an on-load tap-changing transformer, and a voltage regulator having a switch with a mechanical contact and a switching switch using a semiconductor switch.

A so-called indirect switching voltage regulator (SVR: Step Voltage Regulator) consists of a series transformer whose secondary winding is connected in series with a distribution line and a regulating transformer whose secondary winding has multiple taps. , a tap changer for switching the taps of the regulating transformer, and a control section for controlling the tap changer. A regulating transformer has a primary winding connected in parallel to a distribution line. A tap changer is provided between each tap of the secondary winding of the regulating transformer and the primary winding of the series transformer. The controller controls the tap changer to adjust the regulated voltage applied from the regulated transformer to the series transformer to keep the distribution line voltage within a target range.

A so-called On-Load Tap Changer (OLTC) switches between an odd-numbered tap selector that selects odd-numbered taps, an even-numbered tap selector that selects even-numbered taps, and an even-numbered tap selector that selects even-numbered taps. and a switching switch (see Patent Literature 1). A switching switch is composed of, for example, a semiconductor switch composed of a thyristor pair and a switch having a mechanical contact connected in parallel with the semiconductor switch (see Patent Document 2).

In the above voltage adjustment device, if the semiconductor switch is accidentally opened or erroneously conducted, or if an overvoltage or short circuit occurs in the distribution system, a high voltage exceeding the withstand voltage is applied to the semiconductor switch of the changeover switch. or overcurrent may flow. On the other hand, in Patent Document 3, when an overvoltage is induced in the primary winding of a series transformer, an electromagnetic contactor connected between the primary windings is turned on, and a tap changer included in the tap changer selects a non-through tap. An automatic voltage regulator is described which protects the tap changer by turning on a semiconductor switch for the .

JP-A-6-118106 Japanese Patent Publication No. 47-26253 JP 2016-42279 A

However, the automatic voltage regulator described in Patent Document 3 uses a thyristor for tap selection to make the tap changer contactless (TVR: Thyristor type Step Voltage Regulator). is different from that described in Patent Document 2. For this reason, it is not possible to protect the changeover switch described in Patent Document 2 by a configuration in which a semiconductor switch selects the open tap. In addition, when the switching switch is protected by the electromagnetic contactor described in Patent Document 3, the delay time from the application of overvoltage to the switching switch to the start of the protection operation is relatively long. It may not be possible to protect the semiconductor switch of the device.

The present invention has been made in view of such circumstances, and its object is to provide an on-load tap-changer, an on-load tap-changing transformer, and an on-load tap-changing transformer capable of protecting a switching switch from overvoltage or overcurrent. An object of the present invention is to provide a voltage regulator.

An on-load tap changer according to the present invention includes an odd tap selector that selects odd-numbered taps of a tapped transformer, an even tap selector that selects even-numbered taps, the odd tap selector and an output terminal. and an even tap switch connected between said even tap selector and said output terminal, said odd tap switch and said even tap switch. includes a semiconductor switch and a switch having a mechanical contact connected in parallel to the semiconductor switch, a control unit for turning on/off the semiconductor switch and the switch having the mechanical contact, the odd tap switch and a self-firing circuit for self-firing a semiconductor switch included in one of the even tap switches based on a voltage applied to the semiconductor switch; and a detection unit for detecting overvoltage or overcurrent associated with the semiconductor switch. wherein, when the detection unit detects the overvoltage or the overcurrent, the control unit turns off the semiconductor switches included in both the odd-numbered tap switch and the even-numbered tap switch, and then switches off the semiconductor included in one of the odd-numbered tap switches and the even-numbered tap switches. A switch is turned on, and later a switch with mechanical contacts contained in said one is turned on.

In the present invention, odd-numbered taps and even-numbered taps of an externally connected tapped transformer are selected by the odd-numbered tap selector and the even-numbered tap selector, respectively, and the selected taps are selected as odd-numbered taps. A switch and an even tap switch selectively connect to the output terminals. Each of the odd-numbered tap switch and the even-numbered tap switch has a semiconductor switch and a switch having a mechanical contact connected in parallel, and a control unit turns on/off these switches. A semiconductor switch included in either the odd tap switch or the even tap switch is self-firing based on the voltage applied to it. For example, an output terminal connected to one winding of another transformer through which current is flowing is connected to the odd-numbered tap by a semiconductor switch included in the odd-tap switch, or the semiconductor included in the even-tap switch. Connected to even numbered taps by a switch.

When the control unit detects an overvoltage or overcurrent related to the semiconductor switches and turns off the semiconductor switches included in both the odd-numbered tap switch and the even-numbered tap switch, the output terminals are in a more reliable open state, and the voltage of the output terminals is accurate. , and the semiconductor switch included in the one immediately self-fires. After that, the control unit turns on the semiconductor switch included in the one as a confirmation. Subsequently, the control unit turns on the switch having the mechanical contact included in one of the above, thereby connecting the tap of the tapped transformer and one winding of the other transformer with the mechanical contact having a high breakdown resistance. Therefore, it is possible to protect the semiconductor switches included in the odd-numbered tap switches and the even-numbered tap switches corresponding to the switching switches from overvoltage or overcurrent.

In the on-load tap changer according to the present invention, the detection unit is a voltage detection unit that detects the voltage of the output terminal, and the control unit detects that the voltage detected by the voltage detection unit is higher than a predetermined voltage threshold. In this case, the overvoltage is detected.

In the present invention, for example, when the semiconductor switch that is on is accidentally turned off, one winding of the other transformer is opened and an overvoltage is generated at the output terminal. The control unit detects overvoltage by determining that the voltage at the output terminal is higher than a predetermined voltage threshold.

The on-load tap changer according to the present invention further includes a fast-blow fuse connected in series to the semiconductor switch included in the other of the odd-numbered tap switch and the even-numbered tap switch, and the detection section blows the fast-blow fuse. and a blowout detection unit for detecting the blowout, and the control unit detects the overcurrent when the blowout detection unit detects the blowout.

In the present invention, for example, when the off-off semiconductor switch is erroneously turned on, a short-circuit occurs between the taps via the odd-numbered taps and the even-numbered taps, and at least the other An overcurrent flows through the included semiconductor switch, blowing the fast-acting fuse connected in series with the semiconductor switch. The control unit detects overcurrent by detecting blowout of the rapid fuse.

In the on-load tap changer according to the present invention, the detection section is a current detection section that detects a current flowing through the output terminal, and the control section controls that the current detected by the current detection section exceeds a predetermined current threshold. If it is large, the overcurrent is detected, and if the semiconductor switch included in the one is turned on when the overcurrent is detected, the semiconductor switch is turned on/off without turning on/off the semiconductor switch. A switch with mechanical contacts included is turned on.

In the present invention, for example, when a short circuit occurs in the connection destination of the other winding of the other transformer, overcurrent flows to the output terminal connected to the one winding. The control unit detects overcurrent by determining that the current flowing through the output terminal is greater than a predetermined current threshold. If the control unit detects overcurrent while the semiconductor switch included in the one is turned on, the control unit immediately turns on the switch having the mechanical contact included in the one. As a result, when one of the semiconductor switches is already on, one of the mechanical contacts is closed without once turning off one of the semiconductor switches.

The on-load tap changer according to the present invention includes a second self-firing circuit for self-firing a semiconductor switch included in the other of the odd-numbered tap switch and the even-numbered tap switch based on the voltage applied to the semiconductor switch. Further prepare.

In the present invention, the semiconductor switch included in the other of the odd tap switch and the even tap switch is also self-ignited based on the voltage applied thereto. When the control unit detects an overvoltage or overcurrent related to the semiconductor switches and turns off the semiconductor switches included in both the odd-numbered tap switch and the even-numbered tap switch, the output terminals are in a more reliable open state, and the voltage of the output terminals is accurate. , and the semiconductor switch included in either one or the other quickly self-fires. As a result, even if the semiconductor switch included in the one does not self-ignite, the semiconductor switch included in the other self-ignites, so that the control unit turns on the switch having the mechanical contact included in the one. When doing so, the voltage applied to the mechanical contacts can be reliably lowered.

The on-load tap changer according to the present invention further comprises an abnormality detection section for detecting an abnormal state in which the switch having the mechanical contact included in one of the switches is not turned on, and the control section detects the abnormal state with the abnormality detection section. When detected, the semiconductor switch included in the both is turned off, the semiconductor switch included in the other is turned on, and then the switch having the mechanical contact included in the other is turned on.

In the present invention, when an abnormal state occurs in which the switch having a mechanical contact included in one of the above is not turned on even though the control unit has turned on the switch, the control unit is included in both of the above again. Turn off the semiconductor switch. In this case, the output terminal becomes open again, the voltage of the output terminal rises, and the semiconductor switch included in the other one quickly self-fires. After that, the control unit turns on the semiconductor switch included in the other one for confirmation. Subsequently, the control unit turns on the switch having the mechanical contact included in the other, whereby the tap of the tapped transformer and one winding of the other transformer are connected by the mechanical contact with a high breakdown resistance.

An on-load tap-changing transformer according to the present invention comprises the above-described on-load tap-changer and the tapped transformer.

In the present invention, tapped transformer taps are selected by an on-load tap changer. Therefore, an on-load tap changer (OLTC) capable of protecting the semiconductor switches included in each of the odd and even tap switches from overvoltage or overcurrent is replaced with a load ratio control transformer (LRT). ) can be applied to

A voltage regulator according to the present invention is a series transformer in which a three-phase secondary winding is connected in series to a distribution line for distributing a three-phase AC voltage from a power source to a load, and a primary winding is connected in three phases. and an on-load tap-changing transformer according to claim 7,
In the on-load tap-changing transformer, the primary winding of the tapped transformer is three-phase connected at a position closer to the load than the connection position of the series transformer in the distribution line, and the primary winding of the series transformer is A line is connected to the output terminal of the on-load tap changer.

In the present invention, the primary winding of a series transformer in which the secondary windings for three phases are connected in series to a three-phase distribution line is three-phase connected, and the on-load tap-changing transformer has a tapped transformer. The primary winding of the generator is three-phase connected to the distribution line. The output terminal of the on-load tap changer included in the on-load tap-changing transformer is connected to the primary winding of the series transformer. This regulates the three-phase voltage of the distribution line by selectively switching the taps of the on-load tap-changing transformer. Therefore, an on-load tap-changing transformer with an on-load tap-changer capable of protecting the semiconductor switches included in each of the odd and even tap switches from overvoltage or overcurrent is applied to the voltage regulator (SVR). can do.

According to the present invention, it is possible to protect semiconductor switches included in odd-numbered tap switches and even-numbered tap switches corresponding to switching switches from overvoltage or overcurrent.

1 is a block diagram showing a configuration example of a voltage regulator according to Embodiment 1; FIG. FIG. 2 is a block diagram showing a portion where an overvoltage occurs when a bidirectional thyristor is erroneously opened in the on-load tap changer according to Embodiment 1; 5 is a flow chart showing a processing procedure of a control unit for detecting an overvoltage of an output terminal and coping with it in the on-load tap changer according to the first embodiment; FIG. 9 is a block diagram showing a path through which overcurrent flows when a bidirectional thyristor is erroneously conductive in the on-load tap changer according to Embodiment 2; 10 is a flowchart showing a processing procedure of a control unit for detecting overcurrent flowing through a bidirectional thyristor in the on-load tap changer according to the second embodiment and coping with it. FIG. 11 is a block diagram showing a path through which overcurrent flows when a system short circuit occurs in the on-load tap changer according to Embodiment 3; 10 is a flow chart showing a processing procedure of a control unit for detecting an overcurrent flowing through an output terminal in an on-load tap changer according to Embodiment 3 and coping with the overcurrent. FIG. 11 is a block diagram showing a configuration example of a voltage regulator according to Embodiment 4; 13 is a flow chart showing a processing procedure of a control unit for detecting an abnormal state of a switch and turning on a substitute switch in the on-load tap changer according to Embodiment 4; FIG. 7 is a block diagram showing a configuration example of a voltage regulator according to Modification 1; FIG. 11 is a block diagram showing a configuration example of a voltage regulator according to Modification 2;

Hereinafter, the present invention will be described in detail based on the drawings showing its embodiments.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a voltage regulator according to Embodiment 1. FIG. In the figure, 1u, 1v, and 1w are distribution lines for distributing U, V, and W three-phase AC voltages from a power source to loads (none of which are shown) in the right direction of the paper surface. When so-called system switching occurs, the direction in which the AC voltage is distributed is reversed to the left on the page. The voltage regulator 100a includes a series transformer 2 in which secondary windings 21s, 22s and 23s are connected in series to the distribution lines 1u, 1v and 1w, respectively, and primary windings 31p and 32p to the distribution lines 1u, 1v and 1w. is connected, the secondary windings 31s, 32s of the regulating transformer 3 and the primary windings 21p, 22p, 23p of the series transformer 2. and a tap changer 4a. The regulating transformer 3 and the on-load tap changer 4a constitute an on-load tap-changing transformer 10a.

In series transformer 2, primary windings 21p, 22p, and 23p correspond to secondary windings 21s, 22s, and 23s, respectively. The primary windings 21p, 22p, and 23p are star (Y) connected, but may be open star connected or delta connected in correspondence with the secondary winding connection of the regulating transformer 3 . One end of each of the primary windings 21p, 22p, and 23p is connected to the neutral point N. Terminals u1, v1, and w1 are the other ends of the primary windings 21p, 22p, and 23p, respectively.

The regulating transformer 3 has a primary winding 31p connected between the distribution lines 1v and 1w, and a primary winding 32p connected between the distribution lines 1u and 1v. That is, in the regulating transformer 3, the primary windings 31p, 32p of the two transformers are V-connected to the distribution lines 1u, 1v, 1w, but the primary windings of the three transformers are V-connected to the distribution lines 1u, 1v, 1w. may be star-connected or delta-connected. The regulating transformer 3 has secondary windings 31s and 32s corresponding to the primary windings 31p and 32p, respectively. Each of the secondary windings 31s, 32s has odd numbered taps t1, t3, t5, t7, t9 and even numbered taps t2, t4, t6, t8 drawn between one end and the other. .

The on-load tap changer 4a has an odd tap selector 41 and an even It has a tap selector 42, an odd tap switch 5a and an even tap switch 6a connected between the odd tap selector 41 and even tap selector 42, respectively, and an output terminal 91. FIG. The on-load tap changer 4a also has an odd tap selector 43 that selects taps t1, t3, t5, t7, t9 and taps t2, t4, t6, t8 of the secondary winding 32s of the regulating transformer 3. and even tap selector 44, odd tap switch 7a and even tap switch 8a connected between output terminal 92 and odd tap selector 43 and even tap selector 44, respectively.

Any one of the taps t1 to t9 of the secondary winding 31s is connected to the output terminal 91 via either the odd tap selector 41 and the odd tap switch 5a or the even tap selector 42 and the even tap switch 6a. is connected to the terminal w1 on the primary side of the series transformer 2 via the terminal w1. Any one of the taps t1 to t9 of the secondary winding 32s is connected to the output terminal 92 via either the odd tap selector 43 and odd tap switch 7a or the even tap selector 44 and even tap switch 8a. is connected to the terminal u1 on the primary side of the series transformer 2 via the . A tap t5 of each of the secondary windings 31s and 32s is fixedly connected to a terminal v1 on the primary side of the series transformer 2 via an output terminal 93 .

The on-load tap changer 4a further selects the taps t1 to t9 by the odd tap selector 41 and the even tap selector 42, selects the taps t1 to t9 by the odd tap selector 43 and the even tap selector 44, A control unit 40 is provided for controlling on/off of the odd tap switches 5a and 7a and the even tap switches 6a and 8a. The control unit 40 includes an input unit 401 for inputting a plurality of contact signals, etc., which will be described later, and a driving unit 402 for turning on/off the odd tap switches 5a and 7a and the even tap switches 6a and 8a. It is connected.

The control unit 40 has a CPU (Central Processing Unit) (not shown), controls the operation of each unit according to a control program stored in advance in a ROM (Read Only Memory), and performs processing such as input/output and calculation. A computer program defining the procedure of each process by the CPU may be loaded in advance into a RAM (random access memory) using means not shown, and the loaded computer program may be executed by the CPU. 40 may consist of a microcomputer or a dedicated hardware circuit.

The odd tap switch 5a includes a series circuit of a bidirectional thyristor (corresponding to a semiconductor switch) 51 and a fast-blow fuse 53, and a switch 52 having a mechanical contact connected in parallel to the series circuit. That is, the bidirectional thyristor 51 and the switch 52 are connected in parallel. The even tap switch 6a includes a bidirectional thyristor 61 and a switch 62 having a mechanical contact connected in parallel with the bidirectional thyristor 61 . A series circuit of a straightening bidirectional thyristor 64 and a current limiting resistor 65 is connected in parallel to the bidirectional thyristor 61 .

The two-way thyristor 64 temporarily intermittently connects the taps via the current-limiting resistor 65 in the process of switching the taps t1 to t9 by the odd-numbered tap selector 41 and the even-numbered tap selector 42. for connecting and disconnecting the current-limiting resistor 65. A self-firing circuit 61b is connected to both ends of the bidirectional thyristor 61 and a trigger terminal (gate). Both ends and trigger terminals of the bidirectional thyristors 51 , 61 , 64 are connected to the driving section 402 . A drive coil for each of the switches 52 and 62 is connected to the drive section 402 .

The odd tap switch 7a includes a series circuit of a bidirectional thyristor 71 and a fast-blow fuse 73, and a switch 72 having a mechanical contact connected in parallel to the series circuit. That is, the bidirectional thyristor 71 and the switch 72 are connected in parallel. The even tap switch 8a includes a bidirectional thyristor 81 and a switch 82 having a mechanical contact connected in parallel with the bidirectional thyristor 81 . A series circuit of a bidirectional thyristor 84 for straightening and a current limiting resistor 85 is connected in parallel to the bidirectional thyristor 81 .

The two-way thyristor 84 temporarily intermittently connects the taps via the current-limiting resistor 85 in the process of switching the taps t1 to t9 by the odd-numbered tap selector 43 and the even-numbered tap selector 44. for connecting and disconnecting the current-limiting resistor 85. A self-firing circuit 81b is connected to both ends of the bidirectional thyristor 81 and the trigger terminal. Both ends and trigger terminals of the bidirectional thyristors 71 , 81 , 84 are connected to the driving section 402 . Drive coils of the switches 72 and 82 are connected to the drive section 402 .

Each of the quick-blow fuses 53 and 73 has alarm contacts 53b and 73b that conduct when blown. The switches 52, 62, 72, 82 are, for example, electromagnetic contactors. Each of the self-starting circuits 61b and 81b has a trigger element connected between the anode and the gate which turns on when the voltage applied across the two-way thyristors 61 and 81 reaches a specified operating voltage. be. Alarm contacts 53 b and 73 b are connected to input section 401 . The alarm contacts 53b and 73b correspond to the fusing detector.

Between the output terminals 91 and 93 is connected a primary winding of a measuring transformer PT1 for measuring the voltage of the output terminal 91 with respect to the potential of the output terminal 93, that is, the voltage applied to one end of the bidirectional thyristors 51 and 61. It is A primary winding of a measuring transformer PT2 is connected between the output terminals 92 and 93 to measure the voltage of the output terminal 92 with respect to the potential of the output terminal 93, that is, the voltage applied to one end of the bidirectional thyristors 71 and 81. It is A secondary winding of each of the instrumentation transformers PT1 and PT2 is connected to the input section 401 . The measuring transformers PT1 and PT2 correspond to the voltage detector.

A current transformer CT1 for detecting the current flowing through the output terminal 91, that is, the current flowing through the bidirectional thyristor 51 or 61 is provided between the connection point of the odd tap switch 5a and the even tap switch 6a and the output terminal 91. there is A current transformer CT2 for detecting the current flowing through the output terminal 92, that is, the current flowing through the bidirectional thyristor 71 or 81 is provided between the connection point of the odd-numbered tap switch 7a and the even-numbered tap switch 8a and the output terminal 92. there is A secondary winding of each of the current transformers CT1 and CT2 is connected to the input section 401 . The current transformers CT1 and CT2 correspond to current detection units.

In addition to the measuring transformers PT1 and PT2, or instead of the measuring transformers PT1 and PT2, another measuring transformer is connected between the output terminals 91 and 92, and the other measuring transformer may detect the voltage between the output terminals 91 and 92 by . In addition to the current transformers CT1 and CT2, or instead of the current transformers CT1 and CT2, the current flowing through the output terminal 93 may be detected by another current transformer. Further, the current flowing through at least one of the distribution lines 1u, 1v, 1w is detected by another current transformer, and the current flowing through at least one of the output terminals 91, 92, 93 is detected based on the transformation ratio of the series transformer 2. may be detected.

During the operation of the voltage regulator 100a configured as described above, the control unit 40 detects the voltages of the distribution lines 1u, 1v, and 1w using the measurement transformers (not shown), and based on the detected voltages, the odd tap selector 41 , 43 and even tap selectors 42, 44 to select each tap, a selection signal is applied to a drive mechanism (not shown). As a result, the taps t1 to t9 of the regulating transformer 3 are selected, the regulated voltage is applied to the series transformer 2, and the three-phase voltages of the distribution lines 1u, 1v, 1w are regulated. Since the control of the drive mechanism by this selection signal is well known, detailed description thereof will be omitted.

As each tap is selected by the odd-numbered tap selectors 41, 43 and the even-numbered tap selectors 42, 44, the control unit 40 switches the odd-numbered tap switch 5a or the even-numbered tap according to whether the selected tap is odd-numbered or even-numbered. The switch 6a is turned on, and the odd tap switch 7a or the even tap switch 8a is turned on. In this case, bidirectional thyristors 51 and 71 are used as odd tap switches 5a and 7a, respectively, and bidirectional thyristors 61 and 81 are used as even tap switches 6a and 8a, respectively.

When ending the operation of the voltage regulator 100a, the control unit 40 turns on the switch 52 or 62 instead of the bidirectional thyristor 51 or 61 that is turned on, and turns on the switch 52 or 62 instead of the bidirectional thyristor 71 or 81 that is turned on. Switch 72 or 82 is turned on. As a result, any one of the taps t1 to t9 of the secondary winding 31s of the regulating transformer 3 is connected to the terminal w1 on the primary side of the series transformer 2 through a mechanical contact, and the tap t1 of the secondary winding 32s t9 is connected to the terminal u1 on the primary side of the series transformer 2 via a mechanical contact.

During operation of the voltage regulator 100a, the control unit 40 outputs contact signals from the alarm contacts 53b and 73b of the fast-blow fuses 53 and 73, detected voltages from the measuring transformers PT1 and PT2, current transformers CT1 and Detected currents from each CT 2 are taken in via the input section 401 . The control unit 40 turns on/off the bidirectional thyristors 51, 61, 64, 71, 81, 84 and the switches 52, 62, 72, 82 by the drive unit 402 based on the contact signal, the detected voltage, and the detected current. drive.

In the first embodiment, the control unit 40 captures the detected voltages from the instrumentation transformers PT1 and PT2, respectively, and based on the captured detected voltages, the overvoltages of the output terminals 91 and 92, that is, the bidirectional thyristors 51, 61, and 71 , 81 is detected. Such an overvoltage is caused, for example, by turning off the bidirectional thyristors 51, 61 and 71, 81 against the control of the control unit 40 (hereinafter referred to as erroneous opening).

When the control unit 40 detects an overvoltage at each of the output terminals 91 and 92, the control unit 40 performs processing to protect the bidirectional thyristors 51, 61 and 71, 81 from destruction due to the overvoltage. When the overvoltage of the output terminal 91 is detected and when the overvoltage of the output terminal 92 is detected, the processing executed by the control unit 40 is clearly similar. will be described. When the bidirectional thyristor 51 erroneously opens and when the bidirectional thyristor 61 erroneously opens, the processing contents of the control unit 40 for detecting and dealing with overvoltage due to these causes are the same. A case where the direction thyristor 51 is erroneously opened will be described.

FIG. 2 is a block diagram showing a portion where an overvoltage occurs when the bidirectional thyristor 51 is erroneously opened in the on-load tap changer 4a according to the first embodiment. Since the connection configuration shown in FIG. 2 is the same as that shown in FIG. 1, description thereof is omitted. In the first embodiment, the alarm contacts 53b, 73b, the current transformers CT1, CT2, and the fast blow fuses 53, 73 are not used.

When the bidirectional thyristor 51 is controlled to be ON, a current proportional to the current of the distribution line 1w flowing in the secondary winding 23s flows through the bidirectional thyristor 51 in the primary winding 23p of the series transformer 2. is flowing. Here, when the bidirectional thyristor 51 is erroneously opened as indicated by a cross in FIG. 2, the primary winding 23p of the series transformer 2 is in an open state. voltage rises. This voltage reaches several kV in some cases.

The control unit 40 detects overvoltage at the output terminal 91 when the voltage detected by the instrumentation transformer PT1 is higher than a predetermined voltage threshold. When the overvoltage is detected, the bidirectional thyristor 51 or 61 is highly likely to be erroneously opened. The thyristor 61 (corresponding to the semiconductor switch included in one side) is self-ignited to promptly secure the connection between the terminal w1 and the secondary winding 31s. After that, the control unit 40 turns on the bidirectional thyristor 61, and later turns on the switch 62 (corresponding to a switch with a mechanical contact included on one side). As a result, the primary winding 23p of the series transformer 2, the mechanical contact of the switch 62, the even tap selector 42, and the secondary winding 31s of the regulating transformer 3 form a closed loop, and the overvoltage at the output terminal 91 is reduced. be canceled.

When the bidirectional thyristor 61 is erroneously opened, even when the bidirectional thyristor 61 cannot be self-ignited or turned on by the control of the control unit 40, the bidirectional thyristor 61 is turned on. The control unit 40 turns on the switch 62 irrespective of whether or not. After turning on the switch 62, the control unit 40 may turn off the bidirectional thyristor 61 or keep it on.

In order to turn off at least the bidirectional thyristors 51 and 61 above and cause the bidirectional thyristor 61 to self-ignite, the control unit 40 turns off all of the bidirectional thyristors 51, 61, 64, 71, 81, 84. . This is to raise the voltage at the output terminal 91 by completely opening at least the primary winding 23p of the series transformer 2 . The voltage of the output terminal 91 when the above-described trigger element included in the self-firing circuit 61b is turned on is set higher than the voltage threshold at which the control section 40 determines overvoltage. Therefore, the control unit 40 can detect the overvoltage of the output terminal 91 before the bidirectional thyristor 61 self-ignites.

In the first embodiment, all of the bidirectional thyristors 51, 61, 64, 71, 81, 84 are turned off in order to self-ignite the bidirectional thyristor 61, but this is not a limitation. do not have. By turning off all of the bidirectional thyristors 51, 61, 64, 71, 81, and 84, all of the primary windings 21p, 22p, and 23p of the series transformer 2 are opened, and the voltage at the output terminal 91 is increased. Rise. However, depending on the design of the series transformer 2, even when only the bidirectional thyristors 51, 61, 64 are turned off, the voltage of the output terminal 91 can be increased appropriately.

The operation of the on-load tap changer 4a described above will be described below with reference to a flow chart showing it. FIG. 3 is a flow chart showing a processing procedure of the control unit 40 for detecting an overvoltage of the output terminal 91 in the on-load tap changer 4a according to the first embodiment and coping with it. The processing shown in FIG. 3 is activated as appropriate during operation of the voltage regulator 100a. In the figure, steps surrounded by broken lines are not processes executed by the control unit 40, but steps executed by the self-firing circuit 61b by means of hardware.

When the process of FIG. 3 is started, the control unit 40 acquires the detected voltage of the transformer for measurement PT1 via the input unit 401 (S10), and checks whether the acquired detected voltage is higher than a predetermined voltage threshold. Determine (S11). If the detected voltage is not higher than the voltage threshold (S11: NO), the controller 40 shifts the process to step S10 to repeat acquisition of the detected voltage of the transformer PT1 for measurement.

If the detected voltage is higher than the voltage threshold (S11: YES), the control unit 40 determines that the overvoltage of the output terminal 91 is detected and detects all the bidirectional thyristors (bidirectional thyristors 51, 61, 64, 71, 81, 84; ) is turned off (S13), and waits for a predetermined first time (S14) until each thyristor is reliably turned off. During this time, the self-firing circuit 61b turns on the bidirectional thyristor 61 (S15), that is, self-firing (the same applies hereinafter). After that, the control unit 40 turns on the bidirectional thyristor 61 (S16), and later turns on the switch 62 (S17).

Next, the control unit 40 waits for a second period of time (S18) in order to wait for the mechanical contact of the switch 62 to turn on reliably, and then turns off the bidirectional thyristor 61 (S19) to perform the processing of FIG. finish. As described above, the processing of steps S18 and S19 may be omitted.

Note that when the bidirectional thyristor 51 is turned on in step S11, a short circuit between taps is prevented from occurring between the turn off of the bidirectional thyristor 51 in step S13 and the turn on of the bidirectional thyristor 61 in step S16. It is necessary to secure time until the bidirectional thyristor 51 is actually turned off. In the first embodiment, immediately after the bidirectional thyristor 51 is actually turned off and the gap between the taps is opened, the self-firing circuit 61b turns on the bidirectional thyristor 61 (that is, self-firing) in step S15. The open time can be minimized.

As described above, according to the first embodiment, the odd-numbered taps t1, t3, t5, t7, and t9 and the even-numbered taps t2, t4, t6, and t8 of the regulating transformer 3, which is a transformer with taps, are Odd tap selector 41 and even tap selector 42 select, and odd tap switch 5a and even tap switch 6a selectively connect the selected taps to output terminal 91, respectively. The odd tap switch 5a has a bidirectional thyristor 51 and a switch 52 having a mechanical contact connected in parallel, and the even tap switch 6a has a bidirectional thyristor 61 and a switch 62 having a mechanical contact connected in parallel. It is A control unit 40 turns on/off these switches. A bidirectional thyristor 61 included in one of the odd-numbered tap switch 5a and the even-numbered tap switch 6a is self-ignited by a self-ignition circuit 61b. The output terminal 91 connected to the primary winding 23p of the series transformer 2 through which the current is flowing is switched to any one of the odd numbered taps t1, t3, t5, t7 and t9 by the bidirectional thyristor 51 included in the odd tap switch 5a. or to any of the even-numbered taps t2, t4, t6, t8 by a bidirectional thyristor 61 included in the even-numbered tap switch 6a.

When the control unit 40 detects an overvoltage on the output terminal 91, that is, an overvoltage on the bidirectional thyristors 51 and 61, and turns off at least the bidirectional thyristors 51 and 61 included in both the odd tap switch 5a and the even tap switch 6a, the output The terminal 91 is brought into a more reliable open state, the voltage of the output terminal 91 is properly increased, and the two-way thyristor 61 included in the one is quickly self-ignited. After that, the control unit 40 turns on the two-way thyristor 61 included in the one for confirmation. Subsequently, the control unit 40 turns on the switch 62 having a mechanical contact included in one of the above, so that any one of the taps t2, t4, t6, and t8 of the regulating transformer 3 and the series transformer 2 are connected by the mechanical contact having a large breakdown resistance. is connected to the terminal w1 of the primary winding 23p to eliminate the overvoltage. Therefore, it is possible to protect the bidirectional thyristors 51 and 61 included in the odd-numbered tap switch 5a and the even-numbered tap switch 6a, respectively, which correspond to switching switches from overvoltage.

Further, according to the first embodiment, when the turned-on bidirectional thyristor 51 is erroneously turned off, the primary winding 23p of the series transformer 2 is opened and an overvoltage is generated at the output terminal 91. . The control unit 40 can detect overvoltage by determining that the voltage at the output terminal 91 is higher than a predetermined voltage threshold.

Furthermore, according to the first embodiment, the on-load tap changer 4a selects the taps t1 to t9 of the regulating transformer 3 . Therefore, the on-load tap-changer 4a capable of protecting the bidirectional thyristors 51 and 61 included in the odd-numbered tap switch 5a and the even-numbered tap switch 6a from overvoltage can be applied to the on-load tap-changing transformer 10a. can.

Further, according to the first embodiment, the primary windings 21p, 22p of the series transformer 2 in which the three-phase secondary windings 21s, 22s, 23s are connected in series to the three-phase distribution lines 1u, 1v, 1w, respectively. , 23p are star-connected, and the primary windings 31p, 32p of the regulating transformer 3 included in the on-load tap-changing transformer 10a are V-connected to the distribution lines 1u, 1v, 1w. Output terminals 91, 92, and 93 of on-load tap changer 4a provided in on-load tap-changing transformer 10a are connected to primary windings 23p, 21p, and 22p of series transformer 2, respectively. Accordingly, by selecting and switching the taps t1 to t9 of the adjustment transformer 3, the three-phase voltages of the distribution lines 1u, 1v, and 1w are adjusted. Therefore, the on-load tap-changing transformer 10a with the on-load tap-changer 4a capable of protecting the bidirectional thyristors 51 and 61 contained in the odd tap switch 5a and the even tap switch 6a, respectively, from overvoltage is used as a voltage regulator. 100a.

(Embodiment 2)
In the first embodiment, the control unit 40 detects overvoltage at the output terminals 91 and 92 and copes with it. It is a form that detects that the flow has been performed and copes with it. In the second embodiment, the control unit 40 acquires contact signals from the alarm contacts 53b and 73b, and based on the acquired contact signals, detects that an overcurrent has flowed through the bidirectional thyristors 51 and 71, that is, the bidirectional thyristor 51 and 71 are detected. Such overcurrent is caused, for example, by turning on the bidirectional thyristors 51, 61 and 71, 81 against the control of the control unit 40 (hereinafter referred to as erroneous conduction).

When the control unit 40 detects that an overcurrent has flowed through each of the bidirectional thyristors 51 and 71, the control unit 40 performs processing to prevent the bidirectional thyristors 51 and 61 and 71 and 81 from being affected by the overcurrent. This is because the processing executed by the control unit 40 is clearly similar between the case of detecting an overcurrent flowing through the bidirectional thyristor 51 and the case of detecting an overcurrent flowing through the bidirectional thyristor 71. In the first embodiment, processing when the control unit 40 detects that an overcurrent has flowed through the bidirectional thyristor 51 will be described. When the bidirectional thyristor 51 erroneously conducts and when the bidirectional thyristor 61 erroneously conducts, the processing contents of the control unit 40 for detecting and dealing with overcurrent due to these causes are the same. A case where bidirectional thyristor 61 is erroneously conductive will be described.

FIG. 4 is a block diagram showing a path through which overcurrent flows when the bidirectional thyristor 61 is erroneously turned on in the on-load tap changer 4a according to the second embodiment. Since the connection configuration shown in FIG. 4 is the same as that shown in FIG. 1, description thereof is omitted. In the second embodiment, the instrumentation transformers PT1 and PT2 and the current transformers CT1 and CT2 are not used.

In the state where the bidirectional thyristor 51 is controlled to be on, if the bidirectional thyristor 61 is erroneously conducted as indicated by the x mark in FIG. A short circuit will occur. Since the short-circuit current in this case reaches several kA in some cases, the fast-blow fuse 53 is quickly blown and the contact signal of the alarm contact 53b is turned on.

When the control unit 40 determines that the contact signal of the alarm contact 53b is on and detects that the fast-blow fuse 53 is blown, it detects that an overcurrent has flowed through the bidirectional thyristor 51 . If it is detected that an overcurrent has flowed, there is a high probability that the bidirectional thyristor 51 or 61 has erroneously conducted. Along with this, the bidirectional thyristor 61 is self-ignited to quickly secure the connection between the terminal w1 and the secondary winding 31s. After that, the control unit 40 turns on the bidirectional thyristor 61 and later turns on the switch 62 . As a result, the primary winding 23p of the series transformer 2, the mechanical contacts of the switch 62, the even tap selector 42 and the secondary winding 31s of the regulating transformer 3 form a closed loop. The inter-tap short-circuit state is eliminated when the fast-blow fuse 53 blows.

In order to turn off at least the bidirectional thyristors 51 and 61 above and cause the bidirectional thyristor 61 to self-ignite, the control unit 40 turns off all of the bidirectional thyristors 51, 61, 64, 71, 81, 84. . This processing and subsequent operation of the control unit 40 are the same as in the case of the first embodiment.

The operation of the on-load tap changer 4a described above will be described below with reference to a flow chart showing it. FIG. 5 is a flow chart showing a processing procedure of the control unit 40 for detecting overcurrent flowing through the bidirectional thyristor 51 in the on-load tap changer 4a according to the second embodiment and coping with it. The processing shown in FIG. 5 is activated as appropriate during operation of the voltage regulator 100a. In the figure, steps surrounded by broken lines are not processes executed by the control unit 40, but steps executed by the self-firing circuit 61b by means of hardware.

When the process of FIG. 5 is started, the control unit 40 takes in the contact signal of the alarm contact 53b via the input unit 401 (S20), and determines whether or not the taken contact signal is ON (S21). . If the contact signal is not ON (S21: NO), the control unit 40 shifts the process to step S20 to repeat acquisition of the contact signal of the alarm contact 53b.

If the contact signal is on (S21: YES), the controller 40 turns off all the bidirectional thyristors (S23). The subsequent processing from steps S24 to S29 is the same as the processing from steps S14 to S19 shown in FIG. 3 of the first embodiment, so description thereof will be omitted.

As described above, according to the second embodiment, when the control unit 40 detects that an overcurrent flows through the bidirectional thyristor 51, that is, an overcurrent related to the bidirectional thyristor 51, at least the odd tap switch 5a and the even tap switch 6a are turned off, the bidirectional thyristor 61 is self-ignited accordingly, and the switch 62 is turned on after the bidirectional thyristor 61 is turned on. As a result, any one of the taps t2, t4, t6, and t8 of the regulating transformer 3 and the terminal w1 of the primary winding 23p of the series transformer 2 are connected by a mechanical contact having a large breakdown resistance. Therefore, it is possible to prevent the overcurrent from remaining in the bidirectional thyristors 51 and 61 included in the odd-numbered tap switch 5a and the even-numbered tap switch 6a, respectively, which correspond to the switching switches.

Further, according to the second embodiment, when the bidirectional thyristor 61 that is turned off is turned on by mistake, any of the odd-numbered taps t1, t3, t5, t7, and t9 and the even-numbered tap t2 are turned on. , t4, t6, and t8, an overcurrent flows through at least the bidirectional thyristor 51, and the rapid fuse 53 connected in series to the bidirectional thyristor 51 blows. The control unit 40 can detect overcurrent by detecting the melting of the fast-blow fuse 53 based on the contact signal from the alarm contact 53b.

(Embodiment 3)
In the first embodiment, the control unit 40 detects overvoltage at the output terminals 91 and 92 and copes with the overvoltage. It is a form of detecting and coping with it. In the third embodiment, the control unit 40 captures the detected currents from the current transformers CT1 and CT2, respectively, and based on the captured detected currents, the overcurrents flowing through the output terminals 91 and 92, that is, the bidirectional thyristors 51, 61, and 71 , 81 is detected. Such an overcurrent occurs, for example, when a short circuit (hereinafter referred to as system short circuit) occurs in the connection destinations of the secondary windings 21 s, 22 s, and 23 s of the series transformer 2 .

When detecting an overcurrent flowing through the output terminals 91 and 92, the control unit 40 performs processing to protect the bidirectional thyristors 51, 61 and 71, 81 from destruction due to the overcurrent. Since the processing executed by the control unit 40 is clearly similar between the case of detecting an overcurrent flowing through the output terminal 91 and the case of detecting an overcurrent flowing through the output terminal 92, in the first embodiment, the output Processing when the control unit 40 detects an overcurrent flowing through the terminal 91 will be described.

FIG. 6 is a block diagram showing a path through which overcurrent flows when a system short circuit occurs in the on-load tap changer 4a according to the third embodiment. Since the connection configuration shown in FIG. 6 is the same as that shown in FIG. 1, description thereof is omitted. In Embodiment 3, the alarm contacts 53b, 73b and the measuring transformers PT1, PT2 are not used.

When a system short-circuit occurs while the bidirectional thyristor 51 is controlled to be on, as indicated by black arrows, the primary windings 22p and 23p of the series transformer 2, the fast-acting fuse 53, and the odd-numbered tap selection An overcurrent flows through the bidirectional thyristor 51 via the transformer 41 and the secondary winding 31 s of the regulating transformer 3 . On the other hand, when a system short circuit occurs while the bidirectional thyristor 61 is controlled to be on, as indicated by black arrows and dashed arrows, the primary windings 22p and 23p of the series transformer 2 and the even taps An overcurrent flows through the bidirectional thyristor 61 via the selector 42 and the secondary winding 31 s of the regulating transformer 3 .

The control unit 40 detects overcurrent flowing through the output terminal 91 when the current detected by the current transformer CT1 is greater than a predetermined current threshold. When this overcurrent is detected, there is a high probability that a system short circuit has occurred. 31s is promptly secured. Note that if the control unit 40 detects melting of the fast-blow fuse 53 by means of the alarm contact 53b before detecting an overcurrent flowing through the output terminal 91, the process according to the second embodiment is executed first, and the process according to the present embodiment is performed. It is assumed that the processing according to form 3 is not executed.

In order to secure the connection between the terminal w1 and the secondary winding 31s by the switch 62, all the bidirectional thyristors 51, 61, 64, 71, 81, 84 are turned off as in the first and second embodiments. Accordingly, the bidirectional thyristor 61 may be self-ignited, and the switch 62 may be turned on after the bidirectional thyristor 61 is turned on. However, unlike the first and second embodiments, the bidirectional thyristors 51 and 61 are not erroneously opened or erroneously conducted, so it is necessary to turn off these bidirectional thyristors 51 and 61 once for safety. There is no

Therefore, in the third embodiment, when an overcurrent flowing through the output terminal 91 is detected and the bidirectional thyristor 51 is turned on, the same processing as in the first and second embodiments is performed. When the two-way thyristor 61 is turned on, the switch 62 is immediately turned on. As a result, when the bidirectional thyristor 61 is turned on, the processing time is shortened, and a voltage high enough to operate the self-firing circuit 61b is not generated between the taps.

The operation of the on-load tap changer 4a described above will be described below with reference to a flow chart showing it. FIG. 7 is a flow chart showing the processing procedure of the control section 40 for detecting overcurrent flowing through the output terminal 91 in the on-load tap changer 4a according to the third embodiment and coping with it. The processing shown in FIG. 7 is activated as appropriate during operation of the voltage regulator 100a. In the figure, steps surrounded by broken lines are not processes executed by the control unit 40, but steps executed by the self-firing circuit 61b by means of hardware.

When the process of FIG. 7 is started, the control unit 40 acquires the detected current of the current transformer CT1 via the input unit 401 (S30), and determines whether or not the acquired detected current is greater than a predetermined current threshold. (S31). If the detected current is not greater than the current threshold (S31: NO), the control unit 40 shifts the process to step S30 to repeat taking in the detected current of the current transformer CT1.

If the detected current is greater than the current threshold (S31: YES), the control unit 40 determines whether or not the bidirectional thyristor 61 is controlled to be turned on (S32). If so (S32: YES), the process moves to step S37, which will be described later, to turn on the switch 62 immediately. Whether or not the bidirectional thyristor 61 is controlled to be ON is determined by the process of causing the odd tap selectors 41 and 43 and the even tap selectors 42 and 44 to select taps t1 to t9. is stored in a storage unit (not shown) of .

On the other hand, if the bidirectional thyristor 61 is not turned on (S32: NO), the control unit 40 turns off all the bidirectional thyristors (S33). The processing from steps S34 to S39 after this is the same as the processing from steps S14 to S19 shown in FIG. 3 of the first embodiment, so description thereof is omitted.

As described above, according to the third embodiment, when the control unit 40 detects an overcurrent flowing through the output terminal 91, that is, an overcurrent related to the bidirectional thyristors 51 and 61, the bidirectional thyristor 51 is turned on. When, at least the bidirectional thyristors 51 and 61 included in both the odd-numbered tap switch 5a and the even-numbered tap switch 6a are turned off, the bidirectional thyristor 61 is self-ignited accordingly, and the bidirectional thyristor 61 is turned on. After that, the switch 62 is turned on. As a result, any one of the taps t2, t4, t6, and t8 of the regulating transformer 3 and the terminal w1 of the primary winding 23p of the series transformer 2 are connected by a mechanical contact having a large breakdown resistance. Therefore, it is possible to protect the bidirectional thyristors 51 and 61 included in the odd-numbered tap switch 5a and the even-numbered tap switch 6a, which correspond to switching switches, from overcurrent.

Further, according to the third embodiment, when a short circuit occurs in the connection destinations of the secondary windings 21s, 22s, and 23s of the series transformer 2, the output terminals 91 and 93 connected to the primary windings 22p and 23p are overloaded. current flows. The control unit 40 can detect overcurrent by determining that the current flowing through the output terminal 91 is greater than a predetermined current threshold. If the control unit 40 detects an overcurrent while turning on the bidirectional thyristor 61, the control unit 40 immediately turns on the switch 62 having a mechanical contact. Therefore, when the bidirectional thyristor 61 is already turned on, the mechanical contact of the switch 62 can be closed without turning off the bidirectional thyristor 61 once.

(Embodiment 4)
While Embodiments 1 to 3 are forms in which no self-firing circuits are connected to the bidirectional thyristors 51 and 71, Embodiment 4 provides self-firing circuits 51b and 51b to the bidirectional thyristors 51 and 71, respectively. 71b is connected, and switches 62 and 82 have auxiliary contacts 62b and 82b, respectively. In the fourth embodiment, when an abnormal state occurs in which the switches 62 and 82 are not turned on, the control unit 40 turns on the switches 52 and 72 instead.

FIG. 8 is a block diagram showing a configuration example of a voltage regulator 100b according to the fourth embodiment. The voltage regulator 100b includes a series transformer 2, a regulation transformer 3, and an on-load tap changer 4b. The regulating transformer 3 and the on-load tap changer 4b constitute an on-load tap-changing transformer 10b. In the on-load tap changer 4b, compared with the on-load tap changer 4a of Embodiment 1, the odd tap switches 5b and 7b further have self-firing circuits 51b and 71b, respectively, and the even tap switches 6b and 8b respectively have self-firing circuits. further has auxiliary contacts 62b and 82b (corresponding to an abnormality detection section).

Each of the self-firing circuits 51b and 71b (corresponding to a second self-firing circuit) is a trigger that turns on when the voltage applied across the two-way thyristors 51 and 71 reaches a specified operating voltage. The element is connected between the anode and the gate. Each of the auxiliary contacts 62b and 82b is turned on/off simultaneously with the mechanical contacts of the switches 62 and 82 to output a contact signal. Auxiliary contacts 62 b and 82 b are connected to input section 401 . In addition, portions corresponding to those in the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

In the fourth embodiment, when the controller 40 detects an abnormal state in which the switches 62 and 82 are not turned on based on the contact signals received from the auxiliary contacts 62b and 82b, respectively, the switches 62 and 82 are replaced by the switch 52. and 72 are turned on. When detecting an abnormal state in which the switch 62 is not turned on and when detecting an abnormal state in which the switch 82 is not turned on, the processing executed by the control unit 40 to deal with these abnormal states is clearly similar. Therefore, the case where the control unit 40 detects an abnormal state in which the switch 62 is not turned on will be described below.

First, how the self-ignition circuit 51b operates when the voltage regulator 100b shown in FIG. 8 is applied to the first and third embodiments will be described with reference to a flowchart. The same applies to the action of the self-starting circuit 71b. Note that when the voltage regulator 100b is applied to the second embodiment, the fast-blow fuse 53 is melted due to the short circuit between the taps caused by the erroneous conduction of the bidirectional thyristor 61, and no voltage is applied to the self-firing circuit 51b. , the self-starting circuit 51b has no particular effect.

When the voltage regulator 100b is applied to Embodiments 1 and 3, in steps S15 and S35 of the flow charts shown in FIGS. 51b turns on the bidirectional thyristor 51, or either event occurs. Therefore, when the self-triggering circuit 61b cannot turn on the bidirectional thyristor 61, the self-triggering circuit 51b inevitably turns on the bidirectional thyristor 51, and the controller 40 switches in steps S17 and S37. Before turning on 62, the voltage at output terminal 91 can be reliably lowered.

On the other hand, in a state where the self-firing circuit 61b is capable of turning on the bidirectional thyristor 61, when the self-firing circuit 51b turns on the bidirectional thyristor 51 first, the controller 40 turns on the bidirectional thyristor 51 in steps S16 and S36. When the thyristor 61 is turned on, a short-circuit occurs between the taps and the fast-blow fuse 53 blows. Therefore, by turning on the switch 62 in steps S17 and S37 by the control unit 40, the bidirectional thyristors 51 and 61 can be protected from overvoltage and overcurrent as in the first and third embodiments.

Next, abnormality processing executed when the control unit 40 cannot turn on the switch 62 in the first to third embodiments will be described. Since the mechanical contact of the switch 62 is turned on when the voltage regulator 100b stops operating, it may fall into an abnormal state where it does not turn on due to poor contact of the contact after a long period of operation. could be. The control unit 40 can detect such an abnormal state by receiving the contact signal of the auxiliary contact 62b, which is turned on/off simultaneously with the main mechanical contact of the switch 62, through the input unit 401. FIG.

When the control unit 40 detects that the switch 62 is in an abnormal state, the control unit 40 turns on the switch 52 instead of the switch 62 . The processing procedure of the control unit 40 for turning on the switch 52 is similar to the processing procedure when the control unit 40 turns on the switch 62 in the first to third embodiments. Specifically, the control unit 40 turns off the bidirectional thyristors 51 and 61 included in at least the odd tap switch 5b and the even tap switch 6b, thereby causing the bidirectional thyristor 51 to self-fire, and further After turning on the bidirectional thyristor 51, the switch 52 is turned on.

The operation of the on-load tap changer 4b described above will be described below with reference to a flow chart showing it. FIG. 9 is a flow chart showing a processing procedure of the control unit 40 for detecting an abnormal state of the switch 62 and turning on the substitute switch 52 in the on-load tap changer 4b according to the fourth embodiment. The process of FIG. 9 is executed following the processes of steps S16, S26, and S36 shown in FIGS. 3, 5, and 7 of the first, second, and third embodiments, respectively. Specifically, step S17b in FIG. 9 corresponds to steps S17, S27, and S37 shown in FIGS. 3, 5, and 7, respectively. Also, steps S17b, S18b, and S19b correspond to steps S17, S18, and S19 shown in FIG. 3 of the first embodiment. The same applies to the second and third embodiments.

The control unit 40 turns on the switch 62 (S17b), waits for the second time (S18b), and then takes in the contact signal of the auxiliary contact 62b (S40). The control unit 40 determines whether or not the received contact signal is on (S41). It is turned off (S19b), and the process of FIG. 9 ends.

On the other hand, if the received contact signal is not ON (S41: NO), that is, if an abnormal state occurs in which the switch 62 is not turned ON, the control section 40 turns OFF the unreliable switch 62 (S42). Next, the control unit 40 turns off all the bidirectional thyristors (S43), waits for a predetermined first time (S44), and waits for each thyristor to turn off reliably. During this time, the self-starting circuit 51b or 61b turns on the bidirectional thyristor 51 or 61 (S45). In the second embodiment, when the fast-acting fuse 53 has already blown, no voltage is applied to the self-firing circuit 51b.

After that, the control unit 40 turns on the bidirectional thyristor 51 (S46). In the first and third embodiments, when the fast-acting fuse 53 is not blown and the bidirectional thyristor 61 is turned on in step S45, a short circuit between taps occurs in step S46. However, since the fast-acting fuse 53 is melted and the short circuit between the taps is eliminated immediately, there is no problem in the following processing steps. Further, in the second embodiment, when the fast-acting fuse 53 has already blown, no voltage is applied to the self-ignition circuit 51b, so the bidirectional thyristor 51 does not turn on in step S46. However, since the bidirectional thyristor 61 is turned on in step S45, the voltage of the output terminal 91 is surely lowered before the switch 52 is turned on in the next step S47.

Next, the controller 40 turns on the switch 52 (S47). When the two-way thyristor 61 is turned on in step S45 while the fast-acting fuse 53 has already blown in the second embodiment, a short circuit between the taps occurs in step S47. However, the current flowing through the bidirectional thyristor 61 crosses zero within several ms, the bidirectional thyristor 61 is turned off, and the short circuit between the taps is resolved, so no particular problem occurs.

Next, the control unit 40 waits for a second period of time (S48) in order to wait for the mechanical contact of the switch 52 to be reliably turned on, and then turns off the bidirectional thyristor 51 (S49) to perform the processing of FIG. finish. As described above, the processing of steps S48 and S49 may be omitted.

As described above, according to the fourth embodiment, the bidirectional thyristor 51 included in the other of the odd tap switch 5b and the even tap switch 6b is also self-fired by the self-fire circuit 51b. When the control unit 40 detects an overvoltage or overcurrent associated with the bidirectional thyristors 51 and 61 and turns off at least the bidirectional thyristors 51 and 61 included in both the odd tap switch 5b and the even tap switch 6b, the output terminal 91 is A more reliable open state is established, and the voltage of the output terminal 91 rises appropriately, and the two-way thyristor 61 or 51 included in one or the other quickly self-ignites. As a result, even if the bidirectional thyristor 61 included in the one does not self-ignite, the bidirectional thyristor 51 included in the other self-ignites. , the voltage applied to the mechanical contact can be reliably lowered when turning on the switch 52 having .

Further, according to the fourth embodiment, when an abnormal state occurs in which the switch 62 having a mechanical contact included in one of the above-mentioned switches 62 is turned on but the switch 62 is not turned on, the control unit 40 At least the bidirectional thyristors 51 and 61 included in both are turned off again. In this case, the output terminal 91 becomes open again, the voltage of the output terminal 91 rises, and the two-way thyristor 51 included in the other side quickly self-ignites. After that, the control unit 40 turns on the bidirectional thyristor 51 included in the other for confirmation. Subsequently, the control unit 40 turns on the switch 52 having a mechanical contact included in the other one, thereby causing any one of the taps t2, t4, t6, and t8 of the regulating transformer 3 and the series transformer 2 to is connected to the terminal w1 of the primary winding 23p. Therefore, the bidirectional thyristors 51 and 61 included in the odd tap switch 5b and the even tap switch 6b can be protected from overvoltage and overcurrent.

(Modification 1)
In the first to third embodiments, the current flowing through the switch 52 having a mechanical contact does not flow through the quick-blow fuse 53 . Similarly, the current flowing through the switch 72 may be configured to flow through the quick-break fuse 73 .

FIG. 10 is a block diagram showing a configuration example of a voltage regulator 100c according to Modification 1. As shown in FIG. The voltage regulator 100c includes a series transformer 2, a regulation transformer 3, and an on-load tap changer 4c. The regulating transformer 3 and the on-load tap changer 4c constitute an on-load tap-changing transformer 10c. The on-load tap changer 4c is different from the on-load tap changers 4a of the first to third embodiments in connection positions of the quick-blow fuses 53 and 73. FIG.

That is, the odd-numbered tap switch 5c has a parallel circuit of a bidirectional thyristor 51 and a switch 52 and a quick-break fuse 53 connected in series. The odd-numbered tap switch 7c has a parallel circuit of a bidirectional thyristor 71 and a switch 72 and a quick-break fuse 73 connected in series. In other words, the connection parts of the switches 52 and 72 are changed compared to the first to third embodiments. In addition, portions corresponding to Embodiments 1 to 3 are denoted by the same reference numerals, and descriptions thereof are omitted.

In Embodiments 1 to 3, the switches 52 and 72 were not turned on during operation of the voltage regulator 100a. Therefore, even if the connecting portions of the switches 52 and 72 are changed in Modification 1, the same effects as in Embodiments 1 to 3 can be obtained. Further, by adding self-firing circuits 51b and 71b to the bidirectional thyristors 51 and 71, respectively, and applying them to the first to third embodiments, the bidirectional thyristors 51 and 71 are more reliably protected from overvoltage and overcurrent. can also

(Modification 2)
In the first to third embodiments, one of the odd tap switches 5a, 7a and the even tap switches 6a, 8a refers to the even tap switches 6a, 8a. For example, if a fast-blow fuse 53 is connected in series to the bidirectional thyristor 51 included in the odd tap switch 5a, and the control unit 40 detects overvoltage and overcurrent associated with the bidirectional thyristors 51 and 61, the even tap switch finally Switch 62 contained in 6a was turned on.

In Modified Example 2, the relationships between even numbers and odd numbers are interchanged. For example, if a fast-blow fuse 63 is connected in series to the bidirectional thyristor 61 included in the even-numbered tap switch 6d, and the control unit 40 detects an overvoltage and overcurrent associated with the bidirectional thyristors 51 and 61, the odd-numbered tap switch finally Switch 52 included in 5d is turned on.

FIG. 11 is a block diagram showing a configuration example of a voltage regulator 100d according to Modification 2. As shown in FIG. The voltage regulator 100d includes a series transformer 2, a regulation transformer 3, and an on-load tap changer 4d. The regulating transformer 3 and the on-load tap changer 4d constitute an on-load tap-changing transformer 10d. Compared to the on-load tap changer 4a of Embodiments 1 to 3, the on-load tap changer 4d does not have the fast-blow fuses 53 and 73, and has the fast-blow fuses 63 and 83 added.

The odd tap switch 5 d includes a bidirectional thyristor 51 and a switch 52 connected in parallel to the bidirectional thyristor 51 . The even tap switch 6d includes a series circuit of a bidirectional thyristor 61 and a fast-blow fuse 63, and a switch 62 connected in parallel to the series circuit. That is, the bidirectional thyristor 61 and the switch 62 are connected in parallel. The fast blow fuse 63 has an alarm contact 63b that conducts when blown. The alarm contact 63b is connected to the input section 401. FIG.

The odd tap switch 7 d includes a bidirectional thyristor 71 and a switch 72 connected in parallel with the bidirectional thyristor 71 . The even tap switch 8d includes a series circuit of a bidirectional thyristor 81 and a fast-blow fuse 83, and a switch 82 connected in parallel to the series circuit. That is, the bidirectional thyristor 81 and switch 82 are connected in parallel. The fast blow fuse 83 has an alarm contact 83b that conducts when blown. The alarm contact 83b is connected to the input section 401. FIG. In addition, portions corresponding to Embodiments 1 to 3 are denoted by the same reference numerals, and descriptions thereof are omitted.

In Modification 2, as described above, the odd tap switches 5d and 7d and the even tap switches 6d and 8d, and the odd tap switches 5a and 7a and the even tap switches 6a and 8a according to Embodiments 1 to 3, Even and odd numbers are interchanged. Therefore, by exchanging the signs of the bidirectional thyristor, the self-starting circuit and the switch in the flow charts shown in FIGS.

For example, in step S15 shown in FIG. 3, "the self-firing circuit 51b turns on the bidirectional thyristor 51", in step S16, "bidirectional thyristor 51 is turned on", in step S17, "switch 52 is turned on", and in step S19. "Bidirectional thyristor 51 OFF". The same applies to FIGS.

By changing the connection portions of the switches 62 and 82 in Modification 2 in the same manner as the connection portions of the switches 52 and 72 in Modification 1, the currents flowing through the switches 62 and 82 are reduced to the fast-acting fuses 63 and 83 You may make it flow to. Even if it is configured in this way, the same effects as those of the first to third embodiments can be obtained, as in the case of the first modification.

Further, an auxiliary contact may be added to each of the switches 52 and 72 in Modification 2, and self-ignition circuits 61b and 81b may be added to each of the two-way thyristors 61 and 81, respectively. In the configuration added in this way, the relationships between the even numbers and the odd numbers of the odd number tap switches 5b and 7b and the even number tap switches 6b and 8b in the on-load tap changer 4b according to the fourth embodiment are exchanged. It has the same effect.

The embodiments disclosed this time should be considered as examples in all respects and not as restrictive. The scope of the present invention is indicated by the scope of the claims rather than the meaning described above, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. Also, the technical features described in each embodiment can be combined with each other.

1u, 1v, 1w distribution line 2 series transformer 21p, 22p, 23p primary winding 21s, 22s, 23s secondary winding u1, v1, w1 terminal N neutral point 3 regulating transformer 31p , 32p primary winding 31s, 32s secondary winding t1, t2, t3, t4, t5, t6, t7, t8, t9 tap 4a, 4b, 4c, 4d on-load tap changer 40 control unit, 401 input section 402 drive section 41, 43 odd tap selector 42, 44 even tap selector 5a, 5b, 5c, 5d, 7a, 7b, 7c, 7d odd tap switch 6a, 6b, 6d, 8a , 8b, 8d even tap switches 51, 61, 64, 71, 81, 84 two-way thyristors 52, 62, 72, 82 switches 53, 63, 73, 83 fast blow fuses 53b, 63b, 73b, 83b alarms Contacts 51b, 61b, 71b, 81b Self-starting circuits 62b, 82b Auxiliary contacts 65, 85 Current limiting resistors PT1, PT2 Measuring transformers CT1, CT2 Current transformers 91, 92, 93 Output terminals 10a, 10b, 10c, 10d on-load tap-changing transformer, 100a, 100b, 100c, 100d voltage regulator

Claims (8)

an odd tap selector that selects odd numbered taps of the tapped transformer; an even tap selector that selects even numbered taps; an odd tap switch connected between said odd tap selector and an output terminal; an on-load tap changer comprising the even tap selector and an even tap switch connected between the output terminals,
each of the odd tap switch and the even tap switch includes a semiconductor switch and a switch having a mechanical contact connected in parallel to the semiconductor switch;
a control unit for turning on/off the switch having the semiconductor switch and the mechanical contact;
a self-firing circuit for self-firing a semiconductor switch included in one of the odd-numbered tap switch and the even-numbered tap switch based on a voltage applied to the semiconductor switch;
a detection unit for detecting overvoltage or overcurrent associated with the semiconductor switch,
When the detection unit detects the overvoltage or the overcurrent, the control unit turns off the semiconductor switches included in both the odd-numbered tap switch and the even-numbered tap switch, and then turns on the semiconductor switch included in one of the odd-numbered tap switches and the even-numbered tap switches. and an on-load tap changer adapted to later turn on a switch having mechanical contacts contained in said one. The detection unit is a voltage detection unit that detects the voltage of the output terminal,
The on-load tap changer according to claim 1, wherein the control section detects the overvoltage when the voltage detected by the voltage detection section is higher than a predetermined voltage threshold. further comprising a fast-blow fuse connected in series to a semiconductor switch included in the other of the odd-numbered tap switch and the even-numbered tap switch;
the detection unit is a blowout detection unit that detects the blowout of the fast-blow fuse;
The on-load tap changer according to claim 1, wherein the control section detects the overcurrent when the fusing detection section detects the fusing. The detection unit is a current detection unit that detects a current flowing through the output terminal,
The control unit
The overcurrent is detected when the current detected by the current detection unit is greater than a predetermined current threshold,
When the overcurrent is detected and the semiconductor switch included in the one is turned on, the switch having the mechanical contact included in the one is turned on without turning on/off the semiconductor switch. 2. The on-load tap changer of claim 1. 5. The device according to any one of claims 1 to 4, further comprising a second self-firing circuit for self-firing a semiconductor switch included in the other of said odd-numbered tap switch and said even-numbered tap switch based on a voltage applied to said semiconductor switch. An on-load tap changer according to any one of claims 1 to 3. Further comprising an abnormality detection unit that detects an abnormal state in which the switch having a mechanical contact included in the one is not turned on,
When the abnormality detection section detects the abnormal state, the control section turns off the semiconductor switches included in the both, turns on the semiconductor switch included in the other, and then turns on the mechanical contact included in the other. 6. The on-load tap changer according to claim 5, wherein the on-load tap changer is adapted to turn on a switch having a an on-load tap changer according to any one of claims 1 to 6;
An on-load tap-changing transformer comprising: the tapped transformer; A series transformer according to claim 7, wherein a three-phase secondary winding is connected in series to a distribution line for distributing a three-phase AC voltage from a power supply to a load, and the primary winding is three-phase connected. A voltage regulator comprising an on-load tap-changing transformer,
In the on-load tap-changing transformer, the primary winding of the tapped transformer is three-phase connected at a position closer to the load than the connection position of the series transformer in the distribution line, and the primary winding of the series transformer is A voltage regulator having a line connected to the output terminal of said on-load tap changer.

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