JP2016046307A - Automatic voltage adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic voltage adjusting device having a long lifetime, which is adaptable to instantaneous voltage variation occurring frequently without causing increase of the cost and inducing increase of the size of the device.SOLUTION: In a tap changer 8 for switching the tap of an adjustment transformer 2, switch main circuits of thyristor switches SS and switch main circuits of mechanical switches MS as load current change-over switches A to C and T1, T2 having liability to switch load current of the adjustment transformer are connected to one another in parallel to construct a composite switch. The thyristor switch SS and the mechanical switch MS constituting the load current change-over switch are controlled so that the thyristor switch SS is set to ON-state, and then the mechanical switch MS is set to ON-state when the load current change-over switch is set to ON-state, and the mechanical switch MS is set to OFF-state and then the thyristor switch SS is set to OFF-state when the load current change-over switch is set to OFF-state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an automatic voltage regulator installed in a power distribution system.

  As an automatic voltage regulator installed in the distribution system, there are an indirect switching type in which the regulating voltage is indirectly applied to the distribution line through the series transformer, and the regulating transformer includes an adjusting voltage output through the tap changer. A direct switching type in which an adjustment voltage output through a tap changer is directly applied to a distribution line is used.

  The indirect switching type automatic voltage adjustment device has a plurality of taps and outputs an adjustment voltage for adjusting the distribution line voltage through the selected energization tap as disclosed in Patent Document 1, for example. A transformer and a plurality of tap selection switches for turning on and off the load currents flowing through the plurality of taps of the adjustment transformer, respectively, and by controlling on / off of the plurality of tap selection switches, the energization tap of the adjustment transformer And a series transformer in which the adjustment voltage output from the adjustment transformer through the energizing tap is applied to the primary winding, and the secondary winding is connected in series to the line.

  The direct-switching automatic voltage regulator includes a regulating transformer having a plurality of taps, and a tap switching device for switching the energizing taps of the regulating transformer, and the voltage on the primary side (power supply side) distribution line is The voltage is input to the adjustment transformer through the tap changer, and the output voltage of the adjustment transformer is applied to the secondary side (load side) distribution line.

  As shown in Patent Document 1, the tap changer used in the automatic voltage regulator is between one of a pair of regulated voltage output terminals and a plurality of taps provided in the secondary winding of the regulating transformer. A plurality of tap selection switches connected to each other and a bridging switch connected in parallel between the adjustment voltage output terminals via a current limiting resistor as tap switching switches. It is known to switch taps without using a mechanical tap selector by turning on and off the switches in a predetermined sequence.

  In addition, a mechanical tap selector that selects the tap provided on the adjustment transformer, and a circuit that connects to the distribution line when the tap selector selects a new tap, switches and connects the tap selector to the newly selected tap. There is also known a tap switch constituted by a switching switch. For example, as shown in Patent Document 2, the change-over switch includes a load switch and a first change-over switch that switches and connects one end of the load switch to an odd-numbered tap selector and an even-numbered tap selector. A current limiting resistor insertion / removal switch whose one end is connected to the other end of the load switching switch through a current limiting resistor, and a current limiting resistor insertion / removal switch as an odd tap selector and an even tap selector. And a second changeover switch for switching connection to the switch, and when the tap selector selects a new tap by operating these tap changeover switches in a predetermined sequence. The circuit connected to the electric wire is switched and connected to the tap selected by the tap selector.

  As described above, the tap changer includes a plurality of tap changeover switches that are on / off controlled when performing tap changeover. These tap changeover switches include a switch that is responsible for switching the load current of the adjustment transformer in the process of changing the tap of the adjustment transformer. In the present specification, among the various tap changeover switches provided in the tap changer, a switch responsible for opening and closing the load current is referred to as a “load current open / close switch”.

  In the tap changer, as the tap changeover switch, as shown in Patent Document 2, a vacuum valve is often used, or an in-oil contact switch for turning on and off the contact in insulating oil is often used. As shown in Patent Document 1, a switch using a thyristor switch (a switch in which a switching element constituting a switch main circuit is a thyristor) is known as a tap switching switch. An automatic voltage regulator using a thyristor switch as a tap switching switch is called a thyristor type automatic voltage regulator.

  The thyristor type automatic voltage adjustment device has a fast thyristor switch operation, so the tap switching speed is faster than an automatic voltage adjustment device using a mechanical switch such as a vacuum valve or oil contact switch as a tap switching switch. It has characteristics. In particular, according to a thyristor type automatic voltage regulator that does not use a mechanical tap selector as disclosed in Patent Document 1, the tap switching speed can be increased to about 0.1 seconds.

  When operating the automatic voltage regulator, the time from when it is sensed that the distribution line voltage deviates from the normal range by the voltage regulating relay until the actual tap switching (time limit of the voltage regulator) Is set as the minimum setting time period, and the voltage adjustment operation is performed so that the tap switching interval does not become shorter than the minimum setting time period. The above-mentioned minimum setting time is the time obtained by adding a slight margin to the shortest switching interval of tap switching that is possible due to the structure of the tap changer (the shortest time interval from one tap switching to the next tap switching). Set to The automatic voltage regulator using a mechanical switch as a tap switching switch has a limited number of durable switchings of about 200,000 times, and the number of tap switching allowed during the expected life of the device is limited. There is a problem that the setting time limit cannot be shortened so much that it cannot cope with a case where instantaneous voltage fluctuation occurs frequently in the system. On the other hand, the thyristor type automatic voltage regulator can eliminate the limit of the number of service life switching, so the minimum set time is set short without shortening the expected life, and the voltage fluctuations in the system are frequent. It is possible to sufficiently cope with the case where it occurs. Because of these characteristics, it is installed in a distribution system that requires a short operation time limit of the voltage regulator because the voltage fluctuation occurs frequently, for example, a distribution system linked with photovoltaic power generation equipment. Employing a thyristor type automatic voltage regulator as an automatic voltage regulator is being studied.

JP-A-8-335121 JP 2014-123599 A

  The thyristor type automatic voltage regulator uses a thyristor, which is a semiconductor element, as a switching element that constitutes a switch main circuit of a load current switching switch. Therefore, compared with a case where a mechanical switch is used as a load current switching switch. There is a problem that the overcurrent resistance is greatly inferior. Therefore, when adopting a thyristor type automatic voltage regulator, in order to cope with a system short circuit accident in which a large current flows through the load current switching switch, it is connected in series with the thyristor switch constituting the load current switching switch. Insert a protective fuse to cut off the overcurrent (short circuit current), or suppress the overcurrent by inserting a current limiting reactor in series with the thyristor switch constituting the load current switching switch. Is required.

  When a protective fuse is inserted in series with the load current switching switch, there arises a problem that the operation of the automatic voltage regulator cannot be continued after the overcurrent is cut off. In addition, when a current limiting reactor is connected in series to the load current switching switch, there is a problem that the apparatus becomes large and the cost increases.

  In addition, the thyristor switch is less reliable than the mechanical switch, including its control operation. If a short-circuit current flows through the thyristor switch, the thyristor switch may be damaged. There is a risk of opening. In the indirect switching type automatic voltage regulator, when the load current switching switch in the tap switch connected to the primary side of the series transformer is opened, the primary side of the series transformer is opened. The line current flowing through the secondary winding of the transformer becomes the excitation current, and an abnormal overvoltage occurs in the secondary winding of the series transformer. This abnormal overvoltage is applied to both ends of the load current switching switch that is off. If it is done, the switch may be damaged.

  The object of the present invention is to greatly improve the reliability compared to the conventional thyristor type automatic voltage regulator, eliminate the need for a protective fuse and a current limiting reactor, increase the cost, and increase the size of the device. It is an object of the present invention to provide an automatic voltage regulator capable of dealing with instantaneous voltage fluctuations that occur frequently without incurring shaping and without shortening the expected life.

In the present specification, in order to achieve the above object, at least first to eighth inventions shown below are disclosed.
1st invention The 1st invention has a plurality of taps, adjusts the distribution line voltage as input, and outputs the voltage corresponding to the selected energization tap as the adjustment voltage used to adjust the distribution line voltage A transformer, a tap changer having a tap changeover switch and switching the energizing tap to be selected from among a plurality of taps of the adjustment transformer with the on / off operation of the tap changeover switch, and adjusting the distribution line voltage Accordingly, the present invention is directed to an automatic voltage regulator including a control unit that controls a tap switching switch. The tap switching switch includes at least one load current switching switch that is responsible for turning on and off the load current of the adjusting transformer in the process of switching the energizing tap of the adjusting transformer.
In addition, as an automatic voltage regulator, an indirect switching method in which the regulated voltage output by the regulating transformer is indirectly applied to the distribution line via a series transformer in which the primary winding is connected in series to the distribution line. And a direct switching system in which the adjustment voltage output from the adjustment transformer is directly applied to the distribution line, but the above-mentioned "adjustment voltage used to adjust the distribution line voltage" It includes both the adjustment voltage applied to the primary winding of the series transformer connected in series to the distribution line and the adjustment voltage applied directly to the distribution line.

  In the present invention, a load current switching switch is a composite in which a switch main circuit of a thyristor switch using a thyristor as a switching element and a switch main circuit of a mechanical switch capable of on / off control are connected in parallel to each other. Consists of switches. The control unit that controls the switch for switching taps turns on the thyristor switch and then turns on the mechanical switch when turning on the load current switching switch and turns on the mechanical switch to turn on the load current through each load current switching switch. During the flow, keep the mechanical switch on, and when turning off each load current switch, turn off the load current switch to turn off the thyristor switch after turning off the mechanical switch. Controls the thyristor switch and mechanical switch.

  The above-mentioned “mechanical switch that can be controlled on and off by an electrical signal” includes a switch body having a mechanical contact such as a vacuum valve, and an operation mechanism that operates the switch body using an electromagnet or the like as a drive source for operation. can do.

  In the automatic voltage regulator, tap switching speed (time required to perform one tap switching), number of service switching (number of tap switching that can be performed before the tap switch reaches the end of its life), expectation The shortest switching interval for tap switching is determined based on the lifetime (the lifetime of the equipment required for installation in the system), and the minimum setting interval (voltage fluctuation is within the normal range) is determined by adding a slight margin to this minimum switching interval. (Minimum value of time from when it is detected that the deviation is detected to when tap switching is actually performed). In principle, the shortest switching interval can be shortened to the tap switching speed. However, if there is a limit on the number of durable switching times, shortening the shortest switching interval reduces the number of tap switching times before the equipment reaches its expected life. Since the number of times of switching will be reached, in practice, the shortest switching interval must be set considerably longer than the tap switching speed, and the minimum setting time must be set longer. If the frequency of instantaneous voltage fluctuations is low, there is no problem even if the minimum setting time is set long.However, instantaneous voltage fluctuations occur frequently, such as in a power distribution system connected to photovoltaic power generation equipment. If this occurs, if the minimum setting time is set to be long, tap switching cannot be performed every time voltage fluctuation occurs, and therefore the follow-up performance of voltage adjustment with respect to voltage fluctuation of the system is deteriorated.

  In the conventional automatic voltage regulator in which the load current of the adjusting transformer is turned on and off by a mechanical switch such as a vacuum valve, the number of service switching times is limited. From the relationship, the minimum setting time period has to be set longer, and it has been impossible to perform tap switching always following voltage fluctuations that occur frequently. On the other hand, when configured as in the present invention, when the tap of the adjustment transformer is switched, the load current of the adjustment transformer is turned on and off by the thyristor. Therefore, the load current open / close switch is configured only by the mechanical switch. In such a case, the number of useful switching times is not limited, and the minimum switching interval can be set equal to the tap switching speed if necessary. Therefore, according to the present invention, it is possible to set the shortest switching interval of tap switching to be significantly shorter than that of the conventional automatic voltage regulator, and to shorten the minimum setting time period, and even when instantaneous fluctuation occurs frequently, the voltage Since the voltage can be adjusted by switching the tap every time the fluctuation occurs, the followability of the voltage adjustment with respect to the voltage fluctuation of the system can be improved.

  In addition, when configured as described above, since the load current can be passed through the mechanical switch except when the tap is switched, the overcurrent withstand capability of the switch can be increased as compared with the case where the load current switching switch is configured only by the thyristor switch. This can improve the reliability and eliminate the need to connect a protective fuse or a current-limiting reactor in series to the load current switching switch. Therefore, according to the present invention, it is possible to obtain an automatic voltage adjustment device that can cope with instantaneous voltage fluctuations that occur frequently without causing an increase in cost or an increase in size of the device.

  With the above configuration, two switches, a thyristor switch and a mechanical switch, are required to configure each load current switching switch, but a protective fuse and a current limiting reactor can be omitted. However, it does not necessarily lead to cost increase.

  Furthermore, as described above, if each load current switching switch is provided with a mechanical switch with a high overcurrent withstand capability and the load current is allowed to flow through the mechanical switch except during tap switching, the load will be It is possible to prevent an accident that the current opening / closing switch is broken due to an overcurrent and is opened. Therefore, when the automatic voltage regulator has an indirect switching type configuration, when the circuit in the tap changer is opened, the primary side of the series transformer is opened, and the primary winding of the series transformer is It is possible to prevent the occurrence of an accident caused by an abnormal overvoltage, and it is possible to eliminate the possibility that the components of the tap changer are damaged by the abnormal overvoltage.

Second invention In the second invention disclosed in the present specification, the control unit first turns on the thyristor switch and then turns on the mechanical switch when turning on each load current switching switch. When the thyristor switch is turned off and only the mechanical switch is turned on, and each load current switching switch is turned off, the thyristor switch that was in the off state is turned on and the mechanical type is turned on. The thyristor switch and the mechanical switch constituting each load current switching switch are controlled so that the thyristor switch is turned off after the switch is turned off.

  When the control unit is configured as described above, when the load current of the adjustment transformer is allowed to flow through the load current switching switch, only the mechanical switch can be turned on so that no current flows through the thyristor switch. Thus, it is possible to reliably protect the thyristor switch.

Third invention In a third invention disclosed in the present specification, when the control unit turns on each load current switching switch, the control signal for turning on the thyristor switch is sent to the control signal. The control signal for turning on the mechanical switch is applied to the mechanical switch simultaneously with the application to the thyristor switch or after the control signal for turning on the thyristor switch is applied to the thyristor switch. When the open / close switch is turned off, a control signal for turning off the mechanical switch is applied to the mechanical switch so that the thyristor switch is turned off after the mechanical switch is turned off. In addition, control signal supply to the thyristor switch and the mechanical contact switch constituting each load current switching switch is controlled.

  When the control unit is configured as described above, both the mechanical switch and the thyristor switch are kept on when the load current flows through the load current switching switch. When an electric current flows, the overcurrent is divided into a mechanical switch and a thyristor switch. Therefore, the overcurrent withstand capability can be improved as compared with the case where the load current opening / closing switch is constituted only by the thyristor switch.

Fourth Invention The fourth invention is applied to any one of the first to third inventions. In the present invention, the automatic voltage regulator has an indirect switching configuration. Therefore, in addition to the adjusting transformer, a series transformer in which the secondary winding is connected in series to the distribution line is provided. The adjustment transformer has a primary winding to which the voltage of the distribution line is input, one end side end tap and the other end side end tap at one end and the other end, respectively, and a plurality of intermediate points between both end taps. A regulation voltage output from the secondary winding of the regulation transformer through the tap changer is applied to the primary winding of the series transformer.

  The tap changer used in the present invention includes the end tap on one end side of the secondary winding of the adjusting transformer and the end of the primary winding of the series transformer, and each intermediate tap of the adjusting transformer and the primary of the series transformer. Tap switching between a plurality of tap selection switches each connected between one end of the winding and a bridge switch connected in parallel to both ends of the primary winding of the series transformer via a current limiting resistor As a switch for switching, the switch for selecting a tap to be closed can be switched while preventing both ends of the primary winding of the series transformer from being opened by temporarily closing the bridge switch. Thus, the adjustment voltage applied from the adjustment transformer to the primary winding of the series transformer is switched. In the present invention, the plurality of tap selection switches constitute a load current switching switch.

Fifth Invention The fifth invention is applied to any of the first to third inventions, and also in the present invention, the automatic voltage regulator has an indirect switching configuration. Therefore, in addition to the adjustment transformer, a series transformer in which the secondary winding is connected in series to the distribution line is further provided. The adjustment transformer has a primary winding to which the voltage of the distribution line is input, one end side end tap and the other end side end tap at one end and the other end, respectively, and a plurality of intermediate points between both end taps. A regulation voltage output from the secondary winding of the regulation transformer through the tap changer is applied to the primary winding of the series transformer.

  The tap changer used in the present invention includes the end tap on one end side of the secondary winding of the adjusting transformer and the end of the primary winding of the series transformer, and each intermediate tap of the adjusting transformer and the primary of the series transformer. A plurality of tap selection switches respectively connected between one end of the winding and the other end of the secondary winding of the adjustment transformer and the other end of the primary winding of the series transformer A first polarity switching switch connected, and a second polarity switching connected between one end-side end tap of the secondary winding of the adjusting transformer and the other end of the primary winding of the series transformer. A switch and a bridging switch connected in parallel via a current limiting resistor at both ends of the primary winding of the series transformer are provided as tap switching switches, and the bridging switch is temporarily closed. By preventing the both ends of the primary winding of the series transformer from being opened, And a regulating transformer by switching the combination of polar switching switch that switches and closed state for tap selection to to switch the adjustment voltage to be applied to the primary winding of the series transformer. In the present invention, the plurality of tap selection switches and the first and second polarity switching switches constitute a load current switching switch.

Sixth Invention The sixth invention is applied to any one of the first to third inventions. In the present invention, the automatic voltage regulator has a direct switching configuration. The tap changer used in the present invention includes a tap selector having an odd tap selector and an even tap selector for selecting an odd tap and an even tap provided in the adjustment transformer, and one end having an odd tap selector and an even tap. An odd tap side tap selection switch and an even tap side tap selection switch, which are respectively connected to the selectors and commonly connected at the other end, and a common connection point of the odd tap side tap selection switch and the even tap side tap selection switch A switch for switching off the current-limiting resistor connected in parallel through a current-limiting resistor between the odd-numbered tap selector or the even-numbered tap selector as a tap switching switch, and an odd-numbered tap-side tap selecting switch and an even-numbered tap selector The common connection point of the tap side tap selection switch is connected to the primary side distribution line connection terminal, and An output terminal of is connected to the secondary side power line connecting terminal. In this case, the odd tap side tap selection switch and the even tap side tap selection switch constitute a load current switching switch.

Seventh Invention The seventh invention is also applied to any one of the first to third inventions. In the present invention, the automatic voltage regulator has an indirect switching type configuration. The tap changer used in the present invention includes a tap selector having an odd tap selector and an even tap selector for selecting an odd tap and an even tap provided in the adjustment transformer, and one end having an odd tap selector and an even tap. Common connection point of odd tap side tap selection switch and even tap side tap selection switch, and odd tap side tap selection switch and even tap side tap selection switch, which are connected to the selectors and connected at the other end in common And a switch for switching off the current limiting resistor connected in parallel through a current limiting resistor between the odd-numbered tap selector and the odd-numbered tap selector or the even-numbered tap selector, And the common connection point of the even tap side tap selection switch is connected to one end of the primary winding of the series transformer. One of the tap provided to adjust the transformer is connected to the other end of the primary winding of the series transformer. In this case, the odd tap side tap selection switch and the even tap side tap selection switch constitute a load current switching switch.

Eighth Invention The eighth invention is applied to any one of the first to seventh inventions. In the present invention, the minimum time interval (shortest switching interval) at which the tap changer performs the tap switching operation. ) Is set in the range of 3 to 10 seconds, the operation characteristics of the voltage adjustment operation with respect to the fluctuation of the distribution line voltage are set.

  If the operating characteristics of the voltage adjustment operation with respect to fluctuations in the system voltage are set so that the minimum value of the tap switching operation interval falls within the above range, the voltage required for the distribution system connected to the photovoltaic power generation equipment It is possible to obtain an automatic voltage regulator having an adjustment tracking performance without an unreasonable design.

  According to the present invention, in the tap changer, the switch that opens and closes the load current of the adjusting transformer at the time of tap switching is a composite in which the switch main circuit of the thyristor switch and the switch main circuit of the mechanical switch are connected in parallel to each other. When the load current switching switch is turned on, the thyristor switch is turned on, the mechanical switch is turned on, and the load current switching switch is turned off. Since the thyristor switch and the mechanical switch that constitute the load current switching switch are controlled so that the thyristor switch is turned off after turning off the thyristor switch, the switching of the adjusting transformer is performed when the tap of the adjusting transformer is switched. The load current can be turned on and off with a thyristor to eliminate the limit on the number of service life changes. That. Therefore, the minimum setting time limit of the voltage adjustment operation can be shortened as compared with the conventional automatic voltage adjustment device in which each load current switching switch is constituted only by a mechanical switch, and it is possible to cope with instantaneous voltage fluctuations that occur frequently. A long-life automatic voltage regulator can be obtained.

  Further, according to the present invention, since the load current of the adjustment transformer can be passed through the mechanical switch, the overcurrent withstand capability of the switch can be improved as compared with the case where the load current switching switch is composed of only the thyristor switch. Reliability can be improved. Therefore, there is no need to connect a protective fuse or a current-limiting reactor in series with the load current switching switch, resulting in an increase in cost or an increase in the size of the device. Therefore, it is possible to obtain an automatic voltage regulator that can cope with instantaneous voltage fluctuations that occur frequently.

  According to the present invention, a mechanical switch having a high overcurrent withstand capability is provided in each load current switching switch so that the load current of the adjustment transformer flows through the mechanical switch. It is possible to prevent an accident that the circuit in the switching device is opened. Therefore, when the automatic voltage regulator has an indirect switching configuration, it is possible to prevent an accident in which the primary side of the series transformer is opened and an abnormal overvoltage occurs in the primary winding of the series transformer. This can eliminate the possibility of breakage of the components of the tap changer due to abnormal overvoltage.

1 is a circuit diagram showing a configuration of a first embodiment of an automatic voltage regulator according to the present invention. It is a circuit diagram which shows the structure of 2nd Embodiment of the automatic voltage regulator which concerns on this invention. It is a circuit diagram which shows the structure of 3rd Embodiment of the automatic voltage regulator which concerns on this invention. It is the time chart which showed an example of the method of control of the composite switch used with the automatic voltage regulator which concerns on this invention. It is the time chart which showed the other example of the method of control of the composite switch used with the automatic voltage regulator which concerns on this invention. It is the time chart which showed the further another example of the control method of the composite switch used with the automatic voltage regulator which concerns on this invention. It is the time chart which showed the further another example of the control method of the composite switch used with the automatic voltage regulator which concerns on this invention.

  Embodiments of an automatic voltage regulator according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of one phase of an embodiment in which the present invention is applied to an indirect switching type automatic voltage regulator. In the figure, 1 is a series transformer having a primary winding 1p and a secondary winding 1s, and 2 is a regulating transformer having a primary winding 2p and a secondary base line 2s. One end and the other end of the secondary winding 1s of the series transformer 1 are respectively connected to the primary side (power supply side) line connection terminal 3 and the secondary side (load side) line connection terminal 4, and the primary side line connection terminal 3 and By connecting the secondary line connection terminal 4 to the primary distribution line 5 and the secondary distribution line 6, respectively, the secondary winding 1s of the series transformer is connected in series to the distribution line. The rated voltage of the distribution line is 6600 volts, for example.

  One end of the primary winding 2 p of the adjustment transformer 2 is connected to the secondary line connection terminal 4, and the other end is connected to the neutral point N. In the present embodiment, the primary winding 2p of the three-phase adjusting transformer is connected in parallel to the distribution line in a star-connected state. The secondary winding 2s of the adjusting transformer 2 has taps 2t1 to 2t4, and the output voltage of the secondary winding 2s is applied to the primary winding 1p of the series transformer 1 through the tap switch 8.

  More specifically, the secondary winding 2s of the adjusting transformer of each phase has one end side end tap 2t1 and the other end side end tap 2t4 at one end and the other end, respectively, and the end tap 2t1 The tap selection switches A, B and C, which have intermediate taps 2t2 and 2t3 between 2t4 and one end of which are connected in common, are connected to the taps 2t1 to 2t3, respectively. A common connection point at one end of C is connected to one end of the series transformer 1. The other ends of the first polarity switching switch T1 and the second polarity switching switch T2 having one end connected in common are connected to the outermost taps 2t4 and 2t1 of the secondary winding 2s of the adjustment transformer 2, respectively. A common connection point at one end of the first polarity switching switch T1 and the second polarity switching switch T2 is connected to the other end of the primary winding 1p of the series transformer 1.

  A current limiting resistor R is connected in parallel to both ends of the primary winding 1p of the series transformer 1 through a bridging switch RS. In this example, a tap selector 8 is configured by the tap selection switches A to C, the first and second polarity switching switches T1 and T2, the current limiting resistor R, and the bridging switch RS. A control unit 9 is provided to control each switch of the switch 8. The tap changer used in the present embodiment is in a closed state while preventing both ends of the primary winding 1p of the series transformer 1 from being opened by temporarily closing the bridging switch RS. The adjustment voltage applied from the adjustment transformer 2 to the primary winding of the series transformer 1 is switched by switching the combination of the tap selection switch and the polarity switching switch to be closed.

  In this embodiment, the tap selection switches A to C and the first and second polarity switching switches T1 and T2 are provided as tap switching switches that perform an on / off operation at the time of tap switching. Among the tap switching switches, the tap selection switches A to C and the polarity switching switches T1 and T2 constitute a load current switching switch that is responsible for switching the load current of the adjusting transformer when the tap is switched. doing.

  In this embodiment, each load current switching switch is connected in parallel to the switch main circuit of the thyristor switch SS and the switch main circuit of the mechanical switch MS that can be turned on / off by an electrical control signal. It consists of a composite switch configured as above.

  The thyristor switch SS includes a bidirectional switch main circuit (a switch circuit for turning on and off the main circuit current) configured by using the thyristor as a switching element, and a driver for supplying a control signal (trigger signal) to the thyristor constituting the switch circuit. Consists of. The switch main circuit of the thyristor switch may be configured by connecting a pair of thyristors having unidirectional characteristics in reverse parallel, or may be configured by bidirectional thyristors (for example, triac). As the thyristor switch, a switch having a discrete configuration in which a thyristor and an electronic component constituting a circuit for supplying a trigger signal to the thyristor may be used. To reduce the cost, a commercially available solid state switch may be used. It is preferable to use a contactor (SSC). A solid-state contactor is a unit consisting of a bidirectional switch main circuit that uses a thyristor as a switching element and a driver that drives the thyristor that constitutes the switch main circuit. The solid-state contactor is controlled on and off by an external control signal. Can

  The mechanical switch MS has a fixed contact and a movable contact. The switch main body performs an on / off operation according to the displacement of the movable contact. A thing provided with the operation mechanism to operate can be used. As the switch body, it is preferable to use a vacuum valve that has been conventionally used as a switch for switching load current in a tap changer. However, as will be described later, in the present invention, the mechanical switch MS is used to generate an arc. Since it can be turned on and off without being accompanied, as the switch body, it is possible to use a movable contact and a stationary contact that open and close in the air, as long as it has a predetermined energization capacity, What is marketed as an electromagnetic switch can also be used as a mechanical switch combined with a thyristor switch.

  As the mechanical switch, a switch operated by an electric cam mechanism or the like can be used. However, in the present invention, the mechanical switch and the thyristor switch are linked to each other. It is preferable to use one that can be controlled on and off by a typical control signal. For example, an electromagnetic switch that is turned on when a drive voltage is applied to an exciting coil of an electromagnet and turned off when the drive voltage is extinguished, and a closing coil and a tripping coil are provided. An electromagnetic switch that is turned on when a voltage is applied and turned off when a voltage is applied to the tripping coil can be used as the mechanical switch MS.

  When the distribution line voltage detected through an instrument transformer (not shown) deviates from the set range, the control unit 9 switches the tap selection switches A to C and the polarity switching switches T1 and T2 of the tap changer 8. By controlling, the energization tap of the adjustment transformer 2 is switched so that the distribution line voltage falls within the set range. Thereby, the adjustment voltage given to the series transformer 1 from the adjustment transformer 2 is adjusted, and the distribution line voltage is maintained in the set range.

  In the tap changer 8 used in the present embodiment, the tap selection switch A is in a closed state, the second polarity switching switch T2 is in a closed state, and other tap selection switches B, C, When the first polarity switching switch T1 and the bridging switch S are in the open circuit state, the adjustment voltage applied from the adjustment transformers 3u to 3w to the primary windings of the series transformers 1u to 1w becomes zero. The tap of 6480 volts is selected, and the tap is switched in 120 volts step by switching the combination of the tap selection switch for closing the circuit and the polarity switching switch for closing the circuit. Can be switched. When switching taps, the circuit that looks at the load tap switch side from the primary winding of the series transformer is opened at the moment when both the tap selection switch and the polarity switching switch are opened. In order to prevent an abnormal voltage from being induced in the primary winding of the transformer, the bridging switch S is temporarily closed, and a current limiting resistor R is connected in parallel across the primary winding of the series transformer. To do.

  For example, when the tap selection switch A is in the closed state, the second polarity switching switch T2 is in the closed state, and the tap selection switches B and C and the bridging switch S are in the open state, the distribution line When the voltage is increased by one step (120 volts) and the 6600 volt tap is selected, the tap selection switch A and the second polarity switching switch T2 remain closed. The bridging switch S is closed, and the current limiting resistor R is connected to both ends of the primary winding of the series transformer. Thereafter, both the tap selection switch A and the second polarity switching switch T2 are opened, and the tap selection switch C and the first polarity switching switch T1 are closed. Next, the bridging switch S is opened, and only the tap selection switch C and the first polarity switching switch T1 are closed. In this state, the voltage across one tap of the secondary winding of the adjustment transformer is applied as the adjustment voltage to the primary winding of the series transformer, and the 6600 volt tap is selected.

Similarly, by setting the bridge switch in the closed state, the both ends of the primary winding of the series transformer are prevented from being opened, while the tap selection switch and the polarity switching switch are closed. By switching the combination, the voltage of the tap to be selected can be adjusted in increments of 120 volts. Table 1 below shows the relationship between the combination of the tap selection switch and the polarity switching switch to be closed and the selected tap voltage.

  The controller 9 used in this embodiment turns on the thyristor switch SS and then turns on the mechanical switch MS when turning on each load current switching switch and turns on the load current switching switch. Keep the mechanical switch in the on state for the duration of the current flow, and when turning off the load current switching switch, set the load current switching switch to turn off the thyristor switch after turning off the mechanical switch. The thyristor switch SS and the mechanical switch MS are configured.

  Various modes are conceivable for the specific control method of the thyristor switch SS and the mechanical switch MS constituting each load current switching switch. FIG. 4 is a time chart showing an example thereof. FIG. 4A shows a trigger signal given to the thyristor switch SS, and FIG. 4B shows an on / off operation of the thyristor switch SS. 4C shows a control signal given to the mechanical switch MS, and FIG. 4D shows an on / off operation of the mechanical switch MS. The mechanical switch MS used in this example is configured to be turned on when a control signal is applied and to be turned off when the control signal is removed.

  In the example shown in FIG. 4, when the load current switching switch is turned on, control signals (control signals for turning each on) are simultaneously applied to the thyristor switch SS and the mechanical switch MS at time t1. Giving. Since the operation speed of the thyristor switch is faster than that of the mechanical switch, when a control signal is simultaneously applied to the thyristor switch SS and the mechanical switch MS, the thyristor switch SS is first turned on, and then the mechanical switch MS is turned on. It becomes a state. In this example, a control signal is continuously applied to the thyristor switch and the mechanical switch for a period in which a load current is passed through the load opening / closing switch, so that both the thyristor switch and the mechanical switch are kept on. In the example shown in FIG. 4, when the load current switching switch is turned off, the control signal applied to the mechanical switch MS is extinguished at time t2, thereby turning the mechanical switch off. At a later time t3, the trigger signal applied to the thyristor switch is extinguished and the thyristor switch is turned off.

  In the tap changer, among the tap changeover switches that perform the on / off operation when the tap changeover is performed, the load current open / close switch that is responsible for opening and closing the load current of the adjustment transformer, the switch main circuit of the thyristor switch SS, When a thyristor switch and a mechanical switch constituting each load current switching switch are controlled as shown in FIG. 4, a regulating transformer is constituted by a composite switch connected in parallel with a switch main circuit of the mechanical switch MS. When switching two taps, the load current is turned on and off by a thyristor switch. Therefore, the tap switching speed is higher than that of a conventional automatic voltage regulator in which each load current switching switch is composed only of a mechanical switch. Can be faster. Moreover, since the load current of the adjustment transformer at the time of tap switching is turned on and off by a thyristor, there is no limitation on the number of times of service switching, and a long-life automatic voltage regulator capable of dealing with instantaneous voltage fluctuations that occur frequently is obtained. Can do.

  Further, if each load current switching switch is controlled as shown in FIG. 4, the load current is passed through the mechanical switch except when the tap is switched. Therefore, the load current switching switch is constituted only by the thyristor switch SS. Compared to the thyristor type automatic voltage regulator, the overcurrent capability of the switch can be increased to reduce the possibility of damage to the load current switching switch in the event of a short-circuit accident, and the reliability of the automatic voltage regulator is improved. Can do. Therefore, it is possible to eliminate the necessity of connecting a protective fuse or a current-limiting reactor in series with the load current switching switch, resulting in an increase in cost and an increase in the size of the device. Therefore, it is possible to obtain an automatic voltage regulator that can cope with instantaneous voltage fluctuations that occur frequently.

  In particular, as shown in FIG. 1, when the automatic voltage regulator has an indirect switching type configuration, if the load current switching switch in the tap switch 8 is broken and opened, the series transformer 1 Although the primary side is open, an accident that an abnormal overvoltage occurs in the primary winding of the series transformer 1 may occur, and the other components of the tap changer 8 may be damaged by this abnormal overvoltage. If configured like a form, such a situation can be prevented from occurring.

  As described above, in the present invention, since the load current switching switch is turned on and off by the thyristor switch, the mechanical switch does not need to switch the current. Therefore, when the mechanical switch is turned on / off, it is possible to prevent the arc from being generated and the contact from being consumed, and the life of the contact of the mechanical switch can be extended. In addition, since the contact of the mechanical switch is not consumed, an inexpensive mechanical switch can be used.

  As shown in FIG. 4, when the control unit 9 is configured to hold both the thyristor switch and the mechanical switch during the period in which the load current flows through the load current switching switch, When a short-circuit accident occurs, a current flows through the mechanical switch MS and a current also flows through the thyristor switch SS. In this case, the accident current is divided between the thyristor switch and the mechanical switch. The risk of the switch being damaged by overcurrent can be eliminated.

  However, the present invention is not limited to the case where the thyristor switch and the mechanical switch are controlled as described above, and various modifications can be considered in the control method of both switches. For example, as shown in FIG. 5, when the load current switching switch is turned on, a control signal is simultaneously given to the thyristor switch and the mechanical switch at time t1 to sequentially turn on the thyristor switch and the mechanical switch. When the control signal supply to the thyristor switch is stopped at time t2 to turn off the thyristor switch and the load current switch is turned off, the control signal is applied to the thyristor switch at time t3. After the thyristor switch is turned on, the supply of the control signal to the mechanical switch is stopped at time t4 to turn off the mechanical switch, and then the supply of the control signal to the thyristor switch is stopped at time t5. The thyristor switch may be turned off.

  When the load current switching switch is controlled as shown in FIG. 5, the thyristor switch can be turned off during the period in which the load current is applied, and only the mechanical switch having a large overcurrent tolerance can be turned on. Therefore, the thyristor switch can be protected more reliably.

  In the example shown in FIG. 4, when the thyristor switch and the mechanical switch are controlled so that both the thyristor switch and the mechanical switch are turned on during the period in which the load current switching switch is kept on, Although the control signal is supplied to the thyristor switch and the mechanical switch at the same time, in order to ensure that the turn-on of the thyristor switch is completed when the mechanical switch is turned on, FIG. As shown in FIG. 5, after supplying the control signal to the thyristor switch at time t1, the control signal may be given to the mechanical switch at time t2 slightly delayed. In the example shown in FIG. 6, the control method of the thyristor switch and the mechanical switch when the load current switching switch is turned off is the same as the example shown in FIG. 4, and the mechanical switch MS is switched to at the time t3. After the control signal supply is stopped and the mechanical switch is turned off, the supply of the control signal to the thyristor switch is stopped and the thyristor switch is turned off at time t4.

  Similarly, when the thyristor switch and the mechanical switch are controlled as shown in FIG. 5, when the load current switching switch is turned on, a control signal is simultaneously applied to the thyristor switch and the mechanical switch. Instead, as shown in FIG. 7, a control signal is applied to the thyristor switch at time t1 to turn on the thyristor switch, and then a control signal is applied to the mechanical switch at time t2 to turn on the mechanical switch. You may make it do. In the example shown in FIG. 7, the method of controlling the thyristor switch and the mechanical switch when the load current switching switch is turned off is the same as in the example shown in FIG. 5, and the control signal is sent to the thyristor switch at time t4. To turn on the thyristor switch, stop supplying the control signal to the mechanical switch at time t5 and turn off the mechanical switch, and then supply the control signal to the thyristor switch at time t6. Stop and turn off the thyristor switch.

  In the embodiment shown in FIG. 1, the present invention is applied to an indirect switching automatic voltage regulator, but the present invention can also be applied when the automatic voltage regulator has a direct switching configuration. FIG. 2 shows a configuration of a main part of a second embodiment in which the present invention is applied to an automatic voltage regulator using a direct-switching tap changer. A single-winding transformer in which a primary winding and a secondary winding share a part of a winding portion is used.

  In this embodiment, the adjustment transformer 2 is provided with taps 2t1 to 2t9, and a mechanical tap selector is provided to select an energizing tap from these taps. In the illustrated example, the taps 2t1 to 2t9 are divided into odd-numbered taps 2t1, 2t3,..., 2t9 and even-numbered taps 2t2, 2t4,. The selector TS1 and the even tap selector TS2 for selecting the even taps 2t2, 2t4,..., 2t8 constitute a tap changer.

  The odd tap selector TS1 is a group of fixed contacts connected to the odd taps 2t1, 2t3,..., 2t9, and an odd tap selector for sequentially selecting the odd taps 2t1, 2t2,. The even-number tap selector TS2 includes a fixed contact group connected to the even-numbered taps 2t2, 2t4,..., 2t8 and an even-numbered tap 2t2, 2t4,. It is comprised by the even-number tap selector 12 selected sequentially.

  In the present embodiment, one end of an odd tap side tap selection switch SW1 and an even tap side tap selection switch SW2 is connected to the odd tap selector 11 and the even tap selector 12, respectively. The other ends of the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2 are connected in common to the primary side line connection terminal 3, and the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2 Between the common connection point and the even-numbered tap selector 12, a current limiting resistor insertion / removal switch RS is connected through a current limiting resistor R. Further, in this example, the tap 2t5 is a through tap, and this through tap is connected to the secondary line connection terminal 4 as an output terminal of the adjustment transformer 2.

  In the present embodiment, the odd tap side tap selection switch SW1, the even tap side tap selection switch SW2 and the current limiting resistor insertion / removal switch RS constitute a tap switching switch, and these tap switching switches. When the tap selector selects a new tap, the switch for switching and connecting the circuit connected to the distribution line to the newly selected tap is constituted by the current limiting resistor R. In this switching switch, the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2 constitute a load current switching switch that is responsible for switching the load current of the adjustment transformer during the tap switching process. doing.

  In the present embodiment, the tap selection switches SW1 and SW2 functioning as load current opening / closing switches include a composite switch configured by connecting a switch main circuit of the thyristor switch SS and a switch main circuit of the mechanical switch MS in parallel. It has become.

  In the present embodiment, the tap selector composed of the odd-numbered tap selector TS1 and the even-numbered tap selector TS2, the tap selection switches SW1 and SW2, the current limiting resistance tripping switch RS, and the current limiting resistor R A tap changer 8 is configured.

  The tap changer shown in FIG. 2 performs a tap changeover operation for changing the tap of the adjustment transformer 2 as follows when the distribution line voltage is out of the set range. When performing tap switching, first, the tap selector different from the tap selector that selects the energized tap is operated to select the next tap, and then the current limiting resistance input / removal switch RS is set. In a turned-on state, a limited short-circuit current between taps flows through the tap selection switch connected to the energized tap, the current limiting resistor R, and the tap selection switch connected to the tap to be selected next. After the process, the tap selection switch connected to the current tap is turned off, and then the tap selection switch connected to the newly selected tap is turned on, and then the current limiting resistor is turned on. By switching off the disconnecting switch RS and pulling off the current limiting resistor, the energizing tap is switched from the odd tap to the even tap or from the even tap to the odd tap.

  For example, tap 2t3 is selected by tap selector 11 of the odd tap selector, tap selection switch SW2 is turned off, and tap selection switch SW1 is turned on (select tap 2t3 as the energizing tap). When the energizing tap is switched to the tap 2t4, the tap selector 12 of the even tap side tap selector is first switched to the tap 2t4 with the even number tap side tap selection switch SW2 turned off. Touch the connected fixed contact. Next, the current limiting resistance input / removal switch RS is turned on, the taps 2t3 and 2t4 are bridged through the switches SW1 and RS and the current limiting resistor R, and the taps between the taps 2t3 and 2t4 are limited. Make sure that a short-circuit current flows. In this state, the odd tap side tap selection switch SW1 is turned off so that a current flows through the current limiting resistor R and the tap 2t4 which is newly energized tap, and then the even tap side tap selection switch SW2 is turned on. After the switch is turned on, the current limiting resistor R is removed by turning off the current limiting resistor input trip switch RS, and the tap switching operation for switching the energizing tap from the odd tap 2t3 to the even tap 2t4 is completed. .

  In the embodiment shown in FIG. 2, the control method of the thyristor switch SS and the mechanical switch MS constituting the tap selection switches SW1 and SW2 is the same as that in the embodiment shown in FIG.

  In the embodiment shown in FIG. 2, a direct-switching automatic voltage regulator is configured using the adjusting transformer 2 and the tap changer 8 using a mechanical tap selector. An indirect switching type automatic voltage regulator can be configured by adding a series transformer to the automatic voltage regulator shown.

  FIG. 3 shows a third embodiment of the present invention in which a series transformer 1 is added to the automatic voltage regulator shown in FIG. 2 to constitute an indirect switching type automatic voltage regulator. In the embodiment shown in FIG. 3, a series transformer in which the secondary winding 1 s is connected in series to the distribution line is provided, and the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2 are provided. Are connected to one end and the other end of the primary winding 1p of the series transformer 1 as output terminals of the adjustment transformer, respectively. The other configuration is the same as that of the embodiment shown in FIG. 2, and in this embodiment, the odd tap side tap selection switch SW1, the even tap side tap selection switch SW2, and the current limiting resistor insertion trip The switch RS constitutes a tap switching switch, and among these tap switching switches, the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2 are adjusting transformers during the tap switching process. The load current switching switch has the responsibility of switching the load current.

  In each of the above embodiments, the operation characteristic of the voltage adjustment operation of the automatic voltage regulator with respect to the fluctuation of the system voltage (performance to follow the voltage fluctuation of the system) is the time interval (one time) when the tap switch 8 performs the tap switching operation. It is desirable to set the minimum value of the time from the completion of the tap switching operation to the start of the next tap switching operation within a range of 3 to 10 seconds.

  Voltage fluctuations that occur in the distribution system to which the photovoltaic power generation facilities are connected are usually in units of several seconds (10 seconds or less). Therefore, the automatic voltage regulator installed in the distribution system to which the photovoltaic power generation facilities are connected is capable of following the voltage regulation operation in 10 seconds or less when voltage fluctuation occurs in the system (voltage regulation operation Tracking performance). Although the time required for the tap switching operation of the automatic voltage regulator is not short, it is common to operate the mechanical contacts and the tap selector of the tap selector at a time interval of less than 3 seconds. On the other hand, the operation characteristic in which the tap switching operation interval is less than 3 seconds is excessive in design and cost with respect to the required operation speed of several seconds. If tap switching is continuously performed at time intervals of less than 3 seconds, it becomes difficult to cool the thyristor, which may cause an excessive temperature rise of the thyristor switch. The continuous tap switching interval (following performance) of the current thyristor type automatic voltage regulator is generally about 4 seconds, but this follow-up performance is caused by voltage fluctuations that occur in the distribution system connected to the photovoltaic power generation equipment. It is enough to cope with. Accordingly, the operation characteristics of the voltage adjustment operation with respect to the fluctuation of the system voltage should be set so that the minimum time interval (shortest switching interval) at which the tap switch 8 performs the tap switching operation falls within the range of 3 to 10 seconds. For example, it is possible to easily cope with voltage fluctuations that occur frequently in a distribution system in which photovoltaic power generation facilities are connected.

  In the embodiment shown in FIG. 1, the on-load tap changer includes three tap selection switches A to C, but the number of tap selection switches is the number of taps provided in the secondary winding of the adjustment transformer. Of course, it differs depending on the situation. In the above embodiment, the load tap changer employs the type using the polarity changeover switches T1 and T2 in addition to the tap selection switch. However, the present invention is the above load tap changer. It is not limited to when using. For example, when voltage adjustment in a necessary adjustment range can be performed by increasing the number of taps provided in the secondary winding of the adjustment transformer, the polarity switching switches T1 and T2 can be omitted.

  In this case, the on-load tap changer is connected between one end of the secondary winding of the regulating transformer and one end of the primary winding of the series transformer and between each tap and one end of the primary winding of the series transformer. A plurality of tap selection switches each inserted and a current limiting resistor connected in parallel through the bridging switch at both ends of the primary winding of the series transformer to temporarily close the bridging switch Applying to the primary winding of the series transformer from the adjustment transformer by switching the tap selection switch to make the closed state while preventing both ends of the primary winding of the series transformer from being opened by setting the state It is configured to switch the adjustment voltage.

  In the example shown in FIG. 2 and FIG. 3, the current limiting resistor is applied and tripped between the common connection point of the odd tap tap selection switch SW 1 and the even tap selection switch SW 2 and the even tap selector 12. The switch RS is connected in parallel through the current limiting resistor R, but the current limiting resistor tripping switch RS is commonly connected to the odd tap side tap selection switch SW1 and the even tap side tap selection switch SW2. The point and the odd tap selector 11 may be connected in parallel through the current limiting resistor R.

DESCRIPTION OF SYMBOLS 1 Series transformer 1p Series transformer primary winding 1s Series transformer secondary winding 2 Adjustment transformer 2p Adjustment transformer primary winding 2s Adjustment transformer secondary winding 3 Primary side line connection terminal 4 2 Secondary side connection terminal 5 Primary side distribution line 6 Secondary side distribution line 8 Tap changer 9 Control unit A to C Tap selection switch T1 First polarity changeover switch T2 Second polarity changeover switch SS Thyristor switch MS Mechanical Switch R Current limiting resistor RS Current limiting resistor input trip switch

Claims (8)

An adjustment transformer that has a plurality of taps and outputs a voltage corresponding to the selected energization tap as an adjustment voltage used to adjust the distribution line voltage; A tap changer for switching a current-carrying tap to be selected from a plurality of taps of the adjustment transformer while controlling the tap changeover switch to adjust the distribution line voltage. The tap switching switch includes at least one load current switching switch that is responsible for turning on and off the load current of the adjusting transformer in the process of switching the energizing tap of the adjusting transformer. In automatic voltage regulator,
The load current switching switch is composed of a composite switch configured by connecting in parallel a switch main circuit of a thyristor switch using a thyristor as a switching element and a switch main circuit of a mechanical switch capable of on / off control,
When the load current switching switch is turned on, the control unit turns on the thyristor switch and then turns on the mechanical switch so that the load current flows through each load current switching switch. A thyristor switch that constitutes the load current switching switch so that the mechanical switch is turned off and then the thyristor switch is turned off when the load current switching switch is turned off. Controlling mechanical switches,
An automatic voltage regulator characterized by. When the load current switching switch is turned on, the control unit first turns on the thyristor switch, turns on the mechanical switch, turns off the thyristor switch, and turns on only the mechanical switch. When each load current switching switch is turned off, the thyristor switch that was in the off state is turned on, the mechanical switch is turned off, and the thyristor switch is turned off. Controlling the thyristor switch and mechanical switch constituting the load current switching switch;
The automatic voltage regulator according to claim 1. The control unit provides a control signal for turning on the thyristor switch to each thyristor switch when turning on each load current switching switch, or control for turning on the thyristor switch. After applying a signal to the thyristor switch, a control signal for turning on the mechanical switch is given to the mechanical switch, and when each load current switching switch is turned off, the mechanical switch is turned off. Thyristor switch and mechanical contact constituting each load current opening / closing switch so as to turn off the thyristor switch after the mechanical switch is turned off by supplying a control signal for switching to the mechanical switch Controlling the supply of control signals to the switch,
The automatic voltage regulator according to claim 1. A series transformer is further provided in which the secondary winding is connected in series with the distribution line;
The adjustment transformer has a primary winding to which the voltage of the distribution line is input, one end side end tap and the other end side end tap at one end and the other end, and a plurality of taps between both end taps. A regulation voltage output from the secondary winding of the regulation transformer through the tap changer is applied to the primary winding of the series transformer, the secondary winding having an intermediate tap.
The tap changer includes an end tap on one end of the secondary winding of the adjustment transformer and an end of the primary winding of the series transformer, and each intermediate tap of the adjustment transformer and the series transformer. A plurality of tap selection switches respectively connected between one end of the primary winding, and a bridging switch connected in parallel to both ends of the primary winding of the series transformer via a current limiting resistor Provided as the tap switching switch, the tap selection for closing the series transformer while preventing the both ends of the primary winding of the series transformer from being opened by temporarily closing the bridge switch Is configured to switch the adjustment voltage applied to the primary winding of the series transformer from the adjustment transformer by switching the switch for
The plurality of tap selection switches constitute the load current switching switch;
The automatic voltage regulator according to claim 1, 2, or 3. A series transformer is further provided in which the secondary winding is connected in series with the distribution line;
The adjustment transformer has a primary winding to which the voltage of the distribution line is input, one end side end tap and the other end side end tap at one end and the other end, and a plurality of taps between both end taps. A regulation voltage output from the secondary winding of the regulation transformer through the tap changer is applied to the primary winding of the series transformer.
The tap changer includes an end tap on one end of the secondary winding of the adjustment transformer and an end of the primary winding of the series transformer, and each intermediate tap of the adjustment transformer and the series transformer. A plurality of tap selection switches respectively connected between one end of the primary winding, the other end side most end tap of the secondary winding of the adjustment transformer, and the other end of the primary winding of the series transformer A first polarity changeover switch connected between the first transformer and a second end of the secondary winding of the adjustment transformer, and a first switch connected between the other end of the primary winding of the series transformer. 2 for switching the polarity, and a switch for bridging connected in parallel via a current limiting resistor to both ends of the primary winding of the series transformer as the tap switching switch. By temporarily closing the switch, both ends of the primary winding of the series transformer An adjustment voltage to be applied from the adjustment transformer to the primary winding of the series transformer by switching the combination of the tap selection switch to be closed and the polarity switch to be closed while preventing the release state. Configured to switch,
The plurality of tap selection switches and the first and second polarity switching switches constitute the load current switching switch;
The automatic voltage regulator according to claim 1, 2, or 3. The tap changer includes a tap selector having an odd-numbered tap selector and an even-numbered tap selector for selecting an odd-numbered tap and an even-numbered tap provided in the adjustment transformer, and one end of the odd-numbered tap selector and the even-numbered tap selector. Odd-numbered tap-side tap selection switch and even-numbered tap-side tap selection switch connected to each of the slaves and connected at the other end in common, and a common connection point of the odd-numbered tap-side tap selection switch and the even-numbered tap-side tap selection switch A switch for switching off and turning on a current limiting resistor connected in parallel through a current limiting resistor between the odd tap selector or the even tap selector, and the odd tap side tap selection. Common connection point of switch for switch and even tap side tap selection switch is connected to primary side distribution line connection terminal Both the output terminal of said adjusting transformer is connected to the secondary side power line connection terminals,
The odd tap side tap selection switch and the even tap side tap selection switch constitute the load current switching switch;
The automatic voltage regulator according to claim 1, 2, or 3. A series transformer is further provided in which the secondary winding is connected in series with the distribution line;
The tap changer includes a tap selector having an odd-numbered tap selector and an even-numbered tap selector for selecting an odd-numbered tap and an even-numbered tap provided in the adjustment transformer, and one end of the odd-numbered tap selector and the even-numbered tap selector. Odd-numbered tap-side tap selection switch and even-numbered tap-side tap selection switch connected to each of the slaves and connected at the other end in common, and a common connection point of the odd-numbered tap-side tap selection switch and the even-numbered tap-side tap selection switch A switch for switching off and turning on a current-limiting resistor connected in parallel through a current-limiting resistor between the odd-numbered tap selector or the even-numbered tap selector; A common connection point of the switch and the even tap side tap selection switch is connected to one end of the primary winding of the series transformer. With the one of the taps provided on the adjustment transformer is connected to the other end of the primary winding of the series transformer,
The odd tap side tap selection switch and the even tap side tap selection switch constitute the load current switching switch;
The automatic voltage regulator according to claim 1, 2, or 3.   The operation characteristic of the voltage adjustment operation with respect to the fluctuation of the distribution line voltage is set so that the minimum value of the time interval at which the tap changer performs the tap change operation falls within the range of 3 to 10 seconds. An automatic voltage regulator according to any one of claims 1 to 7.

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