JPH0261043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a static automatic voltage regulator that adjusts line voltage by switching taps by turning on and off a thyristor.

Static automatic voltage regulators use thyristor switches in place of the mechanical tap changers of the conventionally widely used automatic voltage regulators, making them contactless and can operate without any limit to the number of tap changes. It has the feature of shortening the time limit. As shown in FIG. 1A, a conventional static automatic voltage regulator is provided with a series transformer _Ts and a regulating transformer _TR , and a thyristor switch is connected to each tap _t1 to _t4 of the regulating transformer. Connect S ₁ ~ S ₄ , series transformer T _s
An indirect switching type is known in which the voltage induced in the secondary winding of the regulator is applied to the primary winding of the regulating transformer T _R via these thyristor switches. Here, each thyristor switch has two thyristors SCR ₁ and SCR ₂ connected in antiparallel as shown in Fig. 1B, and a surge absorption capacitor C ₀ and a resistor connected in parallel to these thyristors. It consists of a series circuit of R ₀ and a semiconductor arrester L _A1 connected, and the line voltage is adjusted to a predetermined value by selecting a tap by making one of the thyristor switches conductive depending on the direction of the line current. It's summery. This type of indirect switching type automatic voltage regulator has the advantage of being able to use low-voltage and inexpensive thyristors, but on the other hand, it requires two transformers, a series transformer and a regulating transformer, which makes the equipment difficult to operate. It has the disadvantage that both size and weight increase, and in particular, as the capacity increases, it becomes difficult to mount it on poles, so it has the disadvantage that only a small capacity can be realized. Furthermore, since this indirect switching type uses a series transformer, it also has the disadvantage of increased loss. In order to eliminate these drawbacks, it is necessary to adopt a direct switching type configuration that does not use a series transformer, but in the case of a direct switching type, all taps may be open due to a failure of the thyristor ignition circuit, etc. If this happens, the entire circuit voltage will be applied to each thyristor, which could cause each thyristor switch to break down and lead to a serious accident.

Therefore, as shown in Japanese Patent Publication No. 54-17428, a static automatic voltage regulator was proposed that was equipped with a circuit that self-ignited the thyristor when the thyristor's ignition power supply was lost.

However, the current fracture shape due to self-ignition is a fracture shape with a missing fracture head, and the current supplied to the load does not become a sine wave, so it is not possible to continue the operating state due to self-ignition until the ignition power is restored. I didn't like it.

The object of the present invention is to self-ignite the thyristor connected to a specific tap when the thyristor ignition power is lost, and to immediately supply power directly from the power supply to the load after taking measures to prevent damage to the thyristor. An object of the present invention is to provide a static automatic voltage regulator that can continue supplying current to a load without any trouble.

The present invention relates to a static automatic voltage regulator equipped with a regulating transformer connected to a line and a thyristor switch for tap selection connected to each tap of the regulating transformer. , In order to achieve the above purpose, a breaker 5 is inserted in the circuit on the power supply side than the regulating transformer TT, and a first automatic switch breaker is inserted in the circuit on the load side than the regulating transformer TT. 6, a second automatic switch 7 that opens and closes between the power supply side terminal of the shield breaker 5 and the load side terminal of the first automatic switch, and the primary side of the regulating transformer TT and 2 When the voltage across the thyristor switch S1 connected to the tap that is directly connected to the next side and does not perform voltage conversion (hereinafter referred to as "transparent tap") t1 reaches a predetermined value, the thyristor switch S1
a self-ignition circuit that provides a firing signal to each thyristor making up the thyristor, and a thyristor firing signal loss detection circuit that detects loss of firing signals to all thyristor switches and outputs a firing signal loss signal e1. 8
00 and the output of the ignition signal loss detection circuit as input, and when the ignition signal loss detection signal e1 is generated, the breaker 5 is opened, the first automatic switch 6 is opened, and the second automatic switch is opened. A control device 8 is provided to sequentially close the circuits 7 and 7.

With the above configuration, when the ignition signal is lost and all taps become open, the thyristor switches connected to the through taps will self-ignite, so the entire circuit voltage will be applied to each thyristor switch. Each thyristor switch can be prevented from being destroyed.

Also, as mentioned above, when it is detected that the ignition signal to all thyristor switches has been lost, the regulator The first automatic switch inserted into the circuit on the load side of the switch is opened, and then the first automatic switch is opened/closed between the power supply side terminal of the shield breaker and the load side terminal of the first automatic switch. By closing the automatic switch 2, it is possible to immediately switch to the operating state where power is directly supplied to the load from the power supply without continuing the operation due to the self-ignition of the thyristor switch connected to the through tap. By shortening the time during which a voltage with a waveform with a missing wavefront is supplied to the load, it is possible to prevent the quality of power supplied to the load from deteriorating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below along with embodiments thereof with reference to the drawings.

Figure 2 shows the overall configuration of the present invention together with a power distribution system. In the figure, 1 is a substation, 2 is a load, and 3 is a direct switching switch connected to a line 4 connecting the substation and the load. type static automatic voltage regulator,
Reference numeral 5 denotes a circuit breaker inserted in a circuit closer to the power source than the voltage regulator 3. 6 is a first automatic switch inserted into the circuit on the load side of the voltage regulator 3; This is a second automatic switch provided to open and close. 8 is a control device that controls the voltage regulator 3, the shield breaker 5, the first automatic switch 6, and the second automatic switch 7; The output of the fluid CT is input. 9 is a control power transformer connected to the line on the power supply side than the disconnector 5, and the output voltage (usually 100V) of this transformer is connected to the control device 8 through the control power cable 10 and the control power switch 11. is supplied to. In FIG. 2, the thick line portion indicates the high voltage section.

In this embodiment, the static automatic voltage regulator 3 is a regulating transformer consisting of an autotransformer having multistage taps t ₁ to _{t 6} (the number of taps is arbitrary) as shown in FIG.
TT, and thyristor switches S ₁ to _{S 6} each having one end connected to the taps t _{1 to t 6 of the regulation transformer TT, and one end of the through-through tap t 1 side of the regulation transformer TT and one end of the thyristor switch S 1} to S ₆ connected to the tap t ₁ of the regulation transformer TT, respectively. The other end is connected to the output terminal 12 through the contacts 61A and 61B of the first automatic switch 6.
r and 12'r, and load-side lines are connected to these output terminals, respectively. The other ends of thyristor switches S ₁ to _{S 6} are each reactor L ₁
~ _L6 , and the other ends of the reactors _L1 ~ _L6 are connected to the input terminal 12s via the main contact 51A of the common connection circuit breaker 5. Further, the other end connected to the output terminal 12'r of the regulating transformer TT is connected to the input terminal 12's via the main contact 51B of the disconnector 5, and the input terminal 12's, 1
A line on the power supply side (substation side) is connected to 2's.
Furthermore, the power supply side terminals of the main contacts 51A and 51B of the breaker 5 and the contacts 61A and 6 of the first automatic switch 6
Contacts 71A and 71B of the second automatic switch 7 are connected to open and close the contacts 71A and 71B, respectively, with the load side terminal of the second automatic switch 7.

Reactor L ₁ ~ _{L 6} and thyristor switch S ₁ ~
An auxiliary current transformer is installed on each line connecting _S6 .
CT ₁ to CT ₆ are provided, and these auxiliary current transformers are adapted to detect the current flowing through the taps t ₁ to _{t 6} .

In this embodiment, the through tap t ₁ is selected as a specific tap for providing the self-starting circuit of the thyristor, and the zener is connected to _the thyristor SCR ₁ and SCR ₂ constituting the thyristor switch S ₁ of this through tap t 1. Diode ZD ₁ , ZD, diode
A self-firing circuit consisting of D ₁ , D ₂ , D ₀₁ , D ₀₂ and a resistor R is provided. More specifically, a diode D ₀₁ , a resistor R, a diode D ₁ and a Zener diode ZD ₁ are connected in series, and the anode and gate of the thyristor SCR ₁ are coupled by a series circuit of these elements. Further, a diode D ₀₂ , a resistor R, a diode D ₂ and a Zener diode ZD ₂ are connected in series, and the anode and gate of the thyristor SCR ₂ are coupled by a series circuit of these elements. That is, in this embodiment, the self-ignition circuit of the thyristor SCR ₁ is formed by the diode D ₀₁ , the resistor R, the diode D ₁ and the Zener diode ZD ₁ , and the diode D ₀₂ , the resistor R,
The diode D ₂ and the Zener diode ZD ₂ each constitute a self-starting circuit of the thyristor SCR ₂ , and the resistor R also serves as current limiting means for both self-starting circuits.

The control device 8 performs the original control operation of the automatic voltage regulator, controlling the on/off of thyristor switches S ₁ to S ₆ according to the output of the voltage regulating relay in order to switch the tap of the regulating transformer TT so as to maintain the line voltage at a predetermined value. In addition to this, there is also a control operation that continuously applies an ignition signal to the thyristor switch connected to the through tap of the regulating transformer to close or open the disconnector, and when an overcurrent is detected. The Nishiya disconnector 5 is opened, the first automatic switch 6 is opened, and when the opening of the tap is detected, the second automatic switch 7 is closed. and a control operation for controlling the switch, and when a short circuit between the taps is detected, the breaker 5 is opened, the first automatic switch 6 is opened, and the second automatic switch 7 is then closed. It is configured to perform a control operation for controlling the disconnector and the first and second automatic switches. Furthermore, in this embodiment, a thyristor firing signal loss detection circuit is provided to detect when firing signals to all thyristor switches are lost, and this detection circuit detects when firing signals to all thyristor switches are lost. When this is detected, a control operation is performed to first close the second automatic switch 7 and then open the shroud breaker 5 and the first automatic switch 6. Furthermore, in this embodiment, a tap open detection circuit is provided in preparation for an abnormal situation in which all taps are open because the thyristor does not fire even though a firing signal is applied to the thyristor. When the open detection circuit detects that all the taps are open, the second automatic switch 7 is closed in the same manner as described above.
Next, a control operation is performed to open the shield breaker 5 and the first automatic switch 6.

An example of the configuration of the control device 8 is shown in FIG. In the same figure, 800 is the ignition signal loss detection circuit,
This detection circuit is designed to output a signal of "1" (H level) when firing signals to all thyristors are lost. In the illustrated example, one thyristor that makes up each thyristor switch
A light emitting diode PD is connected in parallel between the gate and cathode of SCR ₂ through a resistor R _g so that this light emitting diode PD emits light when an ignition signal is applied.
By detecting the light by the photoelectric detection means PS, it is detected whether or not an ignition signal is given to each thyristor switch. Although means for detecting the presence or absence of an ignition signal are provided for all the thyristor switches, in order to avoid complexity, only the detection means for the thyristor switch _S1 is shown in FIG. 4.
For example, as shown in FIG. 5, the ignition signal loss detection circuit 800 has six input terminals h ₁ and h ₂ to which signals for detecting the presence or absence of ignition signals of the thyristor switches S ₁ to S ₆ F are input. ...h ₆ , and a flip-flop circuit _FF0 whose set input is the output of this NOR circuit, and the firing signals of all thyristor switches are lost and all the input signals of the NOR circuit NOR become "0". ”, the flip-flop circuit FF ₀ is set at the rising edge of the “1” signal output from the NOR circuit,
The ignition signal loss detection signal _e1 in the state of "1" is obtained at the positive logic output terminal Q.

The above ignition signal loss detection signal e ₁ is a delay circuit 801
It is supplied to the base of the transistor Tr1 whose emitter is grounded through the OR circuit _ORx . A DC power source 8 is connected to the collector relay RY ₁ of the transistor Tr ₁ through a parallel circuit with the coil of the relay RY 1 and the diode D ₁ .
Connected to the positive output terminal of 02, the detection signal e ₁
When a certain period of time has elapsed after this occurs, the transistor Tr ₁ becomes conductive and the relay RY ₁ is energized.

803 is a control power-on detection circuit that outputs one pulse signal when the switch 11 shown in FIG.
Transistor whose emitter is grounded through 04
The collector of the transistor Tr ₂ is connected to the positive output terminal of the DC power supply 802 via a parallel circuit of the coil of _the relay RY ₂ and the diode D ₂ . The output of the control power-on detection circuit 803 is also the ignition signal loss detection signal e ₁
It is also input to the base of the transistor Tr ₃ whose emitter is grounded through the OR circuit ORa, and the collector of the transistor Tr ₃ is connected to the DC power supply 8 through the parallel circuit of the coil of the relay RY ₃ and the diode D ₃ .
It is connected to the positive side output terminal of 02. 80
5 is the opening of the tap, that is, the tap of the regulating transformer TT.
This tap open detection circuit 805 outputs a detection signal when it is detected that all of t ₁ to _{t 6} are disconnected from the power supply and are not energized. An input signal is obtained from the circuit 811, and its output signal is supplied to the base of the transistor Tr ₁ via the delay circuit 806 and the OR circuit OR _x , and is also supplied to the base of the transistor Tr ₃ via the OR circuit OR _a . ing.

The relay RY ₁ has a normally open contact RY _1a and a normally closed contact RY _1b , and the relay RY ₂ has a normally open contact RY _2a , RY′ _2a and a normally closed contact RY _2b . Relay RY ₃ C has a normally open contact RY _3a , and the coil of relay RY ₄ is connected to DC power supply 802 via this normally open contact RY _3a and the above-mentioned normally closed contact Y _2b . Relay RY ₄ has normally open contacts RY _4a , RY' _4a , one normally open contact
RY _4a is connected in parallel with the normally open contact RY _3a . Also, contact RY _2a of relay RY ₂ B and relay RY ₁
are connected in series with normally closed contacts RY _1b , and the coil of relay RY ₅ is connected to the DC power supply 80 through these contacts.
Connected to 2. Relay RY ₅ is a normally open contact
RY _5a and RY′ _5a , one normally open contact RY _5a is connected in parallel to the contact RY _2a .

Normally open contacts RY _1a and RY′ _2a of relays RY ₁ and RY ₂
It is connected to the chopper and disconnection control circuit 807. The breaker control circuit 807 includes a full-wave rectifier _Rec1 to which an AC voltage of 100V is input from the control power transformer 9 shown in FIG. 2 through the control power switch 1, and a A series circuit of the contact RY′ _2a , the coil of the relay RY ₆ , and the normally closed contact RY _7b of the relay RY ₇ , and a series circuit of the diode D ₄ , the resistor R ₁ , and the capacitor C ₁ are connected in parallel. A series circuit consisting of the coil of relay RY ₇ and normally open contact RY _7a of relay RY ₇ is connected in parallel to both ends of the series circuit consisting of the coil of relay RY ₆ and normally closed contact RY _7b , and resistor R ₁ and capacitor C Normally open contact RY _1a at connection point ₁
The ends are connected.

In the example shown in FIG.
Main contacts 51A and 5 that open and close the main tracks respectively
1B are provided with auxiliary contacts 52A and 52B that open and close in conjunction with these main contacts, and the auxiliary contact 52A
and 52B have one end commonly connected to the negative output terminal of the rectifier _Rec1 . Also, auxiliary contact 5
The other end of RY 2A is connected to the other end of the normally open contact RY _1a via a trip coil 53T, and is connected to the auxiliary contact 52.
The other end of B is connected to the connection point between the coil of relay RY ₇ and contact RY _7a . The breaker 5 is also provided with a closed coil 53C, which is connected in parallel between the DC output terminals of the rectifier _Rec1 via a normally open contact _RY6a of a relay _RY6 .

The first and second automatic switches 6 and 7 are constantly energized automatic switches that do not have a mechanical lock mechanism that closes only while the closed coil CC is energized, and the closed coil CC of these switches is It is connected between input terminals a and b via a resistor _R2 . A series circuit of resistors R ₃ and R ₄ and the coil of relay X is connected between input terminals a and b, and the coil of relay M _c is connected to both ends of the series circuit via the normally closed contact X _b of relay X. are connected in parallel. Relay X
A capacitor C ₂ is connected in parallel to both ends of the coil, and a normally open contact M _ca of relay M _c and a normally closed contact X' _b of relay X are connected in parallel to both ends of resistor R ₂ and both ends of resistor R ₃ , respectively. has been done. In addition, a flywheel diode is installed at both ends of the cooled coil CC of the second automatic switch 7 to delay the opening operation.
D ₅ are connected in parallel. The output of the transformer 9 is input between the input terminals a and b of the first automatic switch 6 via the control power switch 11. The output of the full-wave rectifier R _ec2 is connected to the normally open contact RY' of the relay _RY5 . _5a , and a smoothing capacitor _C3 is connected in parallel to the output terminal of the rectifier _Rec2 . Furthermore, between the input terminals a and b of the second automatic switch 7, the output of the full-wave rectifier _Rec3 to which the output of the control power transformer 9 is input via the switch 11 is applied. A smoothing capacitor _C4 is connected in parallel between the output terminals of the wave rectifier _Rec3 .

When voltage is applied between the input terminals a and b of the first automatic switch 6, the relay _{M c}
Current flows through the coil and the contact M _ca closes. As a result, the closed coil CC is excited, and the contacts 61A and 61B of the automatic switch 6 are closed. The voltage applied between input terminals a and b is also applied to capacitor C ₂ via contact X' _b and resistor R ₄ , and when charging of capacitor C ₂ is completed, relay X is energized. This opens contacts X _b and X' _b and deenergizes relay M _c . In this state, the excitation current of the closed coil CC is limited by the resistor _R2 , and the current of the closed coil CC is reduced to the holding current required to keep the switch in the closed state. Further, the excitation current of relay X is also limited to the holding current by resistors R ₃ and R ₄ . When the voltage between input terminals a and b is removed, the closed coil CC is deenergized and the contacts 61A and _61B open. Same as above except for the delay.

In FIG. 4, A ₁₁ to A ₁₆ , A ₂₁ to A ₂₆ and A ₃₁ to
A ₃₆ is a 2-input AND circuit, OR ₁ to OR ₆ are OR circuits,
FF ₁ ~ FF ₆ F is flip-flop circuit, A _n1 ~ _{A n6}
is an amplifier consisting of a transistor, _P1 to _P6 is a DC power supply and a pulse transformer Pt, and when a signal of "1" is input to each of the amplifiers A _n1 to _{A n6} , a pulsed ignition signal eg ₁ is generated. and eg ₂ at the same time, F ₁ to F ₆ are full wave rectifiers
This is a filter circuit for both direct current conversion and noise removal, consisting of _Recf , resistor Rf, and capacitor Cf, and these constitute a circuit that controls on/off of thyristors S ₁ to S ₆ . More specifically, the rectangular pulse signal _e3 obtained from the signal source circuit 808 is input to one input terminal of each of the AND circuits _A11 to _A16 and _A21 to _A26 , and the AND circuits A11 to _A26 receive the rectangular pulse signal e3 obtained from the signal source circuit 808. _A16
A voltage regulating relay 8 is connected to the other input terminal of each
09a and the output of the tap switching command signal generation circuit 810 controlled by the reversible binary counter 809b.
v ₁ to _{v 6} are input. The tap switching command signal generation circuit 810 is composed of, for example, a decoder, and switches between taps t1 to _t1 in response to a signal from the voltage adjustment relay 809a.
Signals commanding the selection of t ₆ respectively v ₁ to _{v 6}
Output one of the following. The outputs of AND circuits A ₁₁ to _{A 16} are flip-flop circuits FF ₁ to FF ₆ , respectively.
is input to the set terminal of the flip-flop circuit.
The outputs of _FF1 to _FF6F are input to one input terminal of AND circuits _A21 to _A26 . The output of the AND circuit A ₂₁ is input to the amplifier A _n1 , and the outputs of the AND circuits A ₂₂ to _{A 26} F are input to the amplifiers A _n2 to _{A n6} , respectively. The outputs of amplifiers A _n2 to _{A n6} are respectively pulse output circuits P ₂ to _{P 6} and filter circuits F ₂ to _{F 6}
The thyristor switches S ₂ to _{S 6} are supplied to the thyristors to select the taps T ₂ to _{T 6} through. Further, the output of AND circuit A ₂₁ is supplied to one input terminal of AND circuit A ₃ C ₁ , and the output of AND circuits A ₂₂ to _{A 26} is supplied to one input terminal of AND circuits A ₃₂ to _{A 36} , respectively. There is. Tap current detection signals u ₁ to u ₆ obtained from the tap current detection circuit 811 are input to the other input terminals of the AND circuits A ₃₁ to A ₃₆ , respectively. The tap current detection circuit 811 is
Signals u′ ₁ to u′ ₆ are obtained by rectifying the outputs of auxiliary current transformers CT ₃ to CT 6 provided for taps t ₁ to t ₆ , respectively, by _Rec4 and making _the voltage constant by voltage regulating diodes ZD.
is input and outputs tap current detection signals u ₁ to _{u 6} to the output terminals corresponding to taps t ₁ to _{t 6} , respectively. When one of the taps is selected and current flows through that tap, the tap current Detection circuit 81
1, a tap current detection signal corresponding to the selected tap is output. The output of AND circuit A ₃₁ is input to OR circuit OR ₂ , and the output of AND circuit A ₃₂ is input to OR circuits OR ₁ and OR ₃ . The output of AND circuit A ₃₃ is an OR circuit
The output _of AND circuit _{A 34 is} input to OR circuits OR ₃ and OR ₅ . Furthermore, the output of AND circuit A ₃₅ is input to OR circuits OR ₄ and OR ₆ , and the output of AND circuit A ₃₆ is input to OR circuit OR _5.
has been entered. The outputs of the OR circuits OR ₁ to _{OR 6} are supplied to the reset terminals of the flip-flop circuits FF ₁ to _{FF 6} , respectively, and when a signal in the state of "1" is output from each of the OR circuits OR ₁ to OR ₆ , the flip-flop circuits FF ₁ The output of ~ _FF6 becomes "0", and the outputs of AND circuits _A21 to _A26 become "0". In order to reset the control circuit when the switch 11 is turned on, a power-on reset circuit 8 is installed.
12 is provided, and the reset signal e _r obtained from this circuit is sent to the reversible binary counter 809b, the tap switching command signal generation circuit 810, the tap open detection circuit 805, and one input terminal of the OR circuits _OR1 to _OR6 . are entered respectively.

The tap current detection circuit 811 is also configured to output a detection signal e ₄ for detecting the opening of each tap, and this detection signal e ₄ is input to the tap open detection circuit 805 . The tap open detection circuit 805 is similar to the ignition signal loss detection circuit shown in FIG.
When _e4 reaches a value indicating an open state, a detection signal is output indicating that all taps are disconnected from the power supply.

Furthermore, AND circuit A ₁₁ ~ _{A 16} ...A ₃₁ ~A ₃₆ , OR circuit
Electric power for operating each part of the control circuit such as OR to OR ₆ and flip-flop circuits FF ₁ to FF ₆ F is supplied by a constant voltage circuit 814 to which the output of the control power ground transformer 9 is input via the control power switch 11. It's starting to be given.

Next, the operation of the above embodiment will be explained. When the control power switch 11 is closed as shown in FIG. 6A at the start of energization, a reset signal e _r (see FIG. 6B) is output from the power-on reset circuit 812, and this reset signal activates the tap switching command signal generation circuit. 8
10. Flip-flop circuits FF ₁ to FF ₆ and tap open detection circuit 805 are reset.

At this time, the tap switching command signal generation circuit 810 generates a signal v ₁ instructing to select the transparent tap t ₁ .
is output, the AND of the AND circuit _A11 is established, and the flip-flop circuit _FF1 is set. At this time, the AND circuit _A21 outputs a rectangular wave signal, and this signal is input to the amplifier A _n1 . This allows the thyristor switch of S ₁ to pass through the thyristor switch of T ₁ .
Ignition signals e _g1 and e _g2 (see FIG. 6) are applied to SCR ₁ and SCR ₂ , and preparation for conduction of thyristor switch S ₁ is completed. On the other hand, turning on of the control power switch 11 is detected by the control power-on detection circuit 803, and this detection circuit supplies one pulse-like signal to the transistor Tr ₃ through the OR circuit _ORa . This makes transistor Tr ₃ conductive and
Relay RY ₃ is energized and its contacts RY _3a are closed.
Closing contact RY _3a energizes relay RY ₄ ,
It is self-maintained by its contact RY _4a . At this time, the contact RY' _4a is also closed, so the automatic switch 7 is closed as shown in FIG. 6D. The above input detection circuit 803
The pulsed output of is also supplied to the transistor Tr ₂ through the delay circuit 804, so that after a certain time ΔT ₁ delay after the switch 11 is turned on, the transistor Tr ₂ becomes conductive for a time corresponding to the width of the output pulse of the turning detection circuit 803. Relay RY ₂ operates for a short time. When contact RY _2a of relay RY ₂ closes, relay RY ₅ is energized and its contact RY′ _5a closes, and the contact
By closing RY′ _2a , the sheath breaker 5 is closed. Furthermore, the relay RY ₅ E is self-held by closing the contact RY _5a , and the automatic switch 6 is closed by closing the contact RY' _5a . Also, when contact RY _2b opens, relay RY ₄
is deenergized, contact RY' _4a opens, but since the deenergization of the closed coil C is delayed due to the flywheel diode _D5 , the automatic switch 7 opens as shown in Fig. 6D.
As shown in FIG. 2, the automatic switch 6 opens after a certain delay time ΔT ₂ has elapsed after the automatic switch 6 closes. At the same time as the automatic switch 7 opens, as shown in FIG. 6F, the thyristor switch _S1 of the through-tap, to which the ignition signal has already been applied, becomes conductive and current flows through the through-tap _t1 . In this way, since thyristor switch _S1 immediately conducts when electricity starts, line voltage is not applied to thyristor switches _S2 to _S6 , and the thyristor of each thyristor switch has a voltage approximately equivalent to the tap-to-tap voltage. Only a small voltage is applied. Here, the delay times ΔT ₁ and ΔT ₂ are set to approximately ΔT ₁ =ΔT ₂ =1 [sec], for example.

After the through tap is selected and energization is started as described above, if the line voltage on the load side decreases due to an increase in load, the voltage adjustment relay 80
According to the operation of step 9a, the tap switching command signal generation circuit 810 outputs one of the command signals _v2 to _v6 instructing to appropriately select the boost taps _t2 to _t6 , and the boost taps _{t2 to} t6 are output. A firing signal is given to a thyristor switch connected to one of _t6 . When one of the auxiliary current transformers CT ₁ to _{CT 6} confirms that the thyristor switch to which the ignition signal is applied is conductive and current flows to the tap to which the thyristor switch is connected, the tap current detection circuit 8
11 outputs a tap current detection signal corresponding to the newly selected tap, and this signal causes the ignition signal given to the thyristor switch of the previously selected tap to disappear. As a result, the thyristor switch of the previously selected tap is turned off, and the switching of the tap is completed. For example, if the tap switching command signal generation circuit 810 outputs a signal v ₂ indicating that the tap should be switched to tap t ₂ while the transparent tap t ₁ is selected, the AND circuit
Since the AND of _A12 is established, flip-flop circuit _FF2 is set, and the AND of AND circuit _A22 is established. Therefore, a rectangular wave signal is applied to the amplifier A _n2 , and an ignition signal is applied to the thyristor switch _S 2 of the tap t ₂ so that the thyristor switch S ₂ becomes conductive. When the thyristor switch _S2 becomes conductive, a current flows through the tap _t2 , so a detection signal _u2 is output from the tap current detection circuit 811, and the AND of the AND circuit _A32 is established. This AND circuit A ₃₂
The square wave signals of are supplied to the reset terminals of flip-flop circuits FF ₁ and FF ₃ corresponding to adjacent taps t ₁ and t ₃ via OR circuits OR ₁ and OR ₃ .

By resetting the flip-flop circuits FF ₁ and FF ₃ , the output signals of the AND circuits A ₂₁ and A ₂₃ become "0", and the inputs of the amplifiers A _n1 and A _n3 become "0".
become. Therefore thyristor switches S ₁ and S ₃
The supply of the ignition signal to the thyristors is stopped, and the thyristor switches S ₁ and S ₃ are cut off when the anode potential of each thyristor becomes negative with respect to the cathode.

Next, during energization, the thyristor firing signal generation circuit 80
If the ignition signals e _g1 and e g2 B are no longer given to all thyristor switches from the control circuit side due to the oscillation of the thyristor switch 8 stopping or the amplifiers A _n1 to A _n6 breaking down, the thyristor switches e g1 and e _g2 When one thyristor switch becomes cut off at the zero point of its current, all the thyristor switches will be cut off from then on, and in this case, the entire circuit voltage will be applied to each thyristor and each thyristor will be destroyed. .

However, in this embodiment, as shown in FIG. 3, since the transparent tap thyristor switch S ₁ is provided with a self-ignition circuit, the ignition signals e _g1 ,
e After _g2 is lost and all thyristor switches are unable to fire, the thyristor switch
When the voltage across _S1 reaches a predetermined value, a firing signal can be given to the thyristor of this thyristor switch. That is, in Fig. 3, the thyristor
When the voltage across the anode of SCR ₁ exceeds the Zener voltage of the Zener diode ZD ₁ during a half cycle in which the anode of the SCR ₁ has a positive potential with respect to the cathode _{, the} thyristor A firing signal is given to SCR ₁ , which causes thyristor SCR ₁
conducts. When thyristor SCR ₁ becomes conductive, the voltage across it decreases, so the firing signal to thyristor SCR ₁ disappears. Similarly, in the half cycle in which the anode of thyristor SCR ₂ has a positive potential with respect to the cathode, a firing signal is given to this thyristor SCR ₂ when the voltage across it exceeds the Zener voltage of Zener diode ZD ₂ , and the thyristor
SCR ₂ becomes conductive. In the self-starting circuit of thyristor switch S ₁ , diodes D ₀₁ and D ₀₂ are
This is to prevent a circuit that bypasses both thyristors SCR ₁ and SCR ₂ connected in antiparallel from being constructed when both are in a cutoff state.

As mentioned above, in the present invention, in order to cause the thyristor switch of a specific tap to self-ignite when the thyristor firing signal is lost, the voltage V ₁ applied to each thyristor switch is set as shown in FIG. Zener diode ZD ₁ and
The Zener voltage V _z can be limited to ZD ₂ .
Incidentally, FIG. 7B shows the waveform of the current ₁ flowing through the thyristor switch of a specific tap (in this embodiment, the transparent tap t ₁ ) when the power factor of the load is 1.

Further, when the firing signal is no longer applied to all the thyristor switches, a high level signal _e1 is output from the thyristor firing signal loss detection circuit 800,
This provides base current to transistor _Tr3 . Therefore, transistor Tr ₃ becomes conductive,
Relay RY ₃ is energized. This causes contact RY _3a
is closed, relay RY ₄ is energized, and automatic switch 7 is closed by the same operation as described above. Since the high level signal _e1 obtained from the ignition signal loss detection circuit 800 is also given to the base of the transistor _Tr1 via the delay circuit 801 and the OR circuit _ORx ,
Transistor Tr ₁ becomes conductive and relay RY ₁ is energized. This closes the contact RY _1a and opens the contact RY _1b , which opens the shield breaker 5 and opens the automatic switch 6. In this case, since the automatic switch 7 is closed first, uninterruptible power is supplied to the load.

The operations when the ignition signal is lost are summarized as shown in FIGS. 8A to 8E. That is, as shown in Figure A, if the energized thyristor is cut off at time _T1 after the firing signal is lost,
Thyristor switch with clear tap as shown in
_S1 self-ignites, and then the automatic switch 7 is closed as shown in FIG. Thereafter, after a certain delay time, the breaker 5 and the automatic switch 6 open, disconnecting the regulating transformer TT from the line. During this time, the load current is
There is no interruption as shown in FIG. 8E.

Next, even if all the taps are open because the thyristor does not fire even though the thyristor firing signal is present, there is a risk that overvoltage will be applied to each thyristor in the same way as above. In this case as well, the self-ignition circuit of the thyristor switch _S1 is activated and the thyristor switch is immediately brought into conduction, so that each thyristor switch can be prevented from being destroyed. Further, in this embodiment, when all the taps are in the open state, the tap open detection circuit 805 outputs the high level tap open detection signal _e2 . This detection signal e ₂ is applied to the transistor Tr ₃ via the OR circuit OR _a , similar to the ignition signal loss detection signal e ₁ , and is also applied to the transistor Tr ₁ via the delay circuit 806 and the OR circuit OR _x . Therefore, the operation is exactly the same as the operation when the ignition signal is lost as shown in FIGS. 8A to 8E.

As described above, according to the present invention, when the ignition signal is lost and all the taps become open, the thyristor switches connected to the through taps self-ignite, so that the total circuit voltage is applied to each thyristor switch. This has the advantage of being able to prevent the thyristor switches from being applied, thereby preventing each thyristor switch from being destroyed.

Further, according to the present invention, when it is detected that the ignition signals to all the thyristor switches have been lost, the regulator Open the first automatic switch inserted in the circuit on the load side of the transformer, and then open/close between the power supply side terminal of the shield breaker and the load side terminal of the first automatic switch. Since the second automatic switch is closed, it is possible to immediately switch to the operating state in which power is supplied directly from the power source to the load without continuing operation due to self-ignition of the thyristor switch connected to the through tap. By shortening the time during which a voltage with a waveform with a missing wavefront is supplied to the load, it is possible to prevent the quality of the power supplied to the load from deteriorating.

[Brief explanation of drawings]

FIG. 1A is a connection diagram showing an example of the configuration of a conventional static automatic voltage regulator, FIG. 1B is a configuration diagram of a thyristor switch, and FIG. 2 schematically shows the overall configuration of an embodiment of the present invention. Single-line connection diagram, FIG. 3 is a connection diagram showing essential parts of an embodiment of the present invention, FIG. 4 is a connection diagram showing an example of the configuration of a control device used in the present invention, and FIG. 5 is a connection diagram showing the control of FIG. 4. A connection diagram showing an example of the ignition signal loss detection circuit used in the device. Lines 6 A to F are diagrams showing the operation when the power is turned on when using the control device shown in Fig. 4. Figs. 7 A and B are Diagrams showing an example of the voltage waveform and current waveform across the thyristor switch when the thyristor switch self-ignites, and Figures 8A to 8E show diagrams when the ignition signal is lost and when the control device of Figure 4 is used. FIG. 4 is a diagram showing the operation when opening. 1... Substation, 2... Load, 3... Automatic voltage regulator, 4... Line, 5... Line breaker, 6... First
automatic switch, 7... second automatic switch, 8...
Control device, ZD ₁ , ZD ₂ ... Zener diode,
D ₁ , D ₂ , D ₀₁ , D ₀₂ ... Diode, R ... Resistor.

Claims (1)

[Scope of Claims] 1. A static automatic voltage regulator comprising a regulating transformer connected to a line and a tap selection thyristor switch connected to each tap of the regulating transformer, wherein the regulating transformer a first automatic switch 6 inserted into a circuit on the load side of the regulating transformer TT; A second automatic switch 7 that opens and closes between the power supply side terminal and the load side terminal of the first automatic switch, and is directly connected to the primary side and secondary side of the regulating transformer TT. A self-ignition circuit that provides a firing signal to each thyristor that constitutes the thyristor switch S1 when the voltage across the thyristor switch S1 connected to the tap t1 that does not perform voltage conversion reaches a predetermined value; and all the thyristor switches. a thyristor ignition signal loss detection circuit 800 that detects the loss of the ignition signal to the ignition signal and outputs an ignition signal loss signal e1; A control device 8 is provided which sequentially opens the shield breaker 5, opens the first automatic switch 6, and closes the second automatic switch 7 when the detection signal e1 is generated. A static automatic voltage regulator characterized by: