JPH0235325B2 - SEISHIGATAJIDODENATSUCHOSEISOCHI - 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 thyristors in the mechanical tap changers of conventionally widely used automatic voltage regulators, making them contactless.
It has the feature that there is no limit to the number of times the taps can be switched, and the operating time can be shortened. 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 S ₁ is connected to each tap t ₁ to _{t 4} of the regulating transformer. _An indirect switching type is known in which the voltage induced in the secondary winding of the series transformer TS is applied to the primary winding of the regulating transformer TR via these thyristor switches. It is being Here, each thyristor switch is as shown in Fig. 1B.
It consists of two thyristors SCR ₁ and SCR ₂ connected in antiparallel, and the line voltage is adjusted to a predetermined value by selecting the tap by making one of the thyristor switches conductive according to the line voltage. It's getting old. This type of indirect switching type automatic voltage regulator has the advantage of being able to use a low-voltage thyristor, but on the other hand, it requires two transformers, a series transformer and a regulating transformer, which makes the device size and It has the disadvantage that the weight also increases, 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, each thyristor switch must be able to withstand the short-circuit current that flows when the load side is short-circuited. It had the disadvantage that it was very expensive because it was necessary. In addition, in static automatic voltage regulators using thyristor switches, if the thyristor accidentally fires due to surge voltage or malfunction of the control circuit, or if the thyristor is permanently destroyed (continuity failure), the taps may be short-circuited. There was a risk that the regulating transformer would burn out.

An object of the present invention is to provide a static automatic voltage regulator that eliminates the need to use a thyristor with a large current capacity, reduces loss, and prevents a regulating transformer from burning out in the event of a short circuit between taps. It is about providing.

The present invention provides 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. The breaker 5 inserted into the side circuit and the regulating transformer
The first automatic switch 6 is inserted into the circuit on the load side of the TT, and is provided so as to be able to open and close between the power supply side terminal of the breaker 5 and the load side terminal of the first automatic switch 6. a second automatic switch 7, a plurality of auxiliary current transformers CT1 _{to CT6} for detecting the current flowing through each of the plurality of taps _t1 to _t6 of the regulating transformer, and a control device 8. It is characterized by The control device 8 outputs a first overcurrent detection signal e1 when the load current becomes an overcurrent that is greater than or equal to the first set value _I1 and _less than the second set value _I2 , and outputs a first overcurrent detection signal _e1 , When it comes to the first
overcurrent detection signal e ₁ and second overcurrent detection signal e ₂
An overcurrent detection circuit 801 that outputs
It is equipped with an inter-tap short circuit detection circuit 813 that generates a detection signal when multiple of CT ₁ to CT ₆ output signals at the same time.
The ignition signal is continuously given to the thyristor switch S ₁ connected to the tap t ₁ (hereinafter referred to as the transparent tap) where the primary side and the secondary side of the TT are directly connected and the voltage is not converted. After the automatic switch 7 is closed and the shroud breaker 5 is turned on and the first automatic switch 6 is closed, the second automatic switch 7 is opened and the first automatic switch 7 is closed.
When the overcurrent detection signal _e1 is generated, the thyristor switch _S1 is made conductive and switched to the through tap _t1 , and when the second overcurrent detection signal _e2 is generated, the thyristor switch S1 is switched on after opening the breaker 5. The opening of the automatic switch 6 and the closing of the second automatic switch 7 are performed in sequence,
When the inter-tap short circuit detection circuit 813 generates a detection signal, the cutter 5 is opened, and then the first automatic switch 6 and the second automatic switch 7 are closed in sequence.

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 cutter 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 portion.

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

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} .

The control device 8 performs the original control operation of an automatic voltage regulator that controls the on/off of thyristor switches S ₁ to S ₆ according to the output of the voltage regulator relay in order to switch the tap of the regulator 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 a firing signal to the thyristor switch connected to a specific tap on the regulating transformer to close or open the disconnector, and when an overcurrent is detected. At times, the capacitor breaker 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. A control operation for controlling an automatic switch, and a control operation for opening a shatter breaker 5 when a short circuit between taps is detected, then opening a first automatic switch 6, and then closing a second automatic switch 7. It is configured to perform a control operation to control the Nishiya breaker and the first and second automatic switches.

An example of the configuration of the control device 8 is shown in FIG. In the same figure, 801 is an overcurrent detection circuit, and this detection circuit is a current transformer installed in the breaker 5.
With the output of the CT as input, when the line current exceeds the first set value I ₁ (for example, 500A), the first overcurrent detection signal e ₁ with a logical value of "1" is output, and the line current is Second set value I ₂ higher than the first set value
(for example, 2500A) or more, the first overcurrent detection signal _e1 and the second overcurrent detection signal whose logic value is "1" are sent.
Outputs overcurrent detection signal _e2 . Such an overcurrent detection circuit includes, for example, a rectifier that rectifies the output of a current transformer CT, and first and second comparators that compare the output of the rectifier with first and second set values, respectively. be done.

Second detection signal e ₂ obtained from the above detection circuit
is a signal instructing to open the circuit breaker 5, and this signal is supplied to the base of the transistor _Tr1 whose emitter is grounded via the OR circuit _ORx . The collector of transistor Tr ₁ is relay RY ₁
is connected to the positive output terminal of the DC power supply 802 through a parallel circuit of the coil and the diode _D1 ,
When the second detection signal e ₂ occurs, the transistor
Tr ₁ is made conductive and relay RY ₁ is energized. 803 is the switch 11 shown in FIG.
This is a control power-on detection circuit that outputs one pulse signal when the transistor _Tr2 is turned on.
The collector of Tr ₂ is connected to the positive output terminal of DC power supply 802 via a parallel circuit of the coil of relay RY ₂ and diode D ₂ . The output of the control power-on detection circuit 803 is also inputted 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 receives direct current through the parallel circuit of the coil of the relay RY ₃ and the diode D ₃ . It is connected to the positive output terminal of the power supply 802. 805 is a tap open detection which outputs a detection signal when it is detected that all taps _t1 to _t6 of the regulating transformers T and T are disconnected from the power supply and are not energized. In the circuit, this tap open detection circuit 805 receives an input signal from a tap current detection circuit 811, which will be described later, and its output signal is supplied to the base of the transistor _Tr3 via a delay circuit 806 and the OR circuit ORa.

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 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 RY _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 . Further, contact RY _2a of relay RY ₂ and contact RY _1b of relay RY ₁ are connected in series, and the coil of relay RY ₅ is connected to DC power supply 802 via these contacts. Relay RY ₅ is a normally open contact RY _5a ,
RY′ _5a , one normally open contact RY _5a is said contact.
Connected in parallel to 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 is connected from the control power transformer 9 in FIG. 2 through the control power switch 11.
Equipped with a full-wave rectifier Rec ₁ to which 100V AC voltage is input, the above contact is connected between the output terminals of this full-wave rectifier.
Series circuit of RY′ _2a , coil of relay RY ₆ , normally closed contact RY _7b of relay RY ₇ , diode D ₄ and resistor
A series circuit of R ₁ and capacitor C ₁ is 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 One end of the normally open contact RY _1a is connected to the connection point of RY _1a .

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 Rec ₁ . The other end of the auxiliary contact 52A is connected to the other end of the normally open contact RY _1a via a trip coil 53T.
The other end of 2B 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 Rec ₁ via a normally open contact RY _6a of a relay RY ₆ .

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 also 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 are connected in parallel. A capacitor C ₂ is connected in parallel to both ends of the coil of relay _X , and a normally open contact M _ca of relay M _c and _a normally open contact M′ _b of relay connected in parallel. Further, a flywheel diode _D5 for delaying the opening operation is connected in parallel to both ends of the closed coil CC of the second automatic switch 7. The output of the transformer 9 is inputted 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 Rec ₂ is connected to the normally open contact of the relay RY ₅ .
It is applied via RY′ _5a , and a smoothing capacitor C ₃ is connected in parallel to the output terminal of the rectifier Rec ₂ .
Further, between the input terminals a and b of the second automatic switch 7, the output of the full-wave rectifier Rec ₃ to which the output of the control power transformer 9 is inputted 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 are opened. The operation of the second automatic switch 7 is similar to that described above, except that the opening operation is delayed by the flywheel diode _D5 .

In Fig. 4, A ₀₀ , A ₁₁ to A ₁₆ , A ₂₁ to _{A 26} and
A ₃₀ to _{A 36} are 2-input AND circuits, OR ₀ to OR ₆ are OR circuits, FF ₀ to _{FF 6} are flip-flop circuits, A _n1
~A _n6 is an amplifier consisting of a transistor, P ₁ ~ _{P 6} is a DC power supply E and a pulse transformer Pt, and when a signal of "1" is input to each of the amplifiers A _n1 ~ _{A n6} , a pulse-like point is generated. A pulse output circuit that simultaneously outputs arc signals e _g1 and e _g2 , F ₁ to _{F 6} are filter circuits that combine direct current conversion and noise removal, consisting of a full-wave rectifier Recf, a resistor Rf, and a capacitor Cf.
These constitute a circuit that controls on/off the thyristors S ₁ to S ₆ . To be more detailed,
A rectangular pulse signal e ₃ obtained from the signal source circuit 808 is input to one input terminal of each of the AND circuits A ₀₀ , A ₁₁ to A ₁₂ and A ₂₁ to _{A 26} , and the output of the AND circuit A ₀₀ is Amplifier A _n1 through circuit OR ₀
has been entered. The output of the flip-flop circuit FF ₀ is input to the other input terminal of the AND circuit A ₀₀ , and the overcurrent detection circuit 80 is input to the set terminal of FF ₀ .
1 first detection signal e ₁ is input. Therefore, when the first detection signal _e1 is generated and the flip-flop circuit _FF0 is set, the AND circuit _A00 outputs a signal of "1" and this signal is output to the OR circuit _OR0.
The signal is inputted to the amplifier A _n1 through the pulse output circuit P ₁ , thereby outputting the ignition signals e _g1 and e _g2 from the pulse output circuit P 1 . These signals are converted into direct current through a filter circuit _F1 and supplied to the gates of thyristors _{SCR1 and SCR2 of} a thyristor switch _S1 connected to a transparent tap t1, respectively.

The other input terminals of the AND circuits A ₁₁ to _{A 16} are provided with the outputs v ₁ to v ₆ of the tap switching command signal generation circuit 801 controlled by the voltage adjustment relay 809, respectively.
is entered. The tap switching command signal generation circuit 810 is made up of, for example, a shift register, and switches between taps t ₁ to _{t 6} in response to a signal from the voltage adjustment relay 809.
Outputs one of signals v ₁ to _{v 6} instructing selection of each. The outputs of AND circuits A ₁₁ to _{A 16} are input to the set terminals of flip-flop circuits FF ₁ to FF ₆ , respectively, and
The outputs of FF ₁ to _{FF 6} are input to one input terminal of AND circuits A ₂₁ to _{A 26} . The output of the AND circuit A ₂₁ is input to the amplifier A _n1 via the OR circuit OR ₀ , and the outputs of the AND circuits A ₂₂ to A ₂₆ are input to the amplifier A n1 via the OR circuit OR 0.
Each is input to A _n2 to A _n6 . amplifier
The outputs of A _n2 to A _n6 are respectively pulse output circuits P ₂ to
Tap t ₂ to _{t 6} via P ₆ and filter circuit F ₂ to F ₆
The thyristor switch to select _S2 ~ _S6 is supplied to the thyristor. In addition, the output of the OR circuit OR ₀ is supplied to one input terminal of the AND circuit A ₃₁ , and the outputs of the AND circuits A ₂₂ to A ₂₂ are supplied to each of the AND circuits.
It is supplied to one input terminal of _A32 to _A36 .
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 rectifies the outputs of the auxiliary current transformers CT ₁ to _{CT 6} provided for the taps t ₁ to _{t 6} by Rec ₄ , respectively, and converts the outputs to a constant voltage by a constant voltage diode ZD. ′ ₁ ~ u′ ₆ as input and tap t ₁
The tap current detection circuit 811 outputs tap current detection signals _{u 1 to u 6} to the output terminals corresponding to the taps, respectively. A tap current detection signal corresponding to the tapped tap is output. Among these tap current detection signals u ₁ to _{u 6} , the signal u ₁ that detects that _current has flowed through the transparent tap t ₁ is also supplied to one input terminal of the AND circuit A ₃₀ . The output of the AND circuit A ₀₀ is supplied to the other input terminal of the . Also, the output of AND circuit A ₃₀ is an OR circuit
It is input to OR ₂ to OR ₆ , and the output of AND circuit A ₃₁ is input to OR circuit OR ₂ . AND circuit A ₃₂
The output of AND circuit A33 is input to OR circuits OR ₁ and OR ₃ , and the output of AND circuit A ₃₃ is input to OR circuits OR ₂ and OR ₄ . Furthermore, the output of AND circuit A ₃₄ is input to OR circuits OR ₃ and OR ₅ , the output of AND circuit A ₃₅ is input to OR circuits OR ₄ and OR ₆ , respectively, and the output of AND circuit A ₃₆ is input to OR circuit OR ₅ . ing.
The outputs of OR circuits OR ₁ to OR ₆ are supplied to the reset terminals of flip-flop circuits FF ₁ to FF ₆ , respectively.
When signals in the state of "1" are output from OR circuits OR ₁ to OR ₆ , flip-flop circuits FF ₁ to
When the output of FF ₆ becomes "0", AND circuit A ₂₁ ~ _{A 26}
The output is set to "0". To reset the control circuit when switch 11 is turned on,
A power-on reset circuit 812 is provided, and a reset signal e _r obtained from this circuit is sent to the tap switching command signal generation circuit 810 and the flip-flop circuit.
FF ₀ reset terminal and OR circuit OR ₁ to 1 of OR ₆
are input to both input terminals.

The tap current detection circuit 811 is also configured to output a detection signal _e4 for detecting the opening of each tap and a detection signal _e5 for detecting a short circuit between the taps. The detection signal _e4 is the tap open detection circuit 8.
05, and the tap open detection circuit 805 outputs a detection signal indicating that all the taps are disconnected from the power supply when the detection signal _e4 for all the taps reaches a value indicating an open state. I'm starting to do that. The detection signal _e5 is output when a plurality of auxiliary current transformers CT1 to CT6 simultaneously output signals. The detection signal _e5 is input to the inter-tap short circuit detection circuit 813, and this detection signal
When _e5 continues for a predetermined time or more, the inter-tap short circuit detection circuit 813 outputs a detection signal indicating that an inter-tap short circuit has occurred. This detection signal is applied to the transistor via the OR circuit OR _x .
It is entered into the base of TR ₁ .

Furthermore, AND circuit A ₀₀ , A ₁₁ ~A ₁₆ ...A ₃₁ ~A ₃₆ , OR circuit OR ₀ ~ OR ₆ , flip-flop circuit FF ₀ ~
Electric power for operating each part of the control circuit such as FF ₆ is supplied to the control power transformer 9 via the control power switch 11.
The output is provided by a constant voltage power supply circuit 814 to which the output is input.

Next, the operation of the above embodiment will be explained. When the control power switch 11 is closed as shown in FIG. 5A at the start of energization, a reset signal e _r (see FIG. 5) is output from the power-on reset circuit 812, and this reset signal causes the tap switching command signal generation circuit 81 to be output.
0, and flip-flop circuits FF ₀ -FF ₆ are reset. At this time, the tap switching command signal generating circuit 810 _outputs a signal _v1 instructing selection of the transparent tap t1, and the AND of the AND circuit _A11 is established to set the flip-flop circuit _FF1 . At this time, the AND circuit A ₂₁ outputs a square wave signal, and this signal is passed through the OR circuit OR ₀ to the amplifier.
A is input to _n1 . This allows the thyristor switch _S1 of tap t1 to pass through, and the thyristors _SCR1 and _{SCR2 of} S1.
ignition signals e _g1 , e _g2 (see Figure 5B) are given,
Preparation for conduction of thyristor switch _S1 is completed.
On the other hand, the turning on of the control power switch 11 is detected by the control power turning on detection circuit 803, and from this detection circuit a signal is sent to the transistor Tr ₃ through the OR circuit OR _a .
gives pulse-like signals. This causes transistor Tr ₃ to conduct, energizing relay RY ₃ and closing its contact RY _3a . Closing contact RY _3a energizes relay RY ₄ , which is self-held by contact RY _4a . At this time, contact RY′ _4a is also closed, so
The automatic switch 7 closes as shown in FIG. 5C. The pulsed output of the above-mentioned closing detection circuit 803 is also supplied to the transistor Tr ₂ through the delay circuit 804, so that after a certain period of time ΔT ₁ after the switch 11 is turned on, the transistor Tr ₂ outputs a signal corresponding to the width of the output pulse of the closing detection circuit 803. Continuous for only time, relay RY ₂
works for a short time. When contact RY _2a of relay RY ₂ closes, relay RY ₅ is energized and its contact RY′ _5a
is closed, and due to the closing of contact RY' _2a , the breaker 5 is closed.
closes. Furthermore, the relay is activated by closing contact RY _5a .
RY ₅ is self-held, and the automatic switch 6 is closed by closing the contact RY′ _5a . Furthermore, when contact RY _2b opens, relay RY ₄ is deenergized, so contact RY′ _4a opens, but since the deenergization of closed coil CC is delayed due to flywheeler diode D ₅ , automatic switch 7 is closed. 5 As shown in Figure C, the automatic switch 6
opens after a certain delay time ΔT ₂ has elapsed after closing. At the same time as the automatic switch 7 opens, as shown in FIG. 5F, 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 the thyristor switch S ₁ becomes conductive immediately, no line voltage is applied to the thyristor switches S ₂ to _{S 6} , and only a small voltage approximately equivalent to the tap-to-tap voltage is applied to the thyristor switches S 2 to S 6. . Here, the delay times ΔT ₁ and ΔT ₂ are set to, for example, approximately ΔT ₁ =ΔT ₂ =1 [sec].

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
9, 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 any 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 81
1, a tap current detection signal corresponding to the newly selected tap is output, 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 A ₁₂
Since the AND of is established, the flip-flop circuit
FF ₂ is set and the AND of AND circuit A ₂₂ 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. Tap when thyristor switch S ₂ conducts.
Since current flows through _t2 , a detection signal _u2 is output from the tap current detection circuit 811, and the AND circuit
The AND of A ₃₂ is established. The rectangular wave signal of this AND circuit _A32 is supplied via OR circuits _OR1 and _OR3 to the reset terminals of flip-flop circuits _FF1 and _FF3 corresponding to adjacent taps _t1 and _t3 . 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". Therefore, the supply of ignition signals to thyristor switches S ₁ and S ₃ is prohibited (at this time, thyristor switch S ₃ is originally not given an ignition signal), and thyristor switch S ₁ is controlled so that the anode potential of each thyristor is When it becomes negative with respect to the cathode, it becomes shut off.

Next, we will explain the operation when an overcurrent flows due to a short circuit accident on the load side while one of the taps is selected and the load is energized. This overcurrent is the first
If the set value I ₁ (e.g. 500A) or more, the second set value I ₂
(for example, 2500 A), only the first detection signal _e1 is generated from the overcurrent detection circuit 801.
At this time, since the flip-flop circuit _FF0 is set, the AND of the AND circuit _A00 is established, and a rectangular wave signal is input to the through-tap amplifier _An1 through the OR circuit _OR0 . Therefore, the thyristor switch _S1 becomes conductive and the clear tap _t1 is selected. As a result, the detection signal _u1 is output from the tap current detection circuit 811, so the AND of the AND circuit _A30 is established, and the rectangular wave output signal of the AND circuit _A30 is passed through the OR circuits _OR2 to _OR6 to the flip-flop circuit FF2 _. ~ _FF6 reset terminals, respectively. As a result, the flip-flop circuit FF ₂ ~
All FFs ₆ are reset, and even if any of the taps _t2 to _t6 is selected, the supply of the ignition signal to the thyristor switch of the selected tap is stopped. At this time, in the thyristor switch of the tap that was energized first, of the two thyristors constituting the thyristor switch, one of the thyristors to which a forward voltage is applied between the anode and cathode is in a conductive state. One of the thyristors is turned off when the polarity of the anode-cathode voltage is reversed. At this time, a forward voltage is applied between the anode and cathode of the other thyristor, but since the supply of the ignition signal to the other thyristor has already been stopped, the thyristor does not become conductive. In this way, if an overcurrent of less than the second set value _I2 occurs, switching to the open tap is performed unconditionally. In addition, if an overcurrent flows while energizing with a transparent tap, the tap will be fixed as is.

Next, when an overcurrent equal to or greater than the second set value I ₂ flows, the overcurrent detection circuit 801 simultaneously outputs the first and second detection signals e ₁ and e ₂ . In this case, the first detection signal e ₁ causes an unconditional tap t ₁
The switching to is performed in the same way as above.
If an overcurrent of _I2 or more occurs at the current time _T1 , the thyristor switch _S1 becomes conductive as shown in _FIG . The thyristor switch shuts it off. This delay time ΔT ₃ is a time corresponding to about 1/2 cycle of the normal power supply voltage. The second detection signal _e2 is sent to the transistor _Tr1 via the OR circuit _ORx .
Since it is input to the base of , transistor Tr ₁ becomes conductive and relay RY ₁ is energized. Therefore, the contact
RY _1a closes and contact RY _1b opens. Since the disconnector 5 is now closed and the auxiliary contacts 52A and 52B are in the closed state, when the contact RY _1a closes, the trip coil 53T is energized, which releases the mechanical lock of the disconnector 5. Main contacts 51A and 51B
opens, and auxiliary contacts 52A and 52B also open. Also, by opening contact RY _1b , relay RY ₅ is deenergized, and contacts RY _5a and RY′ _5a are opened. This opens the first automatic switch 6 as shown in FIG. 6D.
Since the automatic switch has a certain time delay after its closed coil is deenergized until the contact opens, the first automatic switch 6 opens a predetermined time later than the disconnector 5. The time ΔT ₄ from when an overcurrent occurs to when the automatic switch 6 opens is approximately three cycles of the power supply. When the tap open detection circuit 805 detects that no tap current is flowing at the time when the breaker 5 is disconnected, the detection circuit 805
A signal is supplied from the transistor Tr ₃ to the transistor Tr 3 via the delay circuit 806 and the OR circuit OR _a . This causes transistor Tr ₃ to conduct, energizing relay RY ₃ and closing its contact RY _3a . At this time the relay
Since the contact RY _2b of RY ₂ is closed, the relay RY ₄ is energized, and the relay RY ₄ is self-held by the contact RY _4a , and by closing the contact RY' _4a ,
The second automatic switch 7 closes as shown in FIG. 6E. When the automatic switch 7 closes, if the fault has not been removed, the fault current will flow to the fault point via the switch 7, and the current will be detected by an overcurrent relay (not shown) in the substation and The breaker opens.
In this case, when the switch 7 closes, the voltage of the control power supply drops extremely due to the accident, but the switch 7 closes and disconnects the substation due to the action of the flywheel diode _D5 in the control circuit. Remain closed for sufficient time before opening. The operation after the fault is removed and the substation switch is turned on again is the same as the operation at the start of energization. If an accident occurs at time T ₁ and the accident has been resolved when the automatic switch 7 closes after the shield breaker 5 opens and the automatic switch 6 opens, the circuit breaker 5 opens and the automatic switch 6 closes. The load is energized through the automatic switch 7 without opening the switch. In this case, the energization state of the line is as shown in FIG. 6F, and after the automatic switch 6 opens, the automatic switch 7
There is a momentary power outage during the time ΔT ₅ until it closes, but thereafter the load is energized without any problem. In this case, the instantaneous power outage time ΔT ₅ is about 0.5 seconds.

Next, when the thyristor switch or the control circuit breaks down due to a surge voltage or the like and any of the taps becomes short-circuited, the tap-to-tap short circuit detection circuit 813 outputs a detection signal, and this detection signal is sent to the OR circuit. It is supplied to transistor TR ₁ via OR _x . As a result, relay RY ₁ is energized, overcurrent flows, and a second detection signal is output from overcurrent detection circuit 801.
The first automatic switch 5 opens by the same operation as when e ₂ occurs, and then the first automatic switch 6 opens. Thereafter, when the opening of the tap is detected, the second automatic switch 7 closes. The voltage regulator 3 that has been disconnected from the line can be operated in the same way as described above by manually opening the control power switch 11 and then turning it on again after completing the repair of the part where the tap-to-tap short circuit has occurred. Then, the control device 8 performs a control operation to return to the normal operating state, which is the same as the operation at the start of energization.

With the configuration of the above embodiment, since the tap is unconditionally switched to the through tap when an overcurrent occurs, it is possible to prevent excessive current from flowing into the thyristor switch of a tap other than the through tap. When turning on the power, first give a continuous ignition signal to the clear tap thyristor switch, then turn on the second automatic switch, and then
Since the second automatic switch is opened after the first automatic switch is turned on, the thyristor switch of the transparent tap is necessarily conductive. Therefore, no circuit voltage is applied to the thyristor switches of other taps. For these reasons, only a transparent tap thyristor switch using a thyristor with a large current capacity is required, and the other tap thyristor switches can be constructed from inexpensive thyristors with a small current capacity. In addition, transparent tap thyristor switches only need to withstand overcurrent for a short period of time before the overcurrent occurs and the circuit breaker opens, which is not necessary for conventional direct switching automatic voltage regulators. A large capacity thyristor is not required.

As in the above embodiment, if a first automatic switch is provided and the first automatic switch is opened after the breaker opens, the first automatic switch will open the load when an accident occurs on the load side. Since the side track can be separated, the load can be protected. Furthermore, if the second automatic switch is closed after the overcurrent is detected and the breaker is opened as in the above embodiment, power can be supplied to the load as is if the fault has been resolved. If the accident has not been resolved, the substation's circuit breakers can be operated.

As mentioned above, when a tap-to-tap short circuit is detected, if the first automatic switch is opened and then the first automatic switch is opened, the regulating transformer is disconnected from the line, so it is connected to the load side line. Since it is possible to prevent the regulating transformer from being reversely energized from other connected adjacent power distribution lines, etc., it is possible to prevent the regulating transformer from being burnt out due to short-circuit current flowing between the taps.

Incidentally, the first and second automatic switches or breakers may be used, but since they do not cut off a large current, a simple switch without a current cutoff function can be used. Furthermore, when the control power switch 11 is closed, it goes without saying that the tap open detection circuit is also reset by a reset signal from the power-on reset circuit.

In the above embodiment, a thyristor switch connected to a through-tap is selected as the thyristor switch that continuously provides an ignition signal before the breaker is turned on, but in some cases, a thyristor switch connected to a through-tap may be used. A connected thyristor switch may also be selected.

In the above explanation, a single-phase circuit was used as an example, but 2
The present invention can be applied in exactly the same manner to a three-phase automatic voltage regulator constructed by V-connecting one regulating transformer or three phase-connecting three regulating transformers.

As described above, according to the present invention, since the breaker is opened when an overcurrent is detected, the thyristor switch can be protected from overcurrent, and a thyristor with a small current capacity can be used. can. Therefore, it is possible to provide a static automatic voltage regulator at a low cost, which takes advantage of the advantages of a direct switching voltage regulator in that the device can be made smaller and losses can be reduced because a series transformer is not used. In addition, in the present invention, when a tap-to-tap short circuit occurs, the shield breaker and automatic switch open to disconnect the regulating transformer from the power supply side and load side lines, so it is possible to prevent the regulating transformer from burning out. can.

[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. 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 FIGS. FIGS. 6A to 6F are diagrams showing the operation when the power is turned on when using the control device shown in the figure, and FIGS. 6A to 6F are diagrams showing the operation when an overcurrent is detected. 1... Substation, 2... Load, 3... Automatic voltage regulator, 4... Line, 5... Line breaker, 6... First
automatic switch, 7... second automatic switch, 8...
Control device.

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 provided to open and close between the power supply side terminal and the load side terminal of the first automatic switch 6; and a plurality of taps _t1 to _t6 of the adjustment transformer. A plurality of auxiliary current transformers CT _{1 to} CT ₆ detect the current flowing through each of
When the overcurrent becomes less than I ₂ , the first overcurrent detection signal e ₁
and an overcurrent detection circuit 801 that outputs a first overcurrent detection signal _e1 and a second overcurrent detection signal _e2 when the value exceeds a second set value _I2 , and the auxiliary current transformer.
A tap-to-tap short circuit detection circuit 813 is provided which generates a detection signal when a plurality of CT ₁ to CT ₆ simultaneously output signals, and when the current is started, the adjustment transformer is
Thyristor switch S ₁ connected to a tap where the primary and secondary sides of the TT are directly connected and the voltage is not converted.
After continuously giving an ignition signal to the switch, the second automatic switch 7 is closed, and the shield breaker 5 is turned on and the first automatic switch 6 is closed in sequence. The second automatic switch 7 is opened, and when the first overcurrent detection signal _e1 is generated, the thyristor switch _S1 is made conductive, so that the primary side and the secondary side are directly connected and no voltage conversion is performed. _t1 , and when the second overcurrent detection signal _e2 is generated, the shield breaker 5 is opened, and then the first automatic switch 6 is opened and the second automatic switch 7 is closed. are performed in sequence, and when the tap-to-tap short circuit detection circuit 813 generates a detection signal, after opening the shield breaker 5, the first automatic switch 6 is opened and the second automatic switch 7 is opened. A static automatic voltage regulator comprising: a control device 8 that sequentially closes and closes a circuit.