JPH035611B2 - - 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 thyristor switches are connected to taps _t1 to _t4 of the regulating transformer, respectively.
An indirect switching type in which S ₁ to _{S 4} are connected and 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 has been known. Here, each thyristor switch is set to 2 as shown in Figure 1B.
It consists of two thyristors SCR ₁ and SCR ₂ connected in antiparallel, and by making the thyristor switch of either tap conductive according to the line voltage, the tap is selected and the line voltage is adjusted to a predetermined value. It's becoming like that. 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 with a direct switching type, the thyristor may accidentally fire due to surge voltage or malfunction of the control circuit. If the thyristor were to fail permanently (continuity failure), the taps would be short-circuited, and there was a risk that the regulating transformer would burn out.

For contact-type load tap switching devices,
As shown in Japanese Patent Application Laid-open No. 54-87834, it has been proposed to cut off the transformer when a short circuit between taps is detected, but this is not desirable because cutting off the transformer would result in a power outage to the load. do not have.

SUMMARY OF THE INVENTION An object of the present invention is to provide a static automatic voltage regulator that prevents a regulating transformer from burning out when a tap-to-tap short circuit occurs and also prevents power outages to the load.

The present invention relates to 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.

In the present invention, in order to achieve the above object, a sheath disconnector 5 is inserted in the circuit on the power side of the regulating transformer TT, and a first automatic switch is inserted in the circuit on the load side of the regulating transformer TT. 6, and then connect the power side terminal of the disconnector 5 and the first automatic switch 6.
A second automatic switch 7 is connected between the load side terminal and the load side terminal.

There is also an inter-tap short circuit detection circuit 801a that detects an inter-tap short circuit of each tap _t1 to _t6 and outputs an inter-tap short circuit detection signal _e'c , and an inter-tap short circuit detection circuit 801a that outputs an inter-tap short circuit detection signal e'c.
Short circuit duration measuring circuit 8 which measures the duration of the short circuit between the taps by inputting e′ _c and outputs the breaker opening command signal e ₁ when the duration reaches a predetermined value.
01b, and a short circuit duration measuring circuit 8 at fixed time intervals.
A reset circuit 801c for resetting the short circuit duration time measuring circuit 801b is provided, and the output of the short circuit duration measuring circuit 801b is input to the control device 8.

The control device 8 opens the shield breaker 5 and opens the first automatic switch 6 when the shield breaker opening command signal _e1 is generated.
The opening of the circuit and the closing of the second automatic switch 7 are performed in sequence.

With the above configuration, when a short circuit between taps is detected, the power supply to the regulating transformer is stopped, so that burnout of the regulating transformer can be prevented.

Also, as mentioned above, if the short circuit between the taps continues for a predetermined period of time, the chisel or disconnector is opened.
Since the chopper and the disconnector do not open due to a momentary short circuit, unnecessary operation of the cutter and disconnector can be prevented, and unnecessary wear and tear on the contacts of the cutter and the disconnector can be prevented.

Furthermore, by providing a reset circuit as described above and resetting the short circuit duration time measuring circuit at regular intervals, it is possible to prevent instantaneous short circuit detections from being accumulated and generating a disconnection command signal. It can be prevented.

Further, as described above, a first automatic switch and a second automatic switch are provided, and when a short circuit between taps is detected, the first automatic switch is opened and then the second automatic switch is closed. In this case, the power supply side and the load side can be connected through the second automatic switch, so that the load can continue to be energized. Therefore, it is possible to protect the regulating transformer without causing a power outage to the load when a short circuit occurs between the taps.

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 _S1 to S6, one end of which is connected to the taps _t1 to _t6 of the regulating transformer TT, _respectively , and are directly connected to the primary and secondary sides of the regulating transformer TT to control the voltage. Tap that does not perform conversion (hereinafter referred to as transparent tap) One end of _t1 side and regulating transformer TT
The other end is the contacts 61A and 6 of the first automatic switch 6
1B to output terminals 12r and 12'r, and load-side lines are connected to these output terminals, respectively. The other ends of the thyristor switches S ₁ to _{S 6} are connected to one end of the 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. 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,
A line on the power supply side (substation side) is connected to the input terminals 12s and 12's. Furthermore, the second automatic switch 7 is configured to open and close between the power side terminals of the main contacts 51A and 51B of the breaker 5 and the load side terminals of the contacts 61A and 61B of the first automatic switch 6, respectively.
Contacts 71A and 71B are connected.

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 a capacitor breaker open command generation circuit, which receives an input signal from a tap current detection circuit 811 (described later) and issues a command to open a capacitor breaker when a short circuit between taps continues for a predetermined period of time. Outputs the Sushiya disconnector open command signal _e1 . The configuration of this circuit breaker opening command generation circuit will be described later. The shield breaker open command signal e ₁ obtained from the open command generation circuit 801 is transmitted through the transistor Tr ₁ whose emitter is grounded.
is supplied to the base. The collector of the transistor Tr ₁ is the coil of the relay RY ₁ and the diode D ₁
It is connected to the positive output terminal of the DC power supply 802 through a variable series circuit, and when the circuit breaker opening command signal _e1 is generated, the transistor _Tr1 becomes conductive and the relay is activated.
RY ₁ is now energized. 803 is 1 when the switch 11 shown in FIG. 2 is turned on.
The output of this detection circuit is supplied to the base of transistor Tr _{2 whose emitter is grounded through a delay circuit 804, and the collector of transistor Tr 2 is} connected to the coil of relay RY ₂ and the diode. It is connected to the positive output terminal of the DC power supply 802 via a parallel circuit with _D2 . . 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 . power supply 8
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 _Tr3 via the delay circuit 806 and the OR circuit ORa.

The relay RY ₁ has a normally open contact RY ₁ a and a normally closed contact RY ₁ b, and the relay RY ₂ has a normally open contact RY ₂ a, RY' ₂ a and a normally closed contact RY ₂ b. . Also relay RY ₃
has normally open contacts RY ₃ a, RY′ ₃ a, and the relay is connected via one normally open contact RY ₃ a and the above normally closed contact RY ₂ b.
The coil of RY ₄ is connected to a DC power supply 802. Relay RY ₄ has normally open contacts RY ₄ a, RY′ ₄ a,
One normally open contact RY ₄ a is connected in parallel with the above normally open contact RY ₃ a. Also the contacts of relay RY ₂
RY ₂ a and contact RY ₁ b 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 has normally open contacts RY ₅ a, RY' ₅ a, one normally open contact
RY ₅ a is connected in parallel to the contact RY ₂ a.

Normally open contacts RY ₁ a and relays RY ₁ and RY ₂
RY′ ₂ a is connected to the breaker 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 between RY′ ₂ a and the coil of relay RY ₆ and normally open contact RY ₇ b of relay RY ₇ and 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 ₇ a 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 ₇ b, and resistors R ₁ and RY 7 a are connected in parallel. One end of the normally open contact RY ₁ a is connected to the connection point of the capacitor C ₁ .

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 ₁ a 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 ₇ a. 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 ₆ a 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 Mc is connected in parallel to both ends of the series circuit via the normally closed contact It is connected. Capacitor _C2 is connected in parallel to both ends of the coil of relay X, and normally open contact Mca of relay Mc and normally closed contact X'b of relay X are connected in parallel to both ends of resistor _R2 and both ends of resistor _R3 , respectively. has been done. 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′ ₅ a, 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 to the output terminal of the wave rectifier _Rec3 .

When voltage is applied between the input terminals a and b of the first automatic switch 6, the relay Mc
Current flows through the coil and contact Mca 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 Xb and X′b,
Relay Mc is deactivated. In this state, the excitation current of the closed coil CC is limited by the resistor _R2 ,
The current in the closed coil CC is reduced to the holding current required to keep the switch closed.
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 controlled by the flywheel diode D ₅
This is the same as above except that the opening operation is delayed.

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 are flip-flop circuits, Am ₁ ~ _{Am 6}
is an amplifier consisting of a transistor, P ₁ to _{P 6} is composed of a DC power supply E and a pulse transformer Pt, and when a signal of "1" is input to each of the amplifiers Am ₁ to _{Am 6} , a pulse-shaped ignition signal e is generated. A pulse output circuit that simultaneously outputs _g1 and e _g2 , and F ₁ to _{F 6} are filter circuits that combine direct current conversion and noise removal, consisting of a full-wave rectifier Fecf, a resistor Rf, and a capacitor _Cf. A circuit is configured to control the on/off of 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 circuit _A11
The other input terminal of ~ _A16 is connected to a tap switching command signal generating circuit 810 controlled by a voltage regulating relay 809a and a reversible binary counter 809b, respectively.
The outputs v ₁ to _{v 6} of are input. The tap switching command signal generation circuit 810 includes, for example, a decoder,
A signal that instructs to select each of taps t ₁ to _{t 6} in accordance with the signal from the voltage adjustment relay 809a.
Outputs one of v ₁ to v ₆ . AND circuit A ₁₁ ~
The outputs of A ₁₆ are each flip-flop circuit FF _1
-FF6 are input to the set terminals, and the outputs of flip-flop circuits _FF1 to _FF6 are input to one input terminal of AND circuits _A21 to _A26 . and circuit
The output of _A21 is input to the amplifier _Am1 , and the outputs of the AND circuits _A22 to _A26 are input to amplifiers _Am2 to _Am6 , respectively. The outputs of the amplifiers Am ₂ -Am ₆ are supplied to thyristors of thyristor switches S ₂ -S ₆ which select taps t ₂ -t ₆ via pulse output circuits P ₂ -P ₆ and filter circuits F ₂ -F ₆ , respectively. ing. In addition, the output of AND circuit A ₂₁ is supplied to one input terminal of AND circuit A ₃₁ , and the AND circuit
The outputs of A ₂₂ to _{A 26} are respectively AND circuits A ₃₂ to _{A 36}
is supplied to one input terminal of the and circuit
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 A ₃₁ to _{A 36} , respectively. The tap current detection circuit 811 detects the outputs of the auxiliary current transformers CT ₁ to _{CT 6} provided for the taps t ₁ to t ₆ , respectively.
The signals u′ ₁ to u′ 6 rectified by Rec ₄ and made constant voltage by the constant voltage diode ZD are input, and the tap current detection signals u ₁ to u′ ₆ are input to the output terminals corresponding to taps t ₁ to t ₆ , respectively.
_u6 , and when any tap is selected and current flows through that tap, the tap current detection circuit 811 outputs a tap current detection signal corresponding to the selected tap. There is. The output of AND circuit A ₃₁ is an OR circuit
The output _{of AND circuit A 32 is} input to OR circuits OR ₁ and OR ₃ . and circuit
The output of A ₃₃ is input to OR circuits OR ₂ and OR ₄ ,
The output of AND circuit _A34 is input to OR circuits _OR3 and _OR5 . In addition, 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
The output of is input to the OR circuit _OR5 . 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 ~ _FF6
The output of the AND circuits A21 to A26 becomes "0" and the outputs of the 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 812 is provided, and a reset signal e _r obtained from this circuit is sent to the reversible binary counter 809b and the tap switching command signal generation circuit 810.
, the tap open detection circuit 805, the shield breaker open command generation circuit 801, and one input terminal of the OR circuits _OR1 to _OR6 , respectively.

The tap current detection signals u ₁ to u ₆ obtained from the tap current detection circuit 811 are also transmitted to the shield breaker opening command generation circuit 801 and the tap open detection circuit 805.
has been entered. Shield breaker open command generation circuit 80
1 is an AND circuit as shown in FIG. 5, for example.
An OR circuit ORx which inputs _A1 to _A15 and the outputs of these AND circuits, a reference clock generation circuit _OS1 which generates a reference clock signal _ec , and an input of the reference clock signal _ec and the output of the OR circuit ORx. An AND circuit AND ₁ , a preset counter PC that counts the pulses obtained from the AND circuit AND ₁ , a unidirectional transistor UJT, and a variable resistor.
The OR circuit consists of an intermittent pulse generation circuit OS ₂ consisting of VR, a capacitor C, and resistors r ₁ and r ₂ , and an OR circuit ORy which inputs the reset signal e _r and the output pulse signal of the intermittent pulse generation circuit OS ₂ . ORy
The output is a reset signal to the preset counter PC.
It is entered as e _r ′. AND circuit A ₁ ~ _{A 15}
The input terminals of are interconnected as shown and connected to detection signal input terminals _a1 to _a6 , and tap current detection signals _u1 to _u6 are input to the input terminals _a1 to _a6 , respectively. In this breaker opening command generation circuit 801, if any of the tap current detection signals _u2 to _u6 is generated simultaneously while the tap current detection signal _u1 is being generated (that is, tap _t1 and tap t If a short circuit occurs between any of ₂ ~ t ₆ ) and circuit A ₁ ~
If any AND of A ₅ is established and any of tap current detection signals u ₃ to u ₆ are generated simultaneously while tap current detection signal u ₂ is generated (tap
When a short circuit occurs between t ₂ and any of the taps t ₃ to _{t 6} ), an AND in one of the AND circuits A ₆ to _{A 9} is established. Also, if a short circuit occurs between tap t ₃ and any of taps t ₄ to t ₆ , the AND circuit A ₁₀ to _{A 12}
If one of the ANDs is true, tap t ₄ and tap
AND circuit if short circuit occurs between t ₅ or t ₆
The AND of A ₁₃ or A ₁₄ is established. Similarly, when a short circuit occurs between tap _t5 and tap _t6 , AND of AND circuit _A15 is established. Therefore, if a short circuit occurs between any of the taps, the AND circuit A ₁ ~
One of A ₁₅ outputs a signal with logical value "1",
This signal is passed through the OR circuit ORx to the AND circuit.
Entered into AND ₁ . Since a clock signal e _c of a predetermined frequency (for example, 60Hz) is also input to the AND circuit AND ₁ , if a short circuit occurs between the taps and the input signal enters the AND circuit AND ₁ from the OR circuit ORx, the input signal will be input from the AND circuit AND _1. A pulsed inter-tap short circuit detection signal e _c ' having the same frequency as the clock signal e _c is output. This detection signal e _c ' is the preset counter
When a preset number of pulse signals e _c ' are counted by the PC, the counter PC outputs a mustard breaker opening command signal e ₁ . That is, in this detection device 801,
When a short circuit occurs between any of the taps and the short circuit continues for a predetermined period of time, the breaker open command signal _e1 is output. Note that the count value of the preset counter PC can be set arbitrarily. When the same tap is energized for a long time (when the line voltage is kept constant), external surges, etc.
The preset counter PC counts one pulse even when the thyristor switch of one of the taps is erroneously fired and an instantaneous short circuit occurs between the taps.
Therefore, if erroneous firing of the thyristor is repeated several times, the number of pulse signals e _c will increase to the preset counter.
The count value set in the PC may be reached, and an unnecessary short circuit between taps will be detected and the breaker open command signal _e1 will be output. To prevent this, in this embodiment, the intermittent pulse generation circuit
The preset counter PC is reset by the output of OS ₂ at predetermined intervals (for example, 1 to 5 seconds).

In this embodiment, an inter-tap short circuit detection circuit detects an inter-tap short circuit using AND circuits A ₁ to _{A 15} , an OR circuit ORx, an AND circuit AND _1, and a reference clock generation circuit OS ₁ and outputs an inter-tap short circuit detection signal. 801a is configured and the preset counter PC
Thus, a short circuit duration measuring circuit 801b is configured which measures the duration of a short circuit between taps and outputs a command signal to open the breaker when the duration reaches a predetermined value. In addition, the intermittent pulse generation circuit OS ₂ and the OR circuit ORy generate the measurement circuit 80 at regular intervals.
A reset circuit 801C is configured to reset 1b.

On the other hand, the tap open detection circuit 805 is connected to the sixth tap, for example.
As shown in the figure, there is a NOR circuit NOR having six input terminals _h1 , _h2 ... _h6 to which tap current detection signals _u1 to _u6 are input, and the output of this NOR circuit is used as a set input. It consists of a flip-flop circuit _FF0 ,
When the firing signals of all thyristor switches are lost and all the input signals of the NOR circuit NOR become "0", "1" is output from the NOR circuit NOR.
Flip-flop circuit at the rising edge of the signal in the state of
Set FF ₀ and set "1" to its positive logic output terminal Q.
A tap open detection signal _e2 in the state of is obtained.

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

Next, the operation of the above embodiment will be explained. When the control power switch 11 is closed as shown in FIG. 7A at the start of energization, a reset signal e _r (see FIG. 7B) is output from the power-on reset circuit 812, and this reset signal activates the tap switching command signal generation circuit. 8
10. The flip-flop circuits FF ₁ to FF ₆ , the shutter open command generation circuit 801 and the tap open detection circuit 805 are reset. At this time, the tap switching command signal generation circuit 810 outputs a signal _v1 instructing to select the transparent tap _t1 , and the AND circuit
Establish the AND of A ₁₁ to create a flip-flop circuit.
Set FF ₁ . At this time, the AND circuit _A21 outputs a rectangular wave signal, and this signal is input to the amplifier _Am1 . As a result, ignition signals e _g1 and e _g2 (see FIG. 7C) are applied to _{the thyristors SCR 1 and} SCR ₂ of the thyristor switch S ₁ of the open tap t 1 , and preparation for conduction of the thyristor switch S ₁ 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 this detection circuit gives one pulse-like signal to the transistor Tr ₃ through the OR circuit ORa. This causes transistor Tr ₃ to conduct, energizing relay RY ₃ and closing its contact RY ₃ a. Closing contact RY ₃ a energizes relay RY ₄ and is self-held by contact RY ₄ a. At this time, since the contact RY' ₄ a is also closed, the automatic switch 7 is closed as shown in FIG. 7D. 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. It conducts for a time and relay RY ₂ operates for a short time. When the contact RY ₂ a of the relay RY ₂ is closed, the relay RY ₅ is energized and its contact RY' ₅ a is closed, and the closing of the contact RY' ₂ a closes the breaker 5. Furthermore, relay RY ₅ is activated by closing contact RY ₅ a.
is self-held, and the automatic switch 6 is closed by closing the contact RY' ₅ a. In addition, when contact RY ₂ b opens, relay RY ₄ is deenergized, so contact RY' ₄ a opens, but the de-energization of closed coil CC is delayed due to flywheel diode D ₅ , so automatic switch 7 is closed. As shown in FIG. 7D, 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. 7F, 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, 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
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 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 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 square wave signal is applied to the amplifier Am ₂ , and an ignition signal is applied to the thyristor switch _S 2 at tap t ₂ , so that the thyristor switch S ₂
conducts. 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
The rectangular wave signal _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 Am ₁ and Am ₃ become "0".

Therefore, the supply of ignition signals to thyristor switches S ₁ and S ₃ 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.

When a tap is energized, due to a malfunction of the thyristor gate circuit or a malfunction of the control circuit, the thyristor switch of a tap other than the one that is energized may turn on.
If this state continues, the taps will be short-circuited. At this time, the disconnector open command generation circuit 801
As a result of the above-described operation, outputs the shield breaker opening command signal e ₁ and makes the transistor TR ₁ conductive. This energizes relay RY ₁ , so contact RY ₁ a closes and contact RY ₁ b opens. Therefore, as shown in FIGS. 8A and _8B , if a short circuit occurs between the taps at time T1, after the settling time _ΔT3 determined by the count value of the preset counter PC has elapsed, the disconnector 5 and the automatic Switch 6 opens.

When the shield breaker 5 opens, no load current flows, so the tap open detection circuit 805 outputs a high level tap open detection signal _e2 . This detection signal e ₂
is applied to the transistor TR ₃ through the delay circuit 806 and the OR circuit ORa.
TR ₃ becomes conductive and relay RY ₃ is energized. This closes the contact RY ₃ a, so that the relay RY ₄ is energized, and the automatic switch 7 is turned on by the same operation as the one when the power is turned on. Here, the delay time ΔT ₄ of the delay circuit 806 is set to about 0.5 [sec]. By turning on the automatic switch 7, power supply to the load is restarted.

As described above, according to the present invention, when a tap-to-tap short circuit is detected, the breaker is opened to stop power supply to the regulating transformer, thereby preventing burnout of the regulating transformer due to the tap-to-tap short circuit. can.

In addition, in this invention, the disconnector is opened when a short circuit between taps continues for a predetermined period of time, so it is possible to prevent unnecessary operation of the disconnector due to an instantaneous short circuit. This can prevent unnecessary wear and tear on the disconnector contacts.

Furthermore, according to the present invention, a reset circuit is set up to reset the short circuit duration measuring circuit at regular intervals, so that instantaneous short circuit detection is integrated and a disconnection open command signal is generated. It is possible to prevent this from happening.

Further, according to the present invention, the first automatic switch and the second automatic switch
A second automatic switch is provided, and when a short circuit between taps is detected, the first automatic switch is opened and then the second automatic switch is closed, thereby opening and closing the power supply side and the load side. Since the connection is made through the device, the load can continue to be energized. Therefore, it is possible to protect the regulating transformer without causing a power outage to the load when a short circuit occurs between the taps.

[Brief explanation of the drawing]

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. 5 and 6 are respectively A connection diagram showing an example of the shield breaker open command generation circuit and the tap open detection circuit used in the control device shown in FIG. 4, and FIGS. 8A to 8C are diagrams illustrating the operation when a short circuit occurs between taps when the control device of FIG. 4 is used. 1... Substation, 2... Load, 3... Automatic voltage regulator, 5... Line breaker, 6... First automatic switch, 7... Second automatic switch, 8... Control device,
801...Shin breaker open command generation circuit, 801a...
...Short circuit detection circuit between taps, 801b...Short circuit duration measurement circuit, 801c...Reset circuit, 80
7...Shield breaker control circuit, 811...Tap current detection circuit, AND ₁ , A ₁ ~ A ₁₅ , A ₁₁ ~ A ₁₆ , A ₂₁ ~
A ₂₆ , A ₃₁ ~ A ₃₆ ...AND circuit, OR ₁ ~ OR ₆ ,
ORx, ORy, ORa...OR circuit, FF ₀ , FF ₁ ~
FF ₆ ... flip-flop circuit, S ₁ to S ₆ ... thyristor switch.

Claims (1)

[Claims] 1. A stationary transformer comprising a regulating transformer TT connected to the line, and tap selection thyristor switches S ₁ to S ₆ connected to each tap t ₁ to _{t 6} of the regulating transformer. type automatic voltage regulator, a circuit breaker 5 inserted in a circuit on the power side side of the regulating transformer TT, and a first automatic switch inserted in a circuit on the load side of the regulating transformer TT. 6, a second automatic switch 7 that opens and closes between the power side terminal of the shield breaker 5 and the load side terminal of the first automatic switch 6, and each of the taps _t1 to _t6 . an inter-tap short-circuit detection circuit 801a that detects a short-circuit between taps and outputs an inter-tap short-circuit detection signal e _{' c ;} a short circuit duration measurement circuit 801b that outputs a breaker open command signal _e1 when the breaker reaches a predetermined value;
A reset circuit _{801c for resetting the circuit breaker 5} and the output of the short circuit duration measuring circuit 801b are input, and when the shield breaker opening command signal _e1 is generated, the circuit breaker 5 is opened and the circuit breaker 5 is opened. A static automatic voltage regulator comprising a control device 8 that sequentially opens the first automatic switch 6 and closes the second automatic switch 7.