JPS5812815B2 - gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protector relay that controls switching on and off of a protector circuit breaker used in a network power distribution system.

In general, in a network power distribution system, when an accident occurs on a certain line, a grotector relay detects the failure and opens the protector breaker of the failed line, automatically disconnecting the failed line and supplying power from other healthy lines without interruption. It is something to do.

The protector relay that controls this protector breaker has the following three functions.

That is, (1) No-voltage closing characteristic When power is supplied from the power supply side when there is no voltage on the load side, a closing command is issued to the protector breaker.

(2) Differential voltage closing characteristics When power is supplied from the power supply side during load side energization, a closing command is issued to the protector breaker on the condition that the current does not flow backwards.

(3) Reverse power cutoff characteristics If the current passing through the protector breaker flows in the opposite direction, a cutoff command is issued to the protector breaker.

For example, the protector relay is explained in the 3-line socket network power distribution system shown in Fig. 1 as CB.
1L, CB2L, CB3L are feeder IL, 2L, 3L
The circuit breakers installed in Tr1, Tr2, Tr
3 is a network transformer, and the primary side is a primary disconnector D
Feeders 1L, 2L, 3 via S1, DS2, DS3
The secondary side is connected to protector fuse Fl, F2.
, F3, current transformers CT1, CT2, CT3, and protector chamber breakers pCB1, PCB2, PCB3 are inserted in series and connected to the load.

R1, R2, and R3 are protector relays that connect the voltage transformers PT1A, PT2A, and P from the power supply side and load side of the protector circuit breakers PCB1, PCB2, and PCB3.
Current transformers CT1, CT2, CT3 connected via T3A and FT PTPT3B and installed on the power supply side
It is designed to perform the three functions described above.

In Fig. 1, when a short circuit or ground fault occurs at point F of feeder 1L, breaker CB1L is opened, but at the same time, fault current flows from feeders 2L and 3L in the direction of the arrow and flows into point F. Therefore, the reverse current is detected by the reverse power detection circuit of the Grotector relay R1 shown in Fig. 2, and the reverse current-operation time characteristic curve shown in Fig. 3 is detected via the cutoff command circuit. After a predetermined time period determined by the reverse current shown in , for example, the operation time t1 corresponding to the reverse current 11, a cutoff command is sent to the protector breaker PCB, the protector breaker PCB1 is opened, and the fault point F is completely disconnected from the system. Thereafter, sleep power is supplied to the load from the feeders 2L and 3L without interruption.

I just mentioned the accident at Feeder 1L, but
If an accident occurs in 3L or 3L, the same operation as described above is performed to disconnect the faulty line from the grid.

The protector relay performs such a reverse power cutoff operation, but if a regenerative load such as an elevator load that generates a transient back electromotive force during regenerative braking is connected to the load, the general power consumption may be reduced late at night, etc. If the power is small, the back electromotive force due to the regenerative load may exceed the power of other loads, and the protector circuit breakers PCB1 and PCB2 of each line
, PCB3 at the same time, the protector relays R1, R2, and R3 detect the reverse power, and the protector circuit breakers PCB1, PCB2, and PCB3 are activated.
Since a cut-off command is sent to open the circuit, there is an inconvenience that the system is completely stopped.

Various proposals have been made in the past to prevent this protector relay from accidentally cutting off the reverse power, but these have resulted in complicated structures and high costs.

The present invention maintains the various characteristics of the protector relay described above, and also reliably prevents erroneous cutoff of reverse power during regenerative load with a simple structure that can be stored in the protector relay.
The purpose is to improve the reliability of power supply.
Below, the embodiment will be explained using figures. In Fig. 4, 1
2 is a reverse power cutoff determination device housed in a protector relay, 2 is a reverse power detection circuit, and the input side is connected to the voltage transformer and current transformer connected to the own line, such as PT1A and PT in Figure 1.
1B and the secondary side of CT1, one of the output sides is connected to the protector breaker and connected to the cutoff command circuit 3 that sends out the cutoff command, and the other side is connected to the reverse power inserted in the protector relay of another line. Shutoff determination device 1'...
. . . 1n's interruption prevention circuit 4' . . . A shield interruption prevention command circuit 7 that connects to 4n and sends a interruption prevention command.
The reverse current flowing through the line is detected, and an output signal corresponding to the magnitude thereof is sent to the cutoff command circuit 3 and the cutoff prevention command circuit 7.

Therefore, when the cutoff command circuit 3 receives the output signal of the reverse power detection circuit 2, when it reaches the time limit level of the inverse time characteristic determined by the magnitude of the output signal, it sets the reverse current one operation time limit as shown in FIG. 3, for example. In terms of characteristics, if the output signal corresponds to the reverse current i2, it will operate when the corresponding operation time t2 is reached and send a cutoff command to the protector circuit breaker, and the cutoff prevention command circuit 7 will output a cutoff command to the protector breaker. When receiving the output signal of the detection circuit 2, at a level lower than the operation level of the cutoff command circuit 3, for example, the operation time t corresponding to the reverse current i2 in the reverse current-operation time characteristic shown in FIG.
It is set to operate in the inverse time limit special note of the time limit t2'(t2>t2') shorter than 2, and always operates before the cutoff command circuit 3 to send the cutoff prevention command to the cutoff prevention circuit 4' of other lines.・・・・・・It is designed to be sent to 4n.

4 is a cutoff prevention circuit, and on the input side there is a reverse power cutoff device 1' inserted into the protector relay of another line.
・A cutoff command suppression circuit 6 is connected via the OR circuit 5 connected to the output side of the cutoff prevention command circuit 7' of 1n, and the output side of this cutoff command suppression circuit 6 is cut off. When connected to the input terminal of the command circuit 3 and receiving a cutoff prevention command from one of the cutoff prevention command circuits 7'...7n of another line via the OR circuit 5,
The cutoff command suppression circuit 6 operates and sends its output signal to the cutoff command circuit 3 to stop the operation before the cutoff command circuit 3 reaches a time limit level determined according to the output signal of the reverse power detection circuit 2 and starts operating. It is designed to stop the protector and prevent a cutoff command from being sent to the protector breaker.

Since these circuit configurations are static, they respond to inputs in an extremely short time, so that cooperative operations are ensured.

Next, to explain this operation, if a short circuit or ground fault occurs on the power supply side of the network transformer, for example at point F of feeder 1L shown in Fig. When a current equal to the sum of the excitation current flows into the fault line and a reverse current flows through the fault line's protector relay, the reverse power detection circuit inserted into the fault line's protector relay detects this reverse current. 2, and sends an output signal corresponding to the magnitude of the reverse current to the cutoff command circuit 3 and the cutoff prevention command circuit 7.

In response to this, when the cutoff command circuit 3 receives an output signal corresponding to the reverse current 11 in the reverse current one operation time limit characteristic shown in FIG. 3, the cutoff command circuit 3 reaches a predetermined time period determined by the output signal. The cut-off prevention command circuit 7 operates first and sends the cut-off prevention command to the cut-off prevention circuits 4'...4n of other lines, and the cut-off prevention command circuits 7 of the other lines operate. 4n operates immediately and sends an output signal to the cutoff command circuit 3'...3n, but the cutoff command circuits 3'-... of other lines
・Reverse power detection circuit 2' 3n does not receive the reverse power detection output signal from 2n, so it simply sends it out.

Subsequently, the cutoff command circuit 3 reaches the operation time limit level corresponding to the reverse power and sends the cutoff command to the fault line (in this example, the feeder 1
L) is sent to the protector circuit breaker to open it and disconnect the faulty line from the system.

At this time, the cutoff prevention circuit 4 is connected to the cutoff prevention command circuit 7'...7n inserted in the protector relay of the other line.
Since the cut-off prevention command has not been received, the cut-off prevention circuit 4
Since no output signal is sent to the cutoff command circuit 3, the reverse power cutoff function of the protector relay is allowed to operate normally without being inhibited, and power is supplied to the load from other healthy lines without interruption.

Next, when reverse current flows in all the lines that are transmitting power by the regenerative load, each of the reverse power detection circuits 2, 2'...2n inserted in the protection relay of each line , the reverse power of the own line is detected, and the output signal is sent to the own line cutoff command circuits 3, 3'...
...3n and cutoff prevention command circuits 7, 7'...
...7n, and in response to this, as described above, first, the cutoff prevention command circuits 7, 7'...7n operate in a time period determined by the input, and transmit the cutoff prevention command to all other lines. The signals are mutually sent to the cutoff prevention circuits 4, 4'...4n, and in response, the cutoff prevention circuits 4, 4 of the own line
'...4n is the output signal cutoff command circuit 3, 3
'......3n and sends it to the cutoff command circuit 3, 3
'...3n is stopped before reaching the operating level, so no cutoff command is sent to the protector breaker.

Since this reverse current caused by the regenerative load is a small current compared to the fault current at the time of a short circuit accident, for example, in the reverse current-operation time characteristic shown in Fig. 3, the reverse current i1 due to the short circuit accident, the regenerative current If the current i2 is in the opposite direction when loaded, the corresponding operating time limits are t1 and t2, respectively.
Since the operating time limit level until sending out the output is in the relationship t1<t2, the cutoff command circuits 3, 3'...3
The time limit during regenerative load until n reaches the operating level and a cutoff command is sent out is quite generous.

Moreover, the cutoff prevention command circuit 7 has an operation time limit t2 of the cutoff command circuit 3 according to the reverse current at the time of the regenerative load, for example, 12.
Since it operates and outputs in a shorter time period 12', the cutoff command circuits 3, 3'...3n are the reverse power detection circuits 2, 2'...2n of the own line. A circuit for preventing circuits 4, 4 from cutting off the receiving line, which continues to receive the output signal even after receiving the output signal of
The cutoff command circuits 3, 3'...3n are activated by the output signals of the cutoff prevention command circuits 7, 7'...7n of other circuits via the circuits '...4n. Since the operation can be stopped before the level is reached, for example before the t2 time limit, erroneous shutoff can be reliably prevented without sending a cutoff command by mistake.

At this time, the regenerative load is cut off by the cutoff prevention command circuits 7, 7'...
...If it runs out before the 7n operation time limit is reached, the operation will stop and preparations will be made for the next generation of reverse power.

According to this embodiment, the cut-off prevention command circuit can operate and output a cut-off command at a lower level than the cut-off command circuit which performs a cut-off command and sends a cut-off command due to the reverse current-operation time limit characteristic. It is possible to prevent a cutoff command from a cutoff command circuit of another line for a time period corresponding to the magnitude of the cutoff command circuit.

FIG. 5 shows another embodiment of this device, and the same reference numerals are used to describe the operations corresponding to those described above. 1 is a reverse power cutoff determination unit housed in a protector relay provided in each line. Device 2 is a reverse power detection circuit that integrally detects reverse power, and is connected to the secondary side of the voltage transformer and current transformer connected to the own line, such as PT, B, and CT1 in Fig. 1. Phase-specific reverse power detection unit 2R that detects reverse power flowing to
, 2s2T, and this phase-specific reverse power detection section 2R, 2s, 2
The output terminal of T is connected in parallel to the input inverting terminal of the operational amplifier 8, and the input non-inverting terminal of the operational amplifier 8 is connected to the ground side. The capacitors 9 are connected in parallel, and the output signals of the phase-specific reverse power detection sections 2R, 2s, and 2T are added by the operational amplifier 8 and the capacitor 9, and the integrated value is sent as the output signal of the reverse power detection circuit 2. It has become.

The phase-specific reverse power detection unit 2R (2S and 2T are similarly configured) detects a current transformer connected to its own line, for example, the first
An auxiliary current transformer 10 is connected to the secondary side of the current transformer CT1 shown in the figure to receive input current IR, and the secondary side of this auxiliary current transformer 10 has a current and a voltage for converting the input current IR into voltage. An amplifier 1 that sends out an output signal obtained by amplifying the input current IR of the auxiliary current transformer 10 so that even a minute current can be detected through the converter 11.
2 is connected to the output side of the amplifier 12, and connected to the input inverting terminal of the operational amplifier 8 via a switching element 13 which is turned on and off by a gate signal, and the gate G of the switching element 13 is connected to An auxiliary transformer 14 connected to the secondary side of the instrument transformer connected to the own line, for example, PT1B in FIG. A rectangular wave shaper 16 that sends out an output signal shaped into a rectangular wave even if the phase voltage VR is a minute voltage via a phase shifter 15 that shifts the phase of the voltage VTR to the phase voltage ■R.
When the gate G of the switching element 13 receives the rectangular wave output signal of the rectangular wave shaper 16, the switching element 13 is turned on only during a predetermined positive or negative half-wave, and the auxiliary transformer is turned on. The input current IR received by the current transformer 10 is made conductive through the current-to-voltage converter 11 and the amplifier 12, and is sent to the operational amplifier 8 and the capacitor 9. The output signals of each predetermined half-wave sent out from the power detection sections 2R, 2s, and 2T are added and integrated, and a value is sent out as an output signal of the reverse power detection circuit 2.

At this time, the output signal sent out every predetermined half wave from the phase-specific reverse power detection units 2R, 2s2T is transmitted to the protector breaker, for example, the first
Since the current flowing through the PCB 1 shown in the figure is sent out as a half-wave output signal for a predetermined phase of the phase voltage that is phase-shifted from the phase-to-phase voltage received at that time, this sum reverse power detection unit 2
When the output signals of R, 2s, and 2T are integrated by the operational amplifier 8 and the capacitor 9, the positive and negative waveforms are smoothed,
When the polarity of the integral value becomes a predetermined polarity, a reverse power signal is sent out as an output signal of the reverse power detection circuit 2.

3 is a cutoff command circuit connected to the output side of the reverse power detection circuit 2, which operates to cut off the protector when the integral value of the reverse power signal of the reverse power detection circuit 2 reaches a predetermined level determined by the amount of reverse power. It is designed to send a cutoff command to the device.

Reference numeral 7 denotes a cutoff prevention command circuit connected in parallel with the cutoff command circuit 3 to the output side of the reverse power detection circuit 2, which receives the reverse power signal from the reverse power detection circuit 2 and lowers the operating level of the cutoff command circuit 3. Also operates at a low level and sends a cutoff prevention command to cutoff prevention circuits 4'...4n inserted in protector relays of other lines.

Therefore, whenever the cutoff command circuit 3 and the cutoff prevention command circuit 7 receive the reverse power signal from the reverse power detection circuit 2, the cutoff prevention command circuit 7 operates first before the cutoff command circuit 3 reaches the operating level. It is set as follows.

4 is a cutoff prevention circuit connected to the output side of the cutoff prevention command circuit 7'...7n inserted in the protector relay of the other line;
. . . 7n. An OR circuit 5 which sends out an output signal when receiving a cutoff prevention command, and the output side of this OR circuit 5 are connected to the base of a transistor 17,
The collector of the transistor 17 is connected to the output terminal of the operational amplifier 8 via the discharge resistor 18, and the emitter is connected to the input inverting terminal of the operational amplifier 8 to form a discharge circuit for the capacitor 9, and the OR circuit 5 is the cutoff prevention command circuit 7' inserted into the protector relay of the other line...
. . . When receiving a cutoff prevention command from any of 7n, the transistor 17 is made conductive and the capacitor 9 is discharged,
The reverse power signal of the reverse power detection circuit 2 sent from the operational amplifier 8 is suppressed so as not to reach the operating level of the cutoff command circuit.

Since these circuits of this device are constructed in a stationary manner, they respond to inputs in a very short time, so that the set cooperative operation can be carried out reliably.

Next, to explain its operation, if a short circuit or ground fault occurs on the power supply side of the network transformer, for example at point F in Figure 1, the short circuit current or current equal to the sum of the ground charging current and the transformer excitation current flows through the fault line. If the reverse current flows in the reverse direction, which reverse current flows into the phase-specific reverse power detection section 2R of the reverse power detection circuit 2,
The 2s and 2T auxiliary current transformers 10 receive the input currents IR, Is and IT, respectively, and send the output signals to the switching element 13 via the current-to-voltage converter 11 and amplifier 12.

On the other hand, the gate G of the switching element 13 is connected to the phase-specific reverse power detection section 2R,
Phase-to-phase voltage VTR received by 2s and 2T auxiliary transformer 14
Rectangular wave signals of phase voltages VR, VS, and ■T are received through the phase shifter 15 and square wave shaper 16, and jVRS% and ■sT are received during a predetermined positive or negative half-wave of this square wave signal. Only the switching element 13 is turned on and the phase-specific reverse power detection parts 2R, 2
The output signals of s and 2T are sent to an operational amplifier 8 and a capacitor 9, and a reverse power signal added and integrated by the operational amplifier 8 and capacitor 9 is sent to a cutoff command circuit 3 and a cutoff prevention command circuit 7.

In response to this, the cutoff prevention command circuit 7 first operates before reaching the operating level of the cutoff command circuit 3 and sends a cutoff prevention command to other lines, such as the line and cutoff prevention circuits 4'...4n. .

The cutoff prevention circuit 4' receives this cutoff prevention command...
. . 4n conducts the transistor 17 through the OR circuit 5 to form a discharge circuit for the capacitor 9, but since no discharge current flows through the other lines as described above, the reverse power detection circuit 2'... ...2n does not detect reverse power and merely forms a discharge circuit for the capacitor 9.

Therefore, since the cutoff prevention circuit of the faulty line does not receive the cutoff prevention command from the cutoff prevention command circuits 7'...7n of other lines, the reverse power signal of the reverse power detection circuit 2 is not suppressed and receives the cutoff command. The cutoff command circuit 3, which has reached the operating level, sends the cutoff command to the protector circuit breaker of the fault line, for example. The power is sent to the PCB 1 in FIG. 1 to open the circuit, disconnect the faulty line from the grid, and supply power to the load from other healthy lines without interruption.

Next, if the back electromotive force due to the regenerative load exceeds the power of other loads and current flows in the opposite direction to all the lines that are transmitting power,
As described above, the reverse power detection circuits 2, 2', . - 3n and the cutoff prevention command circuits 7, 7'...7n, and in response to this, as described above, first the cutoff prevention command circuits 7, 7'
. . . 7n operates and mutually sends the interruption prevention command to the interruption prevention circuits 4, 4', . . . 4n of other lines, and the transistors 1
7 is made conductive and the reverse power detection circuit 2, 2'...2
The reverse power detection circuits 2, 2', .
... 2n reverse power signal cutoff command circuit 3, 3'...
In order to prevent the operation level of 3n from reaching the operating level, the cutoff command circuits 3, 3'...3n do not send a cutoff command to the protector circuit breaker, but instead shut down the line on which power is being transmitted. All protective circuit breakers remain closed and load power is supplied without power outage.

According to this embodiment, the operation levels of the cut-off command circuit and the cut-off prevention command circuit are each set at a constant level, but the time limit until each operation level is reached is as follows.
Since the reverse power detection circuit adds and integrates the reverse power of each phase and outputs the result, the operation time is determined according to the amount of reverse power.In other words, the operating time is variable according to the magnitude of the reverse current. When looking at the operating time limit, it shows a reverse time-limited operation. Therefore, when the regenerative load is applied, the operating time limit for both circuits is longer than at the time of an accident, and the output of the reverse power detection circuit due to the regenerative load reaches the operating level of the breaker prevention command circuit. If the cutoff prevention command is not reached, the cutoff prevention command circuit can prepare for the next generation of reverse power without sending out the cutoff prevention command.

According to the present invention, a cutoff command is sent to the output terminal of the reverse power detection circuit inserted into each line and outputs an output corresponding to the reverse power when an operation time limit determined according to the magnitude of the input is reached. When a time limit determined by a cutoff command circuit and an input magnitude shorter than the operating time limit of this cutoff command circuit is reached, a cutoff prevention command is sent to stop the operation of the cutoff command circuit of the other line. A blocking command circuit is installed in parallel to determine reverse power cutoff, so before sending a cutoff command to the protector breaker of the own line during regenerative load, it is possible to prevent the cutoff command from being sent from other lines. Not only can it be reliably blocked by a command, but the operation time limit of the cutoff command circuit and the cutoff prevention command circuit is determined by the reverse time depending on the magnitude of the reverse power, so the reverse operation of temporary regenerative load, etc. For electric power, without immediately stopping the operation of the cutoff command circuit,
The operation can be continued until the operation time limit corresponding to the magnitude of the input to the cutoff prevention command circuit is reached.

This eliminates unnecessary locking of the cutoff command circuit, which has the great effect of allowing immediate response in the event of an accident and overcurrent flowing following the occurrence of a regenerative load. Furthermore, since there is no need to provide a means including a time-limited relay that immediately issues a cutoff command when a regenerative load occurs and releases it after a certain period of time, the configuration can be simplified.

In addition, since this device is constructed as a stationary type, there is no need to worry about wear and tear on the contacts, etc., and stable operation can be achieved over a long period of time.The quick response eliminates the risk of malfunction, and the power supply is reliable. It has great practical advantages, such as being able to further improve the performance of the device, and furthermore, by simplifying the structure, the device can be miniaturized and easily incorporated into an existing protector relay.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram illustrating a three-line spot network power distribution system, Fig. 2 is a block diagram of a conventional reverse power cutoff device, Fig. 3 is a diagram illustrating the reverse current-operation time characteristic during reverse power cutoff, FIG. 4 is a block diagram showing an embodiment of the present device, and FIG. 5 is a block diagram showing another embodiment of the present device. 1: Reverse power cutoff determination device, 2: Reverse power detection circuit 3:
Cutoff command circuit, 4: Cutoff prevention circuit, 7: Cutoff prevention command circuit.

Claims (1)

[Claims] 1 Each line of the network power distribution system is provided with a reverse power detection circuit that responds to the reverse power of the line, and when any reverse power detection circuit of the power transmission line is activated, a cut-off command is given to the corresponding protector breaker, and the power is transmitted. In a protector relay that prevents a cutoff command by the output of the reverse power detection circuit of another line 1 when all the reverse power detection circuits of the line are activated, the reverse power detection circuit has an output according to the magnitude of the reverse power. At the output end of this circuit, there is a cutoff command circuit that sends out a cutoff command with an operating time determined by the magnitude of the input, and a cutoff command circuit with an operating time determined by the magnitude of the input. A feature is that a cutoff prevention command circuit is installed in parallel to send a cutoff prevention command to the cutoff command circuit of another circuit in a time period shorter than the operating time limit of the circuit, and a reverse power failure is determined. Reverse power cutoff determination device.