JPH09252524A - Protection relay device and ac contact detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a protection relay device which surely prevents a mistrip even when an erroneous thyristor drive signal is inputted due to the contact of a DC control power supply with an AC power supply, by a method wherein a second photocoulpler circuit is installed in parallel with a first photocoupler circuit and the output of the first photocoupler circuit is locked by the output of the second photocoupler circuit. SOLUTION: A current flows to a photodiode inside a photocoupler PC2 by a current which flows in a first route, and the photocoupler PC2 is turned on. However, a current flows to a photodiode inside a photocoupler PC3 by a current which flows in a second route, the output of the photocoupler PC3 is turned on so as to lock outputs of AND logic circuits A1, A2, and a thyristor TH2 is not turned on. In addition, a current which flows to a circuit at a photocoupler PC1 becomes a reversed polarity, the output of the photocoupler PC1 is turned off, and the thyristor TH1 is not turned on. As a result, even when the AC contact in both of the positive electrode and the negative electrode of a DC control voltage occurs, it is possible to surely prevent a mistrip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective relay device that does not accidentally trip a circuit breaker even if grounding of a DC control power supply or AC power contact occurs, and an AC power contact detection circuit for detecting AC power contact. .

[0002]

2. Description of the Related Art In recent years, along with the digitization of protective relay devices and labor saving in maintenance, a direct trip system is adopted in which a circuit breaker is tripped directly using a thyristor circuit for the purpose of high-speed shutdown in the event of an accident. Often. Along with this, a circuit breaker trip command from an external device or other device is taken into the protective relay device, and the circuit breaker is tripped via a thyristor trip circuit. By the way, such a trip command is taken into the device by using a high-sensitivity photocoupler element.However, if the positive or negative electrode of the DC control power supply of the protective relay is mistakenly grounded, or if there is an AC contact. When it occurs, it is possible that the photocoupler is turned on due to the influence of the stray capacitance of the external cable connected to another device, and the breaker is accidentally tripped.

An example of a conventional thyristor trip circuit is shown in FIG. 5 showing a trip command circuit and a thyristor trip circuit from another device, and the positive pole P of the DC control power supply shown in FIG.
In the following, description will be given with reference to FIG. 6, which is a timing chart showing the response of each part when the AC power supply is in contact with each other.

In FIG. 5, 11 is a DC control power supply, P and N are positive and negative electrodes of the DC control power supply, 12 is a trip contact from another device, 13 is an AC power supply in contact with the positive electrode of the DC power supply, and C1 and C2. Is a stray capacitance of an external cable for taking in a trip contact of another device, PC1 and PC2 are photocoupler elements, R1 and R2 are limiting resistors, D1 and D2 are photocoupler protection diodes, N1 and N2 are NOT logic, and T11. , T12 are on-delay timers to prevent malfunction due to excessive input, and T21 and T22 are off-delay timers.
The timers TH1 and TH2 are thyristors.

First, the route of the current that flows when the AC power source 13 in contact with the P pole of the DC control power source is positive half-wave will be described. There are two routes for the current that flows when the AC power source has a positive half-wave, and the first route is the AC source 13-limiting resistor R.
1-Photocoupler PC1-Stray capacitance C1 of external cable
-Earth-The route that flows in the order of AC power supply 13, the second route is AC power supply 13-DC power supply 11-Protection diode D2
It is a route that flows in the order of the limiting resistance R2-the stray capacitance C2-ground of the external cable and the AC power supply 13.

Due to the current flowing through the first route, the photocoupler PC1 is turned on during the positive half-wave of the AC power source, and the N in the latter stage
The output of the OT logic N1 is "1", and the off-delay timer T21 after the time delay of the on-delay timer T11 is "1".
And the thyristor TH1 is turned on. Next, when the AC power supply changes to a negative half-wave, PC1 turns off and NO
T logic N1 output is "0", on-delay timer T11
The thyristor TH1 is turned off after the instant delay and the off-delay timer T21 are timed.

Since the current flowing through the second route flows in the direction opposite to that of the photocoupler PC2, the diode D
The current is bypassed by 2 and eventually the photocoupler PC
2 remains OFF during the positive half-wave of the AC power supply.

Next, the route of the current flowing when the AC power supply has a negative half-wave will be described. First, the first route is a route that flows in the order of AC power supply 13-ground-stray capacitance C2-limiting resistor R2-photocoupler PC2-DC power supply 11-AC power supply 13, and the second route is AC power supply 13-ground-stray capacitance. It is a route that flows in the order of C1-protection diode D1-limiting resistor R1-AC power supply 13.

Due to the current flowing through the first route, the photocoupler PC2 is turned on when the AC power source has a negative half-wave, and the photocoupler PC2 is connected to the N stage at the rear stage.
The output of the OT logic N2 is "1", and the off-delay timer T22 after the time delay of the on-delay timer T12 is "1".
And the thyristor TH2 is turned on. Next, when the AC power supply changes to a positive half-wave, PC2 turns off and N
OT logic N2 output is "0", on-delay timer T1
2 Momentarily OFF, the thyristor TH2 is turned OFF after the time delay of the OFF delay timer T22.

Since the current flowing through the second route flows in the direction opposite to that of the photocoupler PC1, the diode D
The current is bypassed by 1, and the photocoupler PC1 remains OFF during the negative half-wave of the AC power supply.

[0011]

The above response is summarized in the timing chart of FIG. 6, but the levels L1 and L2 shown in the timing chart of the AC voltage of FIG. 6A are the sensitivity of the photocouplers PC1 and PC2. The voltage is a voltage, and the photocouplers PC1 and PC2 are turned on as shown in (b) and (d) of FIG.
The photocouplers PC1 and PC2 are alternately turned on and off for each half-wave of alternating current due to alternating current contact. Further, as shown in (c) of the figure and (e) of the figure, the thyristors TH1 and TH2 are temporarily turned on-delay timers T11 and T.
If there are 12 or more photocoupler operations, the delay will be delayed by the off-delay timers T21 and T22 in the subsequent stage. Therefore, as shown in FIG.
There is a possibility that 1 and TH2 are turned on at the same time, and trip output is erroneously output. In the above description, description of AC contact with the negative electrode of the DC power supply is omitted,
Similar to the above, there is a possibility that trip output will be erroneously output.

The present invention has been made in order to solve the above problems, and an object of claims 1 and 2 of the present invention is to issue a trip command from another device due to contact between a DC control power supply and an AC power supply of a protective relay device. It is an object of the present invention to provide a protective relay device capable of surely preventing a mistrip even if an erroneous thyristor drive signal is input to the receiving circuit. Claim 3 of the present invention
It is an object of the present invention to provide an AC contact detection circuit that detects a contact of an AC power source and prevents a miss strip.

[0013]

In order to achieve the above object, the first aspect of the present invention is configured such that an external circuit breaker trip command is received by a first photocoupler circuit to trip the circuit breaker. In the protective relay device described above, in parallel with the first photocoupler circuit that is energized by the external trip command,
A circuit breaker trip circuit is provided in which a second photocoupler circuit whose conduction direction is opposite to that of the first photocoupler circuit is provided and the output of the second photocoupler circuit locks the output of the first photocoupler circuit. It is characterized by

According to a second aspect of the present invention, in a protective relay device configured to receive a circuit breaker trip command from the outside by a first photocoupler circuit and trip the circuit breaker, the external trip command is used. A second photocoupler circuit whose conduction direction is opposite to that of the first photocoupler circuit is provided in parallel with the energized first photocoupler circuit, and the trip lock by the output of the second photocoupler circuit is provided in parallel. The third photocoupler circuit output biased by the external trip command on the other side is locked.

According to a third aspect of the present invention, there is provided an alternating current contact detecting circuit,
A first resistor, a first photocoupler, and a first capacitor are connected in series between the positive electrode and ground so that the cathode side of the first photocoupler is the positive electrode, and a second resistor and a second resistor are connected between the negative electrode and ground.
The photocoupler and the second capacitor are connected in series so that the anode side of the second photocoupler is the negative side.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a trip command receiving circuit and a thyristor trip circuit from another device of the protective relay device according to the first embodiment of the present invention (corresponding to claim 1). , To trip circuit A
ND logics A1 and A2 are provided, and photocouplers PC1 and
Attach photocouplers PC3 and PC4 instead of the photocoupler protection diode connected in parallel with PC2,
The cathode Ca is attached so as to face the positive electrode side, and its output is the condition of the AND logic A1 and A2.
Since the other points are the same, the same parts are denoted by the same reference numerals, and the duplicate description will be omitted.

In the same figure, the timing of the positive half-wave of the AC power supply which is in contact with the P pole of the DC control power supply will be examined. The route of the current that flows when the positive half-wave of the AC power supply is 2
There is one, the first route is a route that flows between AC power supply 13-limiting resistor R1-photocoupler PC1-floating capacitance C1 of the external cable-ground-AC power supply 13, and the second route is AC power supply 13-DC power supply 11-photo. It is a route in which the coupler PC4-the limiting resistor R2-the stray capacitance of the external cable C2-ground-the AC power source 13 flow in this order.

The current flowing in the first route causes a current to flow in the photodiode in the photocoupler PC1, but during this positive half-wave, the current flowing in the second route causes a current to flow in the photodiode in the photocoupler PC4. The output of the photocoupler PC4 is turned on. Therefore, the collector terminal C of the photocoupler PC4 becomes "0" level, and AN
Since the outputs of the D logics A1 and A2 are locked, the outputs of the subsequent timers T11 and T12 are "0", and the thyristor T
H1 never turns ON. Similarly for the thyristor TH2 circuit, since the current flowing through the circuit of the photocoupler PC2 has the opposite polarity, the output of the photocoupler PC2 is OF.
F, and the thyristor TH2 is never turned on.

Next, the influence of the current flowing during the negative half-wave of the AC power source will be examined. There are two routes for the current that flows during the negative half-wave of the AC power supply, and the first route is the AC power supply 13
-Earth-Floating capacitance C2-Limiting resistor R2-Photo coupler PC2-DC power source 11
The route is a route that flows in the order of AC power supply 13-ground-stray capacitance C1-photocoupler PC3-limiting resistor R1-AC power supply 13.

The current flowing through the first route causes a current to flow through the photodiode in the photocoupler PC2, turning on the photocoupler PC2. At this time, the current flowing through the second route causes a current in the photodiode within the photocoupler PC3. Flow, the photo coupler PC3 output is turned on, and A
Since the outputs of the ND logics A1 and A2 are locked, the thyristor TH2 never turns ON. At this time, the current flowing through the circuit of the photocoupler PC1 has a reverse polarity, the output of the photocoupler PC1 is OFF, and the thyristor TH1 is never turned ON.

In the above description, the contact of the alternating-current power source with the negative electrode of the direct-current limited power source is omitted, but the thyristor TH2 is not turned on as in the above. Therefore, as in the present embodiment, the photocoupler circuit is arranged so as to sandwich the trip contact from another device, and another photocoupler circuit whose conduction direction is opposite to that of the photocoupler circuit is provided in parallel with the photocoupler circuit. By locking the trip circuit, even if AC contact with the positive and negative electrodes of the DC control power source occurs,
The thyristors TH1 and TH2 are not turned on, and the miss strip can be surely prevented.

FIG. 2 is a circuit diagram of a trip command receiving circuit and a thyristor trip circuit from another device of the protective relay device according to the second embodiment (corresponding to claim 2) of the present invention. The first embodiment has already been described. The difference from the embodiment is only that the photocoupler PC4 and the AND logic A1 of the first embodiment are deleted, and the other points are the same. Therefore, the same parts are denoted by the same reference numerals and duplicate description is omitted. .

In this embodiment, the current flowing through the photodiode in the photocoupler PC1 due to the current flowing during the positive half-wave due to the alternating current contact causes the output of the photocoupler PC1 to be turned on and the thyristor TH1 to be turned on.
Since the current flowing through C2 has the opposite polarity, the photocoupler PC2 output is OFF and the thyristor TH2 is not ON. Further, during the negative half-wave, the output of the photocoupler PC3 is turned on and the output of the AND logic A2 is locked as described above, so that the thyristor TH2 is not turned on, and it is possible to prevent the mistrip due to the AC contact.

As described above, in the present embodiment, the photocoupler PC4 and the AND logic A1 of the first embodiment can be deleted, and the photocoupler PC3 and the AND logic A2 can also prevent the mistrip due to the AC contact.

As a modified example of this embodiment, the photocoupler PC3 and the AND logic A2 are deleted to replace the photocoupler PC.
Even when only 4 and AND logic A1 are used, it is possible to prevent a mistrip due to alternating current contact as in the present embodiment.

FIG. 3 is a circuit diagram of a trip command receiving circuit and a thyristor trip circuit from another device of the protective relay device according to the third embodiment (corresponding to claim 2) of the present invention. The difference from the second embodiment is as follows. Photocoupler PC4 and AND logic A1
Is added, and the other points are the same. Therefore, the same portions are denoted by the same reference numerals, and duplicate description will be omitted.

In this embodiment, a photocoupler PC4 and an AND logic A1 are added to the second embodiment,
Similar to the first embodiment of FIG. 1, the thyristors TH1 and TH2 are never turned on regardless of the timing of contact with any AC power source.
And a highly reliable trip circuit can be obtained.

FIG. 4 is an AC contact detection circuit diagram of a fourth embodiment (corresponding to claim 3) of the present invention. As shown in the figure,
In this embodiment, a resistor R1 is provided between the positive electrode P of the DC control power source and the ground.
Photocoupler PC3 and capacitor C3 are connected in series,
In addition, a resistor R2, a photocoupler PC4, and
The capacitor C4 is connected in series, and the photocoupler PC3,
Off delay timer T2 with PC4 output as common
Enter 3 The output of the off-delay timer T23 detects alternating current contact.

In this embodiment, capacitors C3 and C4 are provided instead of the stray capacitance of the cable in each of the above-mentioned embodiments, and when AC contact is made, the same operation as that of the photocouplers PC3 and PC4 in each of the above-mentioned embodiments is performed. The off-delay timer T23 is provided in order to make the alternating current contact detection signal intermittent due to the touching voltage of the photocouplers PC3 and PC4. Therefore, according to the present embodiment, it is possible to detect the alternating current contact.

[0030]

As described above, according to the first aspect of the present invention.
According to another aspect of the present invention, another photocoupler circuit having a reverse conduction direction is provided in the photocoupler circuit of the circuit breaker trip command receiving circuit from another device or apparatus, and the photocoupler circuit outputs the photocoupler. Since the circuit output is locked, it has high reliability that the circuit breaker will not accidentally trip even if the DC power supply of the protective relay is touched by the AC power supply or the DC power supply is grounded accidentally. A protective relay device can be provided.

According to claim 3 of the present invention, a capacitor is provided instead of the stray capacitance of the cable, and when AC contact is performed, the same operation as that of the photocoupler in each of the above claims is performed. Since the detection signal is made continuous, it is possible to detect alternating current contact.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a trip command receiving circuit and a thyristor trip circuit from another device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a trip command receiving circuit from another device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a trip command receiving circuit from another device according to a third embodiment of the present invention.

FIG. 4 is an AC mixed contact detection circuit diagram of a fourth embodiment of the present invention.

FIG. 5 is a conventional trip command receiving circuit and thyristor trip circuit diagram.

6 is a timing chart for explaining the response of FIG.

[Explanation of symbols]

PC1, PC2, PC3, PC4 ... Photo coupler, D
1, D2, D3, D4 ... Diode, C1, C2 ... Cable stray capacitance, C3, C4 ... DC cut capacitor, R1, R2 ... Limiting resistance, T11, T12 ... On-delay timer, T21, T22, T23 ... Off-delay tanker, TH1, TH2 ... Thyristor, 12 ... Trip command from external device, 13 ... AC power supply.

Claims (3)

[Claims] 1. A protective relay device configured to receive a circuit breaker trip command from the outside by a first photocoupler circuit and trip the circuit breaker, wherein the first trip command is activated by the external trip command. A second photocoupler circuit whose conduction direction is opposite to that of the first photocoupler circuit is provided in parallel with the first photocoupler circuit, and the first photocoupler circuit outputs the first photocoupler circuit.
A protective relay device comprising a circuit breaker trip circuit configured to lock the output of a photocoupler circuit. 2. A protective relay device configured to receive a circuit breaker trip command from the outside by a first photocoupler circuit and trip the circuit breaker, wherein the first trip command is activated by the external trip command. A second photocoupler circuit whose conduction direction is opposite to that of the first photocoupler circuit is provided in parallel with the first photocoupler circuit, and the trip lock by the output of the second photocoupler circuit is provided outside the parallel side. A protective relay device, characterized in that it is configured to lock the output of a third photocoupler circuit which is activated by a trip command. 3. A first resistor, a first photocoupler, and a first capacitor are connected in series between the positive electrode and ground so that the cathode side of the first photocoupler becomes the positive electrode, and between the negative electrode and ground.
An alternating current contact detection circuit, wherein a second resistor, a second photocoupler, and a second capacitor are connected in series so that the anode side of the second photocoupler is the negative side.