JP3538975B2 - Protection relay system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection relay system of a current differential relay system, and more particularly to a pause end detecting device for preventing a blind spot in a system.

[0002]

2. Description of the Related Art As a protection relay system of this kind, for example, there is a PCM current differential relay system in which signal transmission in a display line relay type current comparison relay is digital data.

In this system, for example, in a three-terminal power transmission system shown in FIG. 5, a PCM current differential relay LP and a bus protection relay BP are provided at terminals A, B, and C, and a secondary current of a current transformer at each terminal is provided. At the same time, sampling and A / D conversion are performed and input to the relay at the own end, and at the same time, transmitted to the other end using a transmission device and a microwave or an optical line, etc., and the current data at the own end and sent from the other end. Based on the differential current principle, the presence / absence of an accident in the protection section is determined by using the obtained current data. In the event of an accident, the self-terminal breaker CB is tripped.

[0004] Measures against blind spots in this protection relay system will be described. For example, in the state where the circuit breaker CB of the terminal A is “OFF”, as shown in FIG.
If an accident occurs at point F between P and BP, the accident current becomes a passing current due to an accident outside the current transformer for relay LP, and the relay LP cannot operate.

[0005] In order to protect the system from this blind spot accident, "zero data control" in which the current at terminal A is set to zero and transmitted to the other end under the condition that the circuit breaker CB (or disconnector) at terminal A is "off".
Thus, at the other terminals B and C, a difference current with the terminal A is obtained at the time of a blind spot accident, and the terminals B and C can trip the circuit breaker CB at the own end.

[0006] In the "zero data control" of the current at each terminal, the fact that the circuit breaker CB or the like at its own terminal has been turned "off" is detected at its own terminal as a pause end, and the result is transmitted to another terminal.

FIG. 6 shows a conventional pause end detection sequence together with a power supply circuit. The on / off state of the pallet switch PS (b contact) of the circuit breaker CB and the disconnector LS is taken into the input condition taking units 1 ₁ and 1 _2.
1, 1 a ₂ at the input signal level conversion from DC110 volts to DC24 volts, takes in further converted into the input circuit 2 in 5 volt level of the microcomputer.

[0008] These conversions are performed while being electrically insulated by a photocoupler. In the input circuit 2, the photocoupler 2 ₁ ,
The signals of the circuit breaker CB and the disconnector LS are taken in by 2 ₂ ,
Uptake and that no feed command in the OFF state of the pallet switch PS of the breaker CB in suppressing circuit 2 ₃ in condition, when one of the circuit breaker CB or disconnector LS in the OR circuit 2 ₄ is turned off To obtain a pause end detection signal.

[0009] Power circuit takes the DC110 volt control power through the control power switch 3, which together with the detection power of the pallet switch PS, low control power
The power of the DC power supply 4 and 5 to become. DC power supply 4 is 24
Bolts and the unit 1 _1, 1 ₂ of the power source, the DC power source 5 5
The volts are used as the power source of the computer including the input circuit 2.
The DC power supplies 4 and 5 are provided with an instantaneous interruption countermeasure, and can maintain the output for a certain period of time even when the 110-volt power supply is instantaneously interrupted.

FIG. 7 shows an example of the circuit of the input condition capturing units 1 ₁ and 1 ₂ . Pallet switch P of breaker CB
The on-off state of the S and the on-off signals of the photo coupler PC, a photo-coupler 2 ₁ drive signal output is amplified by the transistor of the input circuit 2 of the photocoupler PC.

[0011]

In a protective relay system in which a conventional blind end detection circuit is used to take measures against blind spots, the control power switch 3 is opened after the breaker at its own end is turned off and the sleep end is established. In this case, the pause end detection may be canceled. This state will be described below with reference to a time chart shown in FIG.

[0012] In FIG. 8, when the circuit breaker CB or disconnector LS terminal A to "OFF" at time t _1, but the input circuit 2 is resting edge detection is made, control thereafter at time t ₂ Power When the switch 3 is turned off (cut), 110 volt power output of the unit 1 _1, 1 ₂ for interruption is immediately turned off.

On the other hand, the DC power supplies 5 and 4 are turned off at times t ₃ and t ₄ which are delayed by the fixed times T ₁ and T ₂ because of the countermeasures against instantaneous interruption. During this time, the microcomputer and its input circuit 2 are also turned off. Works fine.

For this reason, the input circuit 2 determines that the circuit breaker CB or the disconnector LS has been turned on after time t ₂ , and transmits a pause end release signal to the other terminals B and C. Thereafter, the voltages of the DC power supplies 4 and 5 decrease, and the microcomputer stops its operation.

In this case, the other terminals B and C, which have received the pause end detection signal, determine that the terminal A has temporarily become the pause end due to the "off" of the circuit breaker CB or the like. It is erroneously determined that the terminal A has been released from the idle end. Terminal
B and C recognize that terminal A is at rest.
In this state, the microcomputer at terminal A is stopped.
In this case, since the current data of the terminal A is controlled to be 0,
Protection is possible and does not result in continuous monitoring failure. Only
Then, the terminals B and C can recognize that the terminal A is the idle end.
Microcomputer stops at terminal A
Until the power is turned on again at terminal A.
At this time, terminals B and C originally receive from terminal A
Since there is no current data to be provided, perform proper protection
Cannot be performed, and monitoring is always failed.

After stopping the microcomputer,
Since data transmission / reception with the terminal A is not performed normally, "zero data control" is performed at the terminals B and C, and a normal protection operation can be performed.

[0017]

SUMMARY OF THE INVENTION According to the present invention, a protection operation is performed at each terminal of a power system by a current differential relay system, and each terminal of the power system is protected .
The ON / OFF state of the circuit breaker or disconnector is determined by the pause end detection signal.
To the other terminal, and the other terminal receives the idle end detection signal.
The current at the relevant terminal to zero to perform the current differential protection operation.
A blind spot countermeasure means, and an input circuit for detecting the pause end.
The circuit shall be opened with the circuit breaker and
Input condition to capture the on / off status of the disconnector
The output signal of the acquisition unit is supplied to the control power supply.
The signal level is converted using the low-voltage control power supply
In the protection relay system configured to obtain a pause end detection signal, the input circuit for detecting the pause end includes a circuit breaker or
Indicates that the control power supply has been turned off with the disconnector turned off.
And a detection circuit for detecting
Hold the pause end detection signal during the `` power supply is normal '' period.
And a holding circuit, wherein the switch is opened after the switch is opened.
Until the pressure control power is turned off, the pause end detection signal is held
Characterized in that it.

The detection of the disconnection of the control power supply is performed by a circuit for directly confirming the normality of the control power supply from the power supply voltage, or by the complementary operation of the contact signals a and b of the pallet switch of a circuit breaker or disconnector. A circuit for confirming normality or a circuit for holding the OFF-state detection signal for a time period during which the low-voltage control power supply is maintained normally.

[0019]

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a pause end detection sequence showing one embodiment of the present invention. In the present embodiment, FIG.
By adding a circuit for directly confirming the normality of the power supply from the voltage and a holding circuit to the sequence, the error of the pause end detection can be prevented.

[0021] Power Good check circuit and holding circuit adds the input condition capturing unit 1 _3, photo-coupler in the input circuit 2 of the microcomputer 2 ₅ and logical element 2 _{6-2 8,}
2 ₁₁ and an on-delay timer 2 ₉ , 2 ₁₀ .

[0022] Unit 1 _3, unit ₁ 1, 1 ₂ and is the same configuration, the positive terminal PC0 of DC110 volts control power to its input, the on-off state of the control power switch 3 corresponding 24 volts The signal is taken out as an on / off signal to obtain a normal / abnormal signal of the control power supply.

The photocoupler 2 ₅ converts the output signal of the unit 1 ₃ 5 volt signal. AND circuit 2 _6, 2 ₈ takes in the output of the control power from the photocoupler 2 ₅ through the inversion circuit 2 ₇ and the output of the OR circuit 2 ₄ on condition confirmation signal that is normal, the AND circuit 2 ₆ the resulting pause end detection signal only when the power supply is normal, obtaining a resting end release signal only when the power supply is normal to the aND circuit 2 _8.

The on-delay timer 2 _9, 2 _10, the output of the AND circuit 2 _6, 2 ₈ generate an output when each lasting a certain time, to prevent the release and rest end to false detection due to noise or the like.

The RS flip-flop ₂₁₁ is set by the output of the on-delay timer 2 ₉ holds the resting edge detection, the holding means for holding a dormant end release is reset by the output of the on-delay timer 2 _10.

The configuration of these timers and logic elements can be replaced by storage elements and logic functions by software of the microcomputer.

The operation of this embodiment will be described with reference to a time chart shown in FIG. When the breaker CB or disconnector LS terminal A at time t ₁ to "Off", the unit 1 _1, 1 at the output of the OR circuit 2 _{4 2} at the input to the input circuit 2 through a logical "
1 "is obtained. In this case, the output of the photocoupler 2 ₅ through the unit 1 ₃ is the logic until the time t ₂ the switch 3 is turned off" 1 "is obtained.

[0028] Thus, from time t ₁ to t ₂ to give a logical "1" to the AND circuit 2 _6, is the flip-flop ₂₁₁ is set when continues for further on-delay time period of the timer 2 _9, rest edge detection Get. The on-delay timer 2 ₉ prevents malfunction of releasing the pause end detected by the photocoupler 2 _1, 2 _2, 2 of ₅ operating variations or noise.

[0029] When the switch 3 at time t ₂ is turned OFF control, it detects the power "abnormal" by the unit 1 ₃ and photocoupler 2 _5, to obtain an output of logic "0" to the photocoupler 2 _5. This output, close the gate of the AND circuit 2 _6, 2 _8, flip-flop ₂₁₁ holds a dormant end detection state.

This holding state continues until time t ₃ when the voltage of the power supply 5 decreases, and the idle terminal detection signal is continuously transmitted to the other terminals B and C. This hold is maintained as a released state when the pause end is released by closing the circuit breaker or the like during the period.

Therefore, the pause end detection sequence directly confirms that the control power supply is normal from the loss of the power supply voltage, and enables the pause end detection only when the power supply is normal. Furthermore, by providing an on-delay timer,
Ensure resting edge detection.

Note that even when the power supply 4 is turned off, the pause end can be detected by confirming that the power supply is normal in the same manner as when the switch 3 is turned off.

FIG. 3 is a pause end detection sequence showing another embodiment of the present invention. The power supply is omitted.
In the present embodiment, an error in the detection of a pause end is prevented by providing a circuit that captures the state signals of both the a contact and the b contact of each of the circuit breaker CB and the disconnector LS and confirms that the power supply is normal by its complementary operation. I do.

The pallet switch PS of the circuit breaker CB and the disconnector LS takes out the a contact and the b contact, and determines the on / off state of these contacts as input condition input units 1 ₁ , 1 ₂ ,
Taking 1 _4, 1 ₅ respectively. Further, the status signal of the pallet switch PS is taken into the input circuit 2 by the photocouplers 2 ₁ , 2 ₂ , 2 ₁₂ and 2 ₁₃ .

The inhibit circuit 2 ₁₄ and 2 _15, photocoupler 2 ₁ as one input to both output of 2 _12, by the inhibit input as the other input, a circuit breaker CB, complementary operation signal contact b Get. Similarly inhibit circuit 2 ₁₆ and 2 _17, disconnector LS
To obtain complementary operation signals at the a and b contacts.

The flip-flop 2 ₁₈ is set by the output of the inhibit circuit _215, is reset by the output of the inhibit circuit 2 _14, to obtain a resting edge detection signal to the OR circuit 2 ₄ through inhibit circuit 2 ₃ in the set state. Similarly, flip-flop 2
₁₉ is set by the output of the inhibit circuit _217, the inhibit circuit 2 ₁₆
It is reset at the output, obtaining a resting end detection signal to the OR circuit 2 ₄ a set state.

[0037] Operation of the present embodiment, after the flip-flop 2 ₁₈ or 2 ₁₉ becomes a set state in a dormant end detection, photocoupler 2 _1, 2 ₂ when the control power is turned "OFF",
Since there is no input to all of 2 ₁₂ and 2 ₁₃ , the suppression circuit 2 ₁₄
Output to 2 ₁₇ are all held at logic "0", the set state of the flip-flops 2 ₁₈ and 2 ₁₉ are retained.

Thus, after the pause end is detected, the pause end can be prevented from being released even when the control power supply is turned off, and the termination end can be prevented from being erroneously transmitted to the other terminals B and C.

It is to be noted that even when the power supply 4 is turned off or when the pallet switch operates abnormally, a pause end can be detected by confirming that the power supply is normal.

FIG. 4 is a pause end detection sequence showing another embodiment of the present invention. In the present embodiment, an off-delay timer that holds a detection signal for a time equal to or longer than the time when the control power supply is normally maintained is added to the sequence of FIG.
Prevent erroneous detection of pause edge.

The photocoupler 2 ₁ of the input circuit 2, 2 ₂ outputs, respectively, through the off-delay timer 2 _20, 2 ₂₁ and the input of the inhibit circuit 2 ₃ and OR circuit 2 _4. Moreover, also input feed command through the off-delay timer 2 ₂₂ to inhibit circuit 2 _3.

[0042] Operation of this embodiment, by retaining only a predetermined time by the off-delay timer 2 _20, 2 ₂₁ in the OFF state change of the pallet switch PS of the breaker CB and disconnecting switch LS, the "OFF" of the control power supply On the other hand, the pause end is prevented from being released. At this time, the off-delay timer ₂₂₂ delays the release of the circuit breaker closing command in accordance with the holding of the pallet switch PS in the off state.

Each off-delay timer 2 ₂₀ , 2 ₂₁ , 2
_The time period ₂₂ is set to the same time period and longer than the time when the power supply 5 is turned off (T _{1 in} FIG. 8).

Thus, the pause end detection state is held by the off-delay timer until the power supply of the input circuit 2 is stopped.

[0045]

As described above, according to the present invention, the control
With the power source switched on, disconnect the breaker and disconnector.
Input condition capture unit that captures on / off status
The output signal of the unit is controlled by a low-voltage control
And an input circuit for converting the signal into a pause end detection signal level.
In a protective relay system with a built-in
To the rest state by turning off the control power switch.
A certain time before the low-voltage control power supply is turned off after opening
Pause end detection is released to hold for
To solve the problem that the protection may not be possible
As a result, there is an effect that the erroneous release of the pause end detection due to the "cut-off" of the control power supply is reliably prevented, and the system protection is ensured.

[Brief description of the drawings]

FIG. 1 is a pause end detection sequence according to an embodiment of the present invention.

FIG. 2 is a time chart of pause end detection in FIG. 1;

FIG. 3 is a pause edge detection sequence according to another embodiment of the present invention.

FIG. 4 is a pause edge detection sequence according to another embodiment of the present invention.

FIG. 5 is a system diagram and a relay configuration diagram for explaining blind spot measures.

FIG. 6 shows a conventional pause end detection sequence example.

FIG. 7 is an example of an input condition capturing unit.

FIG. 8 shows an example of a conventional release of a pause end detection.

[Explanation of symbols]

1 _1, 1 _2, 1 ₃ ... input condition capturing unit 2 ... input circuit 2 _{1, 2} 2, 2 _5, 2 _12, 2 ₁₃ ... photocoupler 2 _9, 2 ₁₀ ... on-delay timer _211, 2 _18, 2 ₁₉ ... flip-flop 2 _20, 2 _21, 2 ₂₂ ... off-delay timer

Continuation of the front page (56) References JP-B 1-52979 (JP, B2) JP-B 63-66136 (JP, B1) JP-B 56-16621 (JP, B1) (58) Fields surveyed (Int .Cl. ⁷ , DB name) H02H 3/28, 7/22

Claims (4)

(57) [Claims] 1. A protection operation is performed by a current differential relay method at each terminal of a power system, and a breaker or a disconnector of each terminal is turned on and off.
Transmitted to another terminal in an OFF state as dormant end detection signal, the other terminal equipped with a blind spot protective means for protecting operation of the current differential as a zero current of the terminal at the receiving of the pause end detection signal, before
The input circuit for detecting the pause end is a switch of the control power supply.
ON / OFF status of circuit breaker and disconnector with
Output of input condition capture unit that captures each state
A signal is supplied from a low-voltage control power supply using the control power supply as a power supply.
To convert the signal level to obtain the pause end detection signal
In the protection relay system, the input circuit for detecting the idle end is a circuit breaker or a disconnection.
A detection circuit that detects that the control power supply has been turned off in the off state of the detector, and a holding circuit that holds a pause end detection signal obtained during the “control power supply is normal” period obtained from the detection circuit. The low pressure control after the switch is opened
Protective relay system until the power is "OFF" is characterized by the this <br/> for holding the pause end detection signal. 2. The protection relay system according to claim 1, wherein the detection circuit is configured to directly check the normality of the control power supply from a power supply voltage. 3. The protection circuit according to claim 1, wherein the detection circuit confirms the normality of the control power supply by a complementary operation of the contact signals a and b of the pallet switch of the circuit breaker or the disconnector. Relay system. 4. The protection relay system according to claim 1, wherein the detection circuit and the holding circuit are configured to hold the OFF-state detection signal for a time period during which the low-voltage control power supply is normally maintained. .