JPH09191557A - Protective device for phase modifying apparatus for electric power - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a protective device which prevents the malfunction of a protective relay when a breaker is closed and by which the detection time of a failure is made quick by a method wherein the output of a cutoff command signal is inhibited until a prescribed time elapses since a breaker closing signal is received. SOLUTION: A device is provided with two AND circuits 2, 3 which inhibit the output of a cutoff command signal until a timer T1 which counts a prescribed time T1 since the cutoff instruction signal of a current differential signal is received and a timer T2 which counts a prescribed time T2 since a breaker closing signal is received are counted up. Then, after a breaker has been closed, the output of the AND circuit 3 remains a logic 1, and the output of the AND circuit 2 remains a logic 0. When the time T2 elapses, the output of the AND circuit 3 is set to the logic 0, and the output of the AND circuit 2 appears according to the output of the timer T1 . Consequently, the output of the cutoff command signal is inhibited until the prescribed time T2 elapses since the breaker closing signal is received. As a result, it is possible to prevent a malfunction when the breaker is closed, and a failure can be detected quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective device for protecting a power phase adjusting device in response to each phase current flowing in the power phase adjusting device or each phase voltage applied to the power phase adjusting device. Is.

[0002]

2. Description of the Related Art Current differential relays and current ratio differential relays are generally used as protection relays for phasing equipment shunt reactors applied to power systems. Dynamic relays and voltage relays are commonly used. Hereinafter, a current differential relay or a current ratio differential relay will be described as an example.

In this specification, the symbols I and V represent vectors unless otherwise specified. A current differential relay or a current ratio differential relay (hereinafter collectively referred to as "current differential relay") detects a differential current flowing in a shunt reactor. When the reactor is normal, no difference current appears, but reactor failure (for example, element short circuit)
When a fault occurs, the impedance of the fault reactor changes and a differential current appears, so the current differential relay is
In response to this difference current, a cutoff command is issued after a lapse of a predetermined time T ₁ .

The above-mentioned "predetermined time T ₁ " is a time settled for confirmation of a reactor failure, and although it cannot be said to be a few seconds in general, it is usually settled within a short time within 1 second.
By the way, even in a state where there is no reactor failure, imbalance occurs in the three-phase currents and a difference current appears in the transient state immediately after the circuit breaker is turned on. Since the time during which this imbalance occurs is usually longer than the above-mentioned “predetermined time T ₁ ”, this may cause the current differential relay to malfunction.

Therefore, conventionally, the original setting value T ₁ of the timer element is used as the timer value T for preventing malfunction when the circuit breaker is closed.
_It was changed to ₂ (T ₂ > T ₁ ; T ₂ is usually settled for about 3 seconds) to prevent malfunction caused by current imbalance immediately after closing the circuit breaker.

[0006]

However, assuming that the timer set value is T ₂ , if an accident occurs in the reactor during operation of the reactor, the operation is delayed by the amount of counting the time (T ₂ −T ₁ ). However, there was a problem that the response was delayed when the reactor accident. Therefore, the present invention solves the above-mentioned technical problem, and provides a protective device for a power phase-modulating device capable of speeding up the failure detection time while preventing malfunction of the protective relay due to closing of a circuit breaker. To aim.

[0007]

According to a first aspect of the present invention, there is provided a protective device for a power phase adjusting device, wherein each phase current flowing through the power phase adjusting device or power phase adjusting device is provided. The detection means for detecting the voltage of each phase to be applied, the calculation means for performing relay calculation for protection of the power phase adjusting device based on the output signal of the detection means, and the calculation result by the calculation means is for the power adjustment. Command means for outputting a break command signal when the set value for phase equipment protection is exceeded, and until the predetermined time T ₂ has elapsed since the breaker closing signal was received, Command prohibiting means for prohibiting output.

The commanding means may have a timer element capable of setting the time T ₁ . According to the above configuration, the output of the shutoff command signal from the command means is prohibited until a predetermined time T ₂ has elapsed after the breaker is closed, so that malfunction due to a transient condition immediately after the breaker is closed can be prevented. . Further, after a lapse of a predetermined time T ₂ after the circuit breaker is turned on, the prohibition of the output of the breaking command signal of the commanding means is released, so that the device functions as a protection device for a power phase adjusting device as usual.

[0009] Incidentally, the instruction means, as long as it has a timer element capable settling time T _1, the time T ₁
Can be set arbitrarily regardless of the predetermined time T ₂ .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sequence block diagram showing a main part of a protective device for a power phase adjusting device, in which the protective device for a power phase modifying device responds to each phase current flowing in a phase modifying equipment shunt reactor. A current differential relay 1 for protecting the elements, a timer T ₁ for counting a predetermined time T ₁ after receiving a breaking command signal of the current differential relay 1, and a predetermined time T ₂ for receiving a breaker closing signal.
A timer T ₂ for counting until the count up of the timer T ₂ are provided with two AND circuits 2 and 3 for prohibiting the output of the interruption command signal of said current differential relay 1.

The above-mentioned current differential relay 1 is shown in FIG.
Connected to line 11 through circuit breaker CB as shown
Shunt reactor L_a, L_b, L_cCurrent I flowing through_a, I
_b, I_cCurrent transformer CT_a, CT_b, CT_cDetected by
And the detected current I_a, I _b, I_cThe size of
Difference current | I_a|-| I_b|, | I_b|-| I_c|, | I_c|-| I_a｜ is calculated and the comparison level with the set value is judged,
If either difference exceeds the set value, the shunt reactor's
The failure S is judged and the predetermined time T₁Breaker breaker command after passing
A relay that outputs a signal.

[0012] The current differential relay 1, the ratio _{(| I a | - | I} b |) / | I b |, (| I b | - | I c |) / | I c |, (| I _c |-| _Ia |) / | _Ia | is calculated, and the level with the given settling value is determined, and if any of the ratios exceeds the settling value, the failure of the shunt reactor is determined. It may be a current ratio differential relay which issues a breaker command signal for the circuit breaker after a lapse of a predetermined time T ₁ .

The timer T ₂ is a timer for preventing malfunction of the current differential relay 1 when the circuit breaker is turned on, and has a settling time T 2.
₂ is usually set to about 3 seconds. Timer T ₁
It is a general timer for preventing malfunction of the current differential relay 1, and the settling time T ₁ varies depending on design conditions, but is set to 1 second, for example.

The AND circuit 2 outputs the output of the timer T ₁ and
Is intended to take the logical product of the negation of the output of the AND circuit 3, AND circuit 3, circuit breaker closing signal and the timer T ₂
It is the logical product of the output and the negation of the output. Although the above-mentioned configuration uses a logic circuit sequence for convenience of description, the function may be actually implemented by using either software or hardware.

With the above construction, after the breaker is turned on,
Interval T_TwoThe output of the AND circuit 3 stays at logic 1 until
Therefore, the output of the AND circuit 2 remains at logic 0. Time
Interval T _TwoIs passed, the output of the AND circuit 3 becomes logic 0.
The output of the AND circuit 2 is the timer T₁According to the output of
Will appear. Therefore, the breaker closing signal is received.
A predetermined time T from the start_TwoUntil the current has passed
Output of current cutoff command signal of current differential relay 1 is prohibited
Will be done.

A predetermined time T after receiving the circuit breaker closing signal
_{After 2} has passed, the time T ₁ originally required for breaking the circuit breaker
Is settled, and protection of the power reactor can be performed. The present invention is not limited to the above-described embodiment, and for example, the settling time T ₁ of the timer T ₁ is 1
The power reactor is not limited to seconds, and can be set from 0 seconds regardless of the predetermined time T _2. Therefore, the original protection of the power reactor can be realized.

In the above embodiment, the power phase shifter is used.
As an example of a rectifier, a shunt reactor is used as an example.
The current differential relay is used as the
In addition, the protection relay
If you use a voltage differential relay or a voltage relay,
Also, the present invention can be applied. FIG. 3 shows a circuit breaker C
Power capacitors for each phase connected to line 11 through B
Sa C ₁, C_TwoThe voltage across both ends is detected by the transformer for instrument
And the detected voltage V₁, V_TwoVoltage difference | V
₁|-| V_TwoCondensed when | exceeds the set value
Sa C₁Or C_TwoDifferential relay 1a for detecting faults
(See Japanese Patent Application Laid-Open No. 6-153383).
It is a circuit diagram which shows the example which applied the protection device.

FIG. 4 shows that the line 11 is connected through the circuit breaker CB.
Power capacitor C for each continued phase _a, C_b, C_cBoth
The end voltage is detected by the transformer for the instrument, and the detected voltage
V₁, V_Two, V_ThreeThe vector sum of₀|
When the capacitor exceeds the set value, the capacitor C_a, C_bor
Is C_cThe voltage relay 1b for detecting the failure of the
It is a circuit diagram which shows the example which applied the protection device.

In any of the circuits, the output of the interruption command signal of the voltage differential relay 1a or the voltage relay 1b due to the imbalance of the voltage is output until the predetermined time T ₂ elapses after receiving the breaker closing signal. Since it is prohibited, it is possible to prevent malfunction due to a transient situation immediately after the breaker is turned on.

[0020]

As described above, according to the protective device for a power phase-modulating device of the present invention, a malfunction due to a transient condition immediately after the breaker is closed is prevented until a predetermined time T ₂ elapses after the breaker is closed. It is possible to prevent this, and for a predetermined time T ₂ after closing the circuit breaker.
After the lapse of time, the cutoff command can be issued as usual, so that the power reactor can be appropriately protected.

[Brief description of the drawings]

FIG. 1 is a sequence block diagram showing a main part of a protection device for a power phase adjusting device.

FIG. 2 is a circuit diagram showing a configuration example of a current differential relay.

FIG. 3 is a circuit diagram showing an example in which the protection device of the present invention is applied to a voltage differential relay.

FIG. 4 is a circuit diagram showing an example in which the protection device of the present invention is applied to a voltage relay.

[Explanation of symbols]

1 current differential relay 1a voltage differential relay 1b voltage relay 2,3 the AND circuit 11 line CB breaker L _a, L _b, L _c reactor C _1, C ₂ capacitors C _a, C _b, C _c capacitor T ₁ timer T ₂ timer

Claims (1)

[Claims] 1. A detecting means for detecting a current of each phase flowing through a power phase adjusting device or a voltage of each phase applied to the power phase adjusting device, and a power phase adjusting device based on an output signal of the detecting means. A power adjustment unit having a calculation unit for performing relay calculation for device protection and a command unit for outputting a cutoff command signal when the calculation result by the calculation unit exceeds a set value for power phase adjustment device protection. In the protection device for the phase equipment, a command prohibiting means for prohibiting the output of the break command signal of the command means is provided until a predetermined time T ₂ has elapsed after receiving the breaker closing signal. Protective device for phase adjusting equipment.