JP2675694B2 - Ratio differential relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ratio differential relay device used for protecting generators, transformers, buses and distribution lines in a power system, and more particularly to measures for preventing unnecessary operation when a current transformer is saturated. .

[0002]

2. Description of the Related Art FIG. 7 is an external connection diagram of a generator protection ratio differential relay device (hereinafter simply referred to as a relay device GP).
Is an internal block diagram of the ratio differential means 87G used in the relay device GP, and FIG. 9 is an explanatory diagram of the operating principle of the relay device GP. In FIG. 7, BUS is a bus of the electric power system, G is a protected generator, TR is a transformer connected to the same bus as the protected generator G, L is a load of the transformer TR, CB ₁ and C.
B ₂ and CB ₃ are circuit breakers, CT ₁ and CT ₂ are current transformers, GP
Is a relay device, I _E is an inrush when the transformer TR is turned on by a circuit breaker CB ₂ , and I ₁ and I ₂ are secondary currents of the current transformers CT ₁ and CT ₂ .

Further, in FIG. 8, I _D is a differential current (I ₁
-I ₂ ), C ₁ , C ₂ , C ₃ are input terminals of the ratio differential means 87G, T _RC is a suppression input transformer for introducing a suppression current I _R = (I ₁ + I ₂ )), and T _OC is differential. The differential input transformer for introducing the current I _D , CM is a comparison means for obtaining a ratio differential characteristic, and when the ratio of the differential current I _{D to} the suppression current I _R is a certain value or more, that is, K = differential current / suppression current _{= I D / I R = I} 1 -I 2 / I 1 + I 2> operating in KS e.g. KS = 0.1.

A conventional relay device G having such a configuration
The operation of P will be described. (1) When an external failure F2 occurs Refer to FIGS. 9 (a) and 9 (c) In the secondary side current of the current transformers CT ₁ and CT ₂ , the inflow current I _1F2 = outflow current I _2F2 suppression current I _R and differential current I. _D is compared by the comparison means CM _K2F = differential current / suppression current = ( _{I1F2- I2F2} ) / ( _I1F2 + _I2F2 ) = 0 / _I1F2 = 0 <KS = 0.1 and the ratio differential means 87G Is not working

(2) When internal failure F1 occurs See FIGS. 9 (b) and 9 (c). Inflow current I ₁ = I _1F1 , outflow current I ₂ = 0, suppression current = differential current I _R = _ID = I _1F1 K _1F = differential current / suppression current = (I _1F1 −I _2F1 ) / (I _1F1 + I _2F1 ) = I _1F1 / I _1F1 = 1> KS = 0.1 and the ratio differential means 87G operates.

[0006]

The problems of the conventional ratio differential relay device having the above-described structure are shown in FIGS. 7, 8, 9, and 10.
Will be described with reference to. In FIG. 7, when the transformer TR is turned on with no load (the circuit breaker CB ₃ is opened) with CB ₂ , a large inrush current I _E including the _DC component I _DC as shown in FIG.
Flows through the current transformers CT ₁ and CT ₂ , but at this time, the secondary current I ₁ = 1 ₂ of the current transformers CT ₁ and CT ₂ should originally be the differential current I _D = 0. However, the magnetic flux due to the direct current component I _D c is sequentially integrated to saturate at least one of the current transformers CT _{1 and} CT ₂ , for example, CT ₂ , and the output current I. When the error differential current I _D flows, that is, when a current in a region shown as an inrush at CT ₂ saturation in FIG. 9C is input, the ratio differential means 87G is not necessary. Working on CB ₁
There was a serious problem that trip output was output.

In order to fundamentally solve the problem caused by CT saturation, it is desirable to use a current transformer having a large capacity. However, there is a limit to increase in size and cost, and in reality, it is extremely difficult to prepare a current transformer of sufficient capacity that does not completely saturate when the inrush containing a DC component is penetrated.

The present invention has been made to solve the above-mentioned problems, and the inrush of a transformer containing a direct current component penetrates the current transformers CT ₁ and CT ₂ and at least one of the current transformers is saturated . An object of the present invention is to provide a highly reliable ratio differential relay device that does not perform unnecessary operation even in the case.

[0009]

The ratio differential relay device according to the first aspect of the present invention and the first and second current differentials detected through the first and second current transformers installed at both ends of a protected device in a power system. Ratio differential means for responding to the ratio of the differential current, which is the difference between the two currents, and the suppression current, which is the sum of the first and second currents, and outputting the trip output to the load circuit breaker of the power system,
Inrush detection means for detecting whether the ratio of the second harmonic to the fundamental wave of the suppression current is a certain value or more and outputting an inrush detection signal, and the inrush detection signal
With the output of the above and without the output of the differential means, the above ratio
And an output control means for blocking the output of the rate differential means for a certain period of time .

[0010] The ratio differential relay apparatus according to a second aspect of this
Is the first installed on both ends of the protected equipment in the power system.
And a trip output in response to the ratio of the differential current, which is the difference between the first and second currents detected by the second current transformer, and the suppression current, which is the sum of the first and second currents, and trips the trip output. Ratio differential means for outputting to the controller, inrush detection means for detecting whether the ratio of the second harmonic to the fundamental wave of the suppression current is a certain value or more and outputting an inrush detection signal, and the first current And the phase relationship between the second current and
The phase discriminating means for outputting the anti-phase detection signal at the time of detecting the anti-phase relationship and the output of the ratio differential means for a certain period of time when the inrush detection signal and the anti-phase detection signal are significant.
And an output control means for stopping . In the ratio differential relay device according to the third aspect of the present invention , the output control means has a ratio difference.
The ratio differential means while the output from the dynamic means is blocked for a certain time
Is a device that enables the trip output when an internal failure is determined.
It includes Noh .

[0011]

According to the first aspect of the invention, the ratio differential means does not move.
When the external failure is detected by the operation and the inrush is detected by the inrush detection means, the output means is activated, and the output from the ratio differential means is blocked for a certain time, so that the inrush penetrates the current transformer. Even if an erroneous kinetic current flows into the differential means for a certain period of time and an erroneous trip output is output, the load circuit breaker will not accidentally operate.

According to the second aspect of the present invention, the output control is performed when the phase determining means determines that the phase relationship between the first current and the second current has an opposite phase relationship, and the inrush detecting means detects the inrush. By operating the means and blocking the output from the ratio differential means for a certain period of time, the inrush penetrates the current transformer and the error motion current flows into the ratio differential means for a certain period of time, and the load is cut off even if the trip output is output. Do not operate the vessel carelessly. According to the third invention,
Internal failure is detected while the output by the ratio differential means is blocked for a certain period of time.
By enabling the above trip output at fixed time,
Even if an internal failure is determined during shutdown, the output control means
The output of the ratio differential means is started.

[0013]

Before explaining the operation of the present invention, the present invention will be summarized. In the present invention, the CT saturation due to the DC component of the inrush does not occur immediately after the inrush is applied to the CT. CT by successive integration of magnetic flux due to DC
It focuses on the fact that the iron core reaches saturation and CT saturation occurs after a predetermined time has elapsed after the inrush application.

That is, the state in which the through-inrush including the DC component is applied but the CT is not saturated is detected as the state in which the inrush detection means is operating but the ratio differential means is not operating. Then, once this state is detected, the output of the ratio differential means is locked and the recovery time timer is energized. After that, either CT is saturated and an error differential current causes the ratio differential means to be unnecessary. CT works
A configuration that keeps the lock until saturation is restored. The time of the recovery time timer for continuing the lock is, for example, about 0.2 seconds.

In the configuration diagram of one embodiment of the present invention in FIG. 1, F _2H is a fundamental wave by an inrush detection means for detecting that the ratio of the second harmonic to the fundamental wave of the suppression current I _R is a certain value or more. It comprises a pass filter F _1P , a second harmonic pass filter F _2P , and a second harmonic detecting means CM _F2 . I
Urging N ₁ is inhibit means for detecting that the in-rush penetrates under the condition of there is output without inrush detector F _2H output ratio rate differential hands stage 87G, T _RE to inhibit means IN ₁ The recovery time timer IN ₂ having a predetermined recovery time is an inhibit means for outputting the trip output of the relay device GP under the condition that the recovery time timer T _RE does not output and the ratio actuating means 87G outputs.

The operation of the relay device GP configured as described above will be described. 1. The inrush including the DC component is the current transformer CT ₁ , CT
_When penetrating ₂ . This will be described with reference to the waveform chart of each part in FIG. When the inrush I _E is applied, the ratio of the second harmonic component to the fundamental wave at the suppression current I _R = (I ₁ + I ₂ ) is equal to or more than a certain value, so that the inrush detecting means F _2H outputs the inrush current. Immediately after the application, since neither CT is saturated, there is no error dynamic current I _{D and} the ratio differential means 87G is inoperative.

[0017] Therefore, when the output inhibit IN ₁ return
Through the inter- timer T _RE , even if the ratio differential means 87G is unnecessarily operated due to the subsequent CT saturation, the relay device GP is locked by the inhibit IN ₂ so as not to trip as the relay device GP.
Note that this lock is the time until the CT saturation is restored after the DC component is lost, the recovery time timer T _RE (for example, about 0.2).
Seconds). Therefore, even if the inrush of the transformer TR penetrates and one of the two CTs is saturated, the relay device GP does not unnecessarily output the trip output.

2. When an external failure F2 occurs , the differential power transfer is performed as described in the related art based on FIG.
Since the flow I _D does not flow, the ratio differential means 87G does not operate.
You. In addition, there is no inrush because an external failure F2 occurs.
Current does not flow. 2.1 When a normal external failure occurs , the fundamental wave of the suppression current I _R
The ratio of the second harmonic component to be generated is the inrush detection means F _2H.
Below the detection level (for example, 12%) that activates
Therefore, the inhibit IN ₁ and the recovery time timer T _RE are issued.
There is no power, and there is no output from the ratio differential means 87G.
There is no trip output from the inhibit IN ₂ . 2.2 For the fundamental wave of the suppression current I _{R in} case of external failure
Inspection of the ratio of the second harmonic content of the inrush detector F _2H that
Even if it is above the exit level (for example, 12%),
The rush detection means F _2H is independent of the inrush current.
Operations to an in-rush detection signal to inhibit IN ₁
Output and return time timer T _RE inhibit IN ₂
The lock output is output to the
No, the ratio differential means 87G does not operate when an external failure F2 occurs.
Therefore, inhibit IN ₂ , that is, the relay device G concerned
There is no P trip output.

3. When an internal fault F1 occurs As described in the related art based on FIG.
Flow = differential current operates the ratio differential means 87G. Only
However, since the internal failure F1 occurs, the inrush current is
Not flowing. Second harmonic component of the suppression current I _R with respect to the fundamental wave
The ratio of 3.1 to the fundamental wave of the suppression current I _R is normal during an internal failure .
The ratio of the second harmonic content of the inrush detector F _2H for
It is below the detection level (for example, 12%) that causes it to operate.
Then, the inrush detection means F _2H is an inrush detection signal.
Inhibit IN ₁ and recovery time timer
-There is no output of T _RE . Therefore, the inhibit IN ₂ is
The output from the rate differential means 87G is tripped as in the conventional case.
Put out as power.

[0020] 3.2 of suppression current I _R at the time of internal failure if
Inrush detection of the ratio of the second harmonic component to the fundamental wave
When the detection level of the means F _2H (for example, 12%) or more _exists
However, the inrush detection means F _2H is
Operates regardless of nothing and outputs inrush detection signal
However, since the ratio differential means 87G is already operating,
Inhibit IN ₁ based on the crash detection signal , recovery time
The inhibit IN ₂ can be set without waiting for the output of the timer T _RE.
A trip output is produced by the output of the ratio differential means 87G.

Embodiment 2 FIG. FIG. 3 shows the configuration of the second embodiment.
In FIG. 3, IN ₃ is an inhibit output that outputs a trip output under the condition that the inrush detection means F _2H has no output and the ratio differential detection means 87G has an output, and OR is an inhibit IN ₂ or IN ₃ output. Outputs the trip output of the relay device GP when there is O
R means.

In the first embodiment, the penetration inrush including the DC component is detected, or the external fault current including the second harmonic component is detected, and the recovery time timer T _RE is energized once, and then the recovery is performed. When an internal failure occurs during counting of the time T _RE , depending on the timing of the internal failure occurrence, in the worst case, the time of the recovery time timer T _RE (for example, about 0.2).
There was a problem that the trip time was delayed by (seconds).

The second embodiment proposes a measure to solve this problem, and trips under the condition that the inrush detection means F _2H has no output and the ratio differential means 87G has an output even during the counting of the recovery time timer T _RE. A route that can be set up is provided to prevent delay in trip time.

Embodiment 3 FIG. FIG. 4 shows a block diagram of a third embodiment of the present invention, and FIG. 5 shows waveform diagrams of respective parts, where T ₁ and T ₂ are CT ₁ ,
Input transformer, PH is the input current I _1, the phase determination means I ₂ is outputted when the phase relation of opposite phase to each other, AN in-rush detecting means for introducing an input current I _1, I ₂ from CT ₂ individually It is detected that the inrush is penetrating under the condition that both the outputs of F _2H and the phase discrimination means PH are present.
ND means, T _RE is a return time timer that is energized by AND means AN and has a predetermined return time, and IN ₂ is a condition that the output of the return time timer T _RE is absent and the output of the ratio differential means 87G is present. It is an inhibit that outputs the trip output of the device GP.

The operation of the relay device GP configured as described above will be described. 1. The inrush including the DC component is the current transformer CT ₁ , CT
_When penetrating ₂ . This will be described with reference to the waveform chart of each part in FIG. When the inrush I _E is applied, the ratio of the second harmonic component to the fundamental wave at the suppression current I _R = (I ₁ + I ₂ ) is equal to or more than a certain value, so that the inrush detection unit F _2H outputs.

On the other hand, immediately after the application of the inrush _IE , none of the current transformers is saturated, so the current transformer CT
The output currents I ₁ and I ₂ of ₁ and CT ₂ are not saturated and their phases are opposite to each other. Therefore, the operation output is output from the phase determining means PH. The AND means AN outputs under the condition that both the _inrush detection means F _2H and the phase determination means PH have outputs, and the recovery time timer T _RE is activated and the inhibit IN _{2 is applied.}
The output of the ratio differential means 87G is locked by.

However, one of the subsequent CTs is saturated and the ratio differential means 87G is operated unnecessarily, and the DC component is attenuated and the CT is reduced.
Since the operation of the ratio differential means 87G continues until the saturation is restored, the recovery time timer T _RE keeps the lock. Therefore, even if the inrush _IE of the transformer penetrates, the relay device GP does not unnecessarily output the trip output.

2. When an external failure F2 occurs In FIG. 9A, the input current I is the same as in the conventional case.
_{Since 1} and I ₂ are in opposite phases and the differential current I _D does not flow, the ratio differential means 87G does not operate. On the contrary, the phase discriminating means PH outputs an operation output. At this time, the suppression current I _R = (I ₁ + I
₂ ) The ratio of the second harmonic component to the fundamental wave is 2.1. The detection level of the _inrush detection means F _2H (for example, 12%).
If not included, the inhibit IN ₁ and the return timer T _RE are not output.

2.2 If the detection level of the _inrush detection means F _2H (for example, 12%) or more is included, the inrush detection means F _2H outputs and the AND means AN and the recovery time timer T _RE output and the inhibit IN. ₂ outputs a lock output, but regardless of the outputs of the AND means AN and the recovery time timer T _RE , the comparison differential means 87G does not operate, so the inhibit IN ₂ , that is, the trip output of the relay device GP concerned, of course, None.

3. When internal failure F1 occurs In the same manner as in the conventional case in FIG. 9B, the ratio differential means 87G operates with the input current = the differential current. On the contrary, since there is no current having a reverse phase with respect to the input current I _{1, the} phase discrimination means PH is inoperative.

At this time, the suppression current I _R = (I ₁ + I ₂ ) contains the ratio of the second harmonic component to the fundamental wave of 3.1 or more (for example, 12%) of the detection level of the _inrush detection means F _2H. without it, do not output the inrush detector F _2H, phase discriminating means PH also aND means aN in inactive, rather than locking the output from the return time timer T _RE, from the inhibit iN _2, similarly to the conventional ratio differential The output of the means 87G is output as a trip output.

3.2 If the detection level of the _inrush detection means F _2H (for example, 12%) or more is included, the inrush detection means F _2H outputs, but the phase determination means PH does not operate, so the inhibit IN ₁ , Return time timer T _RE
Inhibit IN ₂ as in 3.1 above without output
Therefore, the output of the ratio differential means 87G is output as a trip output as in the conventional case.

Embodiment 4 FIG. FIG. 6 shows the configuration of the fourth embodiment.
In FIG. 6, IN ₃ is an inhibit output which outputs a trip output under the condition that the inrush detection means F _2H has no output and the ratio differential detection means 87G has an output, and OR is output to either the inhibit IN ₂ or the inhibit IN _3. Outputs the trip output of the relay device GP when there is O
R means. The fourth embodiment is proposed to the third embodiment for the same purpose as the second embodiment with respect to the first embodiment, and there is no output to the inrush detection means F _2H even during the counting of the recovery time timer T _{RE, and the} ratio differential means 87G. It has a route that can be tripped with output.

In the above description, the present invention is applied to the generator protection ratio differential relay device GP, but the invention is not limited to this, and the transmission line protection ratio differential relay device is not limited to this. Needless to say, the present invention can be similarly applied to a busbar protection ratio differential relay device, a transformer protection ratio differential relay device, and the like.

[0035]

As described above, according to the first aspect of the present invention, one of the current transformers for detecting the first current or the second current is penetrated by the inrush current to be in a saturated state and the ratio differential means. to be trip output error dynamic current flows is output, together with the in-rush test digital by inrush detection means
When the output of the ratio differential means is not output, the output of the ratio differential means is prevented until the saturation state is resolved, so that the trip output is not carelessly output to the load circuit breaker. There is an effect that a high ratio differential relay can be provided.

According to the second aspect of this, one of the current transformer for detecting the first current or the second current in-rush current through becomes saturated, the error dynamic current the ratio differential means also trip output flow is output, block the output of the ratio differential means by the output control means when a reverse phase relationship detection between the respective currents by phase discrimination means together with inrush detection by the inrush detection means to eliminate saturation doing, there is an effect of providing a first high percentage differential relay device of Ri reliability due to pair invention for the trip output is not output to inadvertently load breaker. According to the third aspect of the present invention, the ratio differential means outputs the ratio while blocking the output for a certain period of time.
The differential means validates the trip output when an internal failure is judged.
By doing so, even if an internal failure is determined during inrush
The output of the ratio differential means is started by the output control means.
Therefore, it is possible to immediately respond to internal failure
This has the effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a relay device GP showing a first embodiment of the present invention.

FIG. 2 is a waveform chart of each part for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a relay device GP showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a relay device GP showing a third embodiment of the present invention.

FIG. 5 is a waveform chart for explaining various parts of the operation of the third embodiment of the present invention.

FIG. 6 is a configuration diagram of a relay device GP showing a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional relay device GP.

FIG. 8 is a configuration diagram of a ratio differential means 87G of a conventional relay device GP.

FIG. 9 is an explanatory diagram of an operation principle of a conventional relay device GP.

FIG. 10 is a waveform diagram of each part for explaining the operation of the conventional relay device GP.

[Explanation of symbols]

G protected generator TR transformer BUS bus CT _1, CT ₂ current transformer I _1, I-rush current GP generator protective relay device ₂ current transformer secondary current I _E transformer (the relay device) 87G Ratio protection means for generator protection F _2H Inrush detection means F _1P Fundamental wave pass filter F _2P Second harmonic pass filter CM _F2 Second harmonic detection means T _RE Recovery time timer PH Phase discrimination means AN AND means

Claims (3)

(57) [Claims] 1. A differential current, which is a difference between first and second currents detected through first and second current transformers installed at both ends of a protected device in a power system, and the first and second currents. A ratio differential unit that outputs a trip output to the load circuit breaker of the power system in response to the ratio of the suppression current, which is the sum, and whether the ratio of the second harmonic to the fundamental wave of the suppression current is a certain value or more. Inrush detection means for detecting and outputting the inrush detection signal, and outputting the inrush detection signal .
When there is force and no output of the ratio differential means, the ratio difference
A ratio differential relay device, comprising: output control means for blocking the output of the operating means for a certain period of time . 2. A differential current, which is the difference between the first and second currents detected by the first and second current transformers installed at both ends of the protected device in the power system, and the first and second currents. A ratio differential means that responds according to the ratio of the suppression current, which is the sum, and outputs a trip output to the load circuit breaker of the power system, and detects whether the ratio of the second harmonic to the fundamental wave of the suppression current is a certain value or more. And an inrush detection means for outputting an inrush detection signal, a phase determination means for detecting the phase relationship between the first current and the second current, and outputting an antiphase detection signal when the antiphase relationship is detected, and the inrush detection means. When the signal and the anti-phase detection signal are significant, the output of the ratio differential means is
A ratio differential relay device, comprising: output control means for blocking for a fixed time . 3. The output control means outputs by the ratio differential means.
When the internal differential of the ratio differential means is judged during
Has a function to enable the trip output above.
The ratio differential relay device according to claim 1, which is a characteristic.