JP3366531B2 - Current differential protection 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 current differential protection relay device, and more particularly to a highly reliable current differential protection relay device which does not perform unnecessary operation when an external fault is removed.

[0002]

2. Description of the Related Art FIG. 20 is a block diagram showing a conventional current differential protection relay device (hereinafter, simply referred to as a relay).
In the figure, L is a protected transmission line, CTA is a current transformer that detects a current flowing through the protected transmission line L, AD is analog / digital conversion means, TR is transmission means, IA is terminal current,
IB and IC are other terminal currents.

DIF is a differential current I calculated by the following arithmetic expression (1).
Differential current deriving means for deriving D, RES is a suppressing current deriving means for deriving the suppressing current IR by the following arithmetic expression (2), A
Is a large current characteristic means for performing characteristic calculation in a large current region by introducing the differential current ID and the suppression current IR, and B is also the differential current I.
D, high-sensitivity small current characteristic means for performing characteristic calculation in the small current region by introducing the suppression current IR, AN1 is a logical product means, and AT is a transceiver connected to the transmission means TR.

The following is an example of each arithmetic expression. Expression for calculating differential current ID by differential current deriving means DIF ID = | IA + IB + IC | (1) Expression for suppressing current IR by suppressing current deriving means RES IR = | IA | + | IB | + | IC | (2) Calculation formula by high current characteristic means A | ID | ≧ KA | IR | + KOA (3) Calculation formula by high sensitivity small current characteristic means B ID ≧ KB | IR | + KOB ・ ・ ・ ( 4) where | X | = √ {X (t) ² + (t-90) ² }, KA
> KB, KOA> KOB. Xt: Current instantaneous value of X Xt-90: Instantaneous value of 90 ° past in electric angle from the present of KA, KB: slopes of straight lines A and B KOA, KOB: intercepts of straight lines A and B on the I- _D axis

FIG. 21 is a characteristic diagram of a current differential protection relay device,
FIG. 22 is a diagram showing a current distribution at the time of an external failure. As shown in FIG. 22, when the external fault FO is removed while the current transformer CTA on the terminal A side where the fault current is concentrated in the external fault FO is saturated with DC, the secondary current of the current transformer CTA is removed. It is known that the DC component transiently remains on the side. At this time, since residual current does not occur on the secondary side of the current transformers CTB and CTC at terminals B and C, this phenomenon appears as an internal failure from the viewpoint of the relay, and the magnitude of the residual current exceeds the sensitivity of the relay. Moreover, if the duration of the residual current exceeds the operation time of the relay, unnecessary operation is performed.

FIG. 23 is a time chart at the time of an external failure. In this time chart, the waveforms of the residual current, the suppression current IR, the differential current ID and the output states of the large current characteristic means A and the high sensitivity small current characteristic means B and FIG. 25 shows the correspondence with the current locus diagram at the time of external failure in FIG. 24.

In the current locus diagram at the time of external failure of FIG. 24, a is at load current (large current characteristic means A: operation, high sensitivity small current characteristic means B:
Not working). B is the current transformer CT at the moment when the external failure occurs (1st wave)
Suppressing current IR when A is not causing DC saturation >>
Differential current ID (large current characteristic means A: operation → non-operation (recovery time t _REA ), high sensitivity small current characteristic means B: non-operation). C is a state in which the differential current ID is increased compared to B during DC saturation (second wave, third wave, fourth wave) (large current characteristic means A: non-operation, high sensitivity small current characteristic means B: non-existence). motion). (D) Immediately after the external fault is removed, the B terminal current IB and the C terminal current I
C becomes zero, and the suppression current IR≈differential current ID (large current characteristic means A: non-operation → non-operation (operation time t _OPA ), high sensitivity small current characteristic means B: Non-operation → instantaneous operation (operation time t _OPB ).

[0008]

Since the conventional current differential protection relay device is constructed as described above, when the external fault is removed while the current transformer only at one end is saturated with direct current due to the external fault. However, there is a problem that a residual current is transiently generated on the secondary side of the current transformer, which is regarded as an internal failure of one end inflow when viewed from the relay, and the current differential protection relay device operates unnecessarily.

As a method of solving this problem, for example, a method disclosed in Japanese Patent Publication No. 1-24012 has been proposed, which is a method of using a large suppression current that is always stored for a certain period of time in the past. Therefore, when an external fault with a large suppression current shifts to an internal fault with a small suppression current, until a large suppression current in the past switches to the current value,
There is a problem that the relay cannot operate, that is, the operation time is delayed.

The present invention has been made to solve the above problems, and an object thereof is to obtain a highly reliable current differential protection relay device which does not perform unnecessary operation when an external fault is removed.

[0011]

According to a first aspect of the present invention, there is provided an AD circuit for sampling digitally data by synchronously sampling each terminal current of a power system.
Conversion means, differential current deriving means for deriving a differential current from the digital data of the terminals, suppression current deriving means for deriving a suppression current from the digital data of the terminals, and the differential current and the suppression current Large current characteristic means, high sensitivity small current characteristic means, low sensitivity small current characteristic means , large current characteristic means output and low sensitivity small current
Second AND output means for outputting the characteristic means, and the large current characteristic means
First logical product of the output of the active means and the output of the sensitive high-current characteristic means
Energized by the output means and the output of the first AND output means.
And a first timer, wherein the first output means is
The output of the logical product output means of 2 or the first timer
The output is a logical sum output .

According to a second aspect of the present invention, there is provided a current differential protection relay device, wherein AD converter means for sampling digitally the digital data by synchronously sampling the current at each terminal of the power system, and the difference from the digital data at each terminal. A differential current deriving means for deriving a dynamic current, a suppression current deriving means for deriving a suppression current from digital data of the terminals, and a large current characteristic means for calculating the differential current and the suppression current to obtain a predetermined characteristic. And a high sensitivity small current characteristic means and a low sensitivity small current characteristic means ,
Second output of high current characteristic means output and low sensitivity small current characteristic means output
Of the logical product output means and the output of the large current characteristic means
The second timer that is used and the output and high of this second timer.
A third logical product output means for outputting the sensitivity small current characteristic means is provided.
The second output means is the second AND output means or
The third logical product output means outputs the logical sum .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. 1 is a block diagram of a current differential protection relay device according to a first embodiment of the present invention, FIG. 2 is an operation characteristic diagram of the device, and FIG.
And FIG. 4 shows a time chart.

In FIG . 1, L is a protected transmission line, CTA.
Is a current transformer that detects the current flowing through the protected transmission line L, AD
Is an analog / digital conversion means (AD conversion means), T
R is a transmission means, IA is a terminal current, and IB and IC are other terminal currents.

[0015] DIF differential in the arithmetic expression (1) the current I
A differential current deriving means for deriving D, RES is a suppressing current deriving means for deriving the suppressing current IR by the arithmetic expression (2), A
Is a large current characteristic means for performing characteristic calculation in a large current region by introducing the differential current ID and the suppression current IR, and B is also the differential current I.
D, a high-sensitivity small current characteristic means for introducing characteristic of the suppression current IR to perform characteristic calculation in a small current region, AT is a transceiver connected to the transmission means TR, C is an arithmetic expression | ID | ≧ KOC, where KOA
<KOB <KOC is a low-sensitivity small-current characteristic means for discriminating between operation and non-operation. Here, KOC is an intercept of the straight line C on the I _D axis, and this KOC is set to a value obtained by adding a margin to the magnitude of the maximum differential current in the current locus when the external fault is removed. That is, the low-sensitivity small-current characteristic does not operate unnecessarily when the external fault is removed.

[0016] AN2 logical product means, T1 is for example, about 40ms and timer means (approximately 24 samples in two cycles, the electrical angle 30 ° period sampled at 50HZ), O
R is a logical sum means. Here, the logical product means AN1, A
The N2, the timer means T1, and the logical sum means OR form a first output means I. The operating time of the timer means T1 is set to a value obtained by adding a margin time to the relay malfunction output continuation time due to the transient residual current when the external fault is removed.

[0017] Next, the operation will be described. (1) Operation when removing external fault As shown in FIG. 3, when removing external fault FO, the current locus Irohanii enters the operating range of the large current characteristic unit A and the operating range of the high sensitivity small current characteristic unit B, and the logical product is obtained. There is an instantaneous output from the means AN1, but since the output disappears within the time until the timer means T1 operates, the timer means T1 is not energized and is not relayed from the OR means OR. At this time, the current locus Elohanii does not pass through the operating range of the low sensitivity small current characteristic means C, so that there is no output from the logical product means AN2. Therefore, when removing the external fault, the logical sum means O
There is no unnecessary output from R, and the relay does not operate unnecessarily.

[0018] (2) then during normal state at internal faults FI1 from the load current, the operation when the internal fault FI1 occurs from the load current operation region of the sensitive low-current characteristic unit B, and the time chart of FIG. 4 described To do. The large current characteristic means A operates at the time of a normal load current, the large current characteristic means A remains operated even at the time of the internal failure FI1, and as soon as the high sensitivity small current characteristic means B operates, the logical product means AN1 outputs and the timer Means T
After the operation time of 1, the logical sum means OR outputs a relay.
That is, the operating time of the relay is the operating time t _OPB + T1 of the high sensitivity small current characteristic means B. On the other hand, at the time of the internal failure FI1, the low-sensitivity small-current characteristic means C does not operate and the logical product means AN2 does not output.

As described above, according to the first embodiment, the timer means is added to the logical product of the high-sensitivity small current characteristic means and the large current characteristic means which may cause an unnecessary operation when the external fault is removed. It is possible to reliably prevent unnecessary operation when removing an external failure.

[0020] Embodiment 2. FIG. 5 is a block diagram of a current differential protection relay device according to a second embodiment of the present invention. In the same configuration as that of FIG. 1 showing the first embodiment, the output of the large current characteristic means A is controlled by a timer. It is supplied to the means T2, and the output of the timer means T2 and the output of the high-sensitivity small current characteristic means B are logical product means AN.
3 is a configuration for supplying the same to the No. 3. Here, the logical product means AN2,
The AN3, the timer means T2 and the OR means OR form a second output means II. The operating time T2 of the timer means T2 is set to a value obtained by adding a margin time to the relay malfunction output continuation time due to the transient residual current when the external fault is removed, for example, about 40 ms. FIG. 6 shows a time chart of the device of FIG.

[0021] Next, the operation will be described. (1) When removing an external fault As shown in FIG. 6, when removing an external fault, the current locus Irohanii enters the operating range of the large current characteristic means A and the sensitive small current characteristic means B, but the timer means T2. Since the output of the high-sensitivity small current characteristic means B disappears within the operating time T2 of
The timer means T2 outputs, but the AND means AN3 does not output. At this time, the current locus does not pass through the operating range of the low sensitivity small current characteristic means C, so that there is no output from the AND means AN2. Therefore, there is no unnecessary output from the OR gate OR when removing an external fault.

[0022] (2) then during normal state at internal faults FI1 from the load current, the operation of when the internal fault FI1 is generated from the load current operation region of the sensitive low-current characteristic means B. At a normal load current, the large current characteristic means A operates,
The large current characteristic means A remains in operation even during the internal failure FI1, that is, the timer means T2 is outputting and the high sensitivity small current characteristic means B is in operation.
Immediately after the operation of
Output from R. In the first embodiment, there is an operating time delay of T1 time at the internal fault FI1 point from the load current, but in the second embodiment, since the large current characteristic means A is operating at the load current input, the timer means T2 has a delay. The difference is that there is no delay. On the other hand, at the time of internal failure FI1, low sensitivity small current characteristic means C
Is inoperative and no output is made from the AND means AN2.

As described above, according to the second embodiment, since the timer means is added to the output of the large current characteristic means, unnecessary operation does not occur at the time of removing an external fault.
Moreover, it is possible to obtain a highly reliable current differential protection relay device with no operation time delay when an internal failure occurs.

Reference Example 1. Figure 7 is thisReference example 1Current differential protection relay device
Figure 1 shows a logical diagram, where N1 is a logical negation
Steps, T3 are timer means, for example, about 40 ms, G1,
G2 is gate means, TBL is suppression of each sampling time
A data memory in which the current IR is stored, and a logical product means
AN1 constitutes the third output means III.

When the timer means T3 outputs, the suppression current IR is switched from the present value to the sampling value past a certain time. This fixed time is set to a time obtained by adding a margin to the duration of the transient residual current when removing the external fault, for example, 24 sampling times (2 cycles). The set value of the timer means T3 is a value shorter than the external failure continuation time, that is, a value obtained by subtracting the margin time from the operation time of the relay plus the operation time of the circuit breaker. Since the other structures are the same as the structures shown in FIG. 1 showing the first embodiment, the same parts are designated by the same reference numerals and the duplicate description thereof will be omitted. Figure 8
Is a time chart of the device of FIG. 7, and FIG. 9 is a current locus diagram.

[0026] Next, the operation will be described. (1) At the time of removing an external fault After the large current characteristic means A returns due to the occurrence of an external fault, and after the operating time of the timer means T3 elapses, that is, before removing the external fault, the suppression current is stored in the data memory TBL as the 24 sampling past value ( (n-sampling past value) Switching is performed by the gates G1 and G2 to use the suppression current of IR-24. Even after the external fault is removed, the 24 sampling time (2 cycles) is a large suppression current. Therefore, the large current characteristic means A operates with a delay of about 24 sampling time after the external fault is removed. Further, since the 24 sampling time after removal is a large suppression current, the high-sensitivity small current characteristic means B does not operate and the logical product means AN1 does not output even with respect to the transient residual current.

In the current locus diagram of FIG. 9, a is a load current state (large current characteristic means A: operation, high sensitivity small current characteristic means B:
(No operation), b is still current transformer CT at the moment of external failure (first wave)
The differential current ID is small when A does not cause DC saturation (large current characteristic means A: operation → non-operation (recovery time t _REA ), high sensitivity small current characteristic means B: non-operation), and C is DC saturation. In the middle (the second wave, the third wave, the fourth wave), the state in which the differential current ID is increased as compared with B, at this time, the timer means T
3 operates and the past sampling value IR of the suppression current IR is 24
Switched to -24 (large current characteristic means A: non-operation, high-sensitivity small current characteristic means B: non-operation), (e) 24 sampling time has passed after elimination of external fault, differential current ID attenuated by residual current (large Current characteristic means A: non-operation, high sensitivity small current characteristic means B: non-operation).

[0028] (2) explaining the operation in the internal fault FI1 generated at the internal fault FI1 from the load current then from the load current in the operation region of high sensitivity low current characteristic means B. At a normal load current, the large current characteristic means A remains in operation even during the internal failure FI1, and the timer means T3 is not activated. Therefore, the suppression current IR is calculated by using the present value, and the high-sensitivity small current characteristic means B operates to be output from the AND means AN1.

As described above, according to the first reference example , if the large current characteristic means is inoperative for a certain period of time or longer, the suppression current is set to the past sampling value of 24 sampling, which may cause an unnecessary operation when the external fault is removed. A high-reliability current differential protection relay device is obtained.

Reference Example 2 FIG. 10 is a block diagram of the current differential protection relay device according to the second reference example, in which the suppression current deriving means RES stores a 24 sampling past value IR-24 in advance, and a suppression current. Mean value deriving means AVE for deriving an average value of the current IR value and the 24-sampling past value IR-24 is provided, and the logical product means AN1 is the fourth.
It constitutes the output means IV of. Other configurations are the same as in Reference Example 1 above.
7 has the same configuration as that of FIG.

[0031] Next, the operation will be described. (1) At the time of removing an external fault After the large current characteristic means A returns due to the occurrence of an external fault, after the operating time of the timer means T3, that is, before removing the external fault, the suppression current I
R is switched by the gates G1 and G2 so as to calculate the average of the suppression current IR of the 24-sampling past value IR-24 stored in the data memory TBL and the present value, and the 24-sampling time (2 cycles ) Is a large suppression current IR, the large current characteristic means A is operated with a delay of about 24 sampling time after the removal. After removal 2
Since the 4-sampling time is a large suppression current IR, the high-sensitivity small-current characteristic means B does not operate, and the logical product means AN1 does not output.

In the current locus diagram of FIG. 11, a is a load current state (large current characteristic means A: operation, high sensitivity small current characteristic means B:
(No operation), b is still current transformer CT at the moment of external failure (first wave)
Suppressing current IR when A does not cause DC saturation >> Differential current ID (Large current characteristic means A: operation → inoperative (recovery time t _REA ), high sensitivity small current characteristic means B: inoperative), During DC saturation (the second wave, the third wave, the fourth wave), the state in which the differential current ID is increased as compared with B, at this time, the timer means T
3 operates and the suppression current IR is 24 sampling past value IR
-24 and the average value of the present value are switched (large current characteristic means A: non-operation, high-sensitivity small current characteristic means B: non-operation), e is 24 sampling time after failure elimination, during which differential current due to residual current ID is attenuated (large current characteristic means A: non-operation, high sensitivity small current characteristic means B: non-operation).

As described above, according to this reference example 2 ,
By using the average value of the past sampling value and the current value of 4 sampling, the suppression current is as small as 1/2 compared to the reference example 1 , and when the internal failure occurs, when the differential current is large, it is possible to operate even with the suppression current of E. It is possible to operate without delay in operating time.

Reference Example 3 FIG. 12 is a block diagram of a current differential protection relay device according to the third reference example . In the figure, IN1 is an inhibit logic means that constitutes a fifth output means V, T3 is a timer means, and T4 is a return timer. The operation time of the recovery timer means T4 is set to a value obtained by adding a margin time to the relay malfunction output continuation time due to the transient residual current when the external fault is removed, for example, about 40 ms. FIG. 13 is a time chart showing the operation of the apparatus shown in FIG.

[0035] Next, the operation will be described. (1) When removing an external fault After the large current characteristic means A recovers due to the occurrence of an external fault, the inhibit logic means IN1 is restored after the operating time of the timer means T3, that is, before the external fault is removed, the reset time T4 of the timer means T4.
Just lock.

[0036] After the external fault clearing, the differential current ID due to the residual current, operates instantaneously sensitive small-current characteristic means B, the lock output of the return time T4 of the return timer means T4 in operation of large current characteristics means A is Since it has been extended, there is no output from the inhibit logic means IN1.

[0037] (2) explaining the operation of the internal fault FI1 upon the occurrence of the operation region from the next load current at the internal fault FI1 from the load current sensitive small-current characteristic means B. At the time of normal load current, the large current characteristic means A is in operation and the internal failure FI1
Even when the large current characteristic means A is still operating, the timer means T3
Will never be activated. Therefore, the inhibit logic means IN1 outputs instantaneously after the operation of the high sensitivity small current characteristic means B.

As described above, according to this reference example 3 , when the large current characteristic means has been inoperative for a certain period of time or more, the output means is locked for the return time of the return timer means, thereby eliminating unnecessary operation when the external failure is eliminated. It is possible to obtain a highly reliable current differential protection relay device that does not have the risk of

Reference Example 4 FIG. 14 is a block diagram of a current differential protection relay device according to this reference example 4. In the figure, IN2 is an inhibit logic means for inputting the output of the timer means T3 and the output of the low sensitivity small current characteristic means C. This inhibit logic means IN2 constitutes means for preventing unnecessary operation when removing an external fault. Since the other configurations are the same as the configurations of FIG. 7 showing the reference example 1 , the same portions are denoted by the same reference numerals and the duplicate description thereof will be omitted.

FIG . 15 is a system diagram when shifting from an external fault to an internal fault, FIG. 16 is a time chart, and FIG. 17 is a diagram showing a current locus when shifting from an external fault to an internal fault.

[0041] Next, the operation will be described. (1) When removing an external fault As shown on the left side of FIG. 16, when the external fault FO is generated and when an external fault is removed, the low-sensitivity small current characteristic means C does not operate and the reference example 1 is used.
Same operation as.

[0042] (2) the right side of the internal fault during 16 externally failure, an internal mechanical failure FI2 is immediately generated,
The suppression current IR is 24 sampling past value IR-24,
Both the large current characteristic means A and the high sensitivity small current characteristic means B are inoperative (portion in FIG. 17), but the differential current ID is the set value KOC of the low sensitivity small current characteristic means C (see FIG. 2). If larger, the low-sensitivity small-current characteristic means C operates to restore the output of the inhibit logic means IN1, and the gate means G2.
Is turned off, and the suppression current IR is set to 2 by turning on the gate means G1.
4 Return from past sampling value IR-24 to current value.

[0043] Thus outputs from the (g portion in FIG. 17) logical product means AN1 large current characteristics means A, sensitive low current characteristic means B are both running. That is, in this reference example 4 , for example, after the occurrence of an internal failure, an output can be obtained within the operating time (10 ms) of the low sensitivity small current characteristic means C + the operating time (10 ms) of the high sensitivity small current characteristic means B.

As described above, according to this reference example 4 , the output of the low-sensitivity small-current characteristic means invalidates the output of the timer means T3 to invalidate the inhibit logic means, thereby suppressing the suppression current by 24 sampling past values. To the current value. As a result, at the time of transition from an external fault with a large suppression current to an internal fault with a small suppression current, the worst 24 sampling time (40 ms on a 50HZ base), the operation time is delayed, and the external fault once. When the internal failure is detected, the recovery timer is locked, and the recovery timer continues to be locked for 40 ms after the internal failure is transferred. Therefore, it is possible to solve the problem of the third reference example in which the delay is 40 ms as in the internal failure transfer.

Although the case where the reference example 4 is applied to the reference example 1 has been described, the same can be applied to the reference examples 2 and 3 .

Reference Example 5 FIG. 18 is a block diagram of a current differential protection relay device according to this reference example 5. In the figure, AC is the ratio of the direct current content ratio to the fundamental wave in the differential current to a certain value or less (for example, 100%). The following is a fundamental wave detection means for detecting
Since the DC component in the normal fault current is 100% or less of the fundamental wave, and the DC component in the residual current at the time of an external fault is 100% or more, the detection sensitivity of the fundamental wave detecting means AC is set to about 100%. . Logical product means AN3, IN3 is inhibit logic means constituting the unnecessary operation protective means during external fault clearing, like reference numerals from other parts of the configuration are the same as in FIG. 14 showing the reference example 4 Will be attached and redundant description will be omitted. FIG. 19 is a time chart explaining the operation of the apparatus of FIG.

[0047] Next, the operation will be described. (1) When removing an external fault As shown on the left side of FIG. 19, when an external fault FO occurs and at the time of removing an external fault, the low-sensitivity small current characteristic means C and the fundamental wave detecting means AC
Both are inoperative, and the operation is the same as in Reference Example 1 .

[0048] (2) the right side of the internal fault during 19 externally failure, an internal fault FI2 suppressing current IR 24 sampling past values IR-24 immediately after the generation, the large current characteristics means A, sensitive low current characteristic means B Both are inoperative (portion in FIG. 19), but low sensitivity small current characteristic means C
And the fundamental wave detecting means AC operate together to perform AND operation means AN3.
Is output, the output of the inhibit logic means IN2 is restored, the gate means G2 is turned off, the gate means G1 is turned on, and the suppression current IR is returned from the 24 sampling past value IR-24 to the present value as in the sixth embodiment. .

[0049] Accordingly, outputs from the (g portion in FIG. 19) logical product means AN1 large current characteristics means A, sensitive low current characteristic means B are both running. That is, in this method, for example, after the occurrence of an internal failure, {the operating time of the small current characteristic means C (1
0 ms) or the operating time of the fundamental wave detecting means AC (20 m
s) slower} + the output can be obtained in the operating time (10 ms) of the high-sensitivity small-current characteristic means B.

As described above, according to this reference example 5 , as compared with the above-mentioned reference example 4 , not only the magnitude of the differential current but also the direct current component is equal to or less than a certain value for canceling the unnecessary operation when removing the external fault. Is added, the distinction from the case of removing the external failure is made more reliable, and the reliability is improved.

The above-mentioned first and second embodiments and reference examples
In 1 and 2 , the case of sampling and calculation at every electrical angle of 30 ° is described, but the same applies to sampling and calculation at every 15 °.

Further , the ratio differential calculation is described in the case where the sum current of each terminal current is used as the suppression, but it can be applied when the maximum value current of each terminal current is used. Furthermore, we have described the application to current differential relays for power transmission lines.
The same can be applied to the transformer protection differential relay and the bus protection differential relay.

[0053]

As described above, according to the first aspect of the invention, the timer means is added to the logical product of the high-sensitivity small current characteristic means and the large current characteristic means which may cause an unnecessary operation when the external fault is removed. With this configuration, there is an effect that a highly reliable current differential protection relay device that does not perform unnecessary operation even when an external failure is removed can be obtained.

[0054] According to the second aspect of the present invention, since it is configured to add a timer means to the output of the large current characteristics means, not unnecessary operation even when an external fault clearing, yet when the internal fault from the load current, operation time There is an effect that a highly reliable current differential protection relay device without delay can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a current differential protection relay device according to a first embodiment of the present invention.

FIG. 2 is an operating characteristic diagram of the current differential protection relay device according to the first embodiment of the present invention.

FIG. 3 is an operation time chart according to the first embodiment of the present invention.

FIG. 4 is an operation time chart when an internal failure occurs according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a current differential protection relay device according to a second embodiment of the present invention.

FIG. 6 is an operation time chart according to the second embodiment of the present invention.

FIG. 7 is a block diagram of a current differential protection relay device according to a first reference example of the present invention.

FIG. 8 is an operation time chart according to Reference Example 1 of the present invention.

FIG. 9 is a current locus diagram at the time of an external failure of the reference example 1 of the present invention.

FIG. 10 is a block diagram of a current differential protection relay device according to a second reference example of the present invention.

FIG. 11 is a current locus diagram at the time of an external failure of reference example 2 of the present invention.

FIG. 12 is a block diagram of a current differential protection relay device according to a third reference example of the present invention.

FIG. 13 is an operation time chart according to Reference Example 3 of the present invention.

FIG. 14 is a block diagram of a current differential protection relay device according to reference example 4 of the present invention.

FIG. 15 is a diagram showing a distribution of a system current at the time of transition from an external failure to an internal failure.

FIG. 16 is an operation time chart according to Reference Example 4 of the present invention.

FIG. 17 is a current locus diagram at the time of transition from an external failure to an internal failure.

FIG. 18 is a block diagram of a current differential protection relay device according to reference example 5 of the present invention.

FIG. 19 is an operation time chart according to Reference Example 5 of the present invention.

FIG. 20 is a block diagram of a conventional current differential protection relay device.

21 is a ratio differential characteristic diagram of the current differential protection relay device of FIG. 20. FIG.

FIG. 22 is a diagram showing a distribution of system current in the event of an external failure.

FIG. 23 is an operation time chart when an external failure occurs.

FIG. 24 is a current locus diagram at the time of an external failure.

[Explanation of symbols]

AC fundamental wave detecting means, AD analog / digital converting means (AD converting means), DIF differential current deriving means,
RES suppression current derivation means, TBL data memory, I
D differential current, IR suppression current, IR-24 24 sampling past value (n sampling past value), A large current characteristic means, B high sensitivity small current characteristic means, C low sensitivity small current characteristic means, IN2, IN3 inhibit logic Means (Measures against unnecessary operation when removing external failure), T1, T2, T
3 timer means, T4 recovery timer means, I first
Output means, II second output means, III third output means, IV fourth output means, V fifth output means.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-5-252645 (JP, A) JP-A-8-116623 (JP, A) JP-B 1-24012 (JP, B2) JP-B 61- 22540 (JP, B2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02H 3/28 H02H 7/22

Claims (2)

(57) [Claims] 1. AD conversion means for sampling digitally data by synchronously sampling each terminal current of a power system,
Differential current deriving means for deriving a differential current from the digital data of the terminals, suppression current deriving means for deriving a suppression current from the digital data of the terminals, and calculating the differential current and the suppression current by a predetermined value. Of the high current characteristic means, the high sensitivity small current characteristic means, the low sensitivity small current characteristic means, the high current characteristic means output and the low sensitivity small current characteristic means output.
A second AND output means, a high current characteristic means output and a high
First AND output means for outputting the sensitivity small current characteristic means, and
The first tie activated by the output of the first logical product output means
And the output of the second AND output means or the first
1. A current differential protection relay device, comprising: a first output means for outputting a logical sum output of the outputs of the first timer . 2. AD conversion means for sampling digitally data by synchronously sampling each terminal current of the power system,
Differential current deriving means for deriving a differential current from the digital data of the terminals, suppression current deriving means for deriving a suppression current from the digital data of the terminals, and calculating the differential current and the suppression current by a predetermined value. Of the high current characteristic means, the high sensitivity small current characteristic means, the low sensitivity small current characteristic means, the high current characteristic means output and the low sensitivity small current characteristic means output.
The second logical product output means and the output of the large current characteristic means are provided.
Activated second timer and output of this second timer
And a third logical product output means of high-sensitivity small current characteristic means output
And the second logical product output means or the third logical product output
Second differential output means for outputting the logical sum output of the means.