JPH09257854A - Protection relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately discriminate the fault of an analog input circuit by subtracting the output obtained by superposing a monitoring inversion signal on respective phase currents from the output obtained by superposing a monitoring signal on the currents, and comparing the subtracted result with an alarm value. SOLUTION: CT2 to CT4 detect phase currents IA to IC of three-phase lines 1, and adders 33 to 35, 36 to 38 respectively superpose monitoring signals IM and monitoring inversion signals -IM generated at 31 on currents IA to IC. After harmonic components are removed from IA+IM, IA-IM of the outputs of the adders 33 to 38 by 39 to 44, they are converted to digital values by A-D converter 52, and output to a calculator 53. A data distributor 54 distributes digital data IA+IM+I1 , IA+IM+K2 (K1 to K6 are errors due to analog input circuit fault) to an adder 55 and a fault discriminating calculator 58. The calculator 58 calculates fault discriminated value of analog data 1 circuit of each phase based on the digital data and set value IMS corresponding to the signal IM, and a fault discriminator 59 discriminates the fault in the analog circuit when it is larger than the alarm value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective relay device having a function of judging a defect in an analog input circuit.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional protective relay device disclosed in, for example, Japanese Patent Publication No. 3-79932.
In the figure, 1 is a three-phase line of a power system, 2 is a current detector for detecting an A-phase current I _A (hereinafter referred to as CT), 3 is a current detector for detecting a B-phase current I _B (hereinafter, referred to as CT). Reference numeral 4 denotes a current detector (hereinafter referred to as CT) for detecting the C-phase current I _C.

Reference numeral 5 is an input converter for converting the A-phase current into a predetermined magnitude for insulation, 6 is an input converter for converting the B-phase current into a predetermined magnitude and insulation, and 7 is a C-phase current. An input converter for converting into a predetermined size and insulating, 8 is a current I _A , I _B , I
A monitoring signal generator for generating a monitoring signal I _4f having a frequency four times that of _C , 9 is an adder for superimposing the monitoring signal I _4f on the current I _A , and 10 is a monitoring signal I _4f for the current I _B , 11 is an adder for superimposing the monitoring signal I _4f on the current I _C.

Reference numerals 12 to 14 are analog filters for removing higher harmonic components from the outputs of the adders 9 to 11 such as I _A + I _4f . Reference numerals 15 to 17 are sample and hold (holding the outputs of the analog filters 12 to 14 for a certain period). Hereinafter, SH is referred to as SH, and 18 is a multiplexer (hereinafter referred to as MPX) that sequentially reads and outputs the data held in SH 15 to 17.
, 19 is an analog / digital converter (hereinafter referred to as an A / D converter) for analog / digital converting the data output from the MPX 18.

[0005] 20 computer to perform a relay operation and poor judgment, etc., 21 a data distribution unit for distributing the output of the A / D converter 19, 22 is digital data (I _A + I _4f + G, which is distributed by the data distributor 21 ₁ ) and a digital filter for extracting a fundamental wave (currents I _A + a ₁ , I _B + a ₂ , I _C + a ₃ ), 23 is a current I _A + a ₁ , I _B + a ₂ ,
Relay trip unit that performs relay calculation based on I _C + a ₃ and trips the circuit breaker based on the calculation result, 2
4 digital to extract digital data _{(I A + I 4f + G} 1 , etc.) 4 of the fundamental wave from the harmonic (monitoring _{I 4f + b 1, I 4f} + b 2, I 4f + b 3) distributed by the data distribution unit 21 A filter 25 is a failure determination unit that determines a circuit failure by comparing the monitoring signal I _4f + b ₁ etc. with a predetermined alarm value ε.

Next, the operation will be described. First, CT2
4 to 4 detect the currents I _A , I _B , and I _C of the respective phases of the three-phase line 1, adders 9 to 11 generate currents I _A , I _B , and I _{C from the} monitoring signal generator 8. The monitoring signal I _4f thus _generated is superimposed. As a result, the outputs of the adders 9 to 11 have the filter characteristics as shown in FIG.
.. to 14, the harmonic components are removed from the outputs of the adders 9 to 11 such as I _A + I _4f .

When the harmonic components are removed from the analog filters 12 to 14, the SHs 15 to 17 temporarily hold the outputs of the analog filters, and the MPX 18 sequentially reads the outputs of the analog filters from the SHs 15 to 17 and outputs A Output to the / D converter 19. This A / D converter 19
Converts the output of MPX 18 from analog to digital and outputs it to the computer 20.

As a result, the data distribution unit 2 of the computer 20
Digital data 1 is output from the A / D converter _{19 (I A + I 4f +} G 1, I B + I 4f + G 2, I C + I 4f +
G ₃ ) is distributed to the digital filters 22 and 24, respectively, as shown in FIG. Here, G _{1 to} G ₃ are analog input circuits (CT2 to CT4, analog filter 12).
.About.14, SH15 to SH17, and MPX18).

Then, the digital filter 22 performs digital filter calculation as shown below to obtain digital data (I _A + I _4f + G ₁ and I _B + I _4f).
The monitoring signal I _4f is removed from + G ₂ , 1 _C + I _4f + G ₃ , and the fundamental wave (currents I _A + a ₁ , I _B + a ₂ , 1 _C + a) is removed.
₃ ) to extract.

Here, a _{1 to} a ₃ are errors at the fundamental wave level due to a defect in the analog input circuit. Fundamental wave = I (t) -I (t -90 °) ····· (1) However, I (t): the digital data of the current (I _A +
I _4f + G _1, etc.) I (t-90 °): digital data before phase Li 90 ° by current _{(I A + I 4f + G} 1 , etc.) By the way, FIG. 7 is a frequency characteristic diagram of the digital filter 22.

Then, when the fundamental wave is extracted from the digital filter 22, the relay trip section 23 performs a relay operation based on the fundamental wave currents I _A + a ₁ , I _B + a ₂ and I _C + a ₃ , and The breaker is tripped based on the calculation result.

On the other hand, the digital filter 24 performs the following digital filter calculation,
Digital data (I _A + I _4f + G ₁ , I _B + I _4f + G
_2. The fourth harmonic of the fundamental wave (monitoring signals I _4f + b ₁ , I _4f + b ₂ , I _4f + b ₃ ) is extracted from ₂ , I _C + I _4f + G ₃ ).

Here, b _{1 to} b ₃ are errors at the fourth harmonic level due to a defect in the analog circuit. 4 harmonic = I (t) + I ( t-180 °) ····· (2) However, I (t): the digital data of the current (I _A +
I _4f + G _1, etc.) I (t-180 °): digital data before phase Li 180 ° by current _{(I A + I 4f + G} 1 , etc.) By the way, FIG. 8 is a frequency characteristic diagram of the digital filter 24.

When the fourth harmonic of the fundamental wave is extracted by the digital filter 24, the failure determining section 25 compares the monitoring signal I _4f + b ₁ etc. with a predetermined alarm value ε, and the monitoring signal I _4f + b. _{When 1} or the like is larger than the predetermined value ε, it is determined that the analog input circuit has a defect, the result of the determination is displayed on a display device or the like (not shown), and the series of processes is ended. * Analog input circuit failure Monitoring signal I _4f + b ₁ etc.> alarm value ε * Analog input circuit normal monitoring signal I _4f + b ₁ etc. ≤ alarm value ε

[0015]

Since the conventional protective relay device is constructed as described above, it is possible to constantly monitor the analog input circuit for defects. Since the defect determination (defect determination of the fourth harmonic level) is performed based on a signal having a frequency different from the fundamental wave, there is a problem that the defect determination cannot be accurately performed. .

A conventional example in which a monitoring signal having the same frequency as the current of each phase is superimposed on the current of each phase is "Electrical Cooperation Research Vol. 50 No. 1," published by the Electric Cooperation Research Group in April 1994.
As disclosed on pages 99 and 109, the conventional example does not separate the currents of the respective phases and the monitoring currents, but performs the failure determination based on the currents of the respective phases on which the monitoring signals are superimposed. Therefore, if the magnitude of the current of each phase fluctuates, the determination accuracy fluctuates.

The present invention has been made to solve the above problems, and provides a protective relay device which can accurately determine a defect in an analog input circuit by using a monitoring signal having the same frequency as the current of each phase. The purpose is to

[0018]

A protective relay device according to a first aspect of the present invention is a first analog filter for deriving a first output by superimposing a monitoring signal on a current of each phase by a superimposing means. Means, second analog filter means for inverting and superimposing the monitoring signal on the current of each phase by the superposing means to derive the second output, and subtracting the second output from the first output, and It is provided with a defect determination means for determining a circuit defect by comparing the absolute value of the subtraction result with a predetermined alarm value.

According to a second aspect of the present invention, there is provided a protective relay device comprising first analog filter means for deriving a first output by superimposing a monitoring signal on the current of each phase by the superimposing means.
Switching means for sequentially switching and outputting a second output obtained by inverting and superimposing the monitoring signal on the current of each phase by the superimposing means,
Defect determination means for subtracting the output of the analog filter means output corresponding to the output phase of the output from the first output, and comparing the absolute value of the subtraction result with a predetermined alarm value to determine circuit failure. It is equipped with and.

According to another aspect of the protection relay device of the present invention, the first analog filter means for deriving the first current output of each phase and the second current output of each phase are sequentially switched and output. The switching means and the output of the analog filter means output corresponding to the output phase of the output from the first output are subtracted, and the absolute value of the subtraction result is compared with a predetermined alarm value to determine a circuit failure. And a defect determining means for performing the above.

According to a fourth aspect of the protection relay device of the present invention, of the currents of the respective phases, the maximum current is multiplied by a predetermined coefficient, and the subtraction result is subtracted by the multiplication result. The alarm values of are compared to determine the circuit failure.

The protective relay device according to the fifth aspect of the present invention is such that the monitoring signal is generated from the monitoring signal generating means only when checking for a circuit failure.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1. 1 is a configuration diagram showing a protective relay device according to Embodiment 1 of the present invention. In the figure, 1 is a three-phase line of a power system and 2 is a CT for detecting an A-phase current I _A.
(Current detector) 3 is a CT for detecting the B-phase current I _B
(Current detector) 4 is a CT for detecting the C-phase current I _C
(Current detector).

Reference numeral 5 denotes an input converter (input conversion means) for converting the A-phase current into a predetermined magnitude and insulating, and 6 denotes an input converter for converting the B-phase current into a predetermined magnitude and insulating. Means), 7 is an input converter (input conversion means) for converting the C-phase current into a predetermined magnitude and insulating it, and 31 is a monitoring signal generator for generating a monitoring signal I _M having the same frequency as the three-phase line. And a monitoring signal generator 31.
Of the output I _M of the inverter I, the adder (superimposing means) 33 of superimposing the monitoring signal I _M on the current I _A, and the current I 34 of the current I A
Adder for superimposing the monitoring signal I _B to _B (superimposing means), 3
5 is an adder (superimposing means) that superimposes the monitoring signal I _M on the current I _C , 36 is an adder (superimposing means) that superimposes an inverted version of the monitoring signal I _M on the current I _A , and 37 is a current I adder for superimposing an inverted monitoring signal I _M to _B (superimposing means), 38 denotes an adder for superimposing the inverse of the monitoring signal I _M in current I _C (superimposing means).

[0025] 39-41 analog filter (analog filter means) for removing harmonic components from the I _A + I _M or the like which is the output of the adder 33 to 35, 42 to 44 adders 3
An analog filter (analog filter means) for removing harmonic components from I _A -I _M which is the output of 6 to 38, 4
5 to 50 are sample and hold (hereinafter, referred to as SH) which holds the outputs of the analog filters 39 to 44 for a certain period.
Reference numeral 1 denotes a multiplexer (hereinafter, referred to as MPX) as a switching unit that sequentially reads and outputs the data held in the SH 45 to 50, and 52 is an analog-digital converter (hereinafter, A) that converts the data output from the MPX 51 into analog-digital. / D converter).

Reference numeral 53 is a computer for performing relay calculation and failure determination, 54 is a data distribution section for distributing the output of the A / D converter 52, and 55 is digital data (I _A + I _M + K) distributed by the data distribution section 54. ₁₎ and digital data _{(I a -I M + K 2} ) or the like is added to remove the monitoring signal I _M relay operation current _{2I a + K 1 + K 2} , 2I B + K 3
_{+ K 4, 2I C + K} 5 + K 6 adder for deriving (trip unit), 56 is a current _{2I A + K 1 + K 2} , 2I B + K
_A relay calculation unit (trip unit, hereinafter referred to as a relay trip unit) that performs a relay calculation based on ₃ + K ₄ , 2I _C + K ₅ + K ₆ and trips the circuit breaker based on the calculation result, 57 is a monitoring signal I Set value I _MS corresponding to _M
(E.g., if the signal level of the monitor signal I _M due to the characteristics of the analog filter 39 to 44 is reduced to 80%, is the set of 80% of the value of the monitoring signal) is a setter for storing.

[0027] 58 the setting value I _MS corresponding to digital data _{(I A + I M1 + K} 1) and digital data _{(I A -I M1 + K 2} ), and the monitoring signal I _M, which is distributed by the data distributor 54 operation to the phase current I _a failure determination value to remove such _{K 1 -K 2, K 3 -K} 4, K 5 defect determination computing unit for deriving the -K ₆ (defect determining means), 59 defect determination value K
_{1 -K 2, K 3 -K 4} , K 5 -K 6 and defect determining unit for determining a circuit failure by comparing a predetermined alarm value ε a (bad determination unit).

Next, the operation will be described. First, CT2
~ CT4 detects the currents I _A , I _B , I _C of each phase of the three-phase line 1, and the adders 33, 34, 35 add the currents I _A , I _B , I.
_The monitoring signal I _M generated from the monitoring signal generator 31 is supplied to _C , and the adders 36, 37, 38 add the current I
_A, I _B, -I obtained by inverting the monitoring signal I _M relative to I _C
Superimpose _M.

As a result, the outputs of the adders 33 to 38 are input to the analog filters 39 to 44 having the filter characteristics shown in FIG. 6, so that the outputs of the adders 33 to 38 are I _A + I _M , I. so that the _a -I _M such harmonic components are removed.

When the harmonic components are removed by the analog filters 39 to 44, the SHs 45 to 50 temporarily hold the outputs of the analog filters 39 to 44, and the MPX 51.
Sequentially output the outputs of the analog filters 39 to 44 from SH45 to
It is read from 50 and output to the A / D converter 52. The A / D converter 52 analog-digital converts the output of the MPX 51 and outputs it to the computer 53.

As a result, the data distribution unit 5 of the computer 53
4 is digital data I _A + I _M + K ₁ , I _A -I _M + K ₂ , I _B + I _M + output from the A / D converter 52.
_{K 3, I B -I M +} K 4, I C + I M + K 5, I C -I M
As shown in FIG. 1, + K ₆ is distributed to the adder 55 and the defect determination calculation section 58, respectively. Here, K _{1 to} K ₆ are analog input circuits (CT2-4, analog filter 39-
44, SH 45 to 50, and MPX 51).

Then, the adder 55, as shown below,
Digital data (I _A + I _M + K ₁ , I _B + I _M + K
₃ , I _C + I _M + K ₅ ) and digital data (I _A -I _M + K ₂ , I _B -I _M + K ₄ , I _C -I _M +) respectively.
K ₆₎ by adding the current relay operation for each phase by removing the monitoring signal _{I M 2I A + K 1 +} K 2, 2I B + K 3 +
Extract K ₄ , 2I _C + K ₅ + K ₆ .

[0033] for the phase A _{2I A + K 1 + K 2} = (I A + I M + K 1) + (I A -I M + K 2) ····· (3) B -phase _{2I B + K 3 + K 4} = ( _{I B + I M + K 3} ) + (I B -I M + K 4) ····· (4) for phase C _{2I C + K 5 + K 6} = (I C + I M + K 5) + (I C -I M ＋ K ₆ ) ・ ・ ・ ・ ・ (5)

Then, when the monitoring signal is removed by the adder 55, the relay trip section 56 causes the current 2I _A + K <sub>1
+ K 2, 2I B + K</sub> 3 + K 4 performs relay operation based, on _{2I C + K 5 + K 6} , to trip the circuit breaker based on the calculation result.

On the other hand, the defect determination calculation unit 58, based on the digital data distributed by the data distribution unit 54 and the set value I _MS corresponding to the monitoring signal I _M , has analog data for each phase and a defect of one circuit. A defect determination value indicating the degree is calculated as shown below.

[0036] A for phase _{(I A + I M + K} 1) - (I A -I M + K 2) -2I MS = K 1 -K 2 ····· (6) B -phase (I _B + I _M + K _{3) - (I B -I M} + K 4) -2I MS = K 3 -K 4 ····· (7) C -phase _{(I C + I M + K} 5) - (I C -I M + K 6) -2I _MS = K ₅ -K ₆ (8)

When the defect determination value is calculated by the defect determination calculation unit 58, the defect determination unit 59 compares the defect determination value with a predetermined alarm value ε, and when the defect determination value is larger than the predetermined alarm value ε. It is determined that the analog input circuit is defective, the result of the determination is displayed on a display device (not shown), and the series of processes is completed.

[0038] * Analog input circuit failure defect determination value | K ₁ -K ₂ | like> alarm value epsilon * analog input circuit normal failure determination value | K ₁ -K ₂ | is equal ≦ alarm value epsilon alarm value epsilon rated current The value is about 20%.

As described above, according to the first embodiment, the monitoring signal I _M is calculated from each phase current on which the monitoring signal I _M is superimposed.
Each phase current on which the inverted −I _{M of M} is superimposed is subtracted to calculate a defect determination value, and the defect determination value and a predetermined alarm value ε.
Since the analog input circuit is judged to be defective by comparing with each other, the defect is judged by the fundamental wave actually used for the relay calculation without being influenced by the fluctuations of the currents I _A , I _B , I _C of the respective phases. As a result, there is an effect that a defect determination can be accurately performed.

Embodiment 2 In the first embodiment, the three-phase current inputs I _A , I _B , and I _C are shown to have six sets of analog filters 39 to 44 and SH45 to 50, but as shown in FIG. ~ 38 output I _A
-I _M, I _B -I _M, the I _C -I _M is obtained by adapted to be commonly input to the analog filter 61 and SH62 through MPX60 performing Setsuri re operate synchronously with MPX63. As a result, the same effects as those of the first embodiment can be obtained, and two sets of analog filters and SH are not required, and the device configuration can be simplified.

Embodiment 3 In the first and second embodiments, the method of superimposing the monitoring signal I _M was used, but in the third embodiment, as shown in FIG. 3, the superimposing means for the monitoring signal I _M is omitted in the second embodiment. It is a thing. The relay calculation unit (trip means) 70 includes analog filters 39, 40,
41 currents I _A + K ₁ , I _B + K ₂ , I _C
+ K ₃ is used.

The defect determination calculation section (defect determination means) 71 performs the following calculation. For the phase A _{(I A + K 1) -} (I A + K 2) = K 1 -K 2 ····· (9) B -phase _{(I B + K 3) -} (I B + K 4) = K 3 - K ₄ ····· (10) C-phase _{(I C + K 5) -} (I C + K 6) = K 5 -K 6 ····· (11)

In the third embodiment, three-phase current input I
When A, IB, and IC are zero, defect detection is impossible, but there is an effect that defect determination can be performed with a simpler configuration than the second embodiment.

Fourth Embodiment In the first embodiment, it is premised that the analog filter or the like has no conversion error and the current of each phase can be accurately detected. Therefore, when the analog filter or the like has conversion error, the absolute value of the current of each phase is The accuracy of the defect determination deteriorates as the size increases.

The failure determination value _{= (I A + I M +} K 1) - (I
When there is no defect in the _{A -I M + K 2) -2I} MS = K 1 -K 2 to the analog input circuit, K _1, K ₂ but should become defective determination value = 0 both at zero, the analog If there is a conversion error in the filter 39, the analog filter 42, etc., the defect determination value = 0 does not hold.

Therefore, in order to compensate the conversion error of the analog filter or the like in the fourth embodiment, instead of the equations (6), (7) and (8) in the first embodiment, as shown below,
Calculate the defect judgment value. For the phase A _{(I A + I M + K} 1) - (I A -I M + K 2) -2I MS -αI A ····· (12) B -phase _{(I B + I M + K} 3) - (I B _{-I M + K 4) -2I MS} -αI B ····· (13) C -phase _{(I C + I M + K} 5) - (I C -I M + K 6) -2I MS -αI C ··· .. (14) where α is a ratio coefficient (eg, 0.05)

Embodiment 5 Although the monitoring signal generator 31 emits the monitoring signal I _M in the first to third embodiments, for example, as shown in FIG. 4, the computer 53 monitors the control signal during inspection. By outputting to the signal generator 31, the monitoring signal I _M may be generated only at the time of inspection for determining a defect in the analog input circuit.

As a result, the adder 55 is used except during inspection.
In, the relay calculation can be performed without performing the addition calculation for deriving the relay calculation current, and the effect of improving the accuracy of the relay calculation is obtained.

[0049]

As described above, according to the first aspect of the invention, the superimposing means superimposes the supervisory signal on the current of each phase from the first output in which the superimposing means superimposes the supervisory signal on the current of each phase. Since the second output that is inverted and superimposed is subtracted, and the absolute value of the subtraction result is compared with a predetermined alarm value to determine the circuit failure, the current fluctuations of the respective phases are not affected,
Further, as a result of the fact that the defect determination can be actually made at the fundamental wave level used for the relay calculation, there is an effect that the circuit defect can be accurately determined.

According to the second aspect of the invention, the first output in which the superimposing means superimposes the monitoring signal on the current of each phase,
The second output, which is obtained by inverting and superposing the monitoring signal on the current of each phase by the superimposing means, is sequentially switched by the switching means and is derived from the analog filter means, and the first output is changed to the output phase of the first output. The output of the corresponding analog filter means is subtracted, and the absolute value of the subtraction result is compared with a predetermined alarm value to determine circuit failure. Without being affected by fluctuations,
Further, as a result of the fact that the defect determination can be actually made at the fundamental wave level used for the relay calculation, there is an effect that the circuit defect can be accurately determined.

According to the third aspect of the invention, the first current output derived from the analog filter means of each phase and the second current output of each phase are sequentially switched by the switching means and derived from the analog filter means. The circuit output is determined by subtracting the output of the analog filter means output corresponding to the output phase of the first output from the first current output and comparing the absolute value of the subtraction result with a predetermined alarm value. Since it is configured as described above, it is possible to make a defect determination at the fundamental wave level used for relay calculation with a simpler configuration than the first and second aspects, and as a result, it is possible to accurately determine a circuit defect.

According to the invention described in claim 4, the maximum current of the currents of the respective phases is multiplied by a predetermined coefficient, and the absolute value of the result of subtracting the multiplication result from the subtraction result and the predetermined alarm value are obtained. Since the circuit failure is determined by comparison, the conversion error proportional to the magnitude of the current can be compensated, and as a result, the circuit is more accurately than the inventions according to claims 1 to 3. There is an effect that a defect can be determined.

According to the fifth aspect of the present invention, the monitoring signal generating means generates the monitoring signal only when inspecting the circuit failure. There is an effect that it is simplified and the accuracy of relay calculation can be improved.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram showing a protective relay device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a protective relay device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a protective relay device according to a fifth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional protective relay device.

FIG. 6 is a characteristic diagram of an analog filter.

FIG. 7 is a frequency characteristic diagram of a digital filter that extracts a fundamental wave.

FIG. 8 is a frequency characteristic diagram of a digital filter that extracts a fourth harmonic.

[Explanation of symbols]

1 3-phase line, 5, 6, 7 input converter (input converting means), 31 monitoring signal generator (monitoring signal generating means), 39 to 44 analog filter (analog filter means), 51 multiplexer (switching means) 5,
5 adder (trip means), 56, 70 relay operation part (trip means), 58, 71 defect determination operation part (defect determination means), 59 defect determination part (defect determination means).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H03M 1/10 H03M 1/10 Z

Claims (5)

[Claims] 1. A three-phase input conversion means for converting a current of each phase of a three-phase line in a power system into a predetermined magnitude, a monitoring signal generating circuit for generating an alternating monitoring signal, and a three-phase input. And a first analog filter means for superimposing the monitoring signal to derive a first output, and a second analog filter means for superimposing a three-phase input and a signal obtained by inverting the monitoring signal to derive a second output.
Analog filter means, trip means for adding the first output and the second output for each phase, and tripping the circuit breaker based on the addition result, and the first output for each phase A protective relay device comprising: a failure determination unit that subtracts the second output and compares the absolute value of the subtraction result with a predetermined alarm value to determine a circuit failure. 2. A three-phase input conversion means for converting a current of each phase of a three-phase line in a power system into a predetermined magnitude, a monitoring signal generating circuit for generating an alternating monitoring signal, and a three-phase input. And a first analog filter means that superimposes the monitoring signal to derive a first output, and a three-phase input and a signal obtained by inverting the monitoring signal are superimposed to sequentially switch and output the second output. Switching means, second analog filter means connected to the output of the switching means, the first output for each phase, and the second analog filter means derived from the second analog filter means in synchronization with the output phase. It is derived from trip means for adding outputs and tripping the circuit breaker based on the addition result, the first output for each phase, and the second analog filter means output in synchronization with the output phase. Subtract the output A protective relay device comprising: a failure determination unit that determines a circuit failure by comparing an absolute value of a calculation result with a predetermined alarm value. 3. A three-phase input conversion means for converting a current of each phase of a three-phase line in a power system into a predetermined magnitude, a first analog filter means for deriving a three-phase input, and the above-mentioned three.
Switching means for sequentially switching and outputting phase inputs, second analog filter means connected to the output of the switching means, the first output for each phase, and the second analog filter in synchronization with this output phase. Trip means for adding outputs derived from the analog filter means and tripping the circuit breaker based on the addition result, the first output for each phase, and the second analog filter in synchronization with the output phase A protective relay device comprising: a failure determination unit that subtracts an output derived from the means, compares the absolute value of the subtraction result with a predetermined alarm value, and determines a circuit failure. 4. The failure determination means determines a circuit failure by multiplying each phase current by a predetermined coefficient and comparing the absolute value of the result obtained by subtracting the multiplication result from the subtraction result with a predetermined alarm value. Any one of claim 1 to claim 3
The protective relay device described in the item. 5. The protective relay device according to claim 1, wherein the monitoring signal generating means generates the monitoring signal only when checking a circuit failure.