JPH04340316A - Digital relay device - Google Patents

Abstract

PURPOSE:To prevent the all-out power stoppage by inputting the state signal of other protective division reciprocally to the digital relay provided in each protective division of a system, and tripping the breaker in other division with its own relay in case that an accident to be protected occurs in other protective division. CONSTITUTION:The system is divided into a plurality of protective divisions (two divisions in the figure), and digital relays 4 and 5 are provided in respective divisions. The power from a power source 1 is supplied to the load outside the figure through breakers 2, 3, CT6, and 7. The digital relays 4 and 5 input the opening and closing signals of contacts Da1 and Da2 and the electric quantity signals i1 and i2 CT6 and 7 corresponding to their own digital relays 4 and 5 to other digital relays, too, during their own inspection. During inspection, the contacts Da1 and Da2 close the path during the inspection of their own digital relays 4 and 5. If an accident occurs in the division while each protective division is inspecting its own division automatically or manually, the relay in other division trips the breaker in its own division. Hereby, all-out power stoppage is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a digital relay device that detects and protects short circuits, ground faults, and other accidents in power systems.

0002

2. Description of the Related Art Conventionally, various relay devices have been used to detect and protect power systems from accidents, and among them, digital relay devices have been widely used because of their reliability. This digital relay device converts the analog electricity amount extracted from the power system into digital data, performs relay judgment calculation based on the digital data,
When a system fault (short circuit fault, ground fault, etc.) is detected, a breaker trip output is sent. Recently, digital relay devices have been used that have an automatic inspection processing function that automatically performs inspections at regular intervals.

FIG. 7 is a block diagram showing a general example of a case where this type of digital relay device is applied to a power system. In FIG. 7, power is supplied from a power source 1 to a load (not shown) via circuit breakers (CB) 2 and 3. Furthermore, digital relays 4 and 5 are installed in each assigned protection section of the power system. These digital relays 4 and 5 convert the electric currents i1 and i2 extracted from the power system by the instrument current transformers 6 and 7 into digital data, perform relay judgment calculations based on the digital data, and perform relay judgment calculations based on the digital data. When an accident occurring in the protected area is detected, a breaker trip output is sent. Furthermore, these digital relays 4 and 5 have an inspection processing function that automatically checks the relay calculation processing function at regular intervals. Next, FIG. 8 is a block diagram showing an example of the configuration of each digital relay 4, 5 in FIG. 7, and FIG. 9 is a flow diagram showing its operation.

In FIG. 8, analog/digital (A/
D) The converter 8 converts the analog amounts of the currents i1 and i2 extracted by the instrument current transformers 6 and 7 into digital data, and inputs this to the arithmetic unit 9. The arithmetic unit 9 uses data input from the analog/digital converter 8 and an accident detection operating value (hereinafter simply referred to as an operating value) in advance.
If the input data is larger than the setting value data, as shown in Figure 9, if the inspection process is not in progress, trip processing is executed immediately, and if the inspection process is in progress, the trip process is executed immediately. If so, trip processing is executed after the automatic inspection is completed, and a breaker trip output is sent out via auxiliary relay A for trip output. Note that the inspection process is locked until the breaker trip output is completed if the trip process has already been executed before starting the inspection.

On the other hand, the inspection process is carried out using digital relays 4 and 5.
Automatic inspection of the breaker trip output function, which is the most important, is carried out to facilitate maintenance and inspection of the circuit breaker at regular intervals (for example, once a day) by the inspection start timer 10. This inspection process is as shown in Figure 9.
After confirming that the input data input from the power system is smaller than the set value data (no accident is being detected), the inspection start is started by the operation signal from the check start timer 10.

That is, first, the trip lock signal output from the breaker is used to send the trip lock output to the outside via the trip lock output auxiliary relay B, and then the answer back signal of this trip lock signal is used as the trip lock output. After being confirmed via auxiliary relay C for answerback, the breaker trip output during inspection is sent to the outside via auxiliary relay A, and the answerback signal is confirmed, and after confirming this, auxiliary relay Reset A, and after a certain time delay, reset the output of auxiliary relay B to complete the inspection.

Note that the trip processing function is locked while the above-mentioned inspection processing is being executed. Further, the above-mentioned time delay of a certain period of time is provided to prevent mistrips due to overlap between the sending timing of the breaker trip output and the sending timing of the trip lock reset output.

On the other hand, FIG. 10 is a block diagram showing another configuration example of each digital relay 4, 5 in FIG. 7, and FIG.
is a flow diagram showing its operation. Note that in FIG. 10, the same elements as those in FIG. 8 are denoted by the same reference numerals.

In FIG. 10, analog/digital (A
/D) The converter 8 converts the analog amounts of the currents i1 and i2 extracted by the instrument current transformers 6 and 7 into digital data, and inputs this to the arithmetic unit 9. In the computing device 9,
Data input from the analog/digital converter 8,
It is compared with the setting value data set in advance as the operating value, and if the input data is larger than the setting value data, trip processing is executed immediately, provided that there is no defective inspection as shown in Fig. 11. If the inspection process is in progress, the trip process is executed after the automatic inspection is completed, and the breaker trip output is sent out via the auxiliary relay A for trip output. Note that the inspection process is locked until the breaker trip output is completed if the trip process has already been executed before starting the inspection.

On the other hand, the inspection process is carried out using the digital relays 4 and 5.
Automatic inspection of the breaker trip output function, which is the most important, is carried out to facilitate maintenance and inspection of the circuit breaker at regular intervals (for example, once a day) by the inspection start timer 10. As shown in Figure 11, this inspection process is performed when the input data input from the power system is smaller than the set value data (no fault detected) if the inspection was defective in the previous inspection, that is, the digital relay is not defective. is confirmed, and the inspection start is started by the operation signal from the inspection start timer 10.

That is, first, the trip lock signal output from the breaker is used to send the trip lock output to the outside via the trip lock output auxiliary relay B, and then the answer back signal of this trip lock signal is used as the trip lock output. After being confirmed via auxiliary relay C for answerback, the breaker trip output during inspection is sent to the outside via auxiliary relay A, and the answerback signal is confirmed, and after confirming this, auxiliary relay Reset A, and after a certain time delay, reset the output of auxiliary relay B to complete the inspection.

Note that the trip processing function is locked while the above-mentioned inspection processing is being executed. Further, the above-mentioned time delay of a certain period of time is provided to prevent mistrips due to overlap between the sending timing of the breaker trip output and the sending timing of the trip lock reset output. Furthermore, if a defect occurred in the above inspection process during the previous inspection, all processes will be locked to prevent inspection defects (defective digital relays).
This prevents malfunctions (erroneous outputs) or malfunctions due to

As described above, each digital relay 4, 5 has two functions: a trip process when an accident is detected and an inspection process by the inspection start timer 10, and each is executed as necessary. However, such a digital relay device has the following problems.

[0014] First, in the former digital relay device, the trip processing function is locked while the inspection process is being executed. Even if this is detected by the digital relay 5, the trip process will not be executed unless the automatic inspection process is completed.

Furthermore, in the latter digital relay device, when an inspection failure occurs due to automatic inspection, all processing functions are locked. If F occurs,
Even if this is detected by the digital relay 5, the trip process will not be executed unless the automatic inspection process is completed.

[0016] For this reason, the protection cut-off by the digital relay 5 in response to an accident F in the power system is delayed, and in the worst case, the digital relay 4 installed in a healthy upper protection section operates first, resulting in poor protection coordination. This would cause the power system to completely shut down.

[0017]

[Problems to be Solved by the Invention] As described above, in the conventional digital relay device, if an accident occurs in the power system during automatic inspection of the digital relay or during an inspection failure, the accident can be detected instantly. There was a problem in that the power system could not be protected and the power system would be completely shut down.

[0018] An object of the present invention is to be able to instantly detect the accident and reliably protect the system even if an accident occurs in the power system during automatic inspection of the digital relay or during defective inspection. It is an object of the present invention to provide an extremely reliable digital relay device that can ensure protection coordination between power systems and prevent a power system from reaching a total stoppage state.

[0019]

[Means for solving the problem] In order to achieve the above objective, the analog electricity quantity extracted from the power system is converted into digital data, and based on the digital data, a relay judgment calculation is performed to detect a system fault. At least two or more digital relays, each consisting of a relay calculation processing means that sends out a breaker trip output and an inspection processing means that automatically inspects the relay calculation processing means at regular intervals, are installed in the power system and assigned to each one. In a digital relay device that detects accidents in protected areas,

002
[0] First, in the invention described in claim 1, analog electrical quantities extracted from other protection sections are respectively input to each digital relay, and a number of accident detection operation values corresponding to the number of input electrical quantities are input to each digital relay. Furthermore, each digital relay is provided with an inspection signal output means for outputting an inspection signal to other digital relays during automatic inspection of its own digital relay, and an inspection signal output means for outputting an inspection signal from other digital relays. an inspection determination means that determines whether the digital relay is under inspection based on the input electricity amount and a comparison result between the input electric quantity and the corresponding accident detection operation value, and determines the protection zone in which the accident occurred. , and based on the determination result and the determination result by the inspection determination means, if an accident is detected in the protection zone of the digital relay during inspection by another digital relay, the assignment is made to the digital relay. and line discrimination processing means for transmitting the breaker trip output of the protected area determined by the protection interval.

Furthermore, in the invention described in claim 1, the analog electrical quantities extracted from other protection sections are respectively input to each digital relay, and the number of accident detection operation values corresponding to the number of input electrical quantities is inputted to each digital relay. In addition, each digital relay is provided with an inspection failure signal output means for outputting an inspection failure signal to other digital relays when an inspection failure occurs due to automatic inspection of its own digital relay, and an inspection failure signal output means for outputting an inspection failure signal to other digital relays when an inspection failure occurs due to automatic inspection of its own digital relay. A defective inspection determination means inputs a defective inspection signal and determines whether the digital relay has a defective inspection, and a comparison result between the input electrical quantity and the corresponding accident detection operation value indicates that an accident has occurred. When the protection zone is determined and, based on the determination result and the determination result by the defective inspection determination means, an accident is detected in the protection zone to be protected by the digital relay while another digital relay has a defective inspection. and line discrimination processing means for transmitting the breaker trip output of the protection section assigned to the digital relay.

[0022]

[Operation] Therefore, in the digital relay device of the invention as claimed in claim 1, the digital relay installed in each protection section of the power system receives the analog electrical quantity extracted from all the protection sections and other digital Inspection signals from the relays are respectively input, and it is determined whether an accident has occurred in any of the protection zones and whether or not any other digital relay is being inspected. If an accident is detected in the protection zone of the digital relay that is to be protected during inspection by another digital relay, the protection zone allocated to the digital relay being inspected will be A breaker trip output is sent out.

Furthermore, in the digital relay device of the invention according to claim 2, the digital relay installed in each protection section of the power system receives the analog electrical quantity extracted from all the protection sections and other digital Inspection failure signals from the relays are respectively input, and it is determined whether an accident has occurred in any of the protected sections and whether or not any other digital relay has inspection failure. If an accident is detected in the protection zone of the digital relay that should be protected while another digital relay has a defective inspection, the protection assigned to the digital relay that has the defective inspection will be transferred from the own digital relay. The section breaker trip output is sent out.

[0024] As a result, even if an accident occurs in the protection area during the automatic inspection of another digital relay installed in another protection area or during a defective inspection, the digital relay installed in the own protection area will not be affected. Accidents can be detected instantaneously and system protection can be reliably performed, thereby preventing the power system from reaching a total shutdown state.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an example of the overall configuration when the digital relay device according to the present invention is applied to an electric power system, and the same parts as in FIG. Now, I will only discuss the different parts.

That is, the digital relay device of this embodiment receives the contact signals of the contacts Da1 and Da2 during inspection of its own digital relays 4 and 5 in FIG. The electric currents i1 and i2 from the devices 6 and 7 are transferred to other digital relays 5 and 7.
4. Here, the contacts Da1 and Da2 during inspection are the own digital relays 4 and 5.
Each circuit is closed when the is under automatic inspection.

FIG. 2 shows each digital relay 4 in FIG.
. In addition, in FIG. 2, only a configuration example of the digital relay 4 is shown as a representative.

That is, this digital relay 4 is configured to have a number of accident detection operation values corresponding to the number of input electric currents (in this case, 2) as setting value data, and is further provided with auxiliary relays D, E, and F. In addition, a line discrimination processing function is added to the arithmetic unit 9 in FIG. 8.

[0030] Here, the auxiliary relay D, which is the inspection determination means,
is provided corresponding to other digital relays 5, and operates when the contact signal of the contact Da2 is detected during the inspection,
The operation signal is input to the line discrimination processing function of the arithmetic unit 9. The auxiliary relay E, which is an inspection signal output means, outputs an inspection signal to other digital relays 5 when automatically inspecting its own digital relay 4. Further, the auxiliary relay F is provided corresponding to the other digital relay 5, and outputs a breaker trip output to the corresponding external breaker 3 based on the line discrimination processing result of the arithmetic unit 9.

On the other hand, the line discrimination processing function of the arithmetic unit 9 is as follows:
Based on the comparison result between the input electric current quantities i1 and i2 and the corresponding accident detection operation value, the protection zone in which the accident occurred is determined, and based on the determination result and the operation signal from the auxiliary relay D, If an accident is detected in the protection zone of the digital relay 5 during inspection by another digital relay 5, the circuit breaker trip output for the protection zone assigned to the digital relay 5 is sent. be. Next, the operation of the digital relay device configured as described above will be explained using the flow diagram shown in FIG. 3.

In FIG. 1, analog amounts of currents i1 and i2 extracted by meter current transformers 6 and 7 are input to each digital relay 4. Then, each analog quantity is converted into digital data by an analog/digital converter 8, and each digital data is input to an arithmetic unit 9. Then, in the arithmetic unit 9, each digital data from the analog/digital converter 8 and the corresponding accident detection operation value are compared, and the comparison result is input to the line discrimination processing function. Further, an operation signal from the auxiliary relay D is also input to this line discrimination processing function. and,
In the line discrimination processing function, input current electricity amount i1,
Based on the comparison result between i2 and the corresponding accident detection operation value, the protection section in which the accident occurred is determined. As a result, if it is detected that an accident has occurred in the protection zone of another digital relay 5, the presence or absence of an operation signal from the auxiliary relay D is determined, and the auxiliary relay D
If there is an operation signal from the other digital relay 5,
The breaker trip output of the protection zone assigned to
It is sent to the breaker 3 of the other line.

[0033] In the above, if it is detected that an accident has occurred in the protection zone that should be protected by the own digital relay 4, the circuit breaker 2 of the own line is tripped as in the conventional case described above. The determination of trip processing is performed with priority, and the trip processing of the circuit breaker 2 of the own line is performed.

Therefore, for example, if a short circuit occurs at point F in the power system shown in FIG.
Even during automatic inspection, fault line discrimination is performed by its own digital relay 4, and trip processing to the circuit breaker 3 is executed. Note that the functions other than those described above are the same as those in the conventional case described above, so the explanation thereof will be omitted here.

As described above, the digital relay device of this embodiment inputs the analog current and electricity extracted from other protection sections to each of the digital relays 4 and 5 installed in each protection section of the power system. At the same time, the number of fault detection operation values corresponding to the number of input electric currents is set, and each digital relay 4, 5 transmits an inspection signal to another when automatically inspecting its own digital relay 4 or 5. The auxiliary relay E, which is an inspection signal output means for outputting the inspection signal to the digital relay, and the inspection signals from the other digital relays 5 and 4 are input to determine whether or not the digital relays 5 and 4 are being inspected. The auxiliary relay D, which is an inspection determination means for determining, determines the protection zone in which the accident occurred based on the comparison result between the input electric current amount and the corresponding accident detection operation value, and the auxiliary relay Based on the judgment result of It is equipped with a line discrimination processing function that sends the breaker trip output of the assigned protection zone.

Therefore, if an accident is detected in the protection area during inspection of the digital relay 5 or 4 that protects another protection area, the digital relay 5 or 4 under inspection
or 4, and the own digital relay 4 or 5 determines that the accident is in another protection zone, and the trip output of the circuit breaker 3 or 2 of the protection zone is sent from the own digital relay 4 or 5. be done. As a result, even if an accident occurs in the power system during automatic inspection of other digital relays 5 or 4, the accident can be instantly detected by the own digital relay 4 or 5 and the system can be reliably protected. Therefore, it is possible to prevent the electric power system from reaching a total shutdown state. Next, other embodiments of the present invention will be described.

FIG. 4 is a diagram showing an example of the overall configuration when the digital relay device according to the present invention is applied to a power system, and the same parts as in FIG. Now, I will only discuss the different parts.

In other words, the digital relay device of this embodiment receives the contact signals of the defective inspection contacts Da3 and Da4 of its own digital relays 4 and 5 in FIG. The electric currents i1 and i2 from the devices 6 and 7 are transferred to the other digital relay 5.
, 4. Here, the defective inspection contacts Da3 and Da4 are the own digital relay 4.
, 5 are each closed when the inspection is defective.

FIG. 5 shows each digital relay 4 in FIG.
. Note that FIG. 5 shows only a representative example of the configuration of the digital relay 4.

That is, the present digital relay 4 is configured to have a number of accident detection operation values corresponding to the number of input electric currents (here, 2) as setting value data, and is further provided with auxiliary relays D, E, and F. In addition, a line discrimination processing function is added to the arithmetic unit 9 in FIG. 8.

[0041] Here, the auxiliary relay G, which is inspection defect determination means, is provided corresponding to the other digital relays 5.
It operates when a contact signal of the defective inspection contact Da4 is detected, and inputs the operating signal to the line discrimination processing function of the arithmetic unit 9. Further, the auxiliary relay H, which is a defective inspection signal output means, outputs a defective inspection signal to other digital relays 5 when its own digital relay 4 has a defective inspection due to automatic inspection. Further, the auxiliary relay I is provided corresponding to the other digital relay 5, and outputs a breaker trip output to the corresponding external breaker 3 based on the line discrimination processing result of the arithmetic unit 9.

On the other hand, the line discrimination processing function of the arithmetic unit 9 is as follows:
Based on the comparison result between the input electric current quantities i1 and i2 and the corresponding accident detection operation value, the protection zone in which the accident occurred is determined, and based on the determination result and the operation signal from the auxiliary relay G, When an accident is detected in the protection zone of the digital relay 5 while another digital relay 5 has a defective inspection, it sends out the breaker trip output of the protection zone assigned to the digital relay 5. It is. Next, the operation of the digital relay device configured as above will be explained using the flow diagram shown in FIG. 6.

In FIG. 4, analog amounts of currents i1 and i2 extracted by meter current transformers 6 and 7 are input to each digital relay 4. Then, each analog quantity is converted into digital data by an analog/digital converter 8, and each digital data is input to an arithmetic unit 9. Then, in the arithmetic unit 9, each digital data from the analog/digital converter 8 and the corresponding accident detection operation value are compared, and the comparison result is input to the line discrimination processing function. Further, an operation signal from the auxiliary relay G is also input to this line discrimination processing function. and,
In the line discrimination processing function, input current electricity amount i1,
Based on the comparison result between i2 and the corresponding accident detection operation value, the protection section in which the accident occurred is determined. As a result, if it is detected that an accident has occurred in the protection zone of another digital relay 5, the presence or absence of an operation signal from the auxiliary relay G is determined, and the auxiliary relay G
If there is an operation signal from the other digital relay 5,
The breaker trip output of the protection zone assigned to
It is sent to the breaker 3 of the other line.

[0044] In addition, in the above, when it is detected that an accident has occurred in the protection zone that should be protected by the own digital relay 4, the circuit breaker 2 of the own line is tripped as in the conventional case described above. The determination of trip processing is performed with priority, and the trip processing of the circuit breaker 2 of the own line is performed.

Therefore, for example, if a short circuit occurs at point F in the power system shown in FIG.
Even if the faulty circuit is under inspection, its own digital relay 4 determines the faulty line, and the circuit breaker 3 is tripped. Note that the functions other than those described above are the same as those in the conventional case described above, so the explanation thereof will be omitted here.

As described above, the digital relay device of this embodiment inputs the analog current and electricity extracted from other protection sections to each digital relay 4 and 5 installed in each protection section of the power system. At the same time, each digital relay 4, 5 is provided with a number of fault detection operation values corresponding to the number of input electric currents, and furthermore, each digital relay 4, 5 is configured to detect a faulty inspection when the self-inspected digital relay 4 or 5 has a faulty automatic inspection. The auxiliary relay H is a defective inspection signal output means that outputs a signal to other digital relays, and the defective inspection signals from the other digital relays 5 and 4 are input, indicating that the digital relays 5 and 4 are defective in inspection. The auxiliary relay G, which is an inspection defect determination means for determining whether or not an accident has occurred, determines the protection zone in which the accident occurred based on the comparison result between the input electric current amount and the corresponding accident detection operation value, and Based on the result and the determination result by the auxiliary relay G, the digital relay 5,
It also has a line discrimination processing function that sends out a breaker trip output for the protection area assigned to the digital relays 5 and 4 when an accident occurrence in the protection area to be protected is detected.

[0047] Therefore, if an accident is detected in the protection area during a defective inspection of the digital relay 5 or 4 that protects another protection area, the relay assigned to the digital relay 5 or 4 that is being inspected is It is determined by the own digital relay 4 or 5 that the accident is in another protection zone, and the trip output of the circuit breaker 3 or 2 in the protection zone is sent from the own digital relay 4 or 5. As a result, even if an accident occurs in the power system while another digital relay 5 or 4 is defective during automatic inspection, the own digital relay 4 or 5 can instantly detect the accident and ensure system protection. Therefore, it becomes possible to prevent the electric power system from reaching a total shutdown state.

[0048] In each of the above embodiments, the case where two digital relays are installed in the protection zone is explained as an example, but the present invention is not limited to this, and the case where there are three or more digital relays installed in the protection zone is not limited to this. The present invention can be similarly applied to the case of a stand.

Furthermore, in the embodiments shown in FIGS. 4 to 6,
Although a case has been described in which a faulty digital relay is determined based on a faulty inspection of the trip output section, the present invention is similarly applicable to other cases as well.

[0050]

[Effects of the Invention] As explained above, according to the present invention, even if an accident occurs in the power system during automatic inspection of digital relays or during defective inspection, the accident can be detected instantly and the system can be protected reliably. It is possible to provide an extremely reliable digital relay device that can ensure protection coordination between digital relays and prevent the power system from reaching a total shutdown state.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment in which a digital relay device according to the present invention is applied to a power system.

FIG. 2 is a block diagram showing a configuration example of a digital relay in the same embodiment.

FIG. 3 is a flow diagram for explaining the operation in the same embodiment.

FIG. 4 is a configuration diagram showing another embodiment in which the digital relay device according to the present invention is applied to a power system.

FIG. 5 is a block diagram showing a configuration example of a digital relay in another embodiment.

FIG. 6 is a flowchart for explaining the operation in another embodiment.

FIG. 7 is a configuration diagram showing a general example when a conventional digital relay device is applied to a power system.

FIG. 8 is a block diagram showing a configuration example of the digital relay in FIG. 7.

FIG. 9 is a flow diagram for explaining the operation in FIG. 7;

FIG. 10 is a block diagram showing another configuration example of the digital relay in FIG. 7.

FIG. 11 is a flow diagram for explaining the operation in FIG. 10.

[Explanation of symbols]

1... Power supply, 2, 3... Breaker, 4, 5... Digital relay, 6, 7... Instrument current transformer, 8... Analog/digital (A
/D) Converter, 9... Arithmetic device, 10... Inspection start timer,
11...Display device, A, B, C, D, E, F, G, H, I...
Auxiliary relay, Da1, Da2...Contact under inspection, Da3
, Da4...Inspection defective contact.

Claims (2)

[Claims] 1. Relay calculation processing means that converts an analog quantity of electricity extracted from a power system into digital data, performs relay judgment calculation based on the digital data, and sends out a breaker trip output when a system fault is detected;
At least two digital relays each comprising an inspection processing means for automatically inspecting the relay calculation processing means at regular intervals are installed in the electric power system to detect accidents in respective assigned protection zones. In the device, inputting analog electric quantities extracted from other protection zones to each of the digital relays, and
During inspection, each digital relay is provided with a number of accident detection operation values corresponding to the number of input electrical quantities, and outputs an inspection signal to other digital relays during automatic inspection of its own digital relay. a signal output means, an inspection determination means for inputting an inspection in progress signal from the other digital relay and determining whether or not the digital relay is being inspected, and the input electric quantity and an accident detection operation corresponding thereto. The protection zone in which the accident occurred is determined based on the comparison result with the value, and based on the determination result and the determination result by the inspection determination means, it is determined that the digital relay should be protected during inspection by another digital relay. A digital relay device comprising: line discrimination processing means for transmitting a breaker trip output of a protection zone assigned to the digital relay when an accident occurrence in the protection zone is detected. 2. Relay calculation processing means that converts an analog quantity of electricity extracted from a power system into digital data, performs a relay judgment calculation based on the digital data, and sends out a breaker trip output when a system fault is detected;
At least two digital relays each comprising an inspection processing means for automatically inspecting the relay calculation processing means at regular intervals are installed in the electric power system to detect accidents in respective assigned protection zones. In the device, inputting analog electric quantities extracted from other protection zones to each of the digital relays, and
A number of fault detection operation values are provided corresponding to the number of input electrical quantities, and each digital relay outputs an inspection failure signal to other digital relays when an inspection failure occurs due to automatic inspection of its own digital relay. a defective inspection signal output means for inputting a defective inspection signal from the other digital relay, and a defective inspection determining means for determining whether or not the digital relay has a defective inspection; The protection zone in which the accident occurred is determined based on the comparison result with the accident detection operation value, and based on the determination result and the determination result by the inspection defect determination means, the protection zone in which the accident occurred is determined based on the comparison result with the accident detection operation value that was detected. A line discrimination processing means for transmitting a breaker trip output for the protection area assigned to the digital relay when an accident occurrence in the protection area to be protected by the digital relay is detected. Digital relay device.