JP7606325B2 - Protection Relay System - Google Patents

Description

The present invention relates to a protective relay system.

In recent years, there has been rapid progress in the study of digitalizing substation equipment, with the aim of streamlining substations, reducing facility construction costs, and cutting labor costs. For example, there is a study being conducted on the realization of digital transmission by replacing the conventional metal wires for analog transmission in the control cables that connect field equipment such as GIS (gas insulated switchgear) to protective relay devices in the control panel room in substations with optical cables.

When transitioning from analog to digital transmission systems as described above, it becomes necessary to configure the protective relay device with separate hardware, depending on its function, into an input device for acquiring information from field devices, and a protective calculation device for executing calculation processing to determine the operation of the protective relay device. This results in a problem that the hardware scale of the protective relay device increases compared to conventional systems, increasing the failure rate of the entire protective relay system including the protective relay device.

Redundancy of protective relay devices is effective in achieving a highly reliable protective relay system with a low failure rate. For example, Patent Document 1 discloses a protective relay system in which the main relay calculation unit and the fail-safe calculation unit are provided in the main and slave protective relays, respectively, and the logical sum of the logical product of the opening command output from the main relay calculation unit of the main system and the opening command output from the fail-safe relay calculation unit of the slave system, and the logical sum of the logical product of the opening command output from the fail-safe relay calculation unit of the main system and the opening command output from the main relay calculation unit of the slave system, is generated as an opening command to a circuit breaker that cuts off the power system.

JP 2013-66267 A

In the protective relay system of Patent Document 1, a trip relay that operates in response to an opening command from the main relay calculation unit and an opening command from the fail-safe relay calculation unit is required for each of the master and slave systems. In addition to this, relays for switching connections between trip relays and relays for trip locking are required to prevent accidental tripping of the circuit breaker due to erroneous output of an opening command. This requires the installation of a large number of relays, which increases the cost of the entire system and poses the problem of reduced reliability of the entire system due to an increased rate of malfunctions.

A protective relay system according to the present invention controls a circuit breaker that breaks a line of a power system to protect the line, and includes first and second input devices that acquire analog information related to a state of the line and convert the acquired analog information into digital information, first and second protective and arithmetic devices that perform predetermined relay calculation processing for protecting the line based on the digital information and output a first shutdown command and a second shutdown command to the circuit breaker, respectively, a network relay device that relays the digital information and the first shutdown command input/output between the first input device and the first protective and arithmetic device, and the digital information and the second shutdown command input/output between the second input device and the second protective and arithmetic device, and a trip circuit that receives the first shutdown command and the second shutdown command and outputs a shutdown signal to cause the circuit breaker to break the line, and the first input device outputs the first shutdown command transmitted from the first protective and arithmetic device via the network relay device to the trip circuit , and also relays the first protective and arithmetic device. the second input device outputs the second shutdown command transmitted from the second protection and calculation device via the network relay device to the trip circuit, and outputs a second bypass switching signal to the trip circuit when it detects an abnormality in a second system including the second protection and calculation device and the second input device; the second input device outputs the second shutdown command transmitted from the second protection and calculation device via the network relay device to the trip circuit, and outputs a second bypass switching signal to the trip circuit when it detects an abnormality in a second system including the second protection and calculation device and the second input device; the trip circuit has a series circuit in which a first contact and a second contact are connected in series, a first bypass circuit formed in response to the first bypass switching signal and bypassing the first contact, and a second bypass circuit formed in response to the second bypass switching signal and bypassing the second contact, and outputs the shutdown signal to the circuit breaker by turning on the first shutdown command or forming the first bypass circuit in response to the first bypass switching signal, and turning on the second shutdown command or forming the second bypass circuit in response to the second bypass switching signal .

The present invention makes it possible to provide a highly reliable protective relay system while minimizing increases in costs.

1 is an example of a schematic configuration diagram of a protection relay system according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a trip circuit; FIG. 4 is a diagram illustrating an example of a functional configuration of a relay calculation unit.

Figure 1 is an example of a schematic configuration diagram of a protective relay system according to one embodiment of the present invention. The protective relay system 100 shown in Figure 1 obtains various information on the state of a line 1 of a power system from a field operation panel 2 via control cables 31, 32, and 33, and protects the line 1 from abnormal voltages and abnormal currents by controlling circuit breakers 21 and 22 provided on the field operation panel 2 based on this information. The protective relay system 100 is configured with protective calculation devices 5a and 5b, input devices 6a and 6b, network relay devices 120 and 121, and a trip circuit 200.

In the on-site operation panel 2, the circuit 1 of the power system is connected to a pair of busbars (busbar A and busbar B) via a relay. The circuit breakers 21 and 22 each operate in response to a disconnection signal output from the protective relay system 100, and electrically disconnect the circuit 1 from these busbars. The circuit breakers 21 and 22 are connected in series, so that even if one of them does not operate due to a fault or the like, the other will operate to protect the circuit 1.

The on-site operation panel 2 detects the voltage of the line 1 and transmits the obtained voltage information to the input devices 6a and 6b via the control cable 31. It also detects the current of the line 1 and transmits the obtained current information to the input devices 6a and 6b via the control cable 32. It also transmits circuit breaker information (30S information) indicating the ON/OFF state of the circuit breakers 21 and 22, and fault information (30F information) indicating the fault state of the circuit breakers 21 and 22 and the on-site operation panel 2 itself to the input devices 6a and 6b via the control cable 33. All of this information is analog information, and is transmitted to the input devices 6a and 6b via the control cables 31 to 33, which are analog transmission paths.

The protection calculation device 5a and the input device 6a cooperate to perform calculation processing related to the control of the circuit breakers 21 and 22, and constitute the first series 500a, which is one of the two processing series of the protection relay system 100. Similarly, the protection calculation device 5b and the input device 6b cooperate to perform calculation processing related to the control of the circuit breakers 21 and 22, and constitute the second series 500b, which is the other of the two processing series of the protection relay system 100. In other words, the protection relay system 100 ensures redundancy in the calculation processing by having two processing series, the first series 500a and the second series 500b.

The protection and calculation device 5a and the input device 6a are connected to each other via network relay devices 120 and 121. Similarly, the protection and calculation device 5b and the input device 6b are connected to each other via network relay devices 120 and 121. These connections via the network relay devices 120 and 121 are made using digital transmission paths such as optical cables.

The input devices 6a and 6b each have an input calculation unit 60a and 60b, which are used to convert the analog information acquired from the field operation panel 2 via the control cables 31 to 33, i.e., the aforementioned voltage information, current information, circuit breaker information, and fault information, into digital information. Each piece of information converted from analog to digital by the input device 6a is transmitted from the input device 6a to the protection calculation device 5a via the network relay device 120 or 121. Similarly, each piece of information converted from analog to digital by the input device 6b is transmitted from the input device 6b to the protection calculation device 5b via the network relay device 120 or 121.

The protection calculation devices 5a and 5b each have a relay calculation unit 50a and 50b, which perform a predetermined relay calculation process based on each digital information transmitted from the input devices 6a and 6b. The relay calculation process performed by the relay calculation units 50a and 50b is a process for determining whether each digital information satisfies a predetermined interruption condition, and if it is determined that the interruption condition is met, for controlling the circuit breakers 21 and 22 to protect the circuit breaker 1 by opening the circuit breakers 21 and 22 and disconnecting the circuit breaker 1 from the busbar.

The protection and calculation devices 5a and 5b output tripping commands to the circuit breakers 21 and 22, respectively, based on the processing results of the relay calculation units 50a and 50b. The tripping command 7a output by the protection and calculation device 5a is transmitted to the input device 6a via the network relay device 120 or 121. Similarly, the tripping command 7b output by the protection and calculation device 5b is transmitted to the input device 6b via the network relay device 120 or 121.

The input device 6a outputs the trip command 7a output from the protection and calculation device 5a via the network relay device 120 or 121 to the trip circuit 200. In addition, if an abnormality or failure occurs in the first series 500a, the input device 6a detects this and outputs a bypass switching command 8a to the trip circuit 200. The input device 6a has a function that can detect operational abnormalities in the protection and calculation device 5a and the input device 6a itself, and can output the bypass switching command 8a using this function. Note that this function of the input device 6a can be realized using any well-known technology, and detailed explanations thereof will be omitted.

The input device 6b outputs the trip command 7b output from the protection and calculation device 5b via the network relay device 120 or 121 to the trip circuit 200. In addition, if an abnormality or failure occurs in the second series 500b, the input device 6b detects this and outputs a bypass switching command 8b to the trip circuit 200. Like the input device 6a, the input device 6b also has a function that can detect operational abnormalities in the protection and calculation device 5b and the input device 6b itself, and can output the bypass switching command 8b using this function.

The network relay devices 120 and 121 relay the digital information and shutoff command 7a input/output between the input device 6a and the protection and calculation device 5a, and the digital information and shutoff command 7b input/output between the input device 6b and the protection and calculation device 5b. Here, the network relay devices 120 and 121 can respectively relay the digital information and shutoff commands 7a and 7b between the input devices 6a and 6b and the protection and calculation devices 5a and 5b via different transmission paths. Therefore, in the protection relay system 100, the digital information and shutoff commands 7a and 7b can be relayed using either the network relay device 120 or 121. In other words, the protection relay system 100 has the network relay devices 120 and 121 that realize a common relay function via different transmission paths, thereby ensuring redundancy of the digital transmission path.

The trip circuit 200 receives the interruption commands 7a, 7b and bypass switching commands 8a, 8b output from the input devices 6a, 6b, respectively. Based on these input commands, the trip circuit 200 generates an interruption signal for causing the circuit breakers 21, 22 to interrupt the line 1, and outputs the signal to the field operation panel 2. The details of the trip circuit 200 will be described later.

When a trip signal is output from the trip circuit 200, the local operation panel 2 switches the circuit breakers 21 and 22 from ON to OFF to cut off the line 1. This protects the line 1.

Next, details of the trip circuit 200 will be described using FIG. 2. FIG. 2 is an example of a schematic configuration diagram of the trip circuit 200.

The trip circuit 200 has a series circuit in which contacts 210 and 211 are connected in series, contacts 220 and 230 are connected in parallel to contact 210 and connected in series to each other, and contacts 221 and 231 are connected in parallel to contact 211 and connected in series to each other. These contacts can be realized, for example, using a logic IC or a PLD (Programmable Logic Device).

The contact 210 is turned on in response to a shutoff command 7a output from the input device 6a of the first series 500a. The contact 211 is turned on in response to a shutoff command 7b output from the input device 6b of the second series 500b. One end of the series circuit of the contacts 210 and 211 is connected to a power source that outputs a predetermined voltage. As a result, when the first series 500a and the second series 500b are both normal, they output the shutoff command 7a and the shutoff command 7b, respectively, and a shutoff signal of a predetermined voltage is output from the trip circuit 200 to the circuit breakers 21 and 22 as the logical product (AND) of these shutoff commands.

The contacts 220 and 231 are each controlled by the input device 6a of the first series 500a, and the contacts 221 and 230 are each controlled by the input device 6b of the second series 500b. The contact 220 is turned ON in response to a bypass switching command 8a output from the input device 6a, and the contact 231 is turned OFF in response to a bypass switching command 8a output from the input device 6a. The contact 221 is turned ON in response to a bypass switching command 8b output from the input device 6b, and the contact 230 is turned OFF in response to a bypass switching command 8b output from the input device 6b.

When the first series 500a is abnormal, the bypass switching command 8a is output, and the contact 220 is turned ON. At this time, if the second series 500b is normal, the bypass switching command 8b is not output. As a result, the contacts 220 and 230 connected in parallel to the contact 210 are both turned ON, and a bypass circuit for the contact 210 is formed. On the other hand, the contacts 221 and 231 connected in parallel to the contact 211 are both OFF, and therefore the bypass circuit for the contact 211 is not formed. As a result, the tripping command 7a from the first series 500a in which an abnormality has occurred is excluded from the output conditions for the tripping signal, and only the tripping command 7b from the normal second series 500b is used to output the tripping signal from the tripping circuit 200 to the circuit breakers 21 and 22. Therefore, even when an abnormality occurs in the first series 500a, the line 1 can be appropriately protected.

When an abnormality occurs in the first series 500a, the contact 231 acts as a locking mechanism that locks the bypass circuit of the contact 211 corresponding to the normal second series 500b in response to the output of the bypass switching command 8a. This makes it possible to prevent the bypass circuit of the contact 211 from being formed even if the contact 221 is mistakenly turned ON.

In addition, when the second series 500b is abnormal, the bypass switching command 8b is output, and the contact 221 is turned ON. At this time, if the first series 500a is normal, the bypass switching command 8a is not output. As a result, the contacts 221 and 231 connected in parallel to the contact 211 are both turned ON, and a bypass circuit for the contact 211 is formed. On the other hand, the contacts 220 and 230 connected in parallel to the contact 210 are both OFF, and therefore the bypass circuit for the contact 210 is not formed. As a result, the cutoff command 7b by the second series 500b in which an abnormality has occurred is excluded from the output conditions for the cutoff signal, and the cutoff signal can be output from the trip circuit 200 to the circuit breakers 21 and 22 using only the cutoff command 7a by the normal first series 500a. Therefore, even when an abnormality occurs in the second series 500b, the line 1 can be appropriately protected.

When an abnormality occurs in the second series 500b, the contact 230 acts as a locking mechanism that locks the bypass circuit of the contact 210 corresponding to the normal first series 500a in response to the output of the bypass switching command 8b. This makes it possible to prevent the bypass circuit of the contact 210 from being formed even if the contact 220 is mistakenly turned ON.

Furthermore, when an abnormality occurs in both the first series 500a and the second series 500b, bypass switching commands 8a and 8b are output to turn off contacts 230 and 231. As a result, the bypass circuits are locked for both contacts 210 and 211, so that even if contacts 210 or 211 in the trip circuit 200 are turned on due to a malfunction, a trip signal is not erroneously output. Therefore, unnecessary operations such as mistripping of circuit breakers 21 and 22 can be prevented.

As described above, in the protection relay system 100 of this embodiment, the communication range of the digital transmission line is separated into the first series 500a and the second series 500b. That is, in the first series 500a, each piece of information acquired by the input device 6a from the field operation panel 2 is received only by the protection calculation device 5a, and the cutoff command from the protection calculation device 5a is received only by the input device 6a. On the other hand, in the second series 500b, each piece of information acquired by the input device 6b from the field operation panel 2 is received only by the protection calculation device 5b, and the cutoff command from the protection calculation device 5b is received only by the input device 6b. With this configuration, even if a failure occurs in a device belonging to each series, it is possible to prevent a mistrip of the circuit breakers 21 and 22 without affecting the normal series. It is also possible to continue protecting the line 1 by the normal series.

In the protection relay system 100 of this embodiment, the communication between the protection calculation devices 5a, 5b and the input devices 6a, 6b can use a communication protocol such as PRP (Parallel Redundancy Protocol) or HSR (High-availability Seamless Redundancy). Therefore, when an abnormality occurs in one of the network relay devices 120 or 121 or in one of the transmission paths to which they are connected, it is possible to communicate between the protection calculation devices 5a, 5b and the input devices 6a, 6b using the other network relay device or transmission path. Therefore, the protection of the line 1 can be seamlessly continued without using the bypass function of the contacts 220 and 221 of the trip circuit 200. In addition, for communication between the protection calculation devices 5a, 5b and the input devices 6a, 6b, it is possible to prevent interference between them by separating the respective transmission paths using, for example, a VLAN (Virtual Local Area Network).

Next, the relay calculation process executed by the relay calculation units 50a and 50b in the protection calculation devices 5a and 5b will be described with reference to FIG. 3. FIG. 3 is an example of a functional configuration diagram of the relay calculation units 50a and 50b. Note that the relay calculation units 50a and 50b have a common functional configuration, and FIG. 3 shows this common functional configuration.

The relay calculation units 50a and 50b each include a main detection element calculation unit 51 that performs relay calculation processing based on the main detection element (M element), a fault detection element calculation unit 52 that performs relay calculation processing based on the fault detection element (FD element), and a logical product calculation unit 53 that calculates the logical product (AND) of the results of these calculations. The relay calculation units 50a and 50b can be realized as software by, for example, executing a predetermined program in a microcomputer. Alternatively, each calculation unit may be realized using hardware such as an FPGA (Field Programmable Gate Array).

The main detection element calculation unit 51 performs relay calculation processing to determine whether or not a predetermined interruption condition is met based on information (M element information) on a predetermined main detection element among various information transmitted from the input devices 6a and 6b. The fault detection element calculation unit 52 performs relay calculation processing to determine whether or not a predetermined interruption condition is met based on information (FD element information) on a predetermined fault detection element different from the main detection element among various information transmitted from the input devices 6a and 6b. Specifically, for example, the main detection element calculation unit 51 performs relay calculation processing based on current information transmitted from the input devices 6a and 6b, with current as the main detection element. On the other hand, the fault detection element calculation unit 52 performs relay calculation processing based on voltage information transmitted from the input devices 6a and 6b, with voltage as the fault detection element. Then, the logical product calculation unit 53 outputs the logical product of these calculation results as the interruption commands 7a and 7b. This makes it possible to prevent mistripping of the circuit breakers 21 and 22 even when field equipment such as a current transformer (CT) or a voltage transformer (VT) breaks down. Note that the main detection elements and fault detection elements are not limited to those described above and can be any combination.

In a digital transmission type protection relay system such as the protection relay system 100 described above, there is a problem (hereinafter referred to as problem 1) in that the failure rate of the entire system increases due to the functional division of the calculation processing related to the control of the circuit breaker between the protection calculation device and the input device. In the protection relay system 100 of this embodiment, problem 1 is solved by redundancy using two processing series, the first series 500a and the second series 500b.

In addition, due to the redundancy of the processing series as described above, there is a problem that the circuit breakers 21 and 22 may mistrip if one of the processing series is abnormal (hereinafter referred to as problem 2). In the protective relay system 100 of this embodiment, the communication range of the digital transmission line is separated into the first series 500a and the second series 500b, and the logical product of the trip commands output from these processing series is output from the trip circuit 200 as a trip signal to the circuit breakers 21 and 22, thereby solving problem 2.

Furthermore, even if the logical product of the tripping processes output from the two processing series as described above is output as a tripping signal to the circuit breakers 21 and 22, there is a possibility of mistripping of the circuit breakers 21 and 22 if field equipment such as a current transformer (CT) or a voltage transformer (VT) fails (hereinafter referred to as problem 3). In the protective relay system 100 of this embodiment, in each of the relay calculation units 50a and 50b, the main detection element calculation unit 51 and the fault detection element calculation unit 52 perform relay calculation processing using different information, and the logical product of these is calculated by the logical product calculation unit 53 and output as tripping commands 7a and 7b, thereby resolving problem 3.

In addition, in a configuration such as that of Patent Document 1, a large number of relays must be installed, which increases the cost of the entire system and reduces the reliability of the entire system due to an increase in the rate of malfunctions (hereinafter referred to as problem 4). In the protective relay system 100 of this embodiment, problem 4 is solved by configuring the trip circuit 200 as shown in Figure 2.

According to the embodiment of the present invention described above, the following effects can be achieved.

(1) The protective relay system 100 protects the line 1 by controlling the circuit breakers 21 and 22 that cut off the line 1 of the power system. The protective relay system 100 includes input devices 6a and 6b that acquire analog information on the state of the line 1 and convert the acquired analog information into digital information, protective calculation devices 5a and 5b that perform a predetermined relay calculation process for protecting the line 1 based on the digital information and output cut-off commands 7a and 7b to the circuit breakers 21 and 22, network relay devices 120 and 121, and a trip circuit 200. The network relay devices 120 and 121 relay the digital information and cut-off command 7a input/output between the input device 6a and the protective calculation device 5a, and the digital information and cut-off command 7b input/output between the input device 6b and the protective calculation device 5b. The trip circuit 200 receives the cut-off commands 7a and 7b and outputs a cut-off signal to cause the circuit breakers 21 and 22 to cut off the line 1. In this protective relay system 100, the input device 6a outputs the trip command 7a output from the protective calculation device 5a via the network relay device 120 or 121 to the trip circuit 200, and the input device 6b outputs the trip command 7b output from the protective calculation device 5b via the network relay device 120 or 121 to the trip circuit 200. The trip circuit 200 has a series circuit in which a contact 210 and a contact 211 are connected in series, and outputs a trip signal to the circuit breakers 21 and 22 by turning on the contact 210 in response to the trip command 7a and turning on the contact 211 in response to the trip command 7b. In this way, it is possible to provide a protective relay system 100 that is highly reliable while suppressing increases in costs.

(2) The protection relay system 100 has two network relay devices 120, 121 capable of relaying digital information and tripping commands 7a, 7b between the input devices 6a, 6b and the protection and calculation devices 5a, 5b, respectively, and relays the digital information and tripping commands 7a, 7b using either the network relay device 120 or 121. This ensures redundancy of the digital transmission path and ensures availability throughout the system.

(3) The protection calculation devices 5a, 5b each have in their relay calculation units 50a, 50b a main detection element calculation unit 51 that performs relay calculation processing based on information related to a specified main detection element among the digital information from the input devices 6a, 6b, a fault detection element calculation unit 52 that performs relay calculation processing based on a specified fault detection element among the digital information from the input devices 6a, 6b, and a logical product calculation unit 53 that outputs a trip command 7a or 7b based on the logical product of the calculation result by the main detection element calculation unit 51 and the calculation result by the fault detection element calculation unit 52. As a result of this, even if field equipment such as a current transformer (CT) or a voltage transformer (VT) breaks down, it is possible to prevent accidental tripping of the circuit breakers 21, 22.

(4) The trip circuit 200 has a contact 220 connected in parallel with the contact 210, a contact 221 connected in parallel with the contact 211, a contact 230 connected in series with the contact 220, and a contact 231 connected in series with the contact 221. The contacts 220 and 231 are each controlled by the input device 6a, and the contacts 221 and 230 are each controlled by the input device 6b. Specifically, the protection relay system 100 has a first series 500a including the input device 6a and the protection calculation device 5a, and a second series 500b including the input device 6b and the protection calculation device 5b. When the first series 500a is abnormal, the input device 6a outputs a bypass switching command 8a to turn on the contact 220 and turn off the contact 231, and when the second series 500b is abnormal, the input device 6b outputs a bypass switching command 8b to turn on the contact 221 and turn off the contact 230. In this way, a trip circuit 200 that can adequately protect the line 1 even if an abnormality occurs in the first series 500a or the second series 500b can be realized at low cost using the minimum necessary hardware.

The present invention is not limited to the above-described embodiments and modifications, and other embodiments that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

1: Power system line 2: On-site operation panel 5a, 5b: Protection calculation device 6a, 6b: Input device 7a, 7b: Shutdown command 8a, 8b: Bypass switching command 21, 22: Circuit breaker 31, 32, 33: Control cable 50a, 50b: Relay calculation unit 51: Main detection element calculation unit 51
52: Fault detection element calculation unit 53: Logical product calculation unit 60a, 60b: Input calculation unit 120, 121: Network relay device 200: Trip circuit 210, 211, 220, 221, 230, 231: Contacts 500a: First series 500b: Second series

Claims (5)

A protective relay system for protecting a power system line by controlling a circuit breaker that interrupts the line,
first and second input devices each for acquiring analog information relating to the state of the line and converting the acquired analog information into digital information;
a first protection calculation device and a second protection calculation device each performing a predetermined relay calculation process for protecting the line based on the digital information and outputting a first shutoff command and a second shutoff command to the circuit breaker,
a network relay device that relays the digital information and the first shutoff command input/output between the first input device and the first protection and calculation device, and the digital information and the second shutoff command input/output between the second input device and the second protection and calculation device;
a trip circuit to which the first trip command and the second trip command are input and which outputs a trip signal for causing the breaker to trip the line,
the first input device outputs the first trip command transmitted from the first protection and calculation device via the network relay device to the trip circuit , and when detecting an abnormality in a first system including the first protection and calculation device and the first input device, outputs a first bypass switching signal to the trip circuit ;
the second input device outputs the second shutoff command transmitted from the second protection and calculation device via the network relay device to the trip circuit , and when detecting an abnormality in a second system including the second protection and calculation device and the second input device, outputs a second bypass switching signal to the trip circuit ;
The trip circuit comprises:
a series circuit in which a first contact and a second contact are connected in series, a first bypass circuit formed in response to the first bypass switching signal and bypassing the first contact, and a second bypass circuit formed in response to the second bypass switching signal and bypassing the second contact ,
the first contact is turned on in response to the first shutoff command , or the first bypass circuit is formed in response to the first bypass switching signal, and the second contact is turned on in response to the second shutoff command , or the second bypass circuit is formed in response to the second bypass switching signal , thereby outputting the shutoff signal to the circuit breaker.
Protection relay system. The network relay device includes a first network relay device and a second network relay device,
the first network relay device and the second network relay device are capable of relaying the digital information, the first shutdown command, and the second shutdown command between the first and second input devices and the first and second protection and calculation devices, respectively;
relaying the digital information, the first shutdown command, and the second shutdown command using either the first network relay device or the second network relay device;
The protective relay system according to claim 1 . The analog information includes first analog information representing a first physical quantity related to a predetermined main detection element in the state of the line, and second analog information representing a second physical quantity related to a predetermined fault detection element in the state of the line, the second physical quantity being different from the first physical quantity;
The first input device and the second input device transmit first digital information obtained by converting the first analog information into digital information and second digital information obtained by converting the second analog information into digital information to the first protection and calculation device or the second protection and calculation device, respectively, via the network relay device;
The first protection and calculation device is
a first main detection element calculation unit that performs the relay calculation process based on the first digital information transmitted from the first input device ;
a first fault detection element calculation unit that performs the relay calculation process based on the second digital information transmitted from the first input device ;
a first logical AND operation unit that outputs the first shutoff command based on a logical AND of a calculation result by the first main detection element calculation unit and a calculation result by the first fault detection element calculation unit,
The second protection and calculation device is
a second main detection element calculation unit that performs the relay calculation process based on the first digital information transmitted from the second input device;
a second fault detection element calculation unit that performs the relay calculation process based on the second digital information transmitted from the second input device;
a second logical AND operation unit that outputs the second shutoff command based on a logical AND of a calculation result by the second main detection element calculation unit and a calculation result by the second fault detection element calculation unit,
The protective relay system according to claim 1 . The trip circuit comprises:
a third contact connected in parallel with the first contact;
a fourth contact connected in parallel with the second contact;
a fifth contact connected in series with the third contact;
a sixth contact connected in series with the fourth contact;
the third contact is turned on when the first bypass switching signal is input from the first input device, and the fifth contact is turned on when the second bypass switching signal is not input from the second input device, thereby forming the first bypass circuit;
the fourth contact is turned on when the second bypass switching signal is input from the second input device, and the sixth contact is turned on when the first bypass switching signal is not input from the first input device, thereby forming the second bypass circuit;
The protective relay system according to claim 1 . the first input device outputs the first bypass switching signal to the trip circuit when the first series is abnormal, thereby turning on the third contact to form the first bypass circuit and turning off the sixth contact to prevent the second bypass circuit from being formed;
the second input device outputs the second bypass switching signal to the trip circuit when the second series is abnormal, thereby turning on the fourth contact to form the second bypass circuit and turning off the fifth contact to prevent the first bypass circuit from being formed .
The protective relay system according to claim 4.

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