Monitoring system

Abstract

To provide a monitoring system capable of checking an operation of a tripping contact of a circuit breaker regardless of an open / closed state of the circuit breaker.SOLUTION: A monitoring system comprises: a protection relay device; a monitoring device that sets a control mode of the protection relay device; and a tripping circuit of a circuit breaker. A series circuit of the protection relay device includes a first contact connected to a power supply, a second contact connected to the first contact, and a digital input circuit connected to the second contact. The first contact is closed when an operation signal is output. The second contact is closed in a test mode. The digital input circuit outputs a first signal when an input of a current is received. Each of a first auxiliary contact and a second auxiliary contact in the tripping circuit is connected between the digital input circuit and a tripping coil. When the circuit breaker is closed, the first auxiliary contact is closed, and when the circuit breaker is opened, the second auxiliary contact is closed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to surveillance systems. [Background technology]

[0002] Conventionally, digital protective relay devices are used to detect accidents or abnormalities that occur in power systems. Protective relay devices collect electrical quantities such as current and voltage from the power system, detect overvoltage or overcurrent caused by accidents, etc., and send a trip signal to the circuit breaker. Since high reliability is required for protective relay devices, tests are regularly conducted to ensure that the protective functions of the protective relay devices are properly performed.

[0003] For example, Japanese Patent Application Laid-Open No. 2011-258375 (Patent Document 1) discloses a protective relay (i.e., protective relay device) equipped with a function for testing a circuit breaker tripping circuit. The protective relay includes a switching unit connected in series to the circuit breaker tripping circuit so as to be able to pass a current flowing through the circuit breaker tripping coil, and a switching unit that switches the connection destination of the switching unit to a first path, which is a path of current that operates the circuit breaker tripping coil, or a second path, which is a path of current limited to a value that does not operate the circuit breaker tripping coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-258375 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the protective relay device according to Patent Document 1, it is considered to check the operation of the circuit breaker tripping contact (i.e., the contact that operates in response to the tripping operation of the protective relay device) during testing without opening the circuit breaker. However, Patent Document 1 is premised on checking the operation when the auxiliary contact of the circuit breaker is closed (i.e., the circuit breaker is closed), and there is a problem in that it is not possible to check the operation of the circuit breaker tripping contact when the auxiliary contact is open (i.e., the circuit breaker is open).

[0006] An object of one aspect of the present disclosure is to provide a monitoring system capable of checking the operation of a trip contact of a circuit breaker regardless of whether the circuit breaker is open or closed. [Means for solving the problem]

[0007] A monitoring system according to an embodiment includes a protective relay device for protecting a power system, a monitoring device for setting a control mode of the protective relay device to a normal mode or a test mode, and a tripping circuit for a circuit breaker. The protective relay device includes an arithmetic processing unit for performing a relay operation using an electrical quantity of the power system and outputting an operation signal based on a result of the relay operation, and a series circuit. The series circuit includes a first digital output circuit having a first contact one end of which is connected to a power source, a second digital output circuit having a second contact one end of which is connected to the other end of the first contact, and a digital input circuit one end of which is connected to the other end of the second contact. The first contact is closed when an operation signal is output. The second contact is opened in the normal mode and closed in the test mode. The digital input circuit outputs a first signal to the arithmetic processing unit when a current is input via the first contact and the second contact. The tripping circuit includes a series body having a first auxiliary contact, a second auxiliary contact and a first resistor, and a tripping coil. One end of each of the first auxiliary contact and the series body is connected to the other end of the digital input circuit, and the other end of each of the first auxiliary contact and the series body is connected to the trip coil. When the circuit breaker is closed, the first auxiliary contact is closed and the second auxiliary contact is open, and when the circuit breaker is open, the first auxiliary contact is open and the second auxiliary contact is closed. Effect of the Invention

[0008] According to the present disclosure, it is possible to check the operation of the breaker trip contacts regardless of the open or closed state of the breaker. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows an example of an overall configuration of a monitoring system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of a series circuit and a tripping circuit; [Diagram 3] FIG. 13 is a diagram for explaining an example of a method for checking the operation of a tripping contact. [Figure 4] FIG. 13 is a diagram for explaining another example of a method for checking the operation of a tripping contact. [Diagram 5] 11A and 11B are diagrams for explaining an example of opening and closing operations of each contact in a normal mode. [Figure 6] 10A to 10C are diagrams for explaining another example of the opening and closing operation of each contact in the normal mode. [Figure 7] FIG. 1 shows an example of an overall configuration of a monitoring system according to a first modification of the first embodiment. [Figure 8] FIG. 13 is a diagram showing an example of an overall configuration of a monitoring system according to a second modification of the first embodiment. [Figure 9] FIG. 13 is a diagram showing an example of an overall configuration of a monitoring system according to a third modification of the first embodiment. [Figure 10] FIG. 11 illustrates an example of a configuration of a monitoring system according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0011] Embodiment 1 <Overall composition> Fig. 1 is a diagram showing an example of an overall configuration of a monitoring system 1000 according to the first embodiment. Referring to Fig. 1, the monitoring system 1000 is a system for performing an operation test of a protective relay device 90 using a monitoring device 10 installed at a remote location. The monitoring system 1000 includes the monitoring device 10, the protective relay device 90, and a tripping circuit 140.

[0012] The monitoring device 10 is configured to be able to communicate with a protective relay device 90 for protecting a power system, and transmits and receives various information to and from the protective relay device 90. The monitoring device 10 is installed remotely from the protective relay device 90, and transmits setting information for setting the control mode of the protective relay device 90, thereby setting the control mode to a normal mode or a test mode. The protective relay device 90 is set to a control mode according to the received setting information.

[0013] The protective relay device 90 is a digital type protective relay device, and is installed in, for example, an electrical station such as a power plant or a substation. The protective relay device 90 has a communication function, collects effective values ​​of system electrical quantities such as current and voltage related to electrical equipment such as a transmission station, a bus bar, and a transformer that constitutes a power system, and controls the devices of the electrical equipment based on the collected system electrical quantities.

[0014] In this embodiment, the protective relay device 90 acquires data on an electrical quantity (e.g., a current or a voltage) related to a power line (e.g., a transmission line) L constituting a power system. The protective relay device 90 uses the electrical quantity data to detect a fault in the power line L, thereby protecting the power line L. The power line L is a three-phase power line consisting of an A-phase power line 11, a B-phase power line 12, and a C-phase power line 13.

[0015] In the example of Fig. 1, current transformers (CTs) 15, 16 and 17 are provided on A-phase power line 11, B-phase power line 12 and C-phase power line 13, respectively. CTs 15, 16 and 17 detect current Ia of A-phase power line 11, current Ib of B-phase power line 12 and current Ic of C-phase power line 13, respectively. Currents Ia to Ic are input to protective relay device 90. Note that a voltage transformer (VT), a transformer, a disconnecting switch and the like may also be provided in the electric station.

[0016] The protective relay device 90 executes calculations required to protect the power system, such as relay calculations, using the collected electrical quantities (currents Ia to Ic in this case), and determines whether a system fault has occurred. When the protective relay device 90 detects a fault in the power line L, it outputs an opening command.

[0017] The tripping circuit 140 is a circuit for tripping a circuit breaker. The tripping circuit 140 operates to open the circuit breaker based on an operation signal (e.g., a trip signal) output from the protection relay device 90. This protects the power system.

[0018] Here, protective relay devices are important devices that are used for the purpose of detecting system faults without fail and preventing the damage from spreading. For this reason, periodic inspections are conducted once a year or every few years. In periodic inspections, it is necessary to check not only the operating values ​​of the protective relay devices, but also the contacts (hereinafter also referred to as "trip operation contacts") that operate in response to the trip operation of the protective relay devices (for example, the output of a trip signal from the protective relay devices).

[0019] Conventionally, when testing a protective relay device, a tester must perform an operation called trip lock at the location where the protective relay device is installed. Trip lock is an operation to remove a link in the trip route (e.g., the wire leading to the trip coil) on the relay panel. This operation prevents current from flowing to the trip coil even if the protective relay device trips, and then the trip operation is checked. This is to prevent power outages and other issues that may occur when opening the circuit breaker when checking the operation of the trip contacts of the protective relay device during testing.

[0020] In the monitoring system 1000 according to the present embodiment, a test of the protective relay device 90 is performed remotely. Specifically, a test is performed remotely to check for abnormalities in the protective relay device 90 by checking for the presence or absence of abnormalities in the tripping action contacts corresponding to the breaker tripping contacts and the presence or absence of abnormalities in the relay calculation function including the input circuit included in the protective relay device 90.

[0021] Next, a description will be given of a hardware configuration of the protective relay device 90. The protective relay device 90 includes input circuits 20 and 30, a calculation processing unit 70, and a series circuit 80.

[0022] The input circuit 20 receives three-phase currents from a power system and converts the three-phase currents into digital data. Specifically, the input circuit 20 includes input converters 21-23, filters 31-33, sample-and-hold circuits (SH circuits) 41-43, a multiplexer 51, and an AD converter 61.

[0023] The input converters 21, 22, 23 respectively receive input of currents Ia, Ib, Ic, convert them into voltage signals (hereinafter also referred to as "waveform signals") suitable for signal processing in the internal circuit, and output them. The filters 31-33 are analog filters. The filters 31-33 remove high-order frequency components such as noise from the waveform signals of the currents output from the input converters 21-23. Specifically, the filter 31 removes noise components from the waveform signal indicating the current Ia and outputs it to the SH circuit 41. The filter 32 removes noise components from the waveform signal indicating the current Ib and outputs it to the SH circuit 42. The filter 33 removes noise components from the waveform signal indicating the current Ic and outputs it to the SH circuit 43.

[0024] The SH circuits 41 to 43 sample the current waveform signals output from the filters 31 to 33 at a predetermined sampling period. The multiplexer 51 sequentially switches the waveform signals input from the SH circuits 41 to 43 in time series based on a timing signal input from the arithmetic processing unit 70, and inputs them to the AD converter 61.

[0025] The AD converter 61 converts the waveform signal input from the multiplexer 51 from analog data to digital data, and outputs it to the arithmetic processing unit 70 .

[0026] The input circuit 30 receives the zero-phase current of the power system and converts the zero-phase current into digital data. Specifically, the input circuit 30 includes an input converter 24, a filter 34, an SH circuit 44, a multiplexer 54, and an AD converter 64.

[0027] The input converter 24 receives an input of a zero-phase current (that is, 3I0=Ia+Ib+Ic) obtained by combining the currents Ia to Ic. The filter 34 removes noise components from a signal indicating the zero-phase current 3I0 and outputs the signal to the SH circuit 44.

[0028] The SH circuit 44 samples the current waveform signal output from the filter 34 at a predetermined sampling period. Based on a timing signal input from the arithmetic processing unit 70, the multiplexer 54 sequentially switches the waveform signals input from the SH circuit 44 in time series and inputs them to the AD converter 64. The AD converter 64 converts the waveform signal input from the multiplexer 54 from analog data to digital data and outputs it to the arithmetic processing unit 70.

[0029] The calculation processing unit 70 is mainly composed of a microcomputer, executes relay calculations using the electrical quantity of the power system, and outputs an operation signal (e.g., a trip signal) based on the result of the relay calculation. Specifically, the calculation processing unit 70 includes a CPU (Central Processing Unit) 72, a ROM (Read Only Memory) 74, a RAM (Random access memory) 76, and a communication interface (IF) 78.

[0030] The CPU 72, as a control unit, controls the operation of the protection relay device 90 by reading and executing a program previously stored in the ROM 74. The RAM 76 as a volatile memory and the ROM 74 as a non-volatile memory are used as the main memory of the CPU 72. The CPU 72 is, for example, a microprocessor. Note that the hardware may be, other than the CPU 72, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or other circuits having a calculation function.

[0031] The CPU 72 takes in digital data from the AD converters 61, 64. The CPU 72 executes relay calculations and various processes using the taken-in digital data in accordance with a program stored in the ROM 74. The CPU 72 determines whether or not there is an accident on the power line L based on the relay calculation results. When the CPU 72 detects an accident (for example, when the calculation value exceeds a set value), it outputs an operation signal to a digital output (DO) circuit included in the series circuit 80. The communication interface 78 mediates data transmission between the protection relay device 90 and the monitoring device 10.

[0032] The series circuit 80 is connected in series to a tripping circuit 140 provided between the power supplies BP and BN. The power supply BP corresponds to the high potential side of the DC power supply, and the power supply BN corresponds to the low potential side of the DC power supply.

[0033] <Series circuit and tripping circuit configuration> (Series circuit) 2 is a diagram showing an example of the configuration of a series circuit and a tripping circuit. The series circuit 80 includes a DO circuit 110, a DO circuit 120, and a DI circuit .

[0034] The DO circuit 110 includes a coil T and a contact 82. One end (i.e., a high-potential terminal) of the contact 82 is connected to the power supply BP via a connection point A1, and the other end (i.e., a low-potential terminal) is connected to the DO circuit 120 via a connection point A2.

[0035] The operation of the contact 82 is controlled by a relay operation signal (e.g., a trip signal) from the arithmetic processing unit 70. Specifically, when an operation signal is output from the arithmetic processing unit 70, a current is supplied to the coil T by a driver element (e.g., a transistor, etc.) that receives the operation signal. When a current flows through the coil T, the contact 82 is closed by electromagnetic force. On the other hand, when no current flows through the coil T, the contact 82 is opened. In this way, the contact 82 that functions as a trip operation contact is open when no operation signal is output from the arithmetic processing unit 70, and is closed when an operation signal is output.

[0036] The DO circuit 120 includes a coil S and contacts 83 to 85. One end of the contact 83 is connected to the other end of the contact 82 via a connection point A2, and the other end is connected to the DI circuit 130 via a connection point B1. One end of the contact 84 is connected to the power source BP via a connection point A1, and the other end is connected to the DI circuit 130 via a connection point B1. One end of the contact 85 is connected to the other end of the contact 82 via a connection point A2, and the other end is connected to the tripping circuit 140 via a connection point B2.

[0037] When the control mode of the protection relay device 90 is set to the test mode, the arithmetic processing unit 70 outputs a control signal to the DO circuit 120. On the other hand, when the control mode of the protection relay device 90 is set to the normal mode (i.e., the non-test mode), the arithmetic processing unit 70 does not output a control signal to the DO circuit 120.

[0038] The operations of contacts 83 to 85 are controlled by a control signal from the calculation processing unit 70. Specifically, when a control signal is output from the calculation processing unit 70, a current is supplied to the coil S by the driver element that receives the control signal. When a current flows through the coil S, the contact 83 is closed by an electromagnetic force, and the contacts 84 and 85 are opened. On the other hand, when the current stops flowing through the coil S, the contact 83 is opened, and the contacts 84 and 85 are closed.

[0039] Thus, in the normal mode (i.e., when no control signal is output from the arithmetic processing unit 70), contact 83 is opened, and contacts 84 and 85 are closed. On the other hand, in the test mode (i.e., when a control signal is output from the arithmetic processing unit 70), contact 83 is closed, and contacts 84 and 85 are opened.

[0040] The DI circuit 130 has one end connected to the other ends of the contacts 83, 84 via a connection point B1, and the other end connected to the tripping circuit 140 via a connection point B2. When the DI circuit 130 receives an input of a current supplied from the power source BP via the contacts 82, 83, or when it receives an input of a current via the contact 84, it outputs a DI signal to the arithmetic processing unit 70. Specifically, the DI circuit 130 includes a resistor 86 and a photocoupler 87.

[0041] One end of the resistor 86 is connected to the other end of the contact 83 and the other end of the contact 84, and the other end is connected to the photocoupler 87. One end of the photocoupler 87 is connected to the other end of the resistor 86, and the other end is connected to the tripping circuit 140. When supplied with current, the photocoupler 87 outputs a DI signal to the arithmetic processing unit 70.

[0042] Resistor 86 is provided to keep the current flowing through photocoupler 87 at a certain value (for example, about several mA to 10 mA) or less, to make the current flowing through photocoupler 87 an appropriate current value, and to suppress heat generation in DI circuit 130. In addition, this current value is not large enough to drive breaker tripping coil 98. For example, when the voltage of power source BP is 100V, a resistor having a resistance value of about 10 kΩ to several tens of kΩ is selected as resistor 86.

[0043] 2, series circuit 80 is configured to include a connection line connecting DO circuit 110 and DO circuit 120 (for example, a connection line connecting contact 82 and contacts 83 to 85) and a connection line connecting DO circuit 120 and DI circuit 130 (for example, a connection line connecting contacts 83 to 85 and resistor 86 or photocoupler 87). However, these connection lines may be configured not to be included in series circuit 80 and to be provided externally.

[0044] (tripping circuit) The tripping circuit 140 is a circuit for tripping a breaker. Specifically, the tripping circuit 140 includes an auxiliary contact 94, a tripping coil 98, and a series body 99. The series body 99 is composed of a resistor 92 and an auxiliary contact 96 connected in series. The series body 99 is connected in parallel with the auxiliary contact 94. Specifically, one end of each of the auxiliary contact 94 and the series body 99 is connected to the other end of the DI circuit 130. The other end of each of the auxiliary contact 94 and the series body 99 is connected to the tripping coil 98.

[0045] One end of the resistor 92 is connected to the other end of the contact 85, the other end of the photocoupler 87, and one end of the auxiliary contact 94. The other end of the resistor 92 is connected to one end of the auxiliary contact 96. The current flowing to the tripping coil 98 via the resistor 92 has a current value that does not cause the circuit breaker to operate (i.e., does not drive the tripping coil 98) and is detectable by the photocoupler 87. The resistance value of the resistor 92 is selected so as to obtain such a current value. For example, the resistor 92 has a resistance value of about 1 kΩ.

[0046] One end of the auxiliary contact 94 is connected to the other end of the contact 85, the other end of the photocoupler 87, and one end of the resistor 92. The other end of the auxiliary contact 94 is connected to a tripping coil 98. One end of the auxiliary contact 96 is connected to the other end of the resistor 92, and the other end is connected to the tripping coil 98.

[0047] One end of the tripping coil 98 is connected to the other end of the auxiliary contact 94 and the other end of the auxiliary contact 96. The other end of the tripping coil 98 is connected to the power source BN.

[0048] The auxiliary contacts 94, 96 are contacts that are linked to the circuit breaking operation of the circuit breaker. The auxiliary contact 94 is closed, for example, when no system fault occurs, and is opened when the circuit breaker is operated due to a system fault. On the other hand, the auxiliary contact 96 performs an operation opposite to that of the auxiliary contact 94. More specifically, when a current of a certain level or more (for example, a current of about 5 to 30 A) flows through the tripping coil 98, the circuit breaker is opened, and the auxiliary contact 94 that operates in conjunction with the circuit breaker is opened. In this case, the auxiliary contact 96 that performs an operation opposite to that of the auxiliary contact 94 is closed.

[0049] The contact 82 functioning as the tripping contact can pass a current of several tens of amperes (e.g., 30 A) when closed, but can cut off a current of less than 1 A when opened. On the other hand, the auxiliary contact 94 can cut off a current greater than the current that flows when closed. Therefore, when the auxiliary contact 94 is opened, the current to the tripping coil 98 via the auxiliary contact 94 is cut off.

[0050] Thus, when the circuit breaker is closed, auxiliary contacts 94 are closed and auxiliary contacts 96 are open, whereas when the circuit breaker is open, auxiliary contacts 94 are open and auxiliary contacts 96 are closed.

[0051] In the example of Fig. 2, one end of the auxiliary contact 96 is connected to the other end of the resistor 92, and the other end of the auxiliary contact 96 is connected to the tripping coil 98. However, a configuration may also be used in which one end of the auxiliary contact 96 is connected to the other end of the contact 85, the other end of the photocoupler 87, and one end of the auxiliary contact 94, and the other end of the auxiliary contact 96 is connected to one end of the resistor 92. In this case, the other end of the resistor 92 is connected to the tripping coil 98. In this case, the resistor 92 may be included in the series circuit 80. In this case, there are two connection lines between the series circuit 80 and the tripping circuit 140.

[0052] <Trip contact operation check method> A method for checking the operation of the contact 82 (that is, the tripping contact) in the test mode will now be described with reference to FIGS.

[0053] Fig. 3 is a diagram for explaining an example of a method for checking the operation of a tripping contact. Fig. 3(a) and Fig. 3(b) show the path of a current flowing through a series circuit 80 when the circuit breaker is closed in a test mode. Specifically, Fig. 3(a) shows the current path when an operation signal is output, and Fig. 3(b) shows the current path when an operation signal is not output.

[0054] 3(a) and 3(b), since the circuit breaker is closed, auxiliary contact 94 is closed and auxiliary contact 96 is open. Also, since it is in the test mode, contact 83 is closed and contacts 84 and 85 are open.

[0055] 3(a), an operation signal is output from the arithmetic processing unit 70, and therefore the contact 82 is closed. In this case, the current output from the power supply BP flows through a path passing through the contact 82, the contact 83, the resistor 86, the photocoupler 87, the auxiliary contact 94, the tripping coil 98, and the power supply BN in this order. As a result, the photocoupler 87 is energized and outputs a DI signal to the arithmetic processing unit 70.

[0056] In the path shown in Fig. 3(a), a current flows through the tripping coil 98 via the resistor 86. Therefore, the current is reduced to a constant value (for example, about several mA to 10 mA) by the resistor 86, which is considerably smaller than several A capable of driving the tripping coil 98. Therefore, the circuit breaker is not opened. This makes it possible to prevent unintended operation of the circuit breaker during the test mode.

[0057] 3(b), since no operation signal is output from the arithmetic processing unit 70, the contact 82 connected to the power supply BP is open. In addition, the contact 84 connected to the power supply BP is also open. Therefore, unlike the case of FIG. 3(a), no current flows from the power supply BP to the series circuit 80. In other words, no current flows through the photocoupler 87, and no DI signal is output to the arithmetic processing unit 70.

[0058] The arithmetic processing unit 70 judges whether or not a condition is satisfied that the input of a DI signal is not detected when the operation signal is not output, and the input of a DI signal is detected when the operation signal is output. If the condition is satisfied, the arithmetic processing unit 70 judges that the contact 82 is appropriately opening and closing in response to the output of the operation signal, and that the current path shown in Fig. 3(a) is normal (for example, there is no break, etc.).

[0059] On the other hand, if the condition is not met (for example, if an operation signal is output but no DI signal input is detected), the calculation processing unit 70 determines that an abnormality has occurred in the opening and closing operation of the contact 82 or in the current path shown in Figure 3(a).

[0060] The calculation processing unit 70 transmits the determination result to the monitoring device 10. The monitoring device 10 displays the determination result on a display or the like, for example. This enables the system operator to remotely determine the presence or absence of an abnormality in the series circuit 80, including the opening and closing operation of the contacts 82.

[0061] Fig. 4 is a diagram for explaining another example of a method for checking the operation of a tripping contact. Fig. 4(a) and Fig. 4(b) show the path of a current flowing through a series circuit 80 when the circuit breaker is open in a test mode. Specifically, Fig. 4(a) shows the current path when an operation signal is output, and Fig. 4(b) shows the current path when an operation signal is not output.

[0062] 4(a) and 4(b), since the circuit breaker is open, auxiliary contact 94 is open and auxiliary contact 96 is closed. Also, since the circuit breaker is in the test mode, contact 83 is closed and contacts 84 and 85 are open.

[0063] 4(a), an operation signal is output from the arithmetic processing unit 70, and therefore the contact 82 is closed. In this case, the current output from the power supply BP flows through a path passing through the contact 82, the contact 83, the resistor 86, the photocoupler 87, the resistor 92, the auxiliary contact 96, the tripping coil 98, and the power supply BN in this order. As a result, the photocoupler 87 is energized, and therefore outputs a DI signal to the arithmetic processing unit 70.

[0064] 4(a), a current flows to the tripping coil 98 via resistors 86 and 92. The current flowing to the tripping coil 98 is reduced by the resistors 86 and 92 to a value less than the current value capable of driving the tripping coil 98, so that no unnecessary controllable current flows through the tripping coil 98 in the open state.

[0065] 4(b), since no operation signal is output from the arithmetic processing unit 70, the contact 82 connected to the power supply BP is open, and the contact 84 connected to the power supply BP is also open. Therefore, unlike the case of FIG. 4(a), no current flows from the power supply BP to the series circuit 80. In other words, no current flows through the photocoupler 87, and no DI signal is output to the arithmetic processing unit 70.

[0066] The arithmetic processing unit 70 judges whether or not the following condition is satisfied: when the operation signal is not output, the input of the DI signal is not detected, and when the operation signal is output, the input of the DI signal is detected. When the condition is satisfied, the arithmetic processing unit 70 judges that the contact 82 is appropriately opening and closing in response to the output of the operation signal, and that the current path shown in FIG. 4(a) is normal.

[0067] On the other hand, if the condition is not satisfied, the arithmetic processing unit 70 determines that an abnormality has occurred in the opening and closing operation of the contact 82. The arithmetic processing unit 70 transmits the result of the determination to the monitoring device 10.

[0068] 3 and 4, it can be seen that in this embodiment, the opening and closing operation of the contacts 82 can be confirmed regardless of the open / closed state of the circuit breaker.

[0069] <Opening and closing operation of each contact in normal mode> The opening and closing operations of the contacts included in the series circuit 80 in the normal mode will be described with reference to FIGS.

[0070] Fig. 5 is a diagram for explaining an example of the opening and closing operation of each contact in the normal mode. Fig. 5(a) and Fig. 5(b) show the path of the current flowing through the series circuit 80 when the circuit breaker is closed in the normal mode. Specifically, Fig. 5(a) shows the current path when an operation signal is output, and Fig. 5(b) shows the current path when an operation signal is not output.

[0071] 5(a) and 5(b), since the circuit breaker is closed, auxiliary contact 94 is closed and auxiliary contact 96 is open. Also, since it is in the normal mode, contact 83 is open and contacts 84 and 85 are closed.

[0072] In the case of Fig. 5(a), the calculation processing unit 70 outputs an operation signal based on the relay calculation result, so that the contact 82 is closed. The paths of the current output from the power supply BP can be the first path (i.e., a path passing through the contact 82, the contact 85, the auxiliary contact 94, the tripping coil 98, and the power supply BN in this order) and the second path (i.e., a path passing through the contact 84, the resistor 86, the photocoupler 87, the auxiliary contact 94, the tripping coil 98, and the power supply BN in this order) shown in Fig. 5(a). However, the second path includes the resistor 86, which has a large resistance value. Therefore, the current from the power supply BP flows through the first path, not the second path.

[0073] In this case, since no current flows through the photocoupler 87, the DI signal is not output to the arithmetic processing unit 70. Thus, in the normal mode, when an operation signal is output, the DI signal is not output to the arithmetic processing unit 70. Therefore, when an operation signal is output in the normal mode, the arithmetic processing unit 70 can recognize that it is normal that no DI signal input is detected, and therefore does not determine that an abnormality has occurred in the series circuit 80 or the tripping circuit 140.

[0074] 5(a), the current flows through the tripping coil 98 without passing through the resistors 86 and 92. Therefore, the current has a current value equal to or greater than a certain value, and the tripping coil 98 is driven. That is, the breaker is operated (i.e., opened) by the tripping coil 98.

[0075] In the case of FIG. 5(b), since no operation signal is output from the arithmetic processing unit 70, the contact 82 connected to the power source BP is open. Therefore, the current output from the power source BP flows through the second path described above. In this case, the photocoupler 87 is in a conducting state and outputs a DI signal to the arithmetic processing unit 70. This allows the arithmetic processing unit 70 to determine whether or not the path from the power source BP to the power source BN (here, the second path) is normal. Specifically, when the arithmetic processing unit 70 does not detect an input of a DI signal, it determines that an abnormality (e.g., a break) has occurred in the above path.

[0076] Fig. 6 is a diagram for explaining another example of the opening and closing operation of each contact in the normal mode. Fig. 6(a) and Fig. 6(b) show the path of the current flowing through the series circuit 80 when the breaker is open in the normal mode. Specifically, Fig. 6(a) shows the current path when an operation signal is output, and Fig. 6(b) shows the current path when an operation signal is not output.

[0077] 6(a) and 6(b), since the circuit breaker is open, auxiliary contact 94 is open and auxiliary contact 96 is closed. Also, since it is in the normal mode, contact 83 is open and contacts 84 and 85 are closed.

[0078] In the case of Fig. 6(a), an operation signal is output, and therefore the contact 82 is closed. The current output from the power supply BP flows through a path passing through the contact 82, the contact 85, the resistor 92, the auxiliary contact 96, the tripping coil 98, and the power supply BN in this order. As in the case of Fig. 5(a), no current flows through the photocoupler 87, and therefore the DI signal is not output to the arithmetic processing unit 70. Therefore, when an operation signal is output in the normal mode, the arithmetic processing unit 70 can recognize that the absence of detection of a DI signal input is normal, and therefore does not determine that an abnormality has occurred in the series circuit 80 or the tripping circuit 140.

[0079] In the case of Fig. 6(b), since no operation signal is output, the contact 82 connected to the power supply BP is open. Therefore, the current output from the power supply BP flows through a path passing through the contact 84, resistor 86, photocoupler 87, resistor 92, auxiliary contact 96, tripping coil 98, and power supply BN in this order. As in the case of Fig. 5(b), the photocoupler 87 is in a conducting state and outputs a DI signal to the arithmetic processing unit 70. Therefore, the arithmetic processing unit 70 can determine whether or not the above path is normal.

[0080] <Input circuit abnormality detection method> Next, an abnormality determination method for the input circuits 20, 30 included in the protective relay device 90 will be described. As shown in Fig. 1, the protective relay device 90 is provided with two input circuits 20, 30. An arithmetic processing unit 70 (e.g., a CPU 72) executes relay calculations using digital data of the currents Ia to Ic received from the input circuit 20. The arithmetic processing unit 70 uses digital data of the zero-phase current 3I0 received from the input circuit 30 as data for abnormality determination of each of the input circuits 20, 30.

[0081] Arithmetic processing unit 70 compares three-phase currents Ia-Ic received from input circuit 20 with zero-phase current 3I0 received from input circuit 30 to determine whether or not there is an abnormality in either input circuit 20 or input circuit 30.

[0082] Specifically, the calculation processing unit 70 calculates the effective value of each of the currents Ia-Ic and the effective value of the sum current Iabc, which is the sum of the instantaneous values ​​of each of the currents Ia-Ic (i.e., Ia+Ib+Ic). The calculation processing unit 70 calculates the effective value of the zero-phase current 3I0. Next, the calculation processing unit 70 determines whether the absolute value of the difference between the effective value of the sum current Iabc and the effective value of the zero-phase current 3I0 is greater than a threshold value Th1. If the absolute value is greater than the threshold value Th1, the calculation processing unit 70 determines that either the input circuit 20 or the input circuit 30 is abnormal.

[0083] In detail, the calculation processing unit 70 judges whether the following formula (1) is satisfied. In the following description, the effective value of the current Ix is written as Ixr. Therefore, the effective values ​​of Ia, Ib, Ic, and 3I0 are written as Iar, Ibr, Icr, and 3I0r, respectively. The effective value of the sum current Iabc (i.e., Iabc=Ia+Ib+Ic) is written as Iabcr.

[0084] |Iabcr-3I0r|>ε1+ε2×max(Iar,Ibr,Icr)…(1) In equation (1), the symbol || indicates an absolute value, ε1 is a fixed error (e.g., 1 to 2% of the rated current), and ε2 is a proportional error (e.g., 1 to 2% of the rated current).

[0085] The right side of the formula (1) corresponds to the threshold value Th1. In this manner, the threshold value Th1 is determined based on the prescribed constants (for example, ε1, ε2) and the maximum value among the effective values ​​Iar, Ibr, and Icr.

[0086] When both input circuits 20 and 30 are normal, the left side of formula (1) (i.e., |Iabcr-3I0|) is equal to or less than threshold value Th1, and formula (1) does not hold. It is extremely unlikely that hardware abnormalities occur in both input circuits 20 and 30 at the same time. Therefore, when formula (1) holds, the calculation processing unit 70 determines that there is an abnormality in either input circuit 20 or input circuit 30.

[0087] The arithmetic processing unit 70 transmits the result of the judgment to the monitoring device 10. The monitoring device 10 displays the result of the judgment received from the arithmetic processing unit 70 on a display or the like. This allows the system operator to constantly monitor the presence or absence of abnormalities in the input circuits 20, 30 from a remote location.

[0088] If an abnormality occurs in the calculation processing unit 70 itself, there is a high possibility that the relay calculation itself will not be performed normally or that the result of the relay calculation will be an abnormal value. The monitoring device 10 may detect an abnormality in the calculation processing unit 70 itself by observing each effective value and the result of the relay calculation received from the calculation processing unit 70.

[0089] <Modification 1 (method of determining abnormality in input circuit)> Fig. 7 is a diagram showing an example of an overall configuration of a monitoring system 1000A according to the first modification of the first embodiment. With reference to Fig. 7, the monitoring system 1000A includes a monitoring device 10 and a protective relay device 90A. The protective relay device 90A includes input circuits 20, 30A, a calculation processing unit 70, and a series circuit 80. The input circuit 20, the calculation processing unit 70, and the series circuit 80 have the same configurations as those described in Fig. 1.

[0090] The input circuit 30A takes in three-phase currents from a power system and converts the three-phase currents into digital data. In the first modification, an input of three-phase currents is input to the input circuit 30A having the same configuration and function as the input circuit 20. Specifically, the input circuit 30A includes input converters 25-27, filters 35-37, SH circuits 45-47, a multiplexer 55, and an AD converter 65.

[0091] The input converters 25-27 have the same functions as the input converters 21-23, respectively. The filters 35-37 have the same functions as the filters 31-33, respectively. The SH circuits 45-47 have the same functions as the SH circuits 41-43, respectively. The multiplexer 55 has the same function as the multiplexer 51. The AD converter 65 has the same function as the AD converter 61.

[0092] In the first modification, for convenience, Ia, Ib, and Ic input from the input circuit 20 to the arithmetic processing unit 70 are written as Ia1, Ib1, and Ic1, respectively. Ia, Ib, and Ic input from the input circuit 30A to the arithmetic processing unit 70 are written as Ia2, Ib2, and Ic2, respectively.

[0093] The calculation processing unit 70 determines whether or not there is an abnormality in either the input circuit 20 or the input circuit 30A by comparing the three-phase currents Ia1-Ic1 received from the input circuit 20 with the three-phase currents Ia2-Ic2 received from the input circuit 30A.

[0094] Specifically, the calculation processing unit 70 compares the phase current received from the input circuit 20 with the phase current received from the input circuit 30A for each phase. For example, the A phase will be described. The calculation processing unit 70 calculates an effective value Ia1r of the current Ia1 received from the input circuit 20 and an effective value Ia2r of the current Ia2 received from the input circuit 30A. The calculation processing unit 70 determines whether or not the absolute value of the difference between the effective value Ia1r and the effective value Ia2r is greater than a threshold value Th2. If the absolute value is greater than the threshold value Th2, the calculation processing unit 70 determines that either the input circuit 20 or the input circuit 30A is abnormal. In detail, the calculation processing unit 70 determines whether or not the following formula (2) is established.

[0095] |Ia1r-Ia2r|>ε1+ε2×Ia1r …(2) The right side of the formula (2) corresponds to the threshold value Th2. In this manner, the threshold value Th2 is determined based on the prescribed constants (for example, ε1, ε2) and the effective value Ia1r.

[0096] When both input circuits 20 and 30A are normal, the left side of formula (2) (i.e., |Ia1r-Ia2r|) is equal to or smaller than threshold value Th2, and formula (2) does not hold. Therefore, when formula (2) holds, the arithmetic processing unit 70 determines that either input circuit 20 or input circuit 30A is abnormal.

[0097] In the above-mentioned variant example 1, the monitoring device 10 displays the result of the judgment received from the calculation processing unit 70 on a display or the like, thereby enabling the system operator to constantly monitor the presence or absence of abnormalities in the input circuits 20, 30A from a remote location.

[0098] <Modification 2 (method of determining abnormality in input circuit)> Fig. 8 is a diagram showing an example of an overall configuration of a monitoring system 1000B according to the second modification of the first embodiment. Referring to Fig. 8, the monitoring system 1000B includes a monitoring device 10 and a protection relay device 90B. The protection relay device 90B includes input circuits 20, 30A, a DA converter 66, an arithmetic processing unit 70, and a series circuit 80. In other words, the protection relay device 90B has a configuration in which a DA converter 66 is added to the protection relay device 90A of Fig. 7. However, the input circuit 30A according to the second modification shown in Fig. 8 differs from the input circuit 30A of Fig. 7 in that it receives an input of a signal from the DA converter 66.

[0099] The arithmetic processing unit 70 outputs the DC voltage signal Vd as a digital signal to the DA converter 66. The DA converter 66 converts the test digital signal according to an instruction from the arithmetic processing unit 70 into an analog signal, and outputs the test analog signal to the filters 35-37.

[0100] As a result, filter 35 receives a signal in which the analog signal is superimposed on a signal corresponding to current Ia received from input converter 25. Filter 36 receives a signal in which the analog signal is superimposed on a signal corresponding to current Ib received from input converter 26. Filter 37 receives a signal in which the analog signal is superimposed on a signal corresponding to current Ic received from input converter 27. AD converter 65 therefore outputs to arithmetic processing unit 70 data obtained by digitally converting the three-phase currents Ia-Ic on which the analog signals are superimposed.

[0101] As described above, the input circuit 30A according to the second modification superimposes an analog signal on the three-phase currents Ia-Ic taken in from the power line L, and converts the three-phase currents Ia-Ic on which the analog signal is superimposed into digital data.

[0102] In variant example 2, for convenience, Ia, Ib, and Ic input from input circuit 20 to calculation processing unit 70 will be written as Ia1, Ib1, and Ic1, respectively, and Ia, Ib, and Ic input from input circuit 30A to calculation processing unit 70 will be written as Ia3, Ib3, and Ic3, respectively.

[0103] Arithmetic processing unit 70 compares the three-phase current received from input circuit 20 with the three-phase current received from input circuit 30A to determine whether or not there is an abnormality in either input circuit 20 or input circuit 30A.

[0104] Specifically, the calculation processing unit 70 compares the phase current received from the input circuit 20 with the phase current received from the input circuit 30A for each phase. For example, the A phase will be described. The calculation processing unit 70 judges whether or not the difference between the instantaneous value data of the current Ia1 received from the input circuit 20 and the instantaneous value data of the current Ia3 received from the input circuit 30A (i.e., Ia3-Ia1) is within a specified range. If the difference is outside the specified range, the calculation processing unit 70 judges that either the input circuit 20 or the input circuit 30A is abnormal. The specified range is determined based on the value of the DC voltage signal Vd. In detail, the calculation processing unit 70 judges whether or not the following formula (3) or formula (4) is satisfied.

[0105] Ia3-Ia1>Vd+ε …(3) Ia3-Ia1 <Vd-ε …(4) In equations (3) and (4), ε is a judgment threshold value (for example, 1 to 2% of the rated current). The value of the DC voltage signal Vd is a value obtained by digitally converting the test analog (i.e., DC voltage) signal from the DA converter 66, which has passed through the filter 35, by the AD converter 65. Typically, the filter 35 is configured as a low-pass filter that cuts harmonic components (for example, harmonic components that are several times or more higher than the system frequency), and therefore passes the DC component. This has the advantage that there is no need to calculate the effective value.

[0106] When both input circuits 20 and 30A are normal, the difference between current Ia1 and current Ia3 is approximately equal to DC voltage signal Vd. Therefore, neither equation (3) nor equation (4) holds. On the other hand, when either equation (3) or equation (4) holds, arithmetic processing unit 70 determines that either input circuit 20 or input circuit 30A is abnormal.

[0107] The arithmetic processing unit 70 may change the magnitude of the DC voltage signal Vd (i.e., the digital signal) from a low level to a high level in sequence at regular time intervals to determine whether the above formula (3) or (4) is satisfied. This makes it possible to check whether the linearity of the output of the input circuit 30A is normal.

[0108] In the above, a configuration has been described in which the digital signal following the instruction of the arithmetic processing unit 70 is the DC voltage signal Vd, but the digital signal may be the AC voltage signal Vs. For example, the DA converter 66 converts the AC voltage signal Vs into an analog signal and outputs it to the SH circuits 45-47. Since the three-phase currents Ia-Ic taken in from the power line L are in a three-phase balanced state, the sum of the currents Ia-Ic (i.e., Ia+Ib+Ic) is approximately zero. On the other hand, since the analog signals output from the DA converter 66 to the SH circuits 45-47 corresponding to the three phases are in phase, the sum of these is three times as large as the AC voltage signal Vs.

[0109] The calculation processing unit 70 calculates an effective value Iabc15r of the difference (i.e., Iabc5-Iabc1) between a sum current Iabc1 (=Ia1+Ib1+Ic1) of the instantaneous values ​​of the currents Ia1-Ic1 received from the input circuit 20 and a sum current Iabc5 (=Ia5+Ib5+Ic5) of the instantaneous values ​​of the currents Ia5-Ic5 received from the input circuit 30A. The calculation processing unit 70 determines whether or not there is an abnormality in either the input circuit 20 or the input circuit 30A using the effective value Iabc15r, the effective value Vsr of the AC voltage signal Vs, and the following equation (5).

[0110] Iabc15r>3×Vsr+ε …(5) where ε is a judgment threshold value (for example, 1 to 2% of the rated current). When the difference between the effective value Iabc15r and three times the effective value Vsr is greater than the judgment threshold value ε (i.e., when formula (5) is satisfied), the calculation processing unit 70 judges that an abnormality exists in either the input circuit 20 or the input circuit 30A.

[0111] In the above-mentioned variant example 2, the monitoring device 10 displays the abnormality determination results of the input circuits 20, 30A received from the calculation processing unit 70 on a display or the like, thereby enabling a system operator to constantly monitor the presence or absence of abnormalities in the input circuits 20, 30A from a remote location.

[0112] <Modification 3 (method of determining abnormality in input circuit)> Fig. 9 is a diagram showing an example of an overall configuration of a monitoring system 1000C according to a third modification of the first embodiment. With reference to Fig. 9, the monitoring system 1000C includes a monitoring device 10 and a protection relay device 90C. The protection relay device 90C includes an input circuit 20, a DA converter 66, an arithmetic processing unit 70, and a series circuit 80. That is, the protection relay device 90C has a configuration in which the input circuit 30A is deleted from the protection relay device 90B of Fig. 8. However, the input circuit 20 according to the third modification shown in Fig. 9 differs from the input circuit 20 of Fig. 1 in that it receives an input of a signal from the DA converter 66.

[0113] The arithmetic processing unit 70 outputs a digital signal (for example, a DC voltage signal Vd) to the DA converter 66. The DA converter 66 converts the digital signal according to an instruction from the arithmetic processing unit 70 into an analog signal, and outputs the analog signal to the filters 31-33. In this case, the input circuit 20 superimposes an analog signal on the three-phase currents Ia-Ic taken in from the power line L, and converts the three-phase currents Ia-Ic on which the analog signal is superimposed into digital data.

[0114] In the test mode (for example, when setting information for setting the control mode of the protective relay device 90C to the test mode is received from the monitoring device 10), the calculation processing unit 70 determines whether or not there is an abnormality in the input circuit 20 by comparing the three-phase current data received from the input circuit 20 when an analog signal is output from the DA converter 66 (i.e., when an analog signal is superimposed on the three-phase current acquired from the power line L) with the three-phase current data received from the input circuit 20 when an analog signal is not output (i.e., when an analog signal is not superimposed on the three-phase current acquired from the power line L).

[0115] For example, in the test mode, for the A phase, if the difference (i.e., Ia7-Ia8) between the current Ia7 obtained from the input circuit 20 when an analog signal is superimposed on the current Ia taken from the power line L and the current Ia8 obtained from the input circuit 20 when no analog signal is superimposed (i.e., Ia8=Ia) is outside a specified range, the calculation processing unit 70 judges that the input circuit 20 is abnormal. The judgment formula in this case corresponds to the formula (3) and formula (4) in which "Ia1" and "Ia3" are replaced with "Ia7" and "Ia8", respectively. Note that this judgment is based on the premise that, after the measurement of the current Ia8, the measurement of the current Ia7 is performed within a certain time after the superimposition of the analog signal (for example, a time longer than the convergence time of the transient change of the filter 35 due to the superimposition of the analog signal and within a time during which there is no change in the load current), and a comparison process between the current Ia7 and the current Ia8 is performed. The certain period of time is, for example, about several hundreds of milliseconds to 1 second.

[0116] The monitoring device 10 displays the abnormality determination result of the input circuit 20 received from the arithmetic processing unit 70 on a display or the like. This allows the system operator to constantly monitor the presence or absence of an abnormality in the input circuit 20 from a remote location.

[0117] The signal input from the input circuit 20 to the arithmetic processing unit 70 is used for the relay calculation. Therefore, when the arithmetic processing unit 70 uses the DA converter 66 to superimpose an analog signal on the three-phase current taken in from the power line L, the arithmetic processing unit 70 executes the relay calculation based on data obtained by subtracting the superimposed digital signal from the data of the three-phase current received from the input circuit 20.

[0118] According to the protective relay device 90C shown in FIG. 9, the input circuits 30, 30A are not necessary, and therefore the presence or absence of an abnormality in the input circuit 20 can be constantly monitored from a distance with a simple configuration.

[0119] <Other> (1) In the above-described first embodiment, the input circuits 20 and 30A receive the three-phase currents Ia to Ic, and the input circuit 30 receives the zero-phase current 3I0. However, the present invention is not limited to this configuration. For example, the input circuits 20 and 30A may receive the voltage Va of the A-phase power line 11, the voltage Vb of the B-phase power line 12, and the voltage Vc of the C-phase power line 13, and the input circuit 30 may receive the zero-phase voltage 3V0 (i.e., 3V0=Va+Vb+Vc).

[0120] In this case, "I" indicating current in equations (1) to (5) is replaced with "V" indicating voltage. The same applies to the effective value of the current. Therefore, the input circuits 20 and 30A may be configured to receive a three-phase electric quantity (e.g., a three-phase current or a three-phase voltage) of the power system and convert the three-phase electric quantity into digital data. The input circuit 30 may be configured to receive a zero-phase electric quantity (e.g., a zero-phase current or a zero-phase voltage) of the power line L and convert the zero-phase electric quantity into digital data.

[0121] In this case, the calculation processing unit 70 judges the normality of the input circuits 20, 30, and 30A using the three-phase electric quantity and the zero-phase electric quantity, etc. For example, the calculation processing unit 70 judges whether or not there is an abnormality in either the input circuit 20 or the input circuit 30 by comparing the three-phase electric quantity received from the input circuit 20 with the zero-phase electric quantity received from the input circuit 30. Alternatively, the calculation processing unit 70 judges whether or not there is an abnormality in either the input circuit 20 or the input circuit 30A by comparing the three-phase electric quantity received from the input circuit 20 with the three-phase electric quantity received from the input circuit 30A.

[0122] (2) In the above-mentioned first embodiment, the calculation processing unit 70 determines the normality of the input circuits 20, 30, and 30A. However, the present invention is not limited to this configuration. For example, the calculation processing unit 70 transmits the calculation values ​​(e.g., each effective value, etc.) used in the above-mentioned determination to the monitoring device 10. The monitoring device 10 may use the received calculation values ​​to determine the normality of the input circuits 20, 30, and 30A using the above-mentioned determination method.

[0123] Embodiment 2 In the second embodiment, a configuration will be described in which the monitoring device 10 determines the normality of the input circuits of the multiple protection relay devices 90 by using the electrical quantity acquired in each of the multiple protection relay devices 90.

[0124] Fig. 10 is a diagram showing an example of a configuration of a monitoring system 1000D according to the embodiment 2. Referring to Fig. 10, the monitoring system 1000D includes a monitoring device 10 and a plurality of protection relay devices 90_1-90_8.

[0125] The power system shown in Fig. 10 is a three-phase power system including a bus J and a plurality of lines (e.g., feeder lines) K1 to K8. Each of the protective relay devices 90_1 to 90_8 is any one of the protective relay devices 90, 90A, 90B, and 90C described above. Each of the protective relay devices 90_1 to 90_8 may have a configuration in which the input circuit 30 is removed from the protective relay device 90 shown in Fig. 1.

[0126] CT2_1 to 2_8 detect currents I1 to I8 on the lines K1 to K8, respectively. The currents I1 to I8 are assumed to be CT primary currents converted based on the input current to the protective relay device 90 and the CT ratio. VT3_1 to 3_3 detect the voltage of the bus J. For convenience, the voltages detected in VT3_1 to 3_3 are referred to as V1 to V3, respectively. VT3_4 and 3_5 detect the voltage of the line K5. For convenience, the voltages detected in VT3_4 and 3_5 are referred to as V4 and V5, respectively. VT3_6 to 3_8 detect voltages V6 to V8 on the lines K6 to K8, respectively. The voltages V1 to V8 are assumed to be VT primary voltages converted based on the input voltage to the protective relay device 90 and the VT ratio.

[0127] The protective relay devices 90_1-90_8 receive inputs of currents I1-I8, respectively. The protective relay devices 90_1-90_8 receive inputs of voltages V1-V8, respectively. The monitoring device 10 receives, from each of the multiple protective relay devices 90_1-90_8, data of electrical quantities (i.e., currents and voltages) acquired in the protective relay device.

[0128] The monitoring device 10 determines whether or not there is an abnormality in any of the multiple input circuits 20 included in each of the multiple protection relay devices 90_1 to 90_8, based on multiple electrical quantity data (e.g., currents I1 to I8 and voltages V1 to V8) received from the multiple protection relay devices 90_1 to 90_8.

[0129] The line K1 branches into lines K2 and K3 via a bus J, the line K2 branches into lines K4 and K5, and the line K3 branches into lines K6 and K7. The line K8 is connected to the line K6 via a transformer 19.

[0130] From the above, when all the input circuits 20 included in each of the protective relay devices 90_1 to 90_8 are normal, the following conditions are satisfied with respect to current: M1 “I1=I2+I3”, M2 “I2=I4+I5”, M3 “I3=I6+I7”, and M4 “I6=TX1×I8”. The coefficient TX1 is a current coefficient based on the transformation ratio of the transformer 19.

[0131] When all of the conditions M1 to M4 are satisfied within an expected error range, the monitoring device 10 determines that the input circuits 20 included in each of the protection relay devices 90_1 to 90_8 are normal. On the other hand, when any of the conditions M1 to M4 are not satisfied, the monitoring device 10 determines that any of the input circuits 20 included in each of the protection relay devices 90_1 to 90_8 is abnormal. For example, when the condition M1 is satisfied but the condition M2 is not satisfied, the monitoring device 10 determines that any of the input circuits 20 included in the protection relay devices 90_4, 90_5 is abnormal.

[0132] In reality, a charging current to the ground occurs due to the capacitance of the power line to the ground according to the distance between each protective relay installation 90, so this charging current must be taken into consideration under the above conditions. However, since the capacitance of the power line to the ground can be calculated from the system voltage, it may be ignored when the above distance is short (for example, 1 km or less).

[0133] Furthermore, when all the input circuits 20 included in each of the protective relay devices 90_1 to 90_8 are normal, the following conditions are satisfied with respect to voltage: condition N1 "V1=V2=V3", condition N2 "V4=V5", condition N3 "V1=V4+Zef×I2", condition N4 "V3=V6+Zeg×I3", condition N5 "V6=V7+Zgh×I7", and condition N6 "V8=TX2×V6". Note that Zef is the line impedance between points E and F. Zeg is the line impedance between points E and G. Zgh is the line impedance between points G and H. Coefficient TX2 is a voltage coefficient based on the transformation ratio of transformer 19.

[0134] When all of the conditions N1 to N6 are satisfied within an expected error range, the monitoring device 10 determines that the input circuits 20 included in each of the protection relay devices 90_1 to 90_8 are normal. On the other hand, when any of the conditions N1 to N6 are not satisfied, the monitoring device 10 determines that any of the input circuits 20 included in each of the protection relay devices 90_1 to 90_8 is abnormal. For example, when the condition N2 is not satisfied, the monitoring device 10 determines that any of the input circuits 20 included in the protection relay devices 90_4, 90_5 is abnormal.

[0135] According to the second embodiment, by using data on the amount of electricity obtained from a plurality of protective relay devices, the monitoring device 10 can monitor the normality of the input circuit included in each protective relay device.

[0136] Other embodiments. (1) In the above-described embodiment, the arithmetic processing unit 70 may be configured to forcibly output an operation signal in accordance with instruction information from the monitoring device 10 in the test mode.

[0137] (2) The configurations exemplified as the above-mentioned embodiments are examples of the configurations of the present disclosure, and may be combined with other known technologies, or may be modified, such as by omitting some parts, without departing from the scope of the present disclosure. In addition, the above-mentioned embodiments may be implemented by appropriately adopting the processes and configurations described in other embodiments.

[0138] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0139] Various aspects of the present disclosure are summarized below as appendices.

[0140] (Appendix 1) The present invention relates to a protective relay device for protecting an electric power system, a monitoring device for setting a control mode of the protective relay device to a normal mode or a test mode, and a circuit breaker tripping circuit, the protective relay device including an arithmetic processing unit that executes a relay operation using an electrical quantity of the electric power system and outputs an operation signal based on a result of the relay operation, and a series circuit, the series circuit including a first digital output circuit having a first contact one end of which is connected to a power source, a second digital output circuit having a second contact one end of which is connected to the other end of the first contact, and a digital input circuit one end of which is connected to the other end of the second contact, the first contact is closed when the operation signal is output and the second contact is opened in the normal mode, and the test mode is a normal mode. a tripping circuit that is closed in a standby mode, the digital input circuit outputting a first signal to the arithmetic processing unit when receiving a current input via the first contact and the second contact, the tripping circuit including a first auxiliary contact, a series body having a second auxiliary contact and a first resistor, and a tripping coil, one end of each of the first auxiliary contact and the series body being connected to the other end of the digital input circuit, and the other end of each of the first auxiliary contact and the series body being connected to the tripping coil, when the circuit breaker is closed, the first auxiliary contact is closed and the second auxiliary contact is open, and when the circuit breaker is open, the first auxiliary contact is open and the second auxiliary contact is closed.

[0141] (Appendix 2) 2. The monitoring system of claim 1, wherein the digital input circuit includes a photocoupler and a second resistor, one end of the second resistor is connected to the other end of the second contact, the other end of the second resistor is connected to one end of the photocoupler, and the other end of the photocoupler is connected to the trip circuit.

[0142] (Appendix 3) The monitoring system of Appendix 2, wherein the second digital output circuit further includes a third contact having one end connected to the power supply and the other end connected to one end of the second resistor, and a fourth contact having one end connected to the other end of the first contact and the other end connected to the tripping circuit, each of the third contact and the fourth contact being closed in the normal mode and open in the test mode.

[0143] (Appendix 4) The monitoring system of any one of Supplementary Note 1 to Supplementary Note 3, wherein the series circuit further includes a first connection line connecting the first digital output circuit and the second digital output circuit, and a second connection line connecting the second digital output circuit and the digital input circuit.

[0144] (Appendix 5) The monitoring system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the protective relay device further includes a first input circuit that takes in a three-phase electric quantity of the power system and converts the three-phase electric quantity into digital data, and a second input circuit that takes in a zero-phase electric quantity of the power system and converts the zero-phase electric quantity into digital data, and the arithmetic processing unit determines whether or not there is an abnormality in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the zero-phase electric quantity received from the second input circuit, and transmits the result of the determination to the monitoring device.

[0145] (Appendix 6) The monitoring system of claim 5, wherein when an absolute value of a difference between the effective value of the sum of three-phase electric quantities received from the first input circuit and the effective value of the zero-phase electric quantity received from the second input circuit is greater than a first threshold value, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal.

[0146] (Appendix 7) The monitoring system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the protective relay device further includes a first input circuit that takes in a three-phase electric quantity of the power system and converts the three-phase electric quantity into digital data, and a second input circuit that takes in the three-phase electric quantity of the power system and converts the three-phase electric quantity into digital data, and the arithmetic processing unit determines whether or not there is an abnormality in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the three-phase electric quantity received from the second input circuit, and transmits the result of the determination to the monitoring device.

[0147] (Appendix 8) The monitoring system of claim 7, wherein when an absolute value of a difference between an effective value of a first phase electric quantity among the three-phase electric quantities received from the first input circuit and an effective value of a first phase electric quantity among the three-phase electric quantities received from the second input circuit is greater than a second threshold value, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal.

[0148] (Appendix 9) The monitoring system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the protective relay device includes a first input circuit that takes in a three-phase electric quantity of the power system and converts the three-phase electric quantity into digital data, a converter that converts a digital signal according to an instruction of the arithmetic processing unit into an analog signal, and a second input circuit that takes in a three-phase electric quantity of the power system, superimposes the analog signal on the three-phase electric quantity, and converts the three-phase electric quantity with the analog signal superimposed thereon into digital data, and the arithmetic processing unit determines whether or not there is an abnormality in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the three-phase electric quantity received from the second input circuit, and transmits the result of the determination to the monitoring device.

[0149] (Appendix 10) The monitoring system of claim 9, wherein when a difference between a first phase electric quantity of the three-phase electric quantities received from the first input circuit and a first phase electric quantity of the three-phase electric quantities received from the second input circuit is outside a specified range, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal, and the specified range is determined based on the magnitude of the digital signal.

[0150] (Appendix 11) 5. The monitoring system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the protective relay device includes a converter that converts a digital signal according to an instruction of the arithmetic processing unit into an analog signal, and an input circuit that takes in a three-phase electric quantity of the power system and converts the three-phase electric quantity into digital data, and when the analog signal is output from the converter, the input circuit superimposes the analog signal on the three-phase electric quantity of the power system and converts the three-phase electric quantity superimposed with the analog signal into digital data, and the arithmetic processing unit determines whether or not there is an abnormality in the input circuit by comparing the three-phase electric quantity received from the input circuit when the analog signal is not output with the three-phase electric quantity received from the input circuit when the analog signal is output, and transmits the result of the determination to the monitoring device.

[0151] (Appendix 12) The monitoring system according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the protective relay device includes an input circuit that takes in an electrical quantity of the power system and converts the electrical quantity into digital data, and the monitoring device receives, from each of the multiple protective relay devices, data on the electrical quantity acquired in the protective relay device, and determines whether or not there is an abnormality in any of the multiple input circuits included in each of the multiple protective relay devices, based on the multiple pieces of data on the electrical quantities received from the multiple protective relay devices. [Explanation of symbols]

[0152] 10 monitoring device, L power line, 19 transformer, 20, 30, 30A input circuit, 21-27 input converter, 31-37 filter, 41-47 SH circuit, 51, 54, 55 multiplexer, 61, 64, 65 AD converter, 66 DA converter, 70 calculation processing unit, 72 CPU, 74 ROM, 80 series circuit, 82, 83, 84, 85 contact, 86, 92 resistor, 87 photocoupler, 90, 90A, 90B, 90C protective relay device, 94, 96 auxiliary contact, 98 tripping coil, 99 series body, 110, 120 DO circuit, 130 DI circuit, 140 tripping circuit, 1000, 1000A-1000D monitoring system, BN, BP power supply.

Claims

1. A protective relay device for protecting a power system; A monitoring device that sets a control mode of the protection relay device to a normal mode or a test mode; A circuit breaker tripping circuit, The protective relay device includes: a processor that performs a relay calculation using an electrical quantity of the power system and outputs an operation signal based on a result of the relay calculation; a series circuit; The series circuit includes: a first digital output circuit having a first contact connected at one end to a power source; a second digital output circuit having a second contact, one end of which is connected to the other end of the first contact; a digital input circuit having one end connected to the other end of the second contact; the first contact is closed when the operation signal is output; the second contact is open in the normal mode and closed in the test mode; the digital input circuit outputs a first signal to the arithmetic processing unit when a current is input via the first contact and the second contact; the tripping circuit includes a first auxiliary contact, a series element having a second auxiliary contact and a first resistor, and a tripping coil; one end of each of the first auxiliary contact and the series body is connected to the other end of the digital input circuit, and the other end of each of the first auxiliary contact and the series body is connected to the tripping coil; When the circuit breaker is closed, the first auxiliary contact is closed and the second auxiliary contact is open, and when the circuit breaker is open, the first auxiliary contact is open and the second auxiliary contact is closed.

2. the digital input circuit includes a photocoupler and a second resistor; one end of the second resistor is connected to the other end of the second contact, and the other end of the second resistor is connected to one end of the photocoupler; The monitoring system according to claim 1 , wherein the other end of the photocoupler is connected to the tripping circuit.

3. The second digital output circuit is a third contact having one end connected to the power source and the other end connected to one end of the second resistor; a fourth contact having one end connected to the other end of the first contact and the other end connected to the tripping circuit; 3. The monitoring system of claim 2, wherein each of the third contact and the fourth contact is closed in the normal mode and open in the test mode.

4. The monitoring system according to any one of claims 1 to 3, wherein the series circuit further includes a first connection line connecting the first digital output circuit and the second digital output circuit, and a second connection line connecting the second digital output circuit and the digital input circuit.

5. The protective relay device includes: a first input circuit for inputting a three-phase electrical quantity of the power system and converting the three-phase electrical quantity into digital data; a second input circuit for receiving a zero-phase electric quantity of the power system and converting the zero-phase electric quantity into digital data; The arithmetic processing unit is determining whether or not an abnormality exists in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the zero-phase electric quantity received from the second input circuit; 4. The monitoring system according to claim 1, wherein a result of the determination is transmitted to the monitoring device.

6. 6. The monitoring system according to claim 5, wherein when an absolute value of a difference between an effective value of a sum of three-phase electric quantities received from the first input circuit and an effective value of a zero-phase electric quantity received from the second input circuit is greater than a first threshold value, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal.

7. The protective relay device includes: a first input circuit for inputting a three-phase electrical quantity of the power system and converting the three-phase electrical quantity into digital data; a second input circuit for inputting a three-phase electrical quantity of the power system and converting the three-phase electrical quantity into digital data; The arithmetic processing unit is determining whether or not an abnormality exists in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the three-phase electric quantity received from the second input circuit; 4. The monitoring system according to claim 1, wherein a result of the determination is transmitted to the monitoring device.

8. 8. The monitoring system according to claim 7, wherein when an absolute value of a difference between an effective value of a first phase electric quantity among the three-phase electric quantities received from the first input circuit and an effective value of a first phase electric quantity among the three-phase electric quantities received from the second input circuit is greater than a second threshold value, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal.

9. The protective relay device includes: a first input circuit for inputting a three-phase electrical quantity of the power system and converting the three-phase electrical quantity into digital data; a converter for converting a digital signal according to an instruction from the arithmetic processing unit into an analog signal; a second input circuit that takes in a three-phase electrical quantity of the power system, superimposes the analog signal on the three-phase electrical quantity, and converts the three-phase electrical quantity on which the analog signal is superimposed into digital data; The arithmetic processing unit is determining whether or not an abnormality exists in either the first input circuit or the second input circuit by comparing the three-phase electric quantity received from the first input circuit with the three-phase electric quantity received from the second input circuit; 4. The monitoring system according to claim 1, wherein a result of the determination is transmitted to the monitoring device.

10. when a difference between a first phase electric quantity of the three-phase electric quantities received from the first input circuit and a first phase electric quantity of the three-phase electric quantities received from the second input circuit is outside a specified range, the calculation processing unit determines that either the first input circuit or the second input circuit is abnormal; The monitoring system according to claim 9 , wherein the prescribed range is determined based on a magnitude of the digital signal.

11. The protective relay device includes: a converter for converting a digital signal according to an instruction from the arithmetic processing unit into an analog signal; an input circuit for inputting a three-phase electrical quantity of the power system and converting the three-phase electrical quantity into digital data; When the analog signal is output from the converter, the input circuit superimposes the analog signal on a three-phase electrical quantity of the power system and converts the three-phase electrical quantity on which the analog signal is superimposed into digital data; The arithmetic processing unit is determining whether or not there is an abnormality in the input circuit by comparing a three-phase electric quantity received from the input circuit when the analog signal is not output with a three-phase electric quantity received from the input circuit when the analog signal is output; 4. The monitoring system according to claim 1, wherein a result of the determination is transmitted to the monitoring device.

12. The protective relay device includes an input circuit that receives an electrical quantity of the power system and converts the electrical quantity into digital data; The monitoring device includes: receiving, from each of the plurality of protective relay devices, data of an electrical quantity acquired in the protective relay device; The monitoring system according to any one of claims 1 to 3, wherein a determination is made as to whether or not there is an abnormality in any of the input circuits included in each of the protection relay devices based on the data of the electrical quantities received from the protection relay devices.

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