JP6428355B2 - Digital protection relay - Google Patents

Description

  The present invention relates to a digital protection relay having a test function for a circuit breaker trip circuit.

  The digital protection relay monitors a system failure including an accident, and operates a circuit breaker installed in the power system in response to an abnormal increase in voltage or current, etc., thereby disconnecting the failure section from the power system. Therefore, it is required that the circuit breaker operates reliably when the system fails.

  In order to check whether the circuit breaker operates reliably, it is ideal to conduct an operation test of the circuit breaker by supplying a current to the circuit breaker trip circuit with the circuit breaker and circuit breaker trip circuit combined. However, an unnecessary power failure occurs due to the breaking operation of the circuit breaker. Therefore, conventionally, an operation test has been performed with the breaker disconnected from the power system.

  However, such a test requires a lot of time and effort because the circuit breaker needs to be removed and reassembled.

  In order to solve such a problem, a digital protection relay having a test function for a circuit breaker tripping circuit used to operate the circuit breaker with the circuit breaker installed in the power system has been proposed. ing.

  The protective relay (digital protection relay) disclosed in Patent Document 1 is a current to a circuit breaker tripping circuit in which a circuit breaker tripping coil and a circuit breaker auxiliary contact linked to the circuit breaker opening / closing are connected in series. An on-off relay having a contact for opening and closing the path, and a path switching relay having a contact for switching between a current path at the time of testing the circuit breaker tripping circuit and a current path at the time of actual use. A resistance element for reducing the current flowing through the circuit breaker tripping coil to a value that does not cause the circuit breaker operation is inserted in the current path during the test of the circuit breaker trip circuit. The switching relay is closed when the power system fails during actual use, and also when the circuit breaker trip circuit is tested.

  With such a configuration, the current flowing through the circuit breaker trip coil during the test of the circuit breaker trip circuit is suppressed to a value equal to or less than the current value at which the circuit breaker does not operate. Therefore, in this protective relay, it is possible to test the circuit breaker trip circuit with the circuit breaker installed in the power system.

JP 2011-258375 A

  In the protective relay (digital protection relay) disclosed in Patent Document 1, during the test, the path switching relay must operate reliably to switch the current path to the current path in which the resistance element is inserted. This is because if a failure occurs in the path switching relay and the current path is not switched, closing the contact point of the switching relay by performing a test will cause the circuit breaker to operate and cause an unnecessary power failure. . However, in the invention disclosed in Patent Document 1, since it cannot be confirmed that there is no abnormality in the path switching relay, the risk of circuit breaker malfunction due to the test cannot be eliminated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a digital protection relay that can prevent malfunction of a circuit breaker that may occur when the soundness of a circuit breaker tripping circuit is confirmed. And

  A digital type protective relay according to the present invention is a digital type having a soundness test function of a circuit breaker tripping circuit installed between a pair of power lines in order to operate a circuit breaker installed for protecting a power system. A protective relay that is connected in series to the circuit breaker trip circuit, opens and closes a current path to the circuit breaker trip circuit, a first connection point to which the switch unit is connected, and the power A second connection point that forms a current path to the circuit breaker tripping circuit when protecting the system; and a third connection point; and a connection destination of the first connection point is the second connection point. A switching unit that switches to one of the point and the third connection point, and one of the second connection point and one of the pair of power lines to which the circuit breaker trip circuit is connected Between one and the first connection point The resistance element connected in parallel with the switching unit, the end of the opening / closing unit opposite to the end connected to the switching unit, and the opening / closing unit between the third connection point A current detection unit that is installed on the parallel current path and outputs a detection signal when a current flows through the parallel current path; and the opening / closing unit and the switching unit are set in advance during the soundness test. And a control unit configured to determine whether to stop or continue the soundness test based on the presence or absence of the detection signal when operation control is performed.

  According to the digital type protective relay according to the present invention, it is possible to prevent the malfunction of the circuit breaker that may occur when the soundness of the circuit breaker tripping circuit is confirmed.

It is a figure which shows the structural example of the digital type protection relay which concerns on Embodiment 1 of this invention. FIG. 3 is a diagram illustrating a configuration example of a control unit of the digital protection relay according to the first embodiment. FIG. 5 is a diagram for explaining details of operations during normal use and during testing of the digital protection relay according to the first embodiment. 3 is a flowchart showing an operation at the time of a test of the digital protection relay according to the first embodiment. It is a figure which shows the structural example of the digital type protection relay which concerns on Embodiment 2 of this invention. FIG. 10 is a diagram for explaining details of an operation during a test of the digital protection relay according to the second embodiment. It is a figure which shows the structural example of the digital type protection relay which concerns on Embodiment 3 of this invention.

(Embodiment 1)
A digital protection relay according to Embodiment 1 of the present invention will be described with reference to FIG. As shown in FIG. 1, the digital protection relay 1 and the circuit breaker tripping circuit 2 are connected in series with each other and are disposed between the positive power line P and the negative power line N. Connected. In the power system corresponding to the power lines P and N, a circuit breaker (not shown) driven by the digital protection relay 1 is installed. When a failure occurs in the electric power system and an abnormal current flows, the digital protection relay 1 detects the occurrence of the failure by an abnormality detection unit (not shown) and energizes the circuit breaker tripping circuit 2 Activate this. When the circuit breaker tripping circuit 2 is activated, a circuit breaker (not shown) installed in the power system in which the failure has occurred performs a circuit breaking operation.

  The digital protection relay 1 includes a control unit 10, a test setting unit 11, a relay 12, a relay 14, a current detection unit 16, and a resistance element 17.

  The test setting unit 11 includes a keyboard or switches, and inputs an instruction to start a test of the digital protection relay 1. The test setting unit 11 transmits a test start signal to the control unit 10 based on this instruction.

  The relay 12 includes an open / close contact 13 and a coil X for driving the open / close contact 13. When the relay 12 is OFF, no current flows through the coil X, and as shown in the figure, the switching contact 13 is arranged so that the point a and the point b are open. When the relay 12 is ON, the coil X is energized. As a result, the switching contact 13 is driven, and the point a and the point b are changed from the open state to the closed state. That is, the relay 12 opens and closes between the points a and b by turning on and off. Therefore, the relay 12 can be referred to as an opening / closing part.

  The relay 14 includes a switching contact 15 and a coil Y for driving the switching contact 15. One end of the switching contact 15 is connected to the point c. The switching contact 15 is in a position where the other end contacts the point d when the relay 14 is OFF. When the relay 14 is ON, the coil Y is energized and the other end of the switching contact 15 is driven to a position in contact with the point e, so that the switching contact 15 connects the point c and the point e. In other words, the relay 14 switches the connection path of the switching contact 15 between the path between the points cd and the path between the points ce by turning on and off. Therefore, it can be said that the relay 14 is a switching unit 14 that switches a route.

  The point a of the relay 12 is connected to the power line P, and the point b is connected to the point c of the relay 14. Therefore, relays 12 and 14 are connected in series. The point d of the relay 14 is connected to one end of the circuit breaker trip circuit 2. A point e of the relay 14 is connected to one end of the current detection unit 16.

  The current detection unit 16 is configured by an ammeter, for example. The current detection unit 16 is connected between the point h between the power line P and the point a of the relay 12 and the point e of the relay 14, detects the presence or absence of current flowing through the connected line, and detects a current detection signal. Is output to the control unit 10. The current detection unit 16 may use a photocoupler. At this time, since the current detection signal is input to the control unit 10 via the photocoupler, interference from the current detection unit 16 with respect to the control unit 10 can be avoided.

  The resistance element 17 (indicated by “R” in FIG. 1) includes a point i that is between a point b of the relay 12 and a point c of the relay 14, a point d of the relay 14, and the circuit breaker tripping circuit 2. Connected to a point j between. The resistance value of the resistance element 17 will be described later.

  The controller 10 controls the operation of the circuit breaker, executes an abnormality diagnosis test, and determines an abnormality from the result of the test by inputting various signals and controlling the ON and OFF instructions for the relays 12 and 14 based on the input signals. Control is performed to output the determination result to an output device (not shown) as necessary.

  Specifically, the control unit 10 performs control in the normal use mode unless otherwise specified. When a test start signal is input via the test setting unit 11, control in the test mode is performed. The normal use mode means that the digital protection relay 1 is in a state where the circuit breaker can be operated when the power system fails. At this time, the control unit 10 outputs an OFF instruction to the relay 14. In this state, a state where no failure has occurred in the power system is referred to as “steady state”. At this time, the control unit 10 outputs an OFF instruction to the relay 12. As a result, the switching contact 13 is opened, and no current flows through the circuit breaker tripping circuit 2. On the other hand, a state where a failure has occurred in the power system is referred to as “at the time of failure”. At this time, the control unit 10 outputs an ON instruction to the relay 12 based on the input abnormality detection signal. As a result, the switching contact 13 is closed, and a current sufficient to activate the circuit breaker flows in the circuit breaker tripping circuit 2.

  The open / closed state of the various contacts shown in FIG. 1 is a normal use mode state, and indicates a “steady state” state in which no failure has occurred in the power system.

  The test mode is a state of the digital protection relay 1 when diagnosing the soundness of the relays 12 and 14 and the circuit breaker tripping circuit 2. In the test mode, the control unit 10 performs control to execute a plurality of tests corresponding to a plurality of combinations of ON / OFF instructions for the relays 12 and 14. The control unit 10 inputs a current detection signal obtained at a predetermined test, determines whether to continue or stop the test from the input current detection signal, and when the test is continued, based on the current detection signal for each test, 12, 14 and the circuit breaker tripping circuit 2 are judged to be sound, and a control result is output.

  As illustrated in FIG. 2, the control unit 10 includes a CPU (Central Processing Unit) 100, a memory 110, a memory 120, an input unit 130, an output unit 140, and a bus line 150. The bus line 150 is a signal transmission / reception line that connects these components.

  The input unit 130 inputs the abnormality detection signal, the current detection signal output from the current detection unit 16, and the test start signal output from the test setting unit 11, and transmits them to the CPU 100.

  The memory 110 is configured by an SRAM (Static Random Access Memory) or the like, and is used as a temporary storage unit for data being processed by the CPU 100, processing results, and the like as a working memory of the CPU 100. The memory 120 is configured by an SRAM or the like, and is used for storing data to be saved and processing programs including processing results in the CPU 100.

  The CPU 100 implements various functions of the control unit 10 by reading and executing a processing program stored in the memory 120 at the start of operation. Specifically, based on the presence or absence of a test start signal input from the test setting unit 11 via the input unit 130, switching control between the above-described normal use mode and test mode is performed. The CPU 100 outputs ON / OFF instruction signals to the relays 12 and 14 via the output unit 140 corresponding to each mode. In the test mode, control is performed to execute multiple tests, and based on the current detection signal that is input at that time, control is performed to determine whether to stop or continue the test. Whether the relays 12 and 14 and the circuit breaker tripping circuit 2 are abnormal is determined based on the test execution control and the presence or absence of a current detection signal at each test. The determination result is output to an output device (not shown) via the output unit 140. The output device is a display device or a printer.

  The circuit breaker trip circuit 2 includes a circuit breaker trip coil 20 (indicated as “TC” in FIG. 1) and a circuit breaker auxiliary contact 21 connected in series thereto.

  The circuit breaker auxiliary contact 21 is in a closed state at times other than the time of system failure in the normal use mode. In the event of a system failure, after a predetermined time has elapsed after the operation of the circuit breaker, the point f and the point g are changed from the closed state to the open state, the system failure is recovered, and the relay 12 returns to the closed state after the relay 12 is turned off.

  The circuit breaker tripping coil 20 operates a circuit breaker installed in the power system when a current greater than a set value flows therethrough. Thereby, an electric power system is interrupted | blocked in the location in which the circuit breaker was installed.

  The operation in the normal use mode and the test mode of the digital protection relay 1 configured as described above will be described with reference to FIG. 3, and the operation in the test mode will be described with reference to FIG. The “mode” at the upper left end of FIG. 3 indicates whether the digital protection relay 1 is in the normal use mode or the test mode. “In use” in FIG. 3 indicates that the digital protection relay 1 is in the normal use mode, and “during test” indicates that the digital protection relay 1 is in the test mode. “In use” includes two situations, “a steady state” in which no failure has occurred in the power system and “at a failure” in which a failure has occurred. Normally, it is “in a steady state”, and the control unit 10 determines “at the time of failure” when an abnormality detection signal is input. In addition, when a test start signal is input via the test setting unit 11, the control unit 10 determines “at the time of test” and basically executes tests from tests A to E. FIG. 4 is a flowchart showing the operation of the control unit 10 of the digital protection relay 1 in each test shown in FIG.

  “At the time of test” is composed of five types of tests from “Test A” to “Test E”, and each test is executed by changing the ON / OFF instruction of the relays 12 and 14. The control unit 10 monitors whether or not a current detection signal is output from the current detection unit 16 at that time, and performs various determinations or abnormality diagnosis based on the information. In the following, when “testing”, “failure”, and “test A” to “test E” are not distinguished, each is referred to as “mode”.

The “relay instruction” column of “instruction / situation” at the upper left of FIG. 3 is ON for the relay 12 (described as “X”) and the relay 14 (described as “Y”) of the control unit 10 in each mode. / OFF instruction, and the “breaker status” column indicates the open / close status of the breaker at that time. The “PC” column shows the current detection result by the current detector 16, and each number in the “possible situation” column shows the circuit breaker tripping when the PC at each test is ON or OFF, respectively. Circuit 2 (in this description, in FIG. 3 and FIG. 4, “TC” representing the circuit breaker tripping coil 20 is substituted), relay 12 (abbreviated as X), and relay 14 (abbreviated as Y) It shows what judgment can be made about the abnormality. In the “Remarks” column, the TC, X, and Y diagnostic results based on the PC results of tests B and C are shown, as well as the cancellation of the test from the viewpoint of preventing the circuit breaker from malfunctioning. ing. Note that “relay instruction” indicates an instruction for X to be in an open state when the switch is “OFF” and an instruction to be in a closed state when it is “ON”. For Y, when “OFF”, the switching contact 15 is driven to connect between the points c and d, and when “ON”, the switching contact 15 connects between the points c and e. Represents an instruction to be driven as follows. “OFF” in the PC column indicates a situation in which no current flows through the current detection unit 16, and “ON” indicates a situation in which a predetermined current flows. The predetermined current is that current I _R flowing through when connecting the power line P and N via the resistor element R, including the scope of the current in consideration of the variation in voltage between power lines P and N.

  The description of the “PC” and “Breaker status” column of “In Use” in FIG. 3 is shown in the “Relay Instruction” column for X and Y in “Normal” and “Failure”, respectively. The current detection result (PC ON / OFF) and the circuit breaker switching state when the ON / OFF instruction is controlled and the relays 12 and 14 operate as instructed without any abnormality are shown.

  The description in the “PC” column and “Circuit breaker status” column of “At test” in FIG. 3 is the PC when the ON / OFF instruction control for X and Y is scheduled at the time of each test. And the circuit breaker switching status. The tests are from tests A to E. The purpose of the test is to determine whether or not there is a possibility of malfunction of the circuit breaker when performing the test for checking the presence or absence of TC abnormality, and X, Y, and It is to diagnose whether there is an abnormality in TC.

  In the “steady state” in “in use” of FIG. 3, that is, when there is no failure in the power system in the normal use mode, the control unit 10 issues an OFF instruction to both the relays 12 and 14. ing. Therefore, X and Y are in the OFF state. That is, in FIG. 1, the switching contact 13 is in an open state, and the switching contact 15 connects the points c and d. At this time, the current detection unit 16 is disconnected from the current path and is in an OFF state in which no current detection signal is output. Therefore, the PC column in FIG. 3 is OFF. Even when there is no failure in the circuit breaker tripping circuit 2, no current flows through the circuit breaker tripping coil 20 when both the relays 12 and 14 are OFF. Therefore, the circuit breaker is in a closed state. The failure of the circuit breaker tripping circuit 2 means that the circuit breaker tripping coil 20 is partially broken, the circuit breaker auxiliary contact 21 that should be normally closed is open, etc. This means that a situation has occurred in which the circuit breaker tripping coil 20 cannot be energized.

  When “failure” in “in use” of FIG. 3, that is, when a failure occurs in the power system in the normal use mode, the control unit 10 keeps the relay 14 off and instructs the relay 12 to turn on. put out. Therefore, Y remains OFF, X becomes ON, and the switching contact 13 shown in FIG. 1 is closed. Then, when there is no abnormality in the circuit breaker tripping circuit 2, a current path in which the impedance Z of the circuit breaker tripping coil 20 is connected between the power lines P and N is formed. At this time, a current determined by the potential difference V between the power lines P and N and the impedance Z flows through the breaker tripping coil 20. Therefore, a current I (= V / Z) sufficient to operate the circuit breaker flows through the circuit breaker tripping coil 20. As a result, the circuit breaker is opened, and the failed power system is disconnected from the other power systems.

  Details of tests A to E will be described with reference to FIGS. 1 and 3, focusing on FIG. 4. Tests A to E are executed according to each step (ST) shown in the flowchart shown in FIG. 4 under the control of the control unit 10. The test starts with test A (ST1). Since the test is started when “in use” and “steady state”, as shown in FIG. 3, both X and Y are OFF, that is, the control unit 10 issues an OFF instruction to the relays 12 and 14. When you are. At this time, both X and Y are assumed to be in the OFF state.

  Next, the control unit 10 determines whether or not a current detection signal output when a current is flowing through the current detection unit 16 is input, that is, whether the PC is ON or OFF (ST2). In Test A, X and Y are assumed to be in an OFF state, so that no current detection signal is output and the PC is OFF (ST2; OFF). When the PC is ON (ST2; ON), the control unit 10 determines that an unexpected abnormality has occurred (ST3) and ends the test. At this time, the fact that some abnormality has occurred may be output to an output device (not shown). Whether or not the circuit breaker tripping circuit 2 is normal during test A is unknown.

  If the PC is OFF (ST2; OFF) in the test A, the control unit 10 can confirm that both X and Y are in the OFF state (ST4), and then execute the test B (ST5). ).

  In the test B, the control unit 10 leaves the instruction to X as in the test A, and issues an ON instruction to Y, that is, an instruction for the switching contact 15 to connect the points c and e (ST5). ). Since X is in the OFF state, a situation in which the circuit breaker malfunctions with the execution of test B cannot occur.

The control unit 10 determines whether the PC is ON or OFF in the test B (ST6). When PC is ON in test B (ST6; ON), a current path including the current detection unit 16 is formed between the power lines P and N. The fact that the current path is formed means that TC is normal and X remains in the OFF state, so that Y must be in the ON state in response to the ON instruction. X and Y at this time are the situation corresponding to the number (1) in the “possible situation” column of FIG. 3, and the control unit 10 determines that TC and Y are normal (ST8). At this time, X is in the same OFF state as in test A, and Y is in the ON state. In FIG. 1, the current path extends from the power line P to the power line N via the current detector 16, the resistance element 17 having a resistance value R, the circuit breaker tripping coil 20, and the circuit breaker auxiliary contact 21 in the closed state. A current I _R flows through the current detection unit 16 and the breaker tripping coil 20, current detector 16 outputs a current detection signal. Accordingly, the PC is turned on. Incidentally, since the current path includes the resistor element 17, the current I _R is V / (Z + R), the resistance value R is set to be R»Z, I _R of the circuit breaker operation Therefore, the current I is sufficiently smaller than the necessary current I. Therefore, even if I _R flows through the circuit breaker tripping coil 20, the circuit breaker does not operate erroneously. The controller 10 executes the test C after ST8 (ST9).

  When the PC is OFF (ST6; OFF) in test B, that is, when no current flows through the current detection unit 16, the control unit 10 determines that the X, Y, and TC states are the first case and the first case described below. In either case, it is determined that the circuit breaker may malfunction as the test continues (ST7), and the subsequent tests including the test C are stopped.

  The first case is a state corresponding to the number (2) in the “possible situation” column of FIG. 3 and is a case where TC is abnormal. At this time, since the circuit breaker tripping circuit 2 is in a state where no current flows, a current path connecting the power lines P and N is not formed (see FIG. 1). Accordingly, no current flows through the current detector 16 and the PC is turned off. In this case, Y can be either normal / abnormal.

  The second case corresponds to the number (3) in the “possible situation” column in FIG. 3, TC is normal, Y is abnormal and does not operate in response to an ON instruction, and is OFF. This is the case when the state remains. About X, since the state of the test A is continued, it is an OFF state. At this time, a current path connecting the power lines P and N is not formed (see FIG. 1), so that no current flows through the current detection unit 16, and the PC is turned off.

  When PC is OFF in test B, it is unknown whether X, Y, and TC are in the first case or the second case. If it is the second case, the test C is executed and an ON instruction is issued to X. If X is normal, X is turned on. In this case, the circuit breaker malfunctions. Therefore, when the PC is OFF in the test B, the control unit 10 determines that the circuit breaker may malfunction as the test continues (ST7).

  In the test C executed when the PC is ON in the test B, the control unit 10 issues an ON instruction to X (ST9), and determines whether the PC at that time is ON or OFF (ST10).

When PC is ON in the test C (ST10; ON), a current path including the current detection unit 16 must be formed between the power lines P and N. In ST8, it is determined that TC is already normal, and it is determined that TC is normal from the determination result in ST10. Since Y is in the ON state as indicated by the determination in ST8, X does not operate normally in response to the ON instruction and current does not flow through the current detector 16 unless it is in the OFF state (FIG. 1). reference). Therefore, the control unit 10 determines that the state corresponding to the number (4) in the “possible situation” column in FIG. 3, that is, X is abnormal (ST12). At this time, X is OFF and Y is ON. In ST12, the fact that X is abnormal may be output to an output device (not shown) to call attention. Thereafter, the control unit 10 executes the test D (ST13). Since when the state corresponding to the number (4) current path including the resistor element 17 is formed (see FIG. 1), the current I _R flows through the breaker trip circuit 2, breaker malfunction do not do.

When the PC is OFF in test C (ST10; OFF), it is determined in ST8 that TC has already been normal, and Y is in the ON state as shown in the determination in ST8. In order for no current to flow through, X must be in the ON state (see FIG. 1). When X and Y are in the ON state, as can be seen from FIG. 1, both ends of the current detection unit 16 are short-circuited via the switching contact 13 of the relay 12, so that current flows through the current detection unit 16. Absent. Therefore, the control unit 10 determines that the state corresponding to the number (6) in the “possible situation” column of FIG. 3, that is, X is normal (ST11). At this time, both X and Y are in the ON state. Since it is determined in ST8 that TC is normal and Y is ON and normal, the state corresponding to the numbers (5), (7), and (8) in FIG. Is excluded from the judgment target. In ST11, the fact that X, Y, and TC are normal may be output to an output device (not shown) to call attention. After ST11, control unit 10 executes test D (ST13). Since when the state corresponding to the numbers in Figure 3 (6) current path including the resistor element 17 is formed (see FIG. 1), the current I _R flows through the breaker trip circuit 2, breaker Does not malfunction.

  The results summarized above are shown in the “Remarks” column of FIG. In the digital protection relay 1 having the configuration shown in FIG. 1, when the control unit 10 obtains a result of PC = OFF in the test B (ST6; OFF), there is a possibility that Y is not in the ON state due to an abnormality. Stop further testing. Thereby, it is possible to prevent the occurrence of malfunction of the circuit breaker accompanying the continuation of the test. When the result of PC = ON is obtained (ST6; ON), the control unit 10 determines that TC and Y are normal (ST8). However, it is still unclear whether X is normal. In the normal use mode, not only to confirm that the TC is normal, but also in response to an instruction that X is ON so that a current can be passed through the circuit breaker tripping circuit 2 when a fault occurs in the power system. It must be confirmed that it is operating normally and turned on. Therefore, the control unit 10 executes the test C (ST9). When the result of PC = ON is obtained in the test C (ST10; ON), the control unit 10 determines that X is abnormal (ST12), and when the result of PC = OFF is obtained (ST10; OFF), X is determined to be normal (ST11).

  Note that since the test A only defines the start state of the test, the tests B and C substantially correspond to the substantial test. According to the digital type protective relay 1, when the PC is OFF in the test B, it is possible to prevent the circuit breaker from malfunctioning that may occur in the subsequent test by stopping the test for determining the presence or absence of TC abnormality.

  Further, according to the digital type protective relay 1, when the PC is ON in the test B, it can be determined that there is no abnormality in TC and Y, and the test C is continuously executed to check the ON / OFF of the PC. Sex can be confirmed. That is, the soundness of the circuit breaker tripping circuit 2 including the relay 12 that ensures the operation of the circuit breaker tripping circuit 2 can be confirmed, and the soundness of the relay 14 that switches to the current path for soundness check is also improved. Can be confirmed.

  Only the test B and the test C are necessary for the abnormality diagnosis test. However, after this test, it is necessary to return the digital protection relay 1 to the normal use mode. Tests D and E are responsible for this.

  After test C, control unit 10 executes test D, issues an OFF instruction to X (ST13), and determines whether the PC is ON or OFF (ST14). When the PC is ON (ST14; ON), the control unit 10 confirms that X is in the OFF state (ST15), and then executes the test E (ST17). After the test C, it is necessary to return the X and Y states to the “in use” and “steady state” X and Y states, that is, the same state as the test A (hereinafter referred to as the test E). When returning to the state of, the circuit breaker may malfunction. In order to avoid this, after the test C is completed, the control unit 10 does not directly return the X and Y states to the test E state, but executes the same test D as the test B. After confirming that X is in the OFF state in ST17, the circuit breaker will not malfunction, so test E can be executed.

  When PC is OFF in test D, control unit 10 determines that an unexpected abnormality has occurred (ST16), and ends the test. As a result, it is possible to prevent the malfunction of the circuit breaker due to the continuation of the test.

  In the test E, the control unit 10 issues an OFF instruction to Y (ST17) and determines ON / OFF of the PC (ST18). When the PC is OFF (ST18; OFF), the control unit 10 confirms that Y is in the OFF state and the digital protection relay 1 has returned to the normal use mode (ST19), and ends the test. When the PC is ON, it is determined that an unexpected abnormality has occurred (ST16), and the test is terminated.

  By executing the tests D and E in this order following the test C, it is possible to prevent the circuit breaker from malfunctioning when the digital protective relay 1 after the test is returned to the normal use mode.

  The digital protection relay 1 according to the first embodiment can achieve the same effect even if the arrangement of the circuit breaker tripping circuit 2 shown in FIG.

  The test setting unit 11 shown in FIG. 1 is premised on manual test start setting, but is provided with a timer so as to automatically start a test every preset period. May be.

  Moreover, when the control part 10 determines with abnormality, you may perform an alarm output and an alarm display. Moreover, you may control so that a retry test may be implemented.

  When a system fault occurs during the test and the control unit 10 determines that an abnormality detection signal has been input, the relays 12 and 14 are preferentially set to “in use” in FIG. ON / OFF instruction for X, Y at the time.

  The control unit 10 may include the test setting unit 11. At this time, an input device connected to the input unit 130 is added to the configuration of the control unit 10 shown in FIG. 2, and this input device becomes the test setting unit 11. The control unit 10 may include an abnormality detection unit (not shown). At this time, the abnormality detection unit determines whether there is an abnormality from the input unit 130 for inputting a signal (current signal or voltage signal of the power system) used for abnormality detection, and determines that there is an abnormality. The CPU 100 executes processing for generating an abnormality detection signal sometimes, a memory 110, and a memory 120 for storing data necessary for processing by the CPU 100.

(Embodiment 2)
FIG. 5 shows a configuration example of the digital protection relay 1 according to the second embodiment. The digital protection relay 1 shown in FIG. 5 is different from the digital protection relay 1 shown in FIG. 1 in that one end of the resistance element 17 is connected to a current path connecting the point d and the circuit breaker tripping circuit 2. Instead, it is connected to the power line N.

  The roles of the relay 12 (hereinafter referred to as X) and the relay 14 (hereinafter referred to as Y) of the digital protection relay 1 are the same as those of the digital protection relay 1 shown in FIG. The same applies to the ON / OFF instruction of X and Y in the tests A to E to be executed.

  FIG. 6 shows the contents of tests A to E. Basically, it is the same as in the case of FIG. 3, but TC is not included in the current path at the time of the test. Is left. This is because the fact that TC is abnormal and a current path is not formed during test execution does not occur in the second embodiment. The numbers in the “possible situation” column in FIG. 6 are the same as the numbers in FIG. The reason why the numbers (2) and (5) are not present is that these situations correspond to TC abnormalities. As a result, when “PC = OFF in test B” in the remarks (A) of FIG. 6, the point that the test C is stopped is the same as in FIG. 3. Column (3)) ”. This is because, when the test C is executed at the number “3” of the “possible situation” in FIG.

  The flowchart showing the operation of the digital protection relay 1 during the test is the same as the flowchart shown in FIG. 4 except for one point. The only difference is that the description about TC is deleted in ST7.

  Since the digital protection relay 1 can confirm the soundness of the relay 14 based on the result of the test B, the risk of malfunction of the circuit breaker can be reduced. In addition, when the relay 14 is normal, the circuit breaker trip circuit 2 is not included in the current path at the time of the test by switching the current path by the relay 14, so that the circuit breaker does not have a risk of malfunction during the test. The soundness of each of 12 and 14 can be confirmed. Therefore, compared with the case where the circuit breaker tripping circuit 2 is included in the current path during the test, the current flowing through the relays 12 and 14 during the test can be increased. Therefore, it is possible to confirm the soundness of the relays 12 and 14 in a state closer to the actual state.

  The digital protection relay 1 according to the first embodiment may be arranged freely as long as it is connected in series with the circuit breaker tripping circuit 2 arranged between the pair of power lines. With regard to the digital protection relay 1 according to the above, it is necessary to pay attention to the arrangement so that the circuit breaker trip circuit 2 is not located on the current circuit including the resistance element 17 during the test.

  The digital protection relay 1 can be easily connected as shown in FIG. 1 by switching the connection end of the resistance element 17 to the power line N. This reconnection may be performed manually by introducing a changeover switch or may be performed via the control unit 10. This changeover switch may be configured using a changeover relay similar to the relay 14. This switching relay also has three connection points, and is arranged between the resistance element 17 and the power line N in FIG. Each connection point is connected to the resistance element 17, one point on the current path connecting the connection point d and the circuit breaker tripping circuit 2, and one point on the power line N. In the case of a switching relay, switching is performed according to an instruction from the control unit 10.

  When the test of the circuit breaker tripping circuit 2 is performed after returning to the arrangement of FIG. 1 after performing the test in the arrangement of FIG. 5, the soundness of the relays 12 and 14 is known in advance. Tests can be performed. Therefore, a safer test can be performed in terms of preventing malfunction of the circuit breaker, and clearer soundness information can be obtained.

(Embodiment 3)
A configuration example of the digital protection relay 1 according to Embodiment 3 is shown in FIG. The digital protection relay 1 shown in FIG. 7 is different from the case of FIG. 1 in that a relay 40 connected in series with the relay 12 is provided and the open / close relay is duplicated. Accordingly, in FIG. 7, the relay 12 is displayed as “X ₁ ” and the relay 40 is displayed as “X ₂ ”. When the relay 40 is in the OFF state, the switching contact 50 opens between the points p and q and closes in the ON state.

  Further, the digital protection relay 1 includes an auxiliary control unit 30 for controlling the relay 40. The auxiliary control unit 30 performs opening / closing control of the relay 40 based on the input abnormality detection signal. The auxiliary control unit 30 includes a CPU 100, a memory 110, a memory 120, an input unit 130, and an output unit 140, similarly to the configuration shown in FIG. The abnormality detection signal is the same abnormality detection signal as the abnormality detection signal input to the control unit 10. In addition, when the control part 10 is comprised so that an abnormality detection part may be included, the auxiliary | assistant control part 30 is also set as the structure also including an abnormality detection part. At this time, instead of the abnormality detection signal, an input signal (current signal or voltage signal of the power system) to the abnormality detection unit is input to the control unit 10 and the auxiliary control unit 30, respectively.

  The control unit 10 outputs an operation instruction signal M when operating the relay 12 during the test. The auxiliary control unit 30 receives this operation instruction signal M and performs opening / closing control of the relay 40 in the same manner as the relay 12. That is, via this operation instruction signal M, the relay 12 is controlled by the control unit 10 and the relay 40 is controlled by the auxiliary control unit 30 so as to be in the same open / close state. The operation instruction signal M plays a role of an abnormality detection signal for the auxiliary control unit in normal times.

  Except for the above points, the digital protection relay 1 shown in FIG. 7 is the same as the digital protection relay 1 shown in FIG. Since the relays 12 and 40 are controlled to open and close simultaneously and in the same way, when each relay is in a normal state, it is the same as the case where there is only one relay 12 shown in FIG.

  The difference is in the case where an abnormality has occurred in either one of them, and the door does not open and close as indicated by the ON / OFF instruction. Therefore, in the digital protection relay 1, it is assumed that the open state of X in FIG. 3 is when both the relays 12 and 40 are open, and when the relays 12 and 40 are both closed, the relays 12 and 40 are closed. To do. That is, when there is no abnormality in both the relays 12 and 40 with respect to the OFF instruction, it is determined to be normal when the relays 12 and 40 are in the open state. Also in the case of an ON instruction, it is determined that both the relays 12 and 40 are normal and in the closed state are normal, and if there is any abnormality, the relays 12 and 40 are determined to be abnormal.

  Since the relays 12 and 40 can be considered as one relay on such a premise, FIGS. 3 and 4 can be applied to the digital protection relay 1 as it is.

  According to the digital protection relay 1, since the relays for opening and closing are doubled in series like the relays 12 and 40, when one of the relays malfunctions for some reason, the circuit breaker is thereby erroneously operated. Since the operation is prevented, a highly reliable digital protection relay can be realized. In other respects, the digital protection relay 1 can achieve the same effects as the effects of the digital protection relay 1 according to the first embodiment.

  In the above description, the abnormality detection signal or abnormality detection unit has been described as being independent of each other by the control unit 10 and the auxiliary control unit 30, but the input of the abnormality detection signal or the abnormality detection unit is the control unit 10. It is also possible to aggregate only. At this time, when the control unit 10 controls the opening and closing of the relay 12, the auxiliary control unit 30 receives the operation signal M and similarly controls the opening and closing of the relay 40. Since the input of the abnormality detection signal or the function of the abnormality detection unit is integrated in the control unit 10, the degree of duplication is slightly reduced, but at least the relay is duplicated, so the digital protection relay 1 according to Embodiment 1 Therefore, it is possible to provide the digital protection relay 1 with higher reliability.

  Alternatively, the auxiliary control unit 30 may be omitted, and the opening / closing control of the relay 12 and the relay 40 may be performed only by the control unit 10. Since the auxiliary control unit 30 is omitted, the degree of duplication is further reduced. However, since the relays are duplicated, it is possible to provide the digital protection relay 1 having higher reliability than the digital protection relay 1 according to the first embodiment. It becomes possible. In such a configuration, the operation instruction signal M is not necessary.

  This digital protection relay 1 may be one in which the opening / closing relay 12 is duplicated in the second embodiment. In this case as well, the reliability of the digital protection relay 1 is improved and the same effect as the effect of the digital protection relay 1 according to the second embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Digital type protective relay 2 Circuit breaker tripping circuit 10 Control part 11 Test setting part 12 Relay (opening and closing part)
13 Open / close contact 14 Relay (switching part)
15 switching contact 16 current detection part 17 resistance element (resistance element)
20 Circuit breaker trip coil (TC)
21 Circuit breaker auxiliary contact 30 Auxiliary control unit 40 Relay (opening / closing unit)
50 Open / close contact M Operation instruction signal

Claims (4)

A digital protection relay having a soundness test function of a circuit breaker tripping circuit installed between a pair of power lines to operate a circuit breaker installed for protection of a power system,
An open / close unit that is connected in series to the circuit breaker trip circuit and opens and closes a current path to the circuit breaker trip circuit;
A first connection point to which the switching unit is connected; a second connection point that forms a current path to the circuit breaker trip circuit for protecting the power system; and a third connection point. A switching unit that switches a connection destination of the first connection point to one of the second connection point and the third connection point;
Between the second connection point and one of the pair of power lines, one of the power lines connected to the circuit breaker trip circuit, and the first connection point, the switching unit is in parallel. A resistive element connected to the
The switching unit is installed on a parallel current path with respect to the switching unit between an end of the switching unit that is opposite to the end connected to the switching unit and the third connection point. A current detection unit that outputs a detection signal when current flows;
At the time of the soundness test, whether to stop or continue the soundness test is determined based on the presence / absence of the detection signal when preset operation control is performed on the opening / closing unit and the switching unit. A control unit configured in
A digital type protective relay comprising: When it is determined that the soundness test is to be continued, the control unit performs other preset operation control for the opening / closing unit and the switching unit, and information on the presence / absence of the detection signal at that time is also provided. Based on the information on the presence or absence of the plurality of detection signals added, configured to determine the soundness of the opening and closing unit and the switching unit,
2. The digital protection relay according to claim 1, wherein: Another switching unit comprising a fourth connection point connected to the resistance element, a fifth connection point connected to the second connection point, and a sixth connection point connected to the one power line. Prepared,
The control unit performs control to switch a connection destination of the fourth connection point of the other switching unit to one of the fifth connection point and the sixth connection point, and then performs the soundness. Configured to run a test,
The digital protection relay according to claim 1 or 2, characterized in that Another switching part connected between the switching part and the switching part, for opening and closing a current path to the circuit breaker tripping circuit;
Upon receiving an instruction from the control unit, another control unit that executes the same open / close control as the open / close control of the open / close unit with respect to the other open / close unit at the same timing;
The digital protection relay according to any one of claims 1 to 3, further comprising:

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