JP5044328B2 - Network power transmission protection device - Google Patents

Description

  The present invention relates to a network power transmission protection device that protects a power transmission system configured in a loop by connecting a plurality of electric stations including an electric station connected to a power supply system through power transmission lines having circuit breakers at both ends.

  Generally, in the power transmission system, when an accident such as a short circuit or a ground fault occurs, the power transmission system is protected by a protective relay that operates the circuit breaker by identifying the position and type of the accident. The conventional power transmission line protection method performs protection independently for each power transmission line. On the other hand, in recent years, a loop-system power transmission system has been implemented in which a plurality of electrical stations including a power source and a circuit breaker are arranged and these are connected in a loop shape by a power transmission line (for example, , See Patent Document 1).

  FIG. 1 shows a configuration of a protection device in such a loop-shaped power transmission system. FIG. 1 is a configuration diagram when there are four electrical stations.

  In FIG. 1, the power transmission system includes four electrical stations 11 to 14 and power transmission lines 41 to 44 that connect these electrical stations. Of the four electric stations 11 to 14, the electric station 11 is connected to the power supply system 71, and the other electric stations 12, 13, and 14 are connected to the load system (not shown). The power transmission lines 41 to 44 connected in a loop shape by connecting the plurality of electric stations 11 to 14 are provided with circuit breakers 31 and 31a, 32 and 32a, 33 and 33a, 34 and 34a, respectively.

  Of the plurality of electric stations 11 to 14, one electric station 11 is provided with an arithmetic station 21, and the remaining electric stations 12, 13, and 14 are provided with terminal stations 22, 23, and 24, respectively. Yes. Information can be exchanged between the arithmetic station 21 and the plurality of terminal stations 22, 23, 24 by communication means including communication lines 61, 62, 63, 64, and constitutes a set of protection systems 60 as a whole. is doing.

  Current transformers 51 and 51a, 52 and 52a, 53 and 53a, 54 and 54a are provided at both ends of each of the power transmission lines 41, 42, 43 and 44 for input of measuring means (not shown). The amount of electricity flowing through the transmission line is extracted individually. In addition, the measuring means is comprised in the calculation station 21 or the terminal stations 22, 23, 24 provided in each electric station 11, 12, 13, 14.

  In the above configuration, the amount of electricity flowing through the power transmission lines 41 and 44 connected to the electric station 11 is measured by the measuring means of the arithmetic station 21, and the amount of electricity flowing through the power transmission lines 41 and 42 connected to the electric station 12 is The amount of electricity measured by the measuring means 22 and flowing through the transmission lines 42 and 43 connected to the electric station 13 is measured by the measuring means of the terminal station 23 and the electricity flowing through the transmission lines 43 and 44 connected to the electric station 14 The quantity is measured by the measuring means of the terminal station 24. The electrical quantity information measured by these terminal stations 22 to 24 is transmitted to the computing station 21 via the carrier network communication lines 61 to 64.

  The computing station 21 detects the presence or absence of an accident for each transmission line by obtaining a difference current ratio between both ends of each transmission line on the basis of the electrical quantity information of each transmission line received from each terminal station 22, 23, 24. When an accident occurs, a shut-off command for the circuit breakers at both ends of the failure section where the accident occurs is sent to the shut-off control circuit (not shown) of each of the electric stations 11 to 14 or the other terminal stations 22, 23, 24. Output via. For example, when the computing station 21 detects an accident in the transmission line 41 in FIG. 1, the computing station 21 outputs a failure cutoff command for the one-way circuit breaker 31 of the transmission line 41 from the own station 21 and the carrier network communication line 61. Is transmitted to the terminal station 22 through the terminal block 22 through the failure interrupt command to the other end circuit breaker 31a. The shut-off control circuit of the arithmetic station 21 opens the one-way circuit breaker 31 in response to a fault shut-off command from the own station. The terminal station 22 outputs a release command to the circuit breaker 31a in response to the failure cutoff command received from the arithmetic station 21. By the above, the circuit breakers 31 and 31a of the both ends of the power transmission line 41 which is a failure area are open | released, and the power transmission line 41 is protected.

  Further, when an accident occurs in the transmission line 42, the computing station 21 determines that the accident has occurred in the transmission line 42 based on the electrical quantity information at both ends of the transmission line 42 sent from the terminal stations 22 and 23. To detect. Then, in order to open the circuit breakers 32 and 32 a provided at both ends of the power transmission line 42, a failure interruption command for the circuit breakers 32 and 32 a is transmitted to the corresponding terminal stations 22 and 23 via the carrier network communication lines 61 and 62. To do. The terminal stations 22 and 23 output an open command to the circuit breakers 32 and 32a in response to the failure interrupt command received from the arithmetic station 21. As described above, the circuit breakers 32 and 32a at both ends of the power transmission line 42, which is the failure section, are opened, and the power transmission line 42 is protected.

The above operation is the same for the other power transmission lines 43 and 44. That is, the accident of the power transmission line 43 corresponds to the accident of the power transmission line 42, the accident of the power transmission line 44 corresponds to the accident of the power transmission line 41, and is the same as the description of the accident of the corresponding power transmission lines 41 and 42, respectively. To work.
Japanese Patent Laid-Open No. 9-233684

  In this way, the arithmetic station 21 obtains information from each of the terminal stations 22, 23, and 24, detects an accident that has occurred in the power transmission lines 41 to 44, isolates the failure section in which the accident has occurred, and returns to the healthy section. Maintain power.

  However, if an abnormality occurs in any one or more of the terminal stations 22, 23, and 24, information from the terminal station that has become abnormal (for example, 22) cannot be obtained in the computing station 21. That is, since the terminal station 22 cannot measure the amount of electricity flowing through the power transmission lines 41 and 42 connected to the electric power station 12, the arithmetic station 21 detects this accident even if an accident occurs in the power transmission line 41 or 42. I can't. For this reason, the circuit breakers 31a and 32 cannot be interrupted at the electric station 12 by a command from the arithmetic station 21, and the fault section cannot be disconnected. In this case, a protection device (not shown) that protects the entire transmission lines 41 to 44 connected in a loop operates, and the circuit breakers 31 and 34a closest to the power supply system 71 are opened to transmit the transmission lines 41 connected in a loop. Protect the entire ~ 44.

  As described above, when any one of the terminal stations 22, 23, and 24 becomes abnormal, the entire loop-shaped power transmission lines 41 to 44 including the healthy section are disconnected, so that the power outage range is expanded.

  An object of the present invention is to provide a network power transmission protection device capable of reliably protecting a power transmission line when an accident occurs in a power transmission line connected in a loop shape and minimizing the power failure range. is there.

The network power transmission protection device of the present invention is a network that protects a power transmission system configured in a loop by connecting a plurality of electric power stations including an electric power station connected to a power supply system through power transmission lines provided with breakers at both ends. A power transmission protection device, which is provided at each end of each power transmission line and individually measures the amount of electricity flowing through the corresponding power transmission line, and two sets provided at one of the plurality of electrical stations computing stations, and has a remaining two pairs respectively provided substation terminal station, the operational stations of each set and between a plurality of terminal stations each other by communication means, the quantity of electricity measured by the terminal station two pairs of the protective system capable exchanged within each set of various types of information including information, the provided two pairs of protective system of the computing station and each terminal station, the abnormality of each self and other stations for each protection system Self / mutual monitoring for mutual monitoring And stage, the substation is provided for each circuit breaker, a blocking control circuit for opening operation of the circuit breaker corresponding, provided operational station of the two pairs of protective systems, each measured by the measuring means the electric variable information at both ends of the transmission line were collected for each protection system, these transmission lines the presence of a fault from the electrical quantity information of both ends by the transmission line is detected for each protection system, in the case of failure there is, the failure period ends A fault section detecting means for outputting a shut-off command for shutting off the circuit breaker to the shut-off control circuit of each electric station for each protection system via its own station or another terminal station ; When the self / mutual monitoring means detects an abnormality of any of the terminal stations for each protection system , the failure section detection means serializes a plurality of transmission lines connected to the electric station having the detected abnormal terminal station. As a section, the corresponding section based on the electricity at both ends of the section The presence or absence of a failure to have a determining section expansion detection function for each protection system, the interruption control circuit of each substation, the logic of blocking command output from the two sets of protection system provided in the own electric station Takes the product to open the corresponding circuit breaker, and each has a bypass circuit for the shut-off command, and the abnormality of either one of the two protection systems provided in the self-electricity station by the self / mutual monitoring means Is detected so that when the two protection systems provided at the own electric power station are abnormal, the shutdown command is not bypassed by the fault protection system. characterized in that it was.

  According to the present invention, even if any one of the terminal stations of each electric power station constituting the loop-shaped power transmission system becomes abnormal, the power transmission line connected to the corresponding electric power station is detected by expanding the failure section. Can be reliably protected, and the power outage section can be minimized.

  Hereinafter, an embodiment of a network power transmission protection device according to the present invention will be described in detail with reference to the drawings.

  The loop-shaped power transmission system to be protected is basically the same as that shown in FIG. 1, and includes four electric stations 11 to 14 and power transmission lines 41 to 44 connecting the electric stations. Of the four electric stations 11 to 14, the electric station 11 is connected to the power supply system 71, and the other electric stations 12, 13, and 14 are connected to a load system (not shown). The power transmission lines 41 to 44 are provided with circuit breakers 31 and 31a, 32 and 32a, 33 and 33a, 34 and 34a at both ends, respectively.

  One electric station 11 is provided with a calculation station 21, and the remaining electric stations 12, 13, and 14 are provided with terminal stations 22, 23, and 24, respectively. Information can be exchanged between the arithmetic station 21 and the plurality of terminal stations 22, 23, 24 by communication means including communication lines 61, 62, 63, 64, and constitutes a set of protection systems 60 as a whole. is doing.

  Measuring means including current transformers 51 and 51a, 52 and 52a, 53 and 53a, 54 and 54a are respectively provided at both ends of each of the power transmission lines 41, 42, 43 and 44, and electricity flowing through the corresponding power transmission lines. Measure quantities individually.

  As shown in FIG. 2, the arithmetic station 21 includes the measurement unit 101, a failure section detection unit 102, a communication unit 103, and a self / mutual monitoring unit 104. Further, the terminal stations 22, 23 and 24 have the measuring means 201, the communication means 203, and the self / mutual monitoring means 204 as shown in FIG. 3 shows the terminal station 22, the other terminal stations 23 and 24 have the same internal configuration.

  The measuring means 101 of the arithmetic station 21 is connected to the secondary circuit of the current transformers 51 and 54 a provided in the electric station 11 and measures the amount of electricity of the power transmission lines 41 and 44. The measuring means 201 of the terminal station 22 (23, 24) is connected to the secondary circuit of the current transformers 51a and 52 (52a and 53, 53a and 54) provided in the electric station 12 (13, 14), The electric quantity of the electric wires 41 and 42 (42 and 43, 43 and 44) is measured. The current value measured by the measuring means 201 of each terminal station 22, 23, 24 is converted into a digital signal to become electric quantity information, and the corresponding communication lines 61, 62, 63 and 64, it is sent to the communication means 103 of the computing station 21 and input to the failure section detection means 102. Further, the current value measured by the measuring means 101 of the arithmetic station 21 is also converted into a digital signal and input to the failure section detecting means 102 as electric quantity information.

  The failure section detection means 102 uses the electrical quantity information measured by the measurement means 101 and the electrical quantity information measured by the measurement means 201 of each terminal station 22, 23, 24 collected by the communication means 103. The difference current ratio between both ends of the electric wires 41 to 44 is obtained, and the presence or absence of an accident is detected for each transmission line. That is, when there is no accident in each of the power transmission lines 41 to 44, the current measurement values at both ends thereof are substantially equal to each other in the same direction. However, when an accident occurs in the power transmission lines 41 to 44, the directions of the currents at both ends of the accident power transmission line are opposite to each other (inward), so that the difference current ratio at both ends of the accident power transmission line increases. The failure section detection means 102 determines that an accident has occurred in this power transmission line if the difference current ratio between both ends of the power transmission line exceeds a threshold value.

  When the fault section detecting means 102 detects a power transmission line in which an accident has occurred by such an accident detection function, the fault control unit 102 has a corresponding circuit breaker to cut off the circuit breakers at both ends of the fault section where the accident has occurred. A cutoff command is output to the circuits 106 and 206. For example, when an accident occurs in the power transmission line 41, the failure section detection unit 102 detects the breakers 31 and 31a at both ends of the power transmission line 41, which is the failure section, of the electrical stations 11 and 12 where they are installed. The interruption | blocking command with respect to the circuit breakers 31 and 31a is output to the interruption | blocking control circuits 106 and 206. FIG. In this case, it is transmitted to the shutoff control circuit 206 of the electric station 12 via the communication means 103, the communication line 61, and the communication means 203 of the terminal station 22.

  When the self / mutual monitoring means 104, 204,... Detects any abnormality of the terminal stations 22, 23, 24, the failure section detection means 102 detects the detected abnormal terminal station (for example, 22 and A plurality of power transmission lines 41 and 43 connected to an electric power station (in this case, 12) having a single section, and a section extension for determining whether there is a failure in the section based on the amount of electricity at both ends of the section Has a detection function.

  The self / mutual monitoring means 104 and 204 provided in the arithmetic station 21 and the terminal stations 22 to 24 have a function of monitoring whether the own station is in a healthy state or whether the adjacent counterpart station is healthy. That is, each of the stations 21, 22, 23, 24 has abnormality detection contacts 105, 205,... That operate when an abnormality occurs, and the states of the contacts 105, 205,. ,... Are monitored by other stations adjacent to each other and whether or not each station is healthy are mutually monitored. The abnormality detection information from each terminal station 22 to 24 to the computing station 21 is transmitted through a remote monitoring transmission line (not shown). In any case, the arithmetic station 21 and the terminal stations 22 to 24 are mutually monitored, and have a function of specifying a station where an abnormality has occurred.

  In the above configuration, the power transmission line protection operation when the terminal stations 22, 23, and 24 are all normal is the same as described above, and a description thereof will be omitted. The following describes the power transmission line protection operation when one or more terminal stations become abnormal.

  When the terminal station 22 becomes abnormal, the arithmetic station 21 detects the abnormality of the terminal station 22 by the self / mutual monitoring means 104. Also, the terminal station 23 detects the abnormality of the terminal station 22 by the self / mutual monitoring means 204 of the terminal station, and transmits the abnormality of the terminal station 22 to the arithmetic station 21 via the carrier network communication lines 63 and 64.

  When the terminal station 23 becomes abnormal, the terminal station 22 detects the abnormality of the terminal station 23 by its self / mutual monitoring means 204 and notifies the arithmetic station 21 of the abnormality of the terminal station 23 via the carrier network communication 61. Send. The terminal station 24 also detects an abnormality of the terminal station 23 by the self / mutual monitoring means 204 and transmits the abnormality of the terminal station 23 to the arithmetic station 21 via the carrier network communication line 64.

  Further, when the terminal station 24 becomes abnormal, the arithmetic station 21 detects the abnormality of the terminal station 24 by the self / mutual monitoring means 104. The terminal station 23 also detects the abnormality of the terminal station 24 by the self / mutual monitoring means 204 and transmits the abnormality of the terminal station 24 to the arithmetic station 21 via the carrier network communication lines 61 and 62.

When the computation station 21 detects an accident in any section of the power transmission lines 41 to 44, the computation station 21 performs failure detection as shown in Table 1 according to the abnormal state of the terminal stations 22 to 24, and both ends of the failure detection section (boundary Send a fault cut-off command to the terminal station.

  Hereinafter, with reference to Table 1, the occurrence of abnormality in the terminal stations 22 to 24 and the accompanying protection operation by the section extension function will be described in different patterns.

  The case where the terminal stations 22 to 24 of (Pattern 1) are all normal is as described above, and the transmission line itself in which an accident has occurred is set as a failure section, and the breakers at both ends are broken and broken.

  (Pattern 2) If the terminal station 22 is abnormal and an accident occurs in the power transmission line 41 or the power transmission line 42, the arithmetic station 21 calculates the electric quantity information of the power transmission line 42 transmitted from the terminal station 23 and the arithmetic station 21. The accident of the power transmission line 41 or the power transmission line 42 is detected based on the electric quantity information of the power transmission line 41 measured by itself. That is, the section 1 and the section 2 by the power transmission line 41 and the power transmission line 42 are integrated and expanded as an accident detection target section. When an accident occurs in one or both of the power transmission line 41 and the power transmission line 42, the circuit breakers 31 and 32a at both ends of the expanded failure section 1 and 2 are broken and interrupted. That is, at the electric station 11, the operation station 21 outputs an opening command to the circuit breaker control circuit 106 for the circuit breaker 31, and the terminal station 23 of the electric station 13 instructs the circuit breaker circuit 32a to open the circuit breaker 32a. Is output. By the above, the both-end circuit breakers 31 and 32a of the extended failure section 1-2 are opened, and the power transmission lines 41 and 42 are protected.

  (Pattern 3) When the terminal station 23 is abnormal, if an accident occurs in the power transmission line 42 or the power transmission line 43, the arithmetic station 21 uses the electric quantity information of the power transmission lines 42 and 43 transmitted from the terminal stations 22 and 24. In addition, an accident in the enlarged section of the power transmission line 42 to the power transmission line 43 is detected, and a failure cutoff command is output to the terminal stations 22 and 24. The terminal station 22 outputs an opening command to the circuit breaker 32 based on the failure cutoff command received from the computing station 21, and the terminal station 24 outputs an opening command to the circuit breaker 33a based on the failure cutoff command received from the computing station 21. As described above, the both-end circuit breakers 32 and 33a in the expanded failure sections 2 to 3 are opened, and the power transmission lines 42 and 43 are protected.

  (Pattern 4) When the terminal station 24 is abnormal, if an accident occurs in the power transmission line 43 or the power transmission line 44, the arithmetic station 21 determines that the electric quantity information of the power transmission line 43 transmitted from the terminal station 23 and the arithmetic station 21 itself Based on the electrical quantity information of the transmission line 44 to be measured, an accident in the expanded sections 3 to 4 of the transmission line 43 to the transmission line 44 is detected. As a result, an opening command for the circuit breaker 34 a is output, and a failure blocking command is output to the terminal station 23. The terminal station 23 outputs an open command to the circuit breaker 33 in response to the failure interrupt command received from the arithmetic station 21. As described above, the both-end circuit breakers 33 and 34a in the expanded failure sections 3 to 4 are opened, and the power transmission lines 43 and 44 are protected.

  (Pattern 5) When the terminal stations 22 and 23 are abnormal, if an accident occurs in any of the power transmission lines 41, 42, and 43, the arithmetic station 21 calculates the electric quantity information of the power transmission line 43 transmitted from the terminal station 24. Based on the electrical quantity information of the power transmission line 41 measured by the computing station 21 itself, an accident in the expanded section of the power transmission lines 41, 42, 43 is detected. As a result, an open command to the circuit breaker 31 is output, and a fault interrupt command is output to the terminal station 24. The terminal station 24 outputs an open command to the circuit breaker 33a in response to the failure interrupt command received from the arithmetic station 21. As described above, the both-end circuit breakers 31 and 33a in the expanded failure sections 1 to 3 are opened, and the power transmission lines 41, 42, and 43 are protected.

  (Pattern 6) When the terminal stations 23 and 24 are abnormal, if an accident occurs in any one of the power transmission lines 42, 43, and 44, the arithmetic station 21 calculates the electric quantity information of the power transmission line 42 transmitted from the terminal station 22. An accident in an enlarged section of the power transmission lines 42, 43, 44 is detected based on the information on the amount of electricity of the power transmission line 44 measured by the computation station 21 itself. As a result, an opening command to the circuit breaker 34 a is output, and a failure blocking command is output to the terminal station 22. The terminal station 22 outputs an open command to the circuit breaker 32 in response to the failure interrupt command received from the arithmetic station 21. As described above, the both-end circuit breakers 32 and 34a in the expanded failure sections 2 to 4 are opened, and the power transmission lines 42, 43, and 44 are protected.

  (Pattern 7) When the terminal stations 22 and 24 are abnormal, if an accident occurs in the power transmission line 41 or the power transmission line 42, the arithmetic station 21 calculates the electrical quantity information of the power transmission line 42 transmitted from the terminal station 23 and the arithmetic station 21 itself. Accidents in the expanded section of the power transmission lines 41 and 42 are detected based on the electrical quantity information of the power transmission line 41 measured by the. As a result, an open command to the circuit breaker 31 is output, and a fault interrupt command is output to the terminal station 23. The terminal station 23 outputs an open command to the circuit breaker 32a in response to the failure interrupt command received from the arithmetic station 21. As described above, the both-end circuit breakers 31 and 32a in one of the expanded failure sections 1 and 2 are opened, and the power transmission lines 41 and 42 are protected. Further, when an accident occurs in the power transmission line 43 or the power transmission line 44, the arithmetic station 21 obtains the electric quantity information of the power transmission line 43 transmitted from the terminal station 23 and the electric quantity information of the power transmission line 44 measured by the arithmetic station 21 itself. Based on this, an accident in an enlarged section of the transmission lines 43 and 44 is detected. As a result, an opening command to the circuit breaker 34 a is output, and a failure blocking command is output to the terminal station 23. The terminal station 23 outputs an open command to the circuit breaker 33 in response to the failure interrupt command received from the arithmetic station 21. As described above, the both-end circuit breakers 33 and 34a in the other expanded failure sections 3 to 4 are opened, and the power transmission lines 43 and 44 are protected.

  (Pattern 8) When the terminal stations 22, 23, and 24 are abnormal in all stations, if an accident occurs in any of the power transmission lines 41 to 44, the arithmetic station 21 measures the amount of electricity of the power transmission lines 41 and 44 that it measures. Based on the information, an accident in the expanded section of the transmission lines 41 to 44 is detected. As a result, an opening command is output to the circuit breakers 31 and 34a. As described above, the both-end circuit breakers 31 and 34a in the expanded failure sections 1 to 4 are opened, and the power transmission lines 41, 42, 43, and 44 are protected.

  In this way, even when one or more terminal stations become abnormal, it is possible to keep the power outage section to a minimum and continue protection of the transmission line.

  Next, the embodiment shown in FIG. 4 will be described. The loop-shaped power transmission system to be protected is basically the same as that shown in FIG. 1, and includes four electric stations 11 to 14 and power transmission lines 41 to 44 connecting the electric stations. Of the four electric stations 11 to 14, the electric station 11 is connected to the power supply system 71, and the other electric stations 12, 13, and 14 are connected to a load system (not shown). The power transmission lines 41 to 44 are provided with circuit breakers 31 and 31a, 32 and 32a, 33 and 33a, 34 and 34a at both ends, respectively.

  One electric station 11 is provided with a calculation station 21, and the remaining electric stations 12, 13, and 14 are provided with terminal stations 22, 23, and 24, respectively. Information can be exchanged between the arithmetic station 21 and the plurality of terminal stations 22, 23, 24 by communication means including communication lines 61, 62, 63, 64, and constitutes a set of protection systems 60 as a whole. is doing.

  In this embodiment, another set of protection systems 60a having the same configuration is provided, and the loop-shaped power transmission system is protected by two sets of protection systems 60 and 60a. The other protection system 60a also includes an arithmetic station 21a provided in one electric station 11, and terminal stations 22a, 23a, and 24a provided in the remaining electric stations 12, 13, and 14. The terminal stations 22a, 23a, and 24a are configured to be able to exchange information by communication means including communication lines 61a, 62a, 63a, and 64a.

  Current transformers 51 and 51a, 52 and 52a, 53 and 53a, 54 and 54a are provided at both ends of each of the transmission lines 41, 42, 43 and 44, respectively, and their secondary circuit is another protection. It is also connected to corresponding measuring means of the arithmetic station 21a and the plurality of terminal stations 22a, 23a, 24a constituting the system 60a.

  The computing station 21 a has the same configuration as the computing station 21 shown in FIG. 2, and includes a measuring unit 101, a failure section detecting unit 102, a communication unit 103, and a self / mutual monitoring unit 104. Also, the terminal stations 22a, 23a, and 24a have the same configuration as the terminal stations 22, 23, and 24 shown in FIG. 3, and include a measuring unit 201, a communication unit 203, and a self / mutual monitoring unit 204.

  Each of the electric stations 11 to 14 is provided with a shut-off control circuit for shutting off the breaker installed therein, but since two sets of protection systems 60 and 60a are provided, these shut-off control circuits are As shown in FIG. 7, the interruption commands 1 and 2 from the two sets of protection systems 60 and 60a are configured to give an interruption condition to the circuit breaker 3 as an AND condition. For example, for the electric station 11, the shut-off command 1 from one protection system 60 is output from the arithmetic station 21 provided in the own power station 11 and shut-off from the other protection system 60a as shown in FIG. The command 2 is output from the arithmetic station 21a similarly provided in the own electric station 11, and is configured to open the circuit breaker 3 (31 or 34a of the electric station 11) when both are turned on.

  As shown in FIG. 7, the bypass circuits 11 and 12 are connected in parallel to the shut-off commands 1 and 2 which are the AND conditions, and the arithmetic station 21 provided in the own electric station 11 becomes abnormal. In this case, the bypass circuit 11 is turned on, and when the arithmetic station 21a becomes abnormal, the bypass circuit 12 is turned on. However, these bypass circuits 11 and 12 are configured so that when both the computation stations 21 and 21a become abnormal, a lock circuit (not shown) is activated so that neither of them is turned on and the cutoff commands 1 and 2 are not bypassed. ing. For this reason, when only one of them is abnormal, the local station bypass action works, and an open command can be output to the circuit breaker 3 only by a normal device.

  These configurations are the same for the shut-off control circuit 206 of the other electrical stations 12, 13, and 14. For example, when viewing the electrical station 12, the shut-off command 1 from one protection system 60 is shown in FIG. As described above, the shut-off command 2 from the other protection system 60a is output from the terminal station 22a provided in the own electric station 12, and is output from the terminal station 22 provided in the own electric station 12. By doing so, the circuit breaker 3 (32 or 31a of the electric station 12) is opened.

  As shown in FIG. 7, the bypass circuits 11 and 12 are connected in parallel with respect to the shut-off commands 1 and 2 which are the AND conditions, and the terminal station 22 provided in the own electric station 12 is abnormal. In this case, the bypass circuit 11 is turned on, and when the terminal station 22a becomes abnormal, the bypass circuit 12 is turned on. However, these bypass circuits 11 and 12 are configured not to be turned on when both terminal stations 22 and 22a become abnormal, and not to block the cutoff commands 1 and 2.

The protection operation of the loop power transmission system by the two sets of protection systems 60 and 60a is basically the same, and when the arithmetic stations 21 and 21a detect an accident in any section of the power transmission lines 41 to 44, the terminal Accident detection as shown in Table 2 is performed according to the abnormal state of the stations 22 to 24 or the terminal stations 22a to 24a, and a failure cutoff command is transmitted to the terminal station having the failure detection section both-end circuit breaker.

  Hereinafter, the occurrence of an abnormality in the terminal stations 22 to 24 and the terminal stations 22a to 24a and the protection operation by the section extension function will be described in different patterns using Table 2.

  As shown in Table 2, the abnormal state of the terminal station is 64 patterns. Among these, the basic operation will be described in the case where the terminal stations 22 to 24 and 22a to 24a of (Pattern 1) are all normal, and then the terminal station has an abnormality taking the following six typical patterns as an example. The protection operation when it occurs will be described.

(Pattern 2): When only one of the two sets of terminal stations provided at all electrical stations becomes abnormal (Pattern 16): Of the two sets of terminal stations provided at all electrical stations, When one set is abnormal and only one other set is abnormal (Pattern 28): Of two sets of terminal stations provided at all electric stations, only two units at the same electric station are abnormal (Pattern 35) ): When one set of two terminal stations provided at all electric power stations and only one other set are abnormal (Pattern 41): Two sets of terminal stations provided at all electric power stations If one set and one set are abnormal (Pattern 59): Of the two sets of terminal stations provided at all electric power stations, one set of two sets and the other set of two sets Case of Abnormality The details of each of the above patterns will be described below.

(Pattern 1)
When the computing stations 21 and 21a detect an accident in any of the power transmission lines 41 to 44, the computing station 21 cuts off the accident to the terminal stations 22 to 24 via the carrier network communication lines 61 to 63 according to the accident occurrence section. Send a command. The arithmetic station 21a also transmits an accident cutoff command to the terminal stations 22a to 24a via the carrier network communication lines 61a to 63a according to the accident occurrence section. The two sets of terminal stations (22 and 22a, 23 and 23a, and 24 and 24a) that have received the accident interruption command output an opening command to the circuit breaker, respectively. Since the shutoff control circuit 206 of each terminal station is configured by the logical product of the shutoff commands 1 and 2 by the two sets of terminal stations as shown in FIG. 6, the two sets of terminal stations are both connected to the same circuit breaker 3. Only when the opening commands 1 and 2 are output, the circuit breaker 3 is opened and the transmission line is protected. In this pattern 1, since the terminal stations 22 to 24 and 22a to 24a are all normal, when the accident occurs on the power transmission line (for example, 42), the circuit breakers 32 and 32a at both ends of the failure section where the accident has occurred. In the installed electric station (for example, 12, 13), since the two sets of terminal stations 22 and 22a, 23 and 23a output the opening commands 1 and 2 to the same circuit breaker 3 (32 and 32a), these failure sections The circuit breakers 3 (32, 32a) at both ends perform a blocking operation.

(Pattern 2)
This pattern 2 is a case where an abnormality has occurred in one of the two sets of terminal stations provided at all electric power stations, that is, the terminal station 22a.

  In such a state, when an accident occurs in the power transmission line 41, the computation station 21 uses the electrical quantity information of the transmission line 41 transmitted from the terminal station 22 and the electrical quantity information of the transmission line 41 measured by the computation station 21 itself. An accident in the transmission line 41 is detected. As a result, the release command 1 is output to the circuit breaker 31 and the failure cutoff command is output to the terminal station 22. The terminal station 22 that has received the failure cutoff command outputs the release command 1 to the circuit breaker 31a.

  Further, since the terminal station 22a is abnormal, the arithmetic station 21a transmits based on the electric quantity information of the power transmission line 42 transmitted from the terminal station 23a and the electric quantity information of the power transmission line 41 measured by the arithmetic station 21a itself. An accident of the electric wires 41 to the transmission line 42 is detected. As a result, the release command 2 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 23a. The terminal station 23a outputs the opening command 2 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21a.

  Here, when an accident occurs in the power transmission line 41, the shut-off control circuits 106, 206,... Arranged at each electric station are logical products of the opening commands 1 and 2 by the two protection systems 60 and 60a. Since the circuit breaker 31 is configured, the release commands 1 and 2 are output from the sound computation stations 21 and 21a. For this reason, the release operation is performed by the logical product of these. In the circuit breaker 31a, since the terminal station 22a is abnormal, the opening command 1 is output only to the terminal station 22. However, when the terminal station 22a is abnormal, the own station bypass circuit 12 shown in FIG. An AND condition is established by the bypass circuit 12, and the opening operation is performed. As for the circuit breaker 32a, the opening command 2 is output from the terminal station 23a as described above. However, since the terminal station 23 is normal, the bypass circuit 11 is not turned on and the opening command 1 remains off. For this reason, it is not opened by the logical product configuration of FIG.

  As described above, when the terminal station 22a is abnormal and an accident occurs in the power transmission line 41, only the power transmission section 1 is opened. Even when an accident occurs in any of the power transmission lines 42, 43, 44, only one of the power transmission sections 2, 3, 4 corresponding to the power transmission line in which the accident has occurred is opened.

  This also applies to the other patterns 3 to 15, and if any one set of terminal poles is normal for all stations, no matter which of the other set of terminal stations is abnormal, Only one of the corresponding power transmission sections 1, 2, 3, 4 is opened.

(Pattern 16)
In this pattern 16, all the terminal stations 22, 23, 24 in one set and one terminal station 22a in the other set are abnormal.

  In such a state, when an accident occurs in the power transmission line 41, the computing station 21 uses the electric quantity information of the power transmission lines 41 and 44 measured by itself because the terminal stations 22, 23 and 24 of the same set are abnormal. Based on this, an accident in an enlarged section of the transmission lines 41 to 44 is detected, and an opening command 1 is output to the circuit breakers 31 and 34a at both ends of the section. Since the computing station 21a is abnormal in the same terminal station 22a, the computing station 21a is based on the electrical quantity information of the transmission line 42 transmitted from the adjacent terminal station 23a and the electrical quantity information of the transmission line 41 measured by the computing station 21a itself. The terminal station detects an accident in an enlarged section of the transmission line 41 to the transmission line 42, outputs an opening command 2 to one of the circuit breakers 31 at both ends of the section, and blocks the other circuit breaker 32a. A fault cutoff command is output to 23a. The terminal station 23a outputs the opening command 2 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21a.

  Here, since the opening commands 1 and 2 are simultaneously output from the two sets of arithmetic stations 21 and 21a, the circuit breaker 31 is opened by satisfying the AND condition of FIG. The circuit breaker 32a outputs only the opening command 2 of the terminal station 23a. For this reason, if the terminal station 23 is normal, the circuit breaker 32a is not opened, but since the terminal station 23 is abnormal, the own station bypass circuit 11 is turned on by its own device and the mutual monitoring means. Therefore, the circuit breaker 32a is opened by the opening command 2 of only the terminal station 23a.

  Also, the opening command 1 is also output from the arithmetic station 21 to the circuit breaker 34a. However, since the arithmetic station 21a is normal, it is not opened due to the logical product configuration of the cutoff control circuit 106.

  As described above, when all the terminal stations 22, 23, and 24 in one set and one of the other sets (22 in pattern 16) are abnormal, two sets of terminal stations (22 and 22a in pattern 16) An electric station (12 in pattern 16) is generated. In this case, in the electric station 12 where the two sets of terminal stations 22 and 22a are abnormal, the amount of electricity of the transmission lines 41 and 42 connected to the electric station cannot be measured. When an accident occurs, the power transmission sections 1 and 2 including the power transmission line 41 are opened. Similarly, when an accident occurs on the power transmission line 42, the power transmission sections 1 and 2 are opened. When an accident occurs in the power transmission line 43, the terminal stations 23 and 24 in one set are abnormal in the electric stations 13 and 14 at both ends, but the terminal stations 23a and 24a in the other set are normal. The circuit breakers 33 and 33a at both ends are opened because the AND condition generated in FIG. 7 is established, and only the power transmission section 3 is opened. Even when an accident occurs in the power transmission line 44, since the normal terminal stations exist at the electric stations 11 and 14 at both ends, the AND conditions generated in FIG. 7 are established for the circuit breakers 34 and 34a at both ends. Therefore, it opens and only the power transmission section 4 is opened.

  These operations are the same for the other similar patterns 17 to 18 and 22 to 24, and are the same for the patterns 19 to 21 and 24 to 27 in which two sets of terminal stations have a plurality of electrical stations. . In either case, at the electric station where two sets of terminal stations become abnormal, the amount of electricity in the connected transmission line cannot be measured, so at least one of the terminal stations expands the section between the normal electric stations. Protection.

(Pattern 28)
This pattern 28 is a case where both sets of terminal stations 22 and 22a have an abnormal electric power station 12.

  When the terminal stations 22 and 22a are abnormal, if the accident occurs in the power transmission line 41, the arithmetic station 21 detects that the power of the power transmission line 42 transmitted from the adjacent terminal station 23 because the same set of terminal stations 22 is abnormal. Based on the quantity information and the electricity quantity information of the transmission line 41 measured by the computing station 21 itself, an accident in the expanded section of the transmission lines 41 to 42 is detected. As a result, the release command 1 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 23. The terminal station 23 outputs the release command 1 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21. Since the same set of terminal stations 22a is abnormal, the arithmetic station 21a uses the electric quantity information of the power transmission line 42 transmitted from the adjacent terminal station 23a and the electric quantity information of the power transmission line 41 measured by the arithmetic station 21a itself. Based on this, an accident in the power transmission line 41 to the power transmission line 42 is detected, and an open command 2 to the circuit breaker 31 is output, and a fault cut-off command is output to the terminal station 23a. The terminal station 23a outputs the opening command 2 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21a.

  In this way, the circuit breaker 31 has the opening instructions 1 and 2 output simultaneously by the arithmetic stations 21 and 21a, and the circuit breaker 32a has the opening instruction 1.2 output simultaneously by the terminal stations 23 and 23a. Each opens.

  As described above, in the electric station 12 where the two sets of terminal stations 22 and 22a are abnormal, the amount of electricity of the transmission lines 41 and 42 connected to the electric station cannot be measured. When an accident occurs in 41), the power transmission sections 1 and 2 including the power transmission line 41 are opened. Similarly, when an accident occurs on the power transmission line 42, the power transmission sections 1 and 2 are opened. When an accident occurs in the power transmission line 43, since both sets of terminal stations 23 and 23 a, 24 and 24 a are normal at the electric stations 13 and 14 at both ends, the circuit breakers 33 and 33 a at both ends are respectively Since the AND condition generated in FIG. 7 is satisfied, the opening operation is performed, and only the power transmission section 3 is opened. Even if an accident occurs in the power transmission line 44, since there are normal terminal stations 11 and 14 at the electric stations at both ends, the AND conditions generated in FIG. 7 are established for the circuit breakers 34 and 34a at both ends. The opening operation is performed and only the power transmission section 4 is opened.

  These operations are the same for the other similar patterns 29 to 30, and are the same for the patterns 31 to 34 in which there are a plurality of electrical stations where the two sets of terminal stations become abnormal. In either case, at the electric station where two sets of terminal stations are abnormal, the amount of electricity in the connected transmission line cannot be measured, so both sets of terminal stations can extend the section between normal electric stations. , Protection is done.

(Pattern 35)
This pattern 35 is a case where one terminal station 22 in one set of electric stations 12 and one terminal station 23a of the other set in another adjacent electric station 13 are abnormal.

  When the terminal stations 22 and 23a are abnormal in this way, when an accident occurs in the power transmission line 41, the computation station 21 is transmitted from the same set of terminal stations 23 adjacent thereto because the same set of terminal stations 22 is abnormal. Accidents in the expanded section of the transmission lines 41 to 42 are detected based on the information on the amount of electricity of the transmission line 42 and the amount of electricity of the transmission line 41 measured by the computing station 21 itself. As a result, the release command 1 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 23. The terminal station 23 outputs the release command 1 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21. The computing station 21a detects an accident in the transmission line 41 based on the electrical quantity information of the transmission line 41 transmitted from the same set of terminal stations 22a and the electrical quantity information of the transmission line 41 measured by the computing station 21a itself. As a result, an open command 2 to the circuit breaker 31 is output, and a fault interrupt command is output to the terminal station 22a. The terminal station 22a that has received the failure cutoff command outputs the opening command 2 to the circuit breaker 31a.

  Here, the circuit breaker 31 performs the opening operation because the opening instructions 1 and 2 are simultaneously output from the arithmetic stations 21 and 21a. In the circuit breaker 31a, the open command 2 is output only from the terminal station 22a, but since the terminal station 22 is abnormal, the own station bypass circuit 11 is turned on by itself and the mutual monitoring means 204. . For this reason, the circuit breaker 31a is opened by the opening command of only the terminal station 22a. Further, the circuit breaker 32a outputs the opening command 1 only to the terminal station 23, and since the terminal station 23a is abnormal, the local station bypass circuit 12 is turned on. Release with the release command.

  In this case, since both-end circuit breakers 31 and 31a of the power transmission section 1 and the circuit breaker 32a on one side of the power transmission section 2 are opened, the power transmission sections 1 and 2 are opened as the power transmission path. When an accident occurs in the power transmission line 42, only the both-end circuit breakers 32 and 32a are cut off, so that only the power transmission section 2 is opened. When an accident occurs in the power transmission line 43, the one-side circuit breaker 32 in the power transmission section 2 and the both-end circuit breakers 33 and 33a in the power transmission section 3 are opened, so the power transmission sections 2 to 3 are opened as a power transmission path. . When an accident occurs in the power transmission line 44, both end circuit breakers 34 and 34a are opened, so that only the power transmission section 4 is opened.

  On the other hand, as shown in pattern 36, one terminal station 22 in one set of electrical stations 12 and one terminal station 24a in the other set in other electrical stations 14 through a healthy section are abnormal. In this case, even if an accident occurs in any of the transmission lines 41 to 44, the circuit breakers at both ends of the transmission line in which the accident has occurred are opened. Therefore, the power transmission section 1 is opened for the power transmission line 41 accident, the power transmission section 2 is opened for the power transmission line 42 accident, the power transmission section 3 is opened for the power transmission line 43 accident, and the power transmission line 44 accident occurs. The power transmission section 4 is opened.

  These relationships are the same for the other patterns 37-40.

(Pattern 41)
This pattern 41 is a case where one terminal station 22 in one set and the two terminal stations 22a and 23a in the other set are abnormal.

  If the terminal station 22 and the terminal stations 22a and 23a are abnormal and an accident occurs in the power transmission line 41, the arithmetic station 21 has the same set of terminal stations 23 adjacent to this because the same set of terminal stations 22 is abnormal. Accidents of the power transmission lines 41 to 42 are detected based on the information on the amount of electricity of the power transmission line 42 transmitted from the power and information on the amount of electricity of the power transmission line 41 measured by the computing station 21 itself. As a result, the release command 1 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 23. The terminal station 23 outputs the release command 1 to the circuit breaker 32a in response to the failure cutoff command received from the arithmetic station 21. Since the computation station 21a is abnormal in the same set of terminal stations 22a and 23a, the electrical quantity information of the power transmission line 43 transmitted from the same set of terminal stations 24a adjacent thereto and the transmission line measured by the computation station 21a itself. An accident in the section of the transmission line 41 to the transmission line 43 is detected based on the electric quantity information 41. As a result, the release command 2 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 24a. The terminal station 24a outputs the release command 2 to the circuit breaker 33a in response to the failure cutoff command received from the arithmetic station 21a.

  Here, the circuit breaker 31 is opened because the opening commands 1 and 2 are simultaneously output from the arithmetic stations 21 and 21a. The circuit breaker 32a outputs the opening command 1 only to the terminal station 23, and since the terminal station 23a is abnormal, the local station bypass circuit 12 is turned on, so the circuit breaker 32a is opened with the opening command 1 only of the terminal station 23. Operate. The circuit breaker 33a outputs the opening command 2 only to the terminal station 24a, but since the terminal station 24 is normal, the bypass circuit 11 is not turned on and is not opened due to the logical product configuration.

  As described above, when the terminal station 22 and the terminal stations 22a and 23a are abnormal and an accident occurs in the power transmission line 41, the circuit breakers 31 and 32a are opened, so that the power transmission sections 1 and 2 are opened. Even when an accident occurs in the power transmission line 42, the power transmission sections 1 and 2 are opened by the same operation. When an accident occurs in the power transmission line 43, only the circuit breakers 33 and 33a are opened, so that only the power transmission section 3 is opened. When an accident occurs on the power transmission line 44, only the circuit breakers 34 and 34a are opened, so that only the power transmission section 4 is opened.

  The other patterns 42 to 58 are combinations when one terminal station of one set and two terminal stations of the other set are abnormal, and are released depending on the position of the terminal station where the abnormality occurred. Although the power transmission section is different, it is the same as the pattern 41 from the viewpoint of protection.

(Pattern 59)
The pattern 59 is a case where the two terminal stations 22 and 23 in one set and the two terminal stations 23a and 24a in the other set are abnormal.

  If the terminal stations 22 and 23 and the terminal stations 23a and 24a are abnormal and an accident occurs in the power transmission line 41, the arithmetic station 21 detects that the same set of terminal stations 22 and 23 is abnormal, and therefore the same set adjacent to the same set. Accidents in the section of the power transmission line 41 to the power transmission line 43 are detected based on the information on the amount of electricity of the power transmission line 43 transmitted from the terminal station 24 and the amount of electricity information of the power transmission line 41 measured by the arithmetic station 21 itself. As a result, the release command 1 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 24. The terminal station 24 outputs the opening command 1 to the circuit breaker 33a in response to the failure interruption command received from the arithmetic station 21. The computation station 21a detects an accident in the transmission line 41 based on the electrical quantity information of the power transmission line 41 transmitted from the same terminal station 22a and the electrical quantity information of the transmission line 41 measured by the computation station 21a itself. As a result, the release command 2 to the circuit breaker 31 is output, and the failure cutoff command is output to the terminal station 22a. The terminal station 22a outputs the release command 2 to the circuit breaker 31a in response to the failure cutoff command received from the arithmetic station 21a.

  Here, the circuit breaker 31 performs the opening operation because the opening instructions 1 and 2 are simultaneously output from the arithmetic stations 21 and 21a. The circuit breaker 31a outputs the opening command 2 only to the terminal station 22a. However, since the terminal station 22 is abnormal, the local station bypass circuit 11 is turned on, and the circuit breaker 31a operates to open using only the terminal station 22a. The circuit breaker 33a outputs the opening command 1 only to the terminal station 24. However, since the terminal station 24a is abnormal, the local station bypass circuit 12 is turned on, and the circuit breaker 33a operates to open with the opening command 1 of only the terminal station 24.

  As described above, since the both-end circuit breakers 31 and 31a in the power transmission section 1 and the one-side circuit breaker 33a in the power transmission section 3 are opened, the power transmission sections 1 to 3 are opened as the power transmission path. When an accident occurs in the power transmission line 42, the circuit breakers 32 and 33a are opened, so that the power transmission sections 2 to 3 are opened. Even when an accident occurs in the power transmission line 43, the circuit breakers 32 and 33a are opened, so that the power transmission sections 2 to 3 are opened. When an accident occurs on the power transmission line 44, the circuit breaker 32 on one side of the power transmission section 2 and the circuit breakers 34, 34a on the power transmission section 4 are opened, so that the power transmission sections 2 to 4 are opened as power transmission paths. The

  The other patterns 60 to 64 are combinations when the two terminal stations of one set and the two terminal stations of the other set are abnormal, and are released depending on the position of the abnormal terminal station. Although the power transmission section is different, it is the same as the pattern 59 from the viewpoint of protection.

  In this way, by providing two sets of protection systems 60, 60a, and by configuring the respective fault cutoff outputs 1, 2 and the fault cutoff output bypass circuits 11, 12 by means of the device's self / mutual monitoring means by logical product, the terminal Even when the station is abnormal, the power transmission line protection function can be maintained. That is, in (Pattern 2) to (Pattern 15), (Pattern 36), and (Pattern 39) in Table 2, it is possible to maintain the protection function for each transmission line regardless of the abnormality of the terminal station. Furthermore, even in other patterns, it is possible to continue supplying power while minimizing the number of power outages.

It is a system configuration | structure figure explaining one Embodiment of the network power transmission protection apparatus by this invention. It is a block diagram explaining the structure of the arithmetic station used for one embodiment same as the above. It is a block diagram explaining the structure of the terminal station used for one embodiment same as the above. It is a system configuration | structure figure explaining other embodiment of the network power transmission protection apparatus by this invention. It is a block diagram explaining the relationship with the interruption | blocking control circuit in the electric station which has two sets of arithmetic stations in other embodiment same as the above. It is a block diagram explaining the relationship with the interruption | blocking control circuit in the electric station which has two sets of terminal stations in other embodiment same as the above. It is a circuit diagram which shows the structure of the interruption | blocking control circuit in other embodiment same as the above.

Explanation of symbols

1, 2, 13, 14 Electric station 21, 21a Arithmetic station 22, 22a, 23, 23a, 24, 24a Terminal station 41, 42, 43, 44 Transmission line 60, 60a Protection system 71 Power supply system 101 , 201 Measuring means 102 Failure section detecting means 103, 203 Communication means 104, 204 Self / mutual monitoring means

Claims (1)

A network power transmission protection device for protecting a power transmission system configured in a loop by connecting a plurality of electric power stations including an electric power station connected to a power supply system by power transmission lines provided with circuit breakers at both ends,
Measuring means that is provided at both ends of each of the transmission lines and individually measures the amount of electricity flowing through the corresponding transmission line;
There are two sets of arithmetic stations provided in one of the plurality of electric stations, and two sets of terminal stations provided in the remaining electric stations, respectively, and the arithmetic station and plural plural stations for each group are provided by communication means. between terminal stations mutually exchanging various types of information and two pairs of protective system capable for each set include an electrical quantity information measured by the terminal station,
Self-mutual monitoring means that is provided in the two sets of protection-system computing stations and each terminal station, and that monitors the presence / absence of abnormality of the self and other stations for each protection system ,
A breaker control circuit that is provided for each breaker in the electrical station and opens the corresponding breaker; and
Electricity information at both ends of each transmission line measured by the measurement means is collected for each protection system , provided in the two sets of protection system calculation stations, and is determined for each transmission line from the electricity quantity information at both ends of the transmission lines. detecting the presence or absence of failure in each protection system, in the case of failure there, cutoff command to shut off the circuit breaker failure period ends on the cut-off control circuit of each substation, each via its own station or another terminal station With fault section detection means for outputting for each protection system ,
The two sets of protection system failure section detection means are connected to the electric station having the detected abnormal terminal station when the self / mutual monitoring means detects an abnormality of any terminal station for each protection system . a plurality of transmission lines as in series with one of the sections, the presence or absence of a failure of the relevant sections have a determining section expansion detection function for each protection system based on both ends electrical quantity of the section,
The shut-off control circuit of each electric station takes a logical product of shut-off commands output from two sets of protection systems provided in the self-power station, opens the corresponding circuit breaker, and bypass circuits for the shut-off commands And when the abnormality of either one of the two protection systems provided in the self-electricity station is detected by the self / mutual monitoring means, the shutdown command by the abnormality protection system is bypassed, A network power transmission protection device configured so as not to perform bypass command bypassing by the abnormality protection system when the two protection systems provided in the system are abnormal .

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