JP6698414B2 - Power transmission line protection system - Google Patents

Description

  The present invention relates to a power transmission line protection system.

  In a conventional low-level substation, for example, for load supply, if the protection relay of the load supply line fails, it will be unprotected, so if an accident occurs, the upper system transformer protection relay will function as a backup protection relay. However, there was a problem that the upper transformers were tripped and other healthy load supply lines also suffered a power failure, causing a wide range of supply problems. On the other hand, by installing a trip device that utilizes a transformer protection relay, the operating state (opening/closing state) of the circuit breaker of the load supply line (transmission line) to be protected can be captured to prevent an accident on the transmission line. On the other hand, a power transmission line alternative protection system has been proposed as a power transmission line protection system capable of gradually tripping a corresponding load supply line and bus, etc. (see, for example, Patent Document 1).

JP, 2011-199962, A (paragraph number 0017-0052 and Drawing 4).

  The conventional power transmission line protection system is configured as described above, and it is necessary to capture the operating states of the circuit breakers for the number of power transmission lines to be protected, and there is a problem that the circuit configuration becomes complicated as the number of power transmission lines increases. there were.

  The present invention has been made to solve the above problems, and an object thereof is to obtain a power transmission line protection system capable of protection with a simple configuration.

In the power transmission line protection system according to the present invention,
A power transmission line protection system for protecting a plurality of power transmission lines connected to a power receiving line, the system including a first abnormality detection device, a third abnormality detection device, and a protection command transmission device,
The first abnormality detection device has a self-monitoring function of detecting its own failure and issuing a failure detection signal, is provided for each of the power transmission lines, and detects an abnormality of each of the power transmission lines to issue a first detection signal. Monodea is,
Before Symbol third abnormality detection device is provided commonly to the first abnormality detection device, the abnormality of the first abnormality detection device the power transmission line in place of the first abnormality detection apparatus either has failed even when a failure of And a third detection signal is emitted when the abnormality is detected.
The protection command transmitter is for transmitting a protection command to identify the transmission line to be protected on the basis of the previous SL failure detection signal and the third detection signal,
The first abnormality detection device and the third abnormality detection device both detect overcurrent,
The first abnormality detection device detects an overcurrent of the power transmission line based on a detection current of a current transformer that detects a current of the power transmission line, and transmits the first detection signal,
The third abnormality detection device can detect the overcurrent of the power transmission line based on the detected current of the current transformer in place of the failed first abnormality detection device when the first abnormality detection device fails. In addition, the third detection signal is transmitted when the overcurrent is detected, and the overcurrent of the power transmission line is supplied by receiving a sum current of the detection currents of all the current transformers. Is detected and the third detection signal is transmitted.

The power transmission line protection system according to the invention, it is possible to obtain a power transmission line protection system capable protected by easy easy Do construction.

It is a block diagram which shows the structure of the power transmission line protection system which is Embodiment 1 of this invention. FIG. 4 is an explanatory diagram showing a current flow when a short circuit accident occurs in the first embodiment. FIG. 3 is a developed connection diagram for explaining the operation of the power transmission line protection system in the first embodiment. It is a block diagram which shows the structure of the power transmission line protection system which is Embodiment 2. FIG. 7 is an explanatory diagram showing a current flow when a short circuit accident occurs in the second embodiment. FIG. 9 is a development connection diagram for explaining the operation of the power transmission line protection system in the second embodiment. It is a block diagram which shows the structure of the power transmission line protection system which is Embodiment 3. FIG. 11 is an explanatory diagram showing a current flow when a short circuit accident occurs in the third embodiment. FIG. 10 is a development connection diagram for explaining the operation of the power transmission line protection system in the third embodiment. It is explanatory drawing which shows the flow of an electric current when a short circuit accident generate|occur|produces during overcurrent relay failure. It is explanatory drawing which shows the flow of an electric current when a short circuit accident generate|occur|produces while another overcurrent relay is out of order.

Embodiment 1.
1 to 3 show Embodiment 1 for carrying out the present invention. FIG. 1 is a configuration diagram showing a configuration of a power transmission line protection system, and FIG. 2 is a diagram showing a current when a short-circuit accident occurs. FIG. 3 is an explanatory diagram showing the flow, and FIG. 3 is an expanded connection diagram for explaining the operation of the power transmission line protection system. In FIG. 1, the main circuit of the substation as a power system is configured as follows. A transformer 3 is connected to the power receiving line 1 via a circuit breaker 2. The power transmission bus 4 is connected to the secondary side of the transformer 3. A series circuit of a power transmission line 5 and a circuit breaker 6 and a series circuit of a power transmission line 7 and a circuit breaker 8 are connected to the power transmission bus 4 and are connected from the power transmission line 5 and the power transmission line 6 via the circuit breakers 6, 8. Electric power is sent to a substation (not shown) below.

  The transmission line protection system is configured as follows. A current transformer 10 is provided in the power receiving line 1, and an overcurrent relay (OCR) 11 as a protection relay and an overcurrent relay 12 as a backup protection and second anomaly detection device are provided on the secondary side of the current transformer 10. And are connected. The output signal side of the overcurrent relay 11 is connected to the control circuit 14. The control circuit 14 is connected to a switchgear (not shown) of the circuit breaker 2. The output signal side of the overcurrent relay 12 is connected to the auxiliary relay (AXR) 13. The auxiliary relay 13 has a coil 13C and amplifies the output signal of the overcurrent relay 12, that is, converts it into an opening/closing signal of a contact 13a capable of flowing a larger current.

  A current transformer 20 is provided in the power transmission line 5, and an overcurrent relay 21 as a first abnormality detection device is connected to the secondary side of the current transformer 20. The output signal side of the overcurrent relay 21 is connected to the control circuit 22. The control circuit 22 is connected to a switchgear (not shown) for the circuit breaker 6. A current transformer 30 is provided in the power transmission line 7, and an overcurrent relay 31 as a first abnormality detection device is connected to the secondary side of the current transformer 30. The output signal side of the overcurrent relay 31 is connected to the control circuit 32. The control circuit 32 is connected to the switchgear (not shown) of the circuit breaker 8. The output side of the auxiliary relay 13 is connected to the control circuits 22 and 32. The overcurrent relay 12 has a self-monitoring function for constantly monitoring its own internal failure, in addition to the normally open contact 12a that is closed when the overcurrent relay 12 operates, and detects a failure when no internal failure is detected. The contact 12x is opened and the failure detection contact 12y is closed. When an internal failure is detected in the overcurrent relay 12, the failure detection contact 12x is closed and the failure detection contact 12y is opened (see FIG. 3).

  As shown in FIG. 3, the overcurrent relay 21 has, in addition to the normally open contact 21a that is closed when it operates, a self-monitoring function that constantly monitors its own internal failure, and when no internal failure is detected, The failure detection contact 21x is opened and the failure detection contact 21y is closed. When an internal failure is detected in the overcurrent relay 21, the failure detection contact 21x is closed and the failure detection contact 21y is opened (see FIG. 3). Although not shown, the same applies to the overcurrent relay 31. Direct current power is supplied to the overcurrent relay 11 and the overcurrent relay 12 from the control power supply lines P1 and N1. DC power is supplied to the overcurrent relay 21 and the overcurrent relay 31 from the control power supply lines P2 and N2. In this embodiment, the overcurrent relay 21 and the overcurrent relay 31 are realized by software processing by digital control by a microprocessor or a digital signal processor (digital relay having a self-monitoring function). There is. The overcurrent relay 12, the auxiliary relay 13, the overcurrent relay 21, the control circuit 22, the overcurrent relay 31, and the control circuit 32 are the protection command transmission device in the present invention.

  Next, the operation will be described. As shown in FIG. 2, when the main circuit is short-circuited at the fault point F1, the fault current J1 flows to the primary side of the transformer 3, and the overcurrent relay 11 connected to the secondary side of the current transformer 10 and the backup device. A current C1 flows through the protective overcurrent relay 12. A fault current J2 flows through the secondary side of the transformer 3, and a current C2 flows through the overcurrent relay 21 connected to the secondary side of the current transformer 20. If there is no abnormality in all of the overcurrent relay 11, the overcurrent relay 12, and the overcurrent relay 21, the overcurrent relay 21 close to the fault point F1 operates due to the magnitude relationship between the settling value and the settling time, and as the first detection signal. The normally open contact 21a is closed and a voltage is applied from the control power supply lines P2 and N2 to the coil 22C of the control circuit 22 to be excited. When the coil 22C is excited, a switching contact signal (not shown) of the coil 22C as a protection command is output to the switchgear of the circuit breaker 6 as a circuit breaker trip signal, which opens the circuit breaker 6 and opens the fault point F1. The disconnection from the power transmission bus 4 is completed.

  Next, a case where the overcurrent relay 21 of the power transmission line 5 is out of order will be described with reference to FIG. In FIG. 3, when the overcurrent relay 21 of the power transmission line 5 is out of order, the failure detection contact 21x as a failure detection signal of the overcurrent relay 21 of the power transmission line 5 is closed. In this state, when the overcurrent relay 12 for protection provided on the power receiving line 1 operates, the voltage is applied from the control power supply lines P1 and N1 to the coil 13C of the auxiliary relay 13 by closing the normally open contact 12a as the second detection signal. It is applied and excited, and its contact 13a is closed. When the contact 13a is closed, the failure detection contact 21x of the overcurrent relay 21 is closed, so that a voltage is applied from the control power supply lines P2 and N2 to the coil 22C of the control circuit 22 to be excited, and the normally open contact is formed. (Not shown) is closed. The normally closed contact closing signal is sent to the switchgear of the circuit breaker 6 to open the circuit breaker 6, and the accident point F1 is disconnected from the power transmission bus 4. Although the current C1 flows into the overcurrent relay 11 during a short-circuit accident, the overcurrent relay 12 operates due to the magnitude relationship between the set value of the overcurrent relay 11 and the overcurrent relay 12 and the settling time, and is close to the fault point F1. The circuit breaker 6 is opened and the circuit breaker 2 is not opened.

  When the overcurrent relay 31 fails, the circuit breaker 8 is opened in the same manner as when the overcurrent relay 21 fails.

  As described above, according to this embodiment, the overcurrent relay 21 and the overcurrent relay 31 having the self-monitoring function of detecting the own failure and issuing the failure detection signal are provided, and the failure detection signal and the backup protection are provided. Since the overcurrent relay 12 and the power transmission line to be backed up are identified by the overcurrent relay 12 and the protection command for protecting the power transmission line is issued, the circuit breaker 6 provided in the power transmission line 5 and the interruption provided in the power transmission line 7 are cut off. It is not necessary to use the information on the open/closed state of the container 8. Therefore, it is possible to prevent the circuit configuration from becoming complicated as the number of power transmission lines increases, and it is possible to obtain a power transmission line protection system having a simple configuration.

Embodiment 2.
4 to 6 show the second embodiment, FIG. 4 is a configuration diagram showing a configuration of a transmission line protection system, FIG. 5 is an explanatory diagram showing a current flow when a short-circuit accident occurs, and FIG. 6 is a developed connection diagram for explaining the operation of the power transmission line protection system. The first embodiment is characterized in that the power receiving line 1 is provided with the overcurrent relay 12. On the other hand, in this embodiment, as shown in FIG. 4, an overcurrent relay 42 as a backup protection and a third abnormality detection device is provided on the power transmission line 5 and power transmission line 7 sides. The overcurrent relay 42 is connected such that the currents of both the current transformer 20 and the current transformer 30 are added (sum of the currents of all power transmission lines), that is, supplied. The overcurrent relay 42 is provided as a backup device common to the overcurrent relay 21 and the overcurrent relay 31.

  The output signal side of the overcurrent relay 42 is connected to the auxiliary relay 43, and the output signal thereof is converted into an opening/closing signal of the contact 43a capable of passing a larger current. The overcurrent relay 42 has a self-monitoring function for constantly monitoring its own internal failure, in addition to the normally open contact 42a that closes when the overcurrent relay 42 operates, and detects a failure when no internal failure is detected. The contact 42x is opened and the failure detection contact 42y is closed. When an internal failure is detected in the overcurrent relay 42, the failure detection contact 42x is closed and the failure detection contact 42y is opened (see FIG. 6). Since other configurations are similar to those of the first embodiment, corresponding components are designated by the same reference numerals, and description thereof will be omitted. The overcurrent relay 21, the control circuit 22, the overcurrent relay 31, the control circuit 32, the overcurrent relay 42, and the auxiliary relay 43 are the protection command transmission device in this invention.

  Next, the operation will be described. As shown in FIG. 5, when the main circuit is short-circuited at the fault point F1, the fault current J1 flows in the power receiving line 1 and the current C1 is generated in the overcurrent relay 11 and the overcurrent relay 12 connected to the current transformer 10. Flowing. A fault current J2 flows through the secondary side of the transformer 3, and a current C3 flows through the overcurrent relay 21 and the overcurrent relay 42 connected to the current transformer 20. At this time, if there is no abnormality in all of the overcurrent relay 11, the overcurrent relay 12, the overcurrent relay 21, and the overcurrent relay 42, the overcurrent relay 21 close to the fault point operates due to the magnitude relationship between the settling value and the settling time. Then, the normally open contact 21a is closed (the failure detection contact 21y is closed), and the coil 22C of the control circuit 22 is excited (see FIG. 6). When the coil 22C is excited, its switching contact signal is output to the switching device of the circuit breaker 6 as a circuit breaker trip signal, and the circuit breaker 6 is opened.

  Hereinafter, a case where the overcurrent relay 21 is out of order will be described. In FIG. 6, when the overcurrent relay 42 operates and the normally open contact 42a as the third detection signal is closed, the coil 43C of the auxiliary relay 43 is excited and the contact 43a is closed. At this time, when the overcurrent relay 21 is out of order, the failure detection contact 21x is closed and the failure detection contact 21y is open. A voltage is applied to the coil 22C of the control circuit 22 to excite it. When the coil 22C is excited, the switching signal of the switching contact of the coil 22C as a protection command is output to the switchgear of the circuit breaker 6 as a circuit breaker trip signal, which opens the circuit breaker 6 and the overcurrent relay 21 operates normally. As in the case of, the disconnection of the accident point F1 from the power transmission bus 4 is completed.

  Even when the overcurrent relay 31 is out of order, as in the case where the overcurrent relay 21 is out of order, when a short circuit occurs at the accident point F1, the overcurrent relay 42 receives the fault current detected by the current transformer 30. Flow, the overcurrent relay 42 operates and the breaker 8 is opened. Since the sum of the currents flowing through the power transmission line 5 and the power transmission line 7 flows through the overcurrent relay 42, the set value of the overcurrent relay 42 is smaller than the sum of the maximum load currents of the power transmission line 5 and the power transmission line 7. When the value is set, the circuit breaker 6 is opened by the operation of the overcurrent relay 42 when the overcurrent relay 21 is broken down, and the circuit breaker 8 is opened when the overcurrent relay 31 is broken down. It will be opened.

  As described above, according to this embodiment, the failure detection signal of the overcurrent relay 21 and the overcurrent relay 31 and the overcurrent relay 42 for protection of the backup equipment are used to specify the transmission line to be protected and the transmission line is protected. Since the protection command for protection is issued, it is not necessary to use the information on the open/close state of the circuit breaker 6 provided in the power transmission line 5 and the circuit breaker 8 provided in the power transmission line 7. Therefore, it is possible to prevent the circuit configuration from becoming complicated as the number of power transmission lines increases, and it is possible to obtain a power transmission line protection system having a simple configuration.

  In the first embodiment shown in FIG. 1, the power receiving line 1 is provided with the overcurrent relay 12 for protection of the power transmission lines 5 and 7 for protection of the power transmission lines 5 and 7. Therefore, the voltage class difference must be taken into consideration when setting the protection. In contrast to this, in the second embodiment, the overcurrent relay 42 for protecting the backup is provided on the side of the power transmission lines 5 and 7 having the same voltage class, so that the settling study of the overcurrent relay 42 becomes easy.

Embodiment 3.
7 to 11 show the third embodiment, FIG. 7 is a configuration diagram showing a configuration of a power transmission line protection system, and FIG. 8 is an explanatory diagram showing a current flow when a short-circuit accident occurs. 9 is a developed connection diagram for explaining the operation of the power transmission line protection system. FIG. 10: is explanatory drawing which shows the flow of an electric current when a short circuit accident occurs while the overcurrent relay is out of order. FIG. 11: is explanatory drawing which shows the flow of an electric current when a short circuit accident occurs while another overcurrent relay is out of order. The second embodiment is characterized in that the overcurrent relay 42 to which the detection currents of both the current transformer 20 and the current transformer 30 are supplied is provided. On the other hand, in this embodiment, as shown in FIG. 7, switching devices 51 and 52 are provided as current switching units that switch and supply the detected currents of the current transformer 20 and the current transformer 30. And In FIG. 7, the overcurrent relay 21 and the switching device 51 are connected to the secondary side of the current transformer 20. An overcurrent relay 31 and a switch 52 are connected to the secondary side of the current transformer 30.

  An overcurrent relay 54 as a backup protection and a third abnormality detection device is connected to the overcurrent relay 21 via the switch 51 and is also connected to the overcurrent relay 31 via the switch 52. The output signal side of the overcurrent relay 54 is connected to the auxiliary relay 55, and the output signal thereof is converted into an opening/closing signal of the contact 55a capable of passing a larger current. The overcurrent relay 54 has a self-monitoring function for constantly monitoring its own internal failure, in addition to the normally open contact 54a that closes when the overcurrent relay 54 operates, and detects a failure when no internal failure is detected. The contact 54x is opened and the failure detection contact 54y is closed. When an internal failure is detected in the overcurrent relay 54, the failure detection contact 54x is closed and the failure detection contact 54y is opened (see FIG. 8). Since other configurations are similar to those of the second embodiment, the corresponding components are designated by the same reference numerals and the description thereof is omitted. In this case as well, the overcurrent relay 54 is provided as having a function as a common backup device for the overcurrent relay 21 and the overcurrent relay 31. The overcurrent relay 21, the control circuit 22, the overcurrent relay 31, the control circuit 32, the overcurrent relay 54, and the auxiliary relay 55 are the protection command transmission device in this invention.

  Next, the operation will be described. In FIG. 7, when the overcurrent relay 21 is not in failure, the switching device 51 is not excited, the two contacts 51a are opened, the contacts 51b are closed, and the overcurrent relay 21 changes current. Connected to the transformer 20, the overcurrent relay 54 is not connected to the current transformer 20. Similarly, when the overcurrent relay 31 is not in failure, the switching device 52 is not excited, the two contacts 52a shown in FIG. 7 are opened, and the contacts 52b are closed, and the overcurrent relay is closed. 31 is connected to the current transformer 30, and the overcurrent relay 54 is not connected to the current transformer 30. In this normal state, when the main circuit is short-circuited at the fault point F1, the fault current J1 flows in the primary side of the transformer 3 and the fault current J2 flows in the secondary side of the transformer 3 as shown in FIG. Each flows. The current C1 that is the secondary side current of the current transformer 10 flows through the overcurrent relay 11 and the overcurrent relay 12, and the current C2 that is the secondary side current of the current transformer 20 flows through the overcurrent relay 21. By setting each of the overcurrent relays 11, 12, and 21, the overcurrent relay 21 closest to the fault point F1 operates to open the circuit breaker 6.

  On the other hand, when the overcurrent relay 21 is out of order, the failure detection contact 21x as a failure detection signal of the overcurrent relay 21 shown in FIG. 9 is closed and the failure detection contact 21y is opened. When the failure detection contact 21x is closed, the coil 51C of the switch 51 is excited, the two contacts 51a (Fig. 7) are closed, and the contact 51b (Fig. 7) is opened. As a result, the overcurrent relay 54 is connected to the current transformer 20, and when the fault current J2 flows through the current transformer 20, the secondary current C4 of the current transformer 20 in the overcurrent relay 54 becomes as shown in FIG. Flowed or supplied as shown. Then, the overcurrent relay 54 operates, the normally open contact 54a as the third detection signal is closed (FIG. 9), and the control power supply line P2 is connected via the normally open contact 54a and the failure detection contact 54y (closed). A voltage is applied from N2 to the coil 55C of the auxiliary relay 55 to be excited, and the contact 55a is closed. When the contact 55a is closed, the overcurrent relay 21 fails and the failure detection contact 21x is closed. Therefore, the coil 22C of the control circuit 22 is excited via the diode 55d, and the coil 22C is opened/closed as a protection command. The contact switching signal is output to the switching device of the circuit breaker 6 as a circuit breaker trip signal, and the circuit breaker 6 is opened.

  When the overcurrent relay 31 fails, the coil (not shown) of the switch 52 is excited in the same manner, the two contacts 52a (Fig. 7) are closed, and the contacts 52b (Fig. 7) are opened. As a result, when the overcurrent relay 54 is connected to the current transformer 30 and a short circuit accident occurs on the load side of the circuit breaker 8, as shown in FIG. 11, the overcurrent relay 54 is connected to the current transformer 30. The secondary side current C5 flows, and the overcurrent relay 54 operates to open the circuit breaker 8.

  As described above, according to this embodiment, the failure detection signal of the overcurrent relay 21 and the overcurrent relay 31 and the overcurrent relay 42 for protection of the backup equipment are used to specify the transmission line to be protected and the transmission line is protected. Since the protection command for protection is issued, it is not necessary to use the information on the open/close state of the circuit breaker 6 provided in the power transmission line 5 and the circuit breaker 8 provided in the power transmission line 7. Therefore, it is possible to prevent the circuit configuration from becoming complicated as the number of power transmission lines increases, and it is possible to obtain a power transmission line protection system having a simple configuration.

  In addition, in the second embodiment, the sum of the currents of the power transmission lines 5 and 7 that is the sum of the currents of all the power transmission lines is supplied (incorporating the sum), whereas in the present embodiment, the failure occurs. The current is supplied only to the power transmission line that the overcurrent relay is responsible for. Therefore, in the second embodiment, when the total sum of the load currents flowing in the respective power transmission lines becomes large, malfunction of the overcurrent relay 42 for protection of the backup equipment is apt to occur, whereas in the third embodiment, for the protection of the backup equipment. By supplying only the required current, malfunctions are less likely to occur, and a more reliable power transmission line protection system can be obtained.

In the above embodiment, the number of power transmission lines is two, but the same effect can be obtained even if the number of lines is three or more, and the effect of the present invention becomes greater as the number of lines increases.
Further, the abnormal phenomenon to be protected is not limited to the overcurrent, and may be other abnormal detection such as detection of overload. However, the same effect is obtained.

  In the present invention, the above-described embodiments can be freely combined, or the embodiments can be appropriately changed or omitted within the scope of the invention.

1 power receiving line, 3 transformer, 5,7 power transmitting line, 10 current transformer, 12 overcurrent relay, 13 auxiliary relay, 14 control circuit, 20 current transformer, 21 overcurrent relay,
22 control circuit, 30 current transformer, 31 overcurrent relay, 32 control circuit,
42 overcurrent relay, 43 auxiliary relay, 51, 52 switching device, 54 overcurrent relay,
55 Auxiliary relay.

Claims (2)

A power transmission line protection system for protecting a plurality of power transmission lines connected to a power receiving line, the system including a first abnormality detection device, a third abnormality detection device, and a protection command transmission device,
The first abnormality detection device has a self-monitoring function of detecting its own failure and issuing a failure detection signal, is provided for each of the power transmission lines, and detects an abnormality of each of the power transmission lines to issue a first detection signal. Monodea is,
Before Symbol third abnormality detection device is provided commonly to the first abnormality detection device, the abnormality of the first abnormality detection device the power transmission line in place of the first abnormality detection apparatus either has failed even when a failure of And a third detection signal is emitted when the abnormality is detected.
The protection command transmitter is for transmitting a protection command to identify the transmission line to be protected on the basis of the previous SL failure detection signal and the third detection signal,
The first abnormality detection device and the third abnormality detection device both detect overcurrent,
The first abnormality detection device detects an overcurrent of the power transmission line based on a detection current of a current transformer that detects a current of the power transmission line, and transmits the first detection signal,
The third abnormality detection device can detect the overcurrent of the power transmission line based on the detected current of the current transformer in place of the failed first abnormality detection device when the first abnormality detection device fails. In addition, the third detection signal is transmitted when the overcurrent is detected, and the overcurrent of the power transmission line is received by receiving the total current of the detection currents of all the current transformers. A power transmission line protection system for detecting a signal and transmitting the third detection signal . The power transmission line protection system according to claim 1, wherein the power reception line and the plurality of power transmission lines are connected via a transformer.

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