JP2013162614A - Ngr automatic insertion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a neutral grounding resistor (NGR) automatic insertion system that can automatically insert an NGR into a system with which the NGR is not connected.SOLUTION: An NGR automatic insertion system is configured to comprise: an A transformer 2 and a B transformer 7 installed on an A-system power transmission line 1 and a B-system power transmission line 6, respectively; an NGR 3 and an NGR 9 comprised in the A transformer 2 and the B transformer 7, respectively; a route transformer 20 for circumventing between the A-system power transmission line 1 and the B-system power transmission line 6; a zero phase current circuit breaker 8 for breaking/connecting zero-phase current flowing in the NGR 9; and an NGR control device 16 which controls braking/connecting of the zero-phase current circuit breaker 8 on the basis of an OVG relay 15 operated by overvoltage generated when the B transformer 7 looses balance and a DG relay 13 comprised in an electromagnetic induction object power transmission line 12 to which a communication line is disposed closely if blackout has occurred to an alternative route connecting between the A-system power transmission line 1 and the B-system power transmission line 6, and a ground fault accident has occurred to another power transmission line 14 connected with the B-system power transmission line 6 during the blackout.

Description

  The present invention relates to an NGR automatic input system, and more particularly to an NGR automatic input system that automatically causes NGR to flow a zero-phase current generated by a ground fault in a system not connected to NGR due to a system power failure.

  The transformer connected to the transmission line has a neutral grounding resistor (NGR) installed between it and the ground in order to flow the zero-phase current generated by the ground fault of the transmission line. ing. However, depending on the transmission line system, there may be a system in which no NGR is connected in the event of a two-transmission line failure (route failure). As a countermeasure in that case, a ground fault overvoltage relay (OVGR) that operates at an overvoltage even if a ground fault current does not flow is installed, and the fault section is cut off by this ground fault overvoltage relay.

FIG. 3 is a block diagram showing a configuration of a conventional power transmission line system. The transmission line system 50 includes an A-system transmission line 51 and a B-system transmission line 56 having different power systems, and an A transformer 52 and a B transformer installed in the A-system transmission line 51 and the B-system transmission line 56, respectively. 57, neutral grounding resistance device (hereinafter referred to as NGR) 53 and NGR 59 provided in the A transformer 52 and the B transformer 57, and between the A system transmission line 51 and the B system transmission line 56, respectively. A power outage occurs in a route transformer 66 that bypasses the zero-phase current breaker 58 that connects and disconnects the zero-phase current flowing in the NGR 59, and a bypass route that connects the A-system transmission line 51 and the B-system transmission line 56, When a ground fault occurs in the other power transmission line 64 connected to the B system power transmission line 56 during the power failure, a ground fault overvoltage relay (hereinafter, referred to as an overvoltage relay that operates with an overvoltage generated due to the balance of the B transformer 57 being lost). With OVG relay Department) 63a, 65a, and ground directional relay (hereinafter indicating the direction of the ground fault current, referred to as DG relay) 63 b, is configured to include a 65b, a.
The power line (referred to as AC line) 55 connecting the A-system transmission line 51 and the route transformer 66 is provided with a circuit breaker 54, and the power line connecting between the B-system transmission line 56 and the route transformer 66 (referred to as BC line). 61) is provided with a circuit breaker 60.

Here, when the BC line 61 is blacked out due to an accident or the like, the breaker 60 cuts off the BC line and a transmission line route breakage accident occurs. As a result, the B system power transmission line 56 is always disconnected from the NGR 59 by the circuit breaker 58, and therefore the B transformer 57 is not connected to the NGR 59. In this state, when a ground fault occurs in the other power transmission line 64, the ground fault current from the NGR 59 is not supplied to the ground fault point, so that a ground fault overvoltage is generated and the fault point is interrupted by the OVG relay 65.
In addition, as a conventional technique for performing natural arc extinction of an accident point arc, Patent Document 1 describes a high-speed accident without wasteful waiting time in cooperation with an arc extinguishing reactor / neutral point grounding resistance control device at the time of a one-line ground fault. A protective relay device that performs section interruption is disclosed.

JP-A-10-271663

However, the OVG relays 63a and 65a cannot be operated faster than the DG relays 63b and 65b because they are relays having a backup role for the DG relays 63b and 65b that operate by sensing zero-phase current. For this reason, there is a possibility that the accident section interruption is delayed and the range of the accident is expanded.
In addition, the conventional technique disclosed in Patent Document 1 may exceed the interruption time defined in the electrical equipment technical standards if the arc extinction (eliminating the arc at the accident point) fails.
The present invention has been made in view of such a problem, and provides an NGR automatic charging system capable of automatically charging NGR of a system not connected to NGR when a transmission line route disconnection accident occurs. For the purpose.

In order to solve such a problem, the present invention provides a first power transmission line and a second power transmission line having different power systems, and the first power transmission line and the second power transmission line, respectively. First and second transformers, a first neutral grounding resistance device provided in each of the first and second transformers, and a second neutral A grounding resistance device, a route transformer that bypasses between the first transmission line and the second transmission line, and a zero-phase current interruption that connects and disconnects the zero-phase current flowing through the second neutral grounding resistance device A power failure occurs in a detour route connecting the first power transmission line and the second power transmission line, and a ground fault occurs in another power transmission line connected to the second power transmission line during the power failure If a fault occurs, a ground fault overvoltage relay that operates with an overvoltage generated due to an imbalance of the second transformer, and a communication line Based on the state of the earth fault directional relay provided in contact disposed electromagnetic induction target transmission line, characterized in that and a NGR control means for controlling connection and disconnection of the zero-phase current interrupter.
When a power failure occurs on the detour route connecting the first power transmission line and the second power transmission line, and a ground fault occurs on another power transmission line connected to the second power transmission line during this power outage, The balance of the second transformer is lost and a zero-phase current is generated at the accident point. At that time, when a zero-phase current flows to the ground fault point through the neutral grounding resistance device, the ground fault direction relay is operated to promptly cut off the transmission line. However, in order to reduce the electromagnetic induction by limiting the zero-phase current that flows through the entire system, the neutral grounding resistance device is always disconnected by the circuit breaker so that the zero-phase current does not flow through the second transformer. It is. For this reason, the transmission line cannot be interrupted immediately, but overvoltage occurs in the system. In the present invention, a ground fault overvoltage relay for detecting this overvoltage and a control means for controlling the zero-phase current breaker according to the state of the ground fault direction relay provided in the electromagnetic induction target transmission line are provided. Thereby, since a zero-phase current can be always sent to the 2nd transformer to which a neutral point grounding resistance apparatus is not connected, accident section interruption can be performed immediately.

According to a second aspect of the present invention, the NGR control means causes a power failure in a detour route connecting the first power transmission line and the second power transmission line, and a ground fault occurs in the other power transmission line during the power failure. When it occurs, the zero-phase current breaker is brought into a contact state on condition that the ground fault overvoltage relay is continuously operated for a predetermined time and the ground fault direction relay is not operated. To do.
When the overvoltage relay operates continuously for a predetermined time, it indicates that a ground fault has occurred and the balance of the transformer has been lost. In such a case, it is necessary to immediately flow the zero-phase current to the accident point through the neutral point grounding resistance device. However, since the zero-phase current cannot flow through the electromagnetic induction target transmission line, the zero-phase current breaker is set to the zero state with the zero-phase current breaker in the contact state on condition that the ground fault direction relay provided for the electromagnetic induction target transmission line is not operating. A phase current is allowed to flow through a neutral point grounding resistance device. As a result, it is possible to prevent electromagnetic induction from being generated in the communication line and to immediately shut off the accident section.

According to a third aspect of the present invention, when the NGR control means detects that the ground fault overvoltage relay is restored, the zero phase current breaker is turned off.
When the zero-phase current breaker is brought into a contact state, the zero-phase current flows through the neutral grounding resistance device, so that the overvoltage generated in the system is reduced and the overvoltage relay is restored. When detecting the state, the NGR control means determines that the zero-phase current has become zero, and turns off the zero-phase current breaker. Thereby, the zero phase current circuit breaker of the second transformer can be automatically returned to the original state.

According to the present invention, since the overvoltage relay for detecting the overvoltage of the power system and the control means for controlling the zero-phase current breaker according to the state of the ground fault direction relay provided in the electromagnetic induction target transmission line, always, By supplying a zero-phase current to the second transformer that is not connected to the neutral grounding resistance device, it is possible to immediately shut off the accident section.
In addition, since the zero-phase current cannot flow in the electromagnetic induction target transmission line, the zero-phase current breaker is set to the contact state and the zero-phase current breaker is in the contact state on condition that the ground fault direction relay provided for the electromagnetic induction target transmission line is not operating. Since the phase current is caused to flow through the neutral grounding resistance device, it is possible to prevent the electromagnetic induction from being generated in the communication line and to immediately shut off the accident section.
Further, when the overvoltage relay detects the return state, it is determined that the zero-phase current has become zero, and the zero-phase current breaker is turned off, so the zero-phase current breaker of the second transformer is automatically turned off. Can be restored to its original state.

It is a block diagram which shows the structure of the NGR automatic injection | throwing-in system which concerns on embodiment of this invention. It is a flowchart explaining operation | movement of the NGR automatic injection | throwing-in system 40 which concerns on this invention. It is a block diagram which shows the structure of the conventional power transmission line system.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

FIG. 1 is a block diagram showing a configuration of an NGR automatic input system according to an embodiment of the present invention. The NGR automatic input system 40 according to the present invention includes an A system transmission line (first transmission line) 1 and a B system transmission line (second transmission line) 6 having different power systems, an A system transmission line 1, and A transformer (first transformer) 2, B transformer (second transformer) 7, A transformer 2, and B transformer 7 installed in B system transmission line 6, respectively. Neutral point grounding resistance device (hereinafter referred to as NGR) (first neutral point grounding resistance device) 3, NGR (second neutral point grounding resistance device) 9, A-system transmission line 1, and A route transformer 20 that bypasses the B-system transmission line 6, a zero-phase current breaker 8 that connects and disconnects the zero-phase current flowing through the NGR 9, and a bypass route that connects the A-system transmission line 1 and the B-system transmission line 6 If a power outage occurs at this point and a ground fault occurs in another power transmission line 14 connected to the B system power transmission line 6 during this power outage , A ground fault overvoltage relay (hereinafter referred to as an OVG relay) 15 that operates at an overvoltage generated when the balance of the B transformer 7 is lost, and a ground provided in the electromagnetic induction target transmission line 12 in which the communication line is disposed in proximity. An NGR control device (NGR control means) 16 that controls connection / disconnection of the zero-phase current breaker 8 based on the state of the tangential relay (hereinafter referred to as DG relay) 13 is configured.
In addition, the circuit breaker 4 is provided in the electric power line (henceforth AC line) 5 which connects between A system power transmission line 1 and the route transformer 20, and the power line (henceforth, hereinafter) which connects between B system power transmission line 6 and the route transformer 20 (Referred to as BC line) 11 is provided with a circuit breaker 10.

  Next, the schematic operation of the NGR automatic charging system 40 of the present invention will be described. For example, when a power failure occurs on the BC line 11 due to a lightning strike or the like, the circuit breaker 10 is cut off and the A system transmission line 1 and the B system transmission line 6 are disconnected (transmission line route disconnection). Assuming that a ground fault has occurred in another power transmission line 14 in this state, the OVG relay 15 is operated by an overvoltage generated in that system, and the signal is transmitted to the NGR control device 16 via the signal line 18. . In addition, since the communication line is disposed close to the electromagnetic induction target transmission line 12, the NGR control is performed via the signal line 19 in order to confirm that the DG relay 13 provided in the transmission line is not working. Is transmitted to the device 16. When the NGR control device 16 confirms that the OVG relay 15 is working and the DG relay 13 is not working, the zero-phase current breaker 8 is brought into contact with the signal line 17 and the zero-phase current is grounded through the NGR 9. The DG relay of the other power transmission line 14 is operated to block the accident point. As a result, when it is confirmed that the OVG relay 15 has returned, the zero-phase current breaker 8 is turned off to return to the original state.

  FIG. 2 is a flowchart for explaining the operation of the NGR automatic loading system 40 according to the present invention. A description will be given with reference to FIG. For example, when a power failure occurs on the BC line 11 due to a lightning strike or the like (Yes in step S1), the circuit breaker 10 is cut off and the A system transmission line 1 and the B system transmission line 6 are disconnected (transmission line route disconnected state). In this state, it is checked whether or not a ground fault has occurred in another power transmission line 14 (S2). If a ground fault occurs (Yes in S2), the OVG relay 15 is activated by an overvoltage generated in the system, The signal is transmitted to the NGR control device 16 via the signal line 18. When the NGR control device 16 detects the signal (Yes in S3), the electromagnetic induction target power transmission line 12 is close to the communication line, and therefore the DG relay 13 provided in the power transmission line is not working. Is confirmed (S4). If the DG relay 13 is working (No in S4), the process ends there. If the DG relay 13 is not working (Yes in S4), the NGR control device 16 has the OVG relay 15 working and the DG relay 13 working. If it is confirmed that the zero-phase current breaker 8 is in contact with the signal line 17 (S5), another transmission line is used to cut off the accident point by flowing the zero-phase current to the ground fault point via the NGR 9. The 14 DG relay is operated (S6). As a result, when it is confirmed that the OVG relay 15 has returned (Yes in S7), the zero-phase current breaker 8 is turned off to return to the original state (S8).

  That is, a power failure occurs in the detour route (AC line 5 and BC line 11) connecting between the A system power transmission line 1 and the B system power transmission line 6, and the other power lines connected to the B system power transmission line 6 during this power failure. When a ground fault occurs in the transmission line 14, the balance of the B transformer 7 is lost and a zero-phase current is generated at the point of the fault. At that time, when a zero-phase current flows to the ground fault point via NGR9, the DG relay is operated to promptly cut off the transmission line. However, in order to limit the zero-phase current flowing through the entire system and reduce electromagnetic induction, the NGR 9 is always disconnected by the zero-phase current breaker 8 so that no zero-phase current flows through the B transformer 7. Yes. For this reason, the transmission line cannot be interrupted immediately, but overvoltage occurs in the system. In the present embodiment, an NGR control device 16 that controls the zero-phase current breaker 8 is provided according to the state of the OVG relay 15 that detects this overvoltage and the state of the DG relay 13 provided in the electromagnetic induction target transmission line 12. As a result, a zero-phase current can always flow through the B transformer 7 to which the NGR 9 is not connected, so that the accident section can be immediately interrupted.

Further, when the OVG relay 15 is continuously operated for a predetermined time, it indicates that a ground fault has occurred and the balance of the B transformer 7 has been lost. In such a case, it is necessary to immediately flow the zero-phase current to the accident point via the NGR 9. However, since the zero-phase current cannot flow through the electromagnetic induction target transmission line 12, the zero-phase current breaker 8 is in a connected state on condition that the DG relay 13 provided for the electromagnetic induction target transmission line 12 is not operating. A zero-phase current is caused to flow through NGR9. As a result, it is possible to prevent electromagnetic induction from being generated in the communication line and to immediately shut off the accident section.
Further, when the zero-phase current breaker 8 is brought into a contact state, since the zero-phase current flows through the NGR 9, the overvoltage generated in the system is reduced and the OVG relay 15 is restored. When detecting the state, the NGR control device 16 determines that the zero-phase current has become zero, and sets the zero-phase current breaker 8 to the disconnected state. Thereby, the zero phase current breaker 8 of the B transformer 7 can be automatically returned to the original state.

As described above, the NGR automatic input system 40 according to the present invention has a zero-phase current interruption depending on the state of the OVG relay 15 that detects an overvoltage of the power system and the DG relay 13 provided in the electromagnetic induction target transmission line 12. Since the NGR control device 16 that controls the generator 8 is provided, the accident section can be immediately cut off by always flowing a zero-phase current to the B transformer 7 to which the NGR 9 is not connected.
In addition, since the zero-phase current cannot flow in the electromagnetic induction target transmission line 12, the zero-phase current breaker 8 is in the contact state on condition that the DG relay 13 provided in the electromagnetic induction target transmission line 12 is not operating. Since the zero-phase current is caused to flow through the NGR 9, it is possible to prevent occurrence of electromagnetic induction in the communication line and to immediately shut off the accident section.
Further, when the OVG relay 15 detects the return state, it is determined that the zero-phase current has become zero, and the zero-phase current breaker 8 is turned off, so that the zero-phase current cutoff of the B transformer 7 is automatically performed. The device 8 can be returned to its original state.

1 A system transmission line, 2 A transformer, 3 NGR, 4 circuit breaker, 5 AC line, 6 B system transmission line, 7 B transformer, 8 zero phase current circuit breaker, 9 NGR, 10 circuit breaker, 11 BC line , 12 Electromagnetic induction target transmission line, 13 DG relay, 14 Other transmission line, 15 OVG relay, 16 NGR control device, 18, 19 Signal line, 20 Route transformer, 40 NGR automatic injection system

Claims (3)

A first power transmission line and a second power transmission line with different power systems;
A first transformer and a second transformer respectively installed in the first transmission line and the second transmission line;
A first neutral grounding resistance device and a second neutral grounding resistance device respectively provided in the first transformer and the second transformer;
A route transformer for detouring between the first transmission line and the second transmission line;
A zero-phase current breaker for connecting and disconnecting a zero-phase current flowing through the second neutral-point grounding resistance device;
A power failure occurred in a detour route connecting the first power transmission line and the second power transmission line, and a ground fault occurred in another power transmission line connected to the second power transmission line during the power failure. The ground fault overvoltage relay operating at the overvoltage generated by the balance of the second transformer being lost, and the ground fault direction relay provided in the electromagnetic induction target transmission line in which the communication line is arranged in proximity. NGR control means for controlling connection and disconnection of the zero-phase current breaker;
An NGR automatic injection system characterized by comprising:   The NGR control means, when a power failure occurs in a detour route connecting the first power transmission line and the second power transmission line, and a ground fault occurs in the other power transmission line during the power failure, 2. The zero-phase current breaker is brought into a contact state on condition that a ground fault overvoltage relay is continuously operated for a predetermined time and the ground fault direction relay is not operated. NGR automatic charging system described.   The NGR automatic charging system according to claim 1, wherein the NGR control means turns off the zero-phase current breaker when detecting that the ground fault overvoltage relay has been restored.

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