JPH04200223A - Protective relay unit - Google Patents

Abstract

PURPOSE:To prevent no-protection state against system fault by a constitution wherein both units do not perform device lock control when both units arranged in two series are detecting defective normal monitoring of a fault detection relay under the influence of system side. CONSTITUTION:Under a state where both series are detecting defective normal monitoring(SVF) of a fault detecting relay under influence of system side, fault detection relays SVF3A, SVF3B in both series have output of '1' and an AND circuit AND 2 produces an output. Output from the AND 2 is fed to an inhibit circuit INH 2 so that output from the fault detection relay SVF3A in one series is locked. Consequently, when both units in two series detect defective normal. monitoring through fault detection relays, the inhibit circuit INH 2 locks trip lock control thus locking device lock control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Field of Industrial Application)] The present invention relates to a protective relay device that has a constant monitoring function and is configured to lock the device and output an alarm when a constant monitoring failure is detected.

(Prior Art) In recent years, as power systems have become more and more ultra-high voltage and their importance has increased, more reliable protective relay devices have been adopted. As an example of this, many protective relay devices have been adopted that have two lines and duplication from the system input to the breaker disconnection coil. It is well known that the reliability of the protection function of the system is improved by employing a dual-system or redundant protective relay device as described above.

FIG. 2 shows an example of duplication of protective relay devices. In Fig. 2, 11 is a bus bar, 12 is a transmission line, 13 is an A series current transformer, 14 is a B series current transformer, 15 is a breaker, and 15A is a current transformer.
, 15B are the tripping coils of the A series and B series of the breaker 15, respectively, indicating that they are duplicated. 16
is an A-series potential transformer, 17 is a B-series potential transformer, 21 is an A-series protective relay device (hereinafter referred to as an A-series relay), and 22 is a B-series protective relay device (hereinafter referred to as a B-series relay). 21T is the tripping command for the A-series relay 21,
The 22nd relay is constituted by a tripping circuit of the B-series relay 22.

If an accident occurs in the power transmission 1i12 shown in FIG. 21T and 22T respectively to the tripping coils 15A and 15B of the circuit breaker 15 in the case of an internal accident.
A tripping command is issued in parallel by T. Also, the A series relay 21. Even if one of the B-series relays 22 becomes defective and no longer functions as a protective relay device, it can be tripped by the other protective relay device. By duplicating the protective relay device in this way, the reliability of the protective function is greatly improved.

On the other hand, automatic monitoring is generally employed to improve the reliability of the protective relay device itself. This automatic monitoring consists of two parts: constant monitoring and automatic inspection.

Continuous monitoring is a method that determines an abnormality when an operation that would never occur under normal conditions continues for a certain period of time, and mainly detects a malfunction. In addition, automatic inspection is a method of applying pre-planned input conditions to the input section of the 8th relay and then checking whether an output that meets the input conditions is obtained, and is mainly a method of detecting defects on the malfunctioning side. It is.

If a defect in an electrical appliance is detected through automatic monitoring, an external display or alarm is issued, or the device is generally locked at the same time. This device lock is effective in preventing the relay from tripping due to an external accident during constant monitoring to detect failure due to malfunction. As mentioned above, the protective relay devices are arranged in two rows, so even if one series constantly detects a monitoring failure and locks the device, it can be tripped by the protective electrical equipment room of one series.

Generally, in order to improve the reliability of protective relay devices, multiplexing is employed to systematically reduce the probability of malfunction or malfunction in both series of protective relay devices. There are various methods for multiplexing, but the commonly used ones are the main detection relay, which responds only when an accident occurs to the protected object, and the main detection relay, which responds not only to the protected object, but also to the system accident. This is a so-called series duplication system, which is composed of detection relays and outputs a trip command only when both operate together. This is intended to prevent malfunctions of the system due to defects in the main detection relay. By using AT devices with different operations, for example, if the input of the main detection relay is taken from the CT and the input of the accident detection relay is taken from the PT, malfunctions will occur even if one of the CT or PT is defective. It is possible to prevent this.

FIG. 3 shows an example of the automatic monitoring protective relay device of the 2^-row and duplex configuration described above. In Fig. 3, 2 is the main detection relay that operates only in the event of an internal accident, 3 is the accident detection relay that is activated in the event of a system failure, 4 is the constant monitoring failure detection circuit, and 2^ and 3^ are the main detection relay 2 and the accident detection relay, respectively. 2^ is the output of detection relay 3's constant monitoring failure detection, 2^ is called main detection relay SVF for constant monitoring failure, and 3A is the fault detection relay SVF for accident detection relay constant monitoring failure.
Indicates the name. ORI is an OR circuit of 28 of main detection relay SVF and 3A of fault detection relay SνF, 5 is a trip lock control circuit when outputting ORI, 6 is a display alarm circuit when a constant monitoring failure is detected, AND 1 is main detection relay 2 and the ND circuit between accident detection relay 3, and TNH1 is an inhibit circuit between the output of AND 1 and the trip lock control circuit.

7 indicates a trip command which receives the output of the inhibit circuit INH1 and passes it to the breaker.

Although the protective relay device configured as described above is shown in one row in FIG. 3, if it is configured in two rows, two sets of devices configured as shown in FIG. 3 are installed. The circuit shown in FIG. 3 will be explained below. Now, when an accident occurs within the protection zone, the main detection relay 2 and the accident detection relay 3 operate, and the AND circuit AND
The output of 1 is introduced into the inhibit circuit INH1. I
On the condition that there is no output from the trip lock control circuit 5, which is one input of the NH1, that is, no constant monitoring failure is detected, the output of the INH1 is output, and a trip command is given to the breaker by the trip command 7. On the other hand, when a constant monitoring failure of the main detection relay or the accident detection relay occurs, the OF1 circuit ORI operates and outputs. OR circuit OR
The output of I is introduced into the trip lock control circuit 5, the output of which enters the inhibit circuit of INH1, and the output of INN1 is input to the inhibit circuit of INH1.
Press one of the inputs AND 1 output, and INH1
I am trying not to output any output. The above is the tri-gamma pro-V ri when a constant monitoring failure is detected.

This is a so-called device lock function. In other words, if an external accident occurs while the main detection relay 2, which is an internal direction detection relay, is malfunctioning for some reason, the accident detection relay 3, which operates even in an out-of-section accident, will operate and misreceive. Mouth/tsuku functions are added.

(Problems to be Solved by the Invention) The following system configuration consists of two series of so-called duplex configuration automatic monitoring protective relay devices that issue a trip command when both the main detection relay and the fault detection relay operate together. Explain the problems when doing so. Fault detection relays generally have a fail-safe function for the main detection relay, and are designed to operate even if a system fault occurs within or outside the section. An example of this fault detection relay is a ground fault overcurrent relay that is driven by the zero-sequence current of the system.

The zero-phase current of the system is normally zero if it is a three-phase balanced system, but depending on the configuration of the system, that is, the operating form of the power transmission line, it may not necessarily be three-phase balanced, but may be three-phase unbalanced. Normally, the zero-sequence current generated due to constant three-phase unbalance is smaller than the zero-sequence current at the time of a system fault, and the settling of the ground fault overcurrent relay is higher than the zero-sequence current due to constantly occurring three-phase unbalance. do. However, since ground fault overcurrent relays are generally set to be highly sensitive, assuming that the zero-sequence current due to three-phase unbalance has become larger than usual due to a change in the power transmission line system, in the worst case this will be the setting value of the ground fault overcurrent relay. In this case, the ground current relay continues to operate. With this operation, when a continuous monitoring failure is detected after a certain period of time,
As described above, the device is locked, that is, a constant monitoring failure is detected even though it is not a malfunction of the relay, and the device is locked, and the function as a protective relay device is lost. Furthermore, if the devices in both systems are in the same state, the protection function of that system is lost and the system becomes unprotected. As another example, a similar phenomenon can be considered in an accident where a tree comes into contact with a power transmission line, that is, a slight ground fault. The tree contact accident will be explained below with reference to Fig. 4.

Figure 4 is a diagram showing a power transmission line causing a tree contact accident, where 12 is a power transmission line, 31 is an arc, and 32 is a tree. Here, a tree contact accident refers to power transmission line 10 and tree 3.
When the separation distance between the tree and the tree becomes close to each other and exceeds a certain limit, an arc discharge occurs between the two and a ground fault current flows through the tree to the ground, a phenomenon that often occurs. In this case, the tree resistance (fault point resistance) is very large compared to the arc resistance and the grounding resistance of the tree, so the fault phase voltage hardly drops, and therefore the undervoltage relay that uses the phase voltage as input is becomes inoperable. Therefore, even if the highly sensitive main detection relay driven by current detects a protected area fault,
If an undervoltage relay is used as the fault detection relay, it will not be able to trip in the case of the above-mentioned slight ground fault. On the other hand, as time passes, the arc spot on the tree side moves downward, and the arc also extends along the tree, causing the ground fault current to increase and the undervoltage relay to tend to operate. However, it takes a long time from the occurrence of the accident until the undervoltage relay operates, and a ground fault current continues to flow during that time. Therefore, if a ground fault overcurrent relay is used, if the ground fault overcurrent relay continues to operate due to the above-mentioned slight ground fault current, a constant monitoring failure will be detected after a certain period of time.
The device will be locked. As a result, if a slight ground fault develops into a ground fault, there is a risk that the device will be unable to trip due to locking.6Also, as mentioned above, the above case is caused not by a faulty relay but by the system condition. Both devices in series become device locked and become unprotected.

The present invention was made in order to solve the above problem, and provides a protective relay device that constantly detects monitoring failures in both devices in two series and prevents device locking due to influence from the power system. is intended to provide.

[Structure of the Invention] (Means and Effects for Solving Problems) In the present invention, when a failure in constant monitoring of the contents of both devices arranged in a row is detected, only a display alarm is output and the device is not locked. The circuit is configured to reliably detect accidents within the 11 sections and issue a trip command.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a protective relay device according to the present invention.

In FIG. 1, the circuit configuration is changed from that in FIG. 3 in order to realize the present invention, and the different parts from FIG. 3 will be explained below. In FIG. 1, 1B indicates the other protection relay system in two series, and 3B indicates the continuous monitoring failure output of the accident detection relay. Protective relay device 1^ (hereinafter referred to as A
The protective relay device IB (hereinafter referred to as B-system protection relay) will be referred to as the other system.

AND 2 is an AND configuration of the accident detection relay SVF of its own series and the accident detection relay SVF of another series.
NH2 is the fault detection relay SVF of the above self-series and N to the above.
An inhibit circuit with O2 and OR2 indicate an OR circuit between the own series main detection relay SVF and the own series accident detection relay SVF. Other than the above, it is completely the same as FIG. 3.

In the protective relay device configured as a system as described above, when a constant monitoring failure of the fault detection relays of both series is detected due to the influence of the grid side, the fault detection relay SVF 3A of the own series and the fault detection relay of the other series are detected. Accident detection relay SVF
Both outputs of 3B become “1” and the AND circuit AN
The output of D2 is output. The output of AND2 is input to the inhibit circuit RINH2 so as to lock the output of the fault detection relay SVF 3A of its own series.

Therefore, if the accident detection relay detects a constant monitoring failure in both devices in two series, the inhibit circuit INH2
is configured to lock the trip lock control, that is, lock the device lock control. Therefore, in this case, the device is not locked and the trip function can be continued to be used.

In addition, the control in this case only locks the device lock control, and the OR circuit O is set so that the display alarm #I6 is output.
It is controlled by R2. By making use of the display alarm circuit, both series are notified that a constant monitoring failure has been detected.
It is necessary to take appropriate measures. On the other hand, regarding the main detection relay.

Based on this principle, it is thought that due to the influence on the system side, it is almost impossible for both systems to detect a continuous monitoring failure. If the main detection relay in both series malfunctions, it will cause a mistrip due to an external accident, so the control should rather lock the device, which is a different concept from the case of accident detection relays. .

Although the description above has focused on the own series, other series are also configured to have exactly the same configuration as the own series.

[Effects of the Invention] As explained above, according to the present invention, if both devices in two systems detect faulty monitoring of the accident detection relay due to the influence of the system, both devices perform device lock control. By configuring the system so that it does not occur, it is possible to provide a protective relay device that does not become unprotected against system accidents.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the protective relay device according to the present invention, Fig. 2 is a diagram for explaining the formation of two lines of the protective relay device, and Fig. 3 is a diagram of the conventional gAtan relay device. The circuit configuration diagram, FIG. 4, is an explanatory diagram of a tree contact accident. 18... A system protection relay 1B... B system protection relay 2... Main detection relay 3... Accident detection relay 4... Constant monitoring failure detection circuit 5... Trip lock control circuit 6. ...Display alarm circuit 7...Trip command 2A
... Main detection relay constant monitoring failure 3^... Accident detection relay constant monitoring failure 11...tm
12... Line for feeding 13... A-system current transformer 14... B-system current transformer 15... Breaker
16...A optical instrument transformer 17...B system instrument transformer 21...A system protective relay device 22...B
System protection relay device 31...Arc 32...Tree 1 Figure 3 Figure 4

Claims (1)

[Claims] A trip circuit is configured by the operation of both the main detection element and the accident detection element, each of the two elements is equipped with a constant monitoring function, and the first circuit is configured to lock the device and output a display alarm when a constant monitoring failure is detected. and a second protective relay device having the same configuration as the first protective relay device for forming two series, the first
When both the protective relay device and the second protective relay device simultaneously detect a constant monitoring failure by the output of the fault detection element, both the first protective relay device and the second protective relay device lock the device. A protective relay device that locks control and outputs only display alarms.