JPS63161810A - Protective relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a protective relay device in which protection functions are multiplexed, each having a constant monitoring circuit, and a monitoring failure detection timer lock. It is something.

(Conventional technology) In the protection of ultra-high voltage power systems, accidents generally have a large impact on the system, and in order to reliably eliminate accidents, it is necessary to install two main protection devices for one protection target, or to install a main protection device. Protection is multiplexed, such as by using equipment and back-up protection equipment. In order to improve the reliability of each protection device, each device is constantly monitored for defects in cables connecting power system transformers and protection devices, defects in tripping circuits, erroneous outputs of protective relays, etc. I'm monitoring it.

When this constant monitoring means detects a monitoring failure, it outputs a display alarm signal to the outside and locks its own device.

Below, regarding conventional protective relay devices, we will take as an example the protection of power transmission lines using main protection devices and back-up protection devices, as shown in Figures 3 and 4.
This will be explained using figures.

Figure 3 is a general power transmission system diagram.
28 Hashi 1!1 disconnector, 381 and 382 are CT, 4A is PT, 58 is main protection relay device of power transmission line protection device, 6^
Similarly, 7 is a back-up protection relay device, and 7 is a power transmission line.

FIG. 4 is a schematic diagram of the functional blocks of the protective relay device,
Both the main protection relay device and the backup protection relay device have the functions shown in FIG.

In the figure, 11 is an accident detection circuit, 12 is a constant monitoring circuit, 13 is a monitoring circuit for the input circuit of CT, PT, and other related equipment that is input to the protection device, and 14 is an output circuit for the protection device such as a circuit breaker disconnection circuit. A monitoring circuit 15 is a monitoring circuit for erroneous output of the protective relay. Reference numeral 16 denotes an on-delay timer, which determines that monitoring is defective when any one of the monitoring signals input to the OR circuit 17 continues for a predetermined period of time or more. 18 is an 807 circuit, and 19 is a NO circuit.

When “1” output is generated from the on-delay timer 16, N
The OT circuit 18 locks the device, and the ND circuit 19 is configured to prevent an erroneous cutoff command from being issued to the mustard cutter.

Although not shown in the figure, the power supply device is also monitored.

Generally, the detection sensitivity of a monitoring failure is higher than the detection sensitivity of a protective function.

(Problems to be Solved by the Invention) Now, let us consider a case where, for example, a power transmission line disconnection accident without a ground fault occurs at point F shown in FIG.

At this time, neither the main protection device nor the backup protection device detects the accident, but due to the continuation of the zero-sequence current and negative-sequence current, a monitoring failure in the input circuit is detected, and after the set time of the on-delay timer 16 has elapsed, the device is locked. A warning is displayed to the outside.

In other words, the device is locked even though the device is not defective. It takes time to discover the nature of the defect, and if an accident such as a short circuit occurs in the grid, both the main protection and back-up protection devices on the power transmission line are constantly monitored to detect defects, and the devices are locked. It becomes unprotected and the breaker 2A becomes unable to shut off, and the impact on the grid is immeasurable.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a protective relay device that eliminates the unprotected state in the event of a system fault.

[Configuration 1 of the Invention (Means for Solving Problems) The present invention will be explained with reference to FIG.
16b are provided with a time difference, and an interlock circuit is provided to prevent the other device from being locked when either device is locked due to monitoring failure.

(Function) Therefore, if a monitoring failure occurs on the constant monitoring circuit 12a side of the main protection device and the main protection device is locked,
Since the output does not satisfy the AND condition through the 807 circuit, the backup protection device is never locked.

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

FIG. 1 is a block diagram of an embodiment of the protective relay device of the present invention.

In this embodiment, the constant monitoring failure detection timers of the main protection device and the backup protection device are provided with different time limits to prevent device locking.

In the figure, the subscript a means the main protection device, and the subscript b means the backup protection device. 12a is a constant monitoring circuit of the main protection device, 16a is its failure detection timer (time limit T1), 12b is a constant monitoring circuit of the backup protection device, 16b is its failure detection timer (time limit T2), and 16a is its failure detection timer (time limit T1). Detection tie? 1
The time limits of 6a and 16b are set to TI < T2.

The output of the defect detection timer 16a is used as the main protection device lock output, and is ANDed via the NOT circuit 18.
It is used as one input of the circuit 19, and an AND condition is taken with the input from the defect detection timer 16b to provide a lock output of the backup protection device.

Now, let us consider a case where an accident occurs at point F in FIG. 3, and the monitoring circuits of each device can detect the abnormality, but the protective relay cannot detect the accident. In this case, the time limit T1 of the defect detection timer 16a
is smaller than the time limit T2 of 16b, the main protection device has a monitoring failure and is locked, but on the back-up protection device side, the lock is prevented by the output of the NOT circuit 18.

Therefore, even if a serious accident occurs in the system during the confirmation of monitoring defects, the accident will be eliminated by the back-up protection device and nothing serious will happen.

On the other hand, a malfunction of the main protection device's relay prevents the device from being locked due to a failure in constant monitoring of the backup protection device, but the main protection device
It is extremely rare for a monitoring failure to occur at the same time as a back-up protection device, and there is no practical problem.

In the above embodiment, an example has been described in which the backup protection device lock is blocked by the monitoring output of the main protection device, but the opposite case may of course be used.

FIG. 2 is a block diagram of another embodiment according to the present invention. In this embodiment, the monitoring content of the main protection device and the backup protection device are compared, and if the same part is defective, it is determined that it is not a defect in that part, but a defect in the previous stage, that is, the system or separate equipment, This prevents device locking.

In FIG. 2, the output of each constant monitoring circuit 12a, 12b is used as the lock output of each protection device via on-delay timers 16a, 16b, as in the previous embodiment. 201 to 203 are AND circuits, 201
are the outputs from the input circuit monitoring circuits 13a and 13b, 202 is the output from the output circuit monitoring circuits 14a and 14b, and 203 is the relay output monitoring circuit 15a.
, 15b are connected, the outputs of the AND circuits are connected to the on-delay timer 22 via the OR circuit 21, and the output of the on-delay timer 22 is connected to the NOT
It is connected to each AND circuit 19a, 19b via a circuit 18.

Note that the time limit T3 of the on-delay timer has a relationship of T3 minus T1 and T3 < T2. Elements indicated by other symbols are the same as in FIG.

It can be said that the frequency of failure of monitoring of the same part by the main protection device and the backup protection device at the same time is even lower. Further, the circuit for determining whether or not there is a monitoring failure in the same part may be provided independently, or may be provided in parallel with either the main protection device or the back-up protection device.

Although each of the above embodiments has been described using a power transmission line protection device as an example, the present invention can be similarly applied to devices in which protection functions are multiplexed, such as other transformer protection devices and bus bar protection devices.

Further, in each of the above embodiments, description has been given of a protection device having two lines, but it goes without saying that the present invention can also be applied to a device having three or more lines.

[Effects of the Invention] As explained above, according to the present invention, in the event of an accident that cannot be detected by a relay and does not cause sudden damage to the system, it is possible to maintain an unprotected state without locking the device. It is possible to provide a protective relay device that can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of one embodiment of the protective relay device according to the present invention, FIG. 2 is a functional block diagram of another embodiment, and FIG.
The figure is a general power transmission system diagram, and FIG. 4 is a functional block diagram of a conventional protective relay device. 12... Constant monitoring circuit

Claims (2)

[Claims] (1) In a protective relay device in which each of the multiplexed protection devices is equipped with a continuous monitoring circuit and the device is locked when a monitoring failure is detected, a monitoring failure detection timer with a different time limit is installed in the continuous monitoring circuit of each device. 1. A protective relay device, characterized in that when one device is locked due to monitoring failure of one device, locking of the other device is prevented. (2) The protection relay according to claim 1, characterized in that device locking is prevented by comparing the details of monitored failures between the multiplexed protection devices and when the contents of the failure are the same. Device.