JPH04190626A - Digital bus protector - Google Patents

Abstract

PURPOSE:To realize a reliable protection of a bridged double bus and to obtain a highly reliable bus protective relay by providing a first mans for detecting fault in the combination of double bus, second and third sans for detecting fault in the individual bus and a fourth means for operating the second and third sans as the first sans upon detection of bridging. CONSTITUTION:Electrical amounts I' proportional to the currents I flowing on a transmission line L connected with buses are selected sequentially by means of a multiplexer 3 and then converted through an A/D converter 4 into digital amounts (i). A protective operation unit 5 employs the digital amounts (i) in the operation of combined protection and provides an output to an output circuit 6 upon decision of an internal fault in a bus. The protective operating unit 5 further performs operation of individual protection based on the digital amounts (i), conditions of a disconnector(LS) fed from a control signal input circuit 7 and a current in a line connected with the bus and provides an output to the output circuit 6 upon decision of an internal fault in that bus. The output circuit 6 a selective interruption output for the bus based on the combined and individual protection outputs and LS conditions.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a protection relay for protecting an electric power system, and in particular,
This invention relates to a digital bus protection device that protects multiple busbars using the differential principle.

(Prior art) As a protection method during a bridge in a bus protection device that selectively protects multiple busbars in a power system using a collective protection device and a split protection device, conventionally, only one of the split protection devices is protected by a second protection device. It was designed to be equivalent to a protection device, and was configured to protect the bus bar together with the collective protection device.

(Problem to be solved by the invention) However, in the conventional technology, as a process during bridging,
A multi-bus line consisting of the first bus line and the second bus line is equipped with a collective protection device and one
Either one of the split protection devices (for example, the instep side split protection device is used as the second collective protection device to provide multi-bus protection.Here, the protection range of the split protection device is controlled by the disconnect switch condition. Generally, they have the disadvantage of low reliability, and if there is a defect in the split protection device on the 1st and 2nd sides, it may not be possible to shut off all the busbars, causing a big problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly reliable busbar protection relay device that reliably protects a multi-busbar during bridging.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a first means (collective protection device) for collectively detecting accidents on multiple busbars, and a second means for detecting accidents on each busbar. It is composed of a third means (each divided protection device) and a fourth means for detecting that the bridging is in progress, and when the fourth means detects that the bridging is in progress, the second... The third means corresponds to the first means for detecting accidents all at once.

(Function) It is possible to send the cutoff output to the breaker using both the cutoff output obtained from the first means and the second means, and the cutoff output obtained from the first means and the third means, so that the reliability is improved. A high bus bar protection device can be obtained.

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

FIG. 1 is a system block diagram of an embodiment of a busbar protection device according to the present invention. Moreover, FIG. 2 is a system diagram of a multi-bus line to which this device is applied. In Figure 1, 1 is an input current transformer, 2 is a sample and hold circuit, 3 is a multiplexer, 4 is an A/D converter, 5 is a protection arithmetic unit composed of a digital arithmetic unit such as a microprocessor, and 6 is an output 7 is a control signal input circuit. Also, the second
In the figure, B is the bus bar to be protected, L is the transmission line, CT is the current transformer, CB is the circuit breaker, and LS is the new line switch.

The amount of electricity I' proportional to the electric current of the transmission line connected to the busbar
is supplied to a sample and hold circuit 2 via a current transformer CT and an input converter 1. These electrical quantities are sequentially selected by the multiplexer 3.

It is introduced into an A/D converter 4 and converted into a digital quantity i.

The protection calculation device 5 performs protection calculation for -batch protection using the digital quantity i, and sends an output to the output circuit 6 if it is determined that there is an internal fault in the bus bar.

In addition, a protective calculation device! 5 performs a protection calculation for division protection with the current of the line connected to the bus according to the digital quantity i and the LS condition from the control signal input circuit 7,
If it is determined that there is an internal fault in the relevant bus, the output is sent to the output circuit 6.

The output circuit 6 sends out a blocking force for selecting a bus line according to each protection output divided into one division and the LS condition.

Next, the processing contents of the protection arithmetic unit 5 are shown in a flowchart in the 311th step.

In step S1, the digital value 1n (n indicates the line number) is read, in step S2, the operation amount Id is calculated using all in, and in step S3, Id is compared with the operation value Io to determine the operation. When operating, S4
Send the output with .

The above is the calculation for batch protection.

Next, the calculation for partition protection is shown.

In step S5, the disconnector conditions jnA and jnB are read. Here, if jn is "1", it is used, and if jn is "1", it is assumed that it is not used.

Next, in step S6, it is determined whether bridging is in progress.

Specifically, the determination can be made based on the presence or absence of a line whose disconnector condition jnA indicates that it is connected to the A bus line and the disconnector condition in B that indicates that it is connected to the A bus line are both "1".

That is, if there are three lines that are all "1", it is determined that the bridge is in progress, and in step S7 all in A and in B are set to '1'.
shall be. Here, there is a process such as eliminating the need for large CT input to the busbar communication unit, but this is omitted as it is outside the main purpose.

First, the case where bridging is not in progress will be explained.

In step S8, the operation amount IdA on the A bus line side is calculated using the digital value of the line connected to the A bus line side under the disconnector condition inA.

In step S9, similarly to step S8, the operation amount Id B on the bus line side is calculated using the digital value of the line connected to the bus line side B according to the disconnector condition in B.

In step S10, an operation determination is made regarding the middle bus bar using IdA, and an output is sent out in step Sll.

In step 512, an operation determination is made regarding the bus line on the 6th side using Id B, and in step S13, the ID is sent out.

The above are the calculations for division protection on the middle side and the second side.

Next, the case where bridging is in progress in step S6 will be described.

In step S7, all middle side disconnector conditions jnA are set to “1”.
In other words, it is assumed that all lines are connected to the middle bus.

In addition, it is assumed that all of the disconnector conditions jn for the Otsu side are set to "1n", and that all lines are also connected to the Otsu side bus line.

However, although not shown, CT input to the busbar communication section is not required. After that, the process advances to step S8, and the process is the same as when the bridge is not in progress.

However, since all LS conditions are "1", the middle side,
Both parties are equivalent to batch processing.

The output circuit configuration at this time is shown in FIG. 4, where 21 is a contact for the collective protection output, 22 is a middle side divided protection output, and 23 is a contact for the O side divided protection output. Further, 24 is a disconnector condition, which is closed if the corresponding line is connected to the middle side, and 25 is closed when it is connected to the second side.

Therefore, during bridging, since the operation outputs of the batch, the middle side division, and the second side division are obtained, both of the cutoff conditions are used, so a highly reliable cutoff circuit can be constructed.

In the above explanation, a current differential method was described in which the differential current is calculated using the currents of all lines for collective protection and the operation is determined. However, the present invention is not limited to this. There is no problem even if it is a high impedance differential system that responds to the voltage difference between the two.

In addition, in the explanation of Fig. 3, the operation is judged only by the magnitude of Id, but this is just an example, and the scalar sum of each line current is calculated, and this is used as the suppression amount to participate in the operation judgment formula. The same effect can be obtained by doing so.

〔Effect of the invention〕

As explained above, according to the present invention, there is a first means for collectively detecting accidents on multiple busbars, and a second means for detecting accidents on each busbar.
．． a third means, and a fourth means for detecting that the bridge is in progress.
means, and the output of the fourth means causes the second. Since both of the third means are equivalent to the first means that performs accident detection all at once, the cutoff command can be sent by both the first and second means and the first and third means, resulting in highly reliable busbar protection. Can provide relay equipment.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a bus protection device according to the present invention, Fig. 2 is a system diagram of a multi-bus bar configuration, Fig. 3 is a flowchart of protection calculation processing of the present invention, and Fig. 4 is a block diagram of an output sequence of the present invention. It is. 1... Input converter 2... Sample hold circuit 3... Multiplexer 4... A/D converter 5... Protection calculation device 6... Output circuit 7
...Input circuit 21...-Block protection output condition 22...A side split protection output condition 23...B side split protection output condition 24.25...Disconnector condition Agent Patent attorney Nori Chika Yu Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A digital bus protection device that selectively protects multiple busbars in a power system by using a collective protection device that determines whether an accident is occurring or not, and a split protection device that determines which bus has an accident. means for detecting that the devices are connected at the same time, and an output from the means that determines that each of the divided protection devices is regarded as a new collective protection device, and that each of the divided protection devices performs bus bar protection together with the collective protection device. Features a digital busbar protection device.