JP3217353B2 - Digital bus protection device - Google Patents

Description

Description: Object of the Invention (Field of Industrial Application) The present invention relates to a protection relay for protecting a power system, and more particularly, to a digital bus protection device for protecting a double bus on a differential principle.

(Prior Art) As a protection method in a bridge in a bus protection device that selectively protects a multiple bus of an electric power system by a collective protection device and a split protection device, only one of the conventional split protection devices is used in a second batch protection device. The protection device is equivalent to the protection device, and the bus is protected together with the collective protection device.

(Problems to be Solved by the Invention) However, in the prior art, as a process during the bridge, a double bus composed of an instep bus and a second bus is either one of a collective protection device and a split protection device (for example, The protection device is a second batch protection device, and double bus protection is performed. Here, the split protection device has a disadvantage that generally the reliability is low because the protection range is controlled by the disconnection condition,
If there is a defect in the backside split protection device, all buses cannot be cut off, which may cause a serious problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a highly reliable bus protection relay device that reliably protects a double bus in a bridge.

[Configuration of the invention]

(Means for Solving the Problems) The present invention provides a first means (collective protection device) for detecting an accident on multiple buses at once, and a second and third means for detecting an accident on each bus.
(Each of the divided protection devices), and fourth means for detecting that both buses are connected (during bridge) based on the disconnector condition connected to each bus, When the bridge is detected by the means (4), the second and third means are collectively equivalent to the first means for detecting an accident.

(Operation) The interruption output obtained from the first means and the second means,
Since the interruption output can be sent to the interrupter with both the interruption output obtained from the first means and the interruption output from the third means, a highly reliable bus protection device can be obtained.

(Example) Hereinafter, an example is described with reference to drawings.

FIG. 1 is a system block diagram of an embodiment of a bus protection device according to the present invention. FIG. 2 is a system diagram of a double bus to which the present apparatus is applied. In FIG. 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 operation device composed of a digital operation device such as a microprocessor, and 6 is an output. Reference numeral 7 denotes a control signal input circuit. Also, the second
In the figure, B is a bus to be protected, L is a transmission line, CT is a current transformer, CB is a circuit breaker, and LS is a disconnector.

An electric quantity I ′ proportional to the current I of the transmission line L connected to the bus is supplied to the sample and hold circuit 2 via the current transformer CT and the input converter 1. The electric quantity I 'is sequentially selected by the multiplexer 3, introduced into the A / D converter 4, and converted into a digital quantity i.

The protection operation device 5 performs a protection operation for collective protection by using the digital quantity i, and sends an output to the output circuit 6 when it is determined that an internal accident has occurred in the bus.

Further, the protection operation device 5 performs a protection operation for division protection using the current of the line connected to the bus in accordance with the digital quantity i and the LS condition from the control signal input circuit 7, and an internal accident of the corresponding bus and If it is determined, the output is sent to the output circuit 6.

The output circuit 6 sends out the selected and cut-off output of the bus in accordance with the LS condition and the output for each protection at once.

Next, FIG. 3 is a flowchart showing the processing contents of the protection arithmetic unit 5.

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

 The above is the operation for collective protection.

 Next, calculation for division protection will be described.

In step S5, disconnector conditions jn A and jn B are read. Here, it is assumed that if jn is "1", it indicates use, and if "0", it indicates nonuse.

 Next, in step S6, it is determined whether or not a bridge is being performed.

Specifically, the determination can be made based on the presence or absence of the rotation that is both "1" in the disconnector condition jn indicating that the vehicle is connected to the instep bus and the disconnector condition jn that indicates that the vehicle is connected to the inversion bus.

That is, when there are three lines that are both “1”, it is determined that the bridge is being bridged, and all the jn A and jn B are set to “1” in step S7.
Here, there is a process of making the CT input of the bus connecting portion unnecessary or the like.

 First, a case in which a bridge is not being performed will be described.

In step S8, the instep bus side operation amount Id is determined by the disconnector condition jn.
The calculation is performed by Party A using the digital value of the line connected to the Party Bus side.

In step S9, as in step S8, the operation amount Id
The operation is performed using the digital value of the line connected to the operation line under the disconnection condition jn.

In step S10, an operation determination is performed on the instep-side bus using Id Party A, and an output is transmitted in step S11.

In step S12, the operation is determined for the bus on the side B using Id B, and the output is transmitted in step S13.

 The above is the calculation for the division protection of the party A and the party B.

Next, a case in which a bridge is being performed in step S6 will be described.

In step S7, all the instep disconnector conditions jn A are set to “1”. That is, it is assumed that all the lines are connected to the back side bus.

In addition, it is assumed that all the disconnector conditions jn for the second party are all “1”, and all the circuits are connected to the second party bus.

However, although not shown, the CT input of the bus connecting part is not required. Thereafter, the process proceeds to the process of step S8, and the same process as when the bridge is not being performed is performed.

However, since all of the LS conditions are “1”, both the instep side and the side B correspond to the batch processing.

The output circuit configuration at this time is shown in FIG. Here, reference numeral 21 denotes a contact of the collective protection output, reference numeral 22 denotes each contact of the former side split protection output, and reference numeral 23 denotes each of the second party side protection output. 24 is a disconnector condition, which is closed if the corresponding line is connected to the instep side,
25 is closed when it is the second party.

Therefore, during the bridge, both the splitting conditions are used because the operation output of the lump, the split of the former side and the split of the second party can be obtained.
A highly reliable shutoff circuit can be configured.

In the above description, the differential current is calculated using the currents of all the lines for collective protection, and the current differential method of determining the operation has been described. However, the present invention is not limited to this.
There is no problem even with a high-impedance differential system that responds to the differential voltage of all lines.

Also, in the description of FIG. 3, the operation is determined only by the magnitude of Id, but this is merely an example, and a scalar sum of each line current is calculated, and this is used as a suppression amount to participate in the operation determination formula. The same effect can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the first means for detecting an accident on multiple buses at once and the second means for detecting an accident on each bus
2, a third means and a fourth means for detecting that a bridge is being performed
Means are provided, and both the second and third means are equivalent to the first means for detecting an accident at once by the output of the fourth means. It is possible to provide a highly reliable bus protection relay that can be transmitted by both of the third means.

[Brief description of the drawings]

FIG. 1 is a block diagram of a bus protection device according to the present invention, FIG. 2 is a system diagram of a double bus configuration, FIG. 3 is a flowchart of protection calculation processing of the present invention, and FIG. 4 is a configuration diagram of an output sequence of the present invention. It is. DESCRIPTION OF SYMBOLS 1 ... Input converter, 2 ... Sample hold circuit 3 ... Mux, 4 ... A / D converter 5 ... Protection arithmetic unit, 6 ... Output circuit 7 ... Input circuit, 21 ... Batch protection output Condition 22: Inverted split protection output condition 23: Invertible split protected output condition 24, 25: Disconnector condition

Continuation of the front page (56) References JP-A-49-70157 (JP, A) JP-A-57-43523 (JP, A) JP-A-62-285628 (JP, A) JP-A-63-124718 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02H 7/22 H02H 3/28

Claims (1)

(57) [Claims] 1. A digital bus protection device for selectively protecting a double bus of an electric power system by a collective protection device for judging whether an accident has occurred inside or outside and a split protection device for judging which bus has an accident. Means for detecting that both buses are simultaneously connected based on the disconnector condition connected to each bus, and the output of this means regards each of the split protection devices as a new collective protection device, A digital bus protection device, each of which performs bus protection together with the collective protection device.