JPH02294221A - Bus protective relay device - Google Patents

Abstract

PURPOSE:To prevent malfunction by the esternal failure of a bus by operating working quantity and inhibitive quantity from the secondary current of current transformers, by storing the maximum value of the inhibitive quantity for a given period when the working quantity gets to the constant value and over, and by outputting a bus failure signal when the working quantity is greater than the value found by the maximum value of the inhibitive quantity multiplied by the constant value. CONSTITUTION:This device is equipped with operation elements 8 and 9 to operate the working quantity and inhibitive quantity from the secondary current of current transformers 4a to 4d, a storage part 14 to store the maximum value of the inhibitive quantity for a given period in a system failure and an operation part 18 to output a bus failure signal when the working quantity is greater than the value found by the maximum value of the inhibitive quantity multiplied by a constant value. The working quantity and inhibitive quantity are operated from the secondary current of current transformers 4a to 4d and in detecting the failure where the working quantity gets to the constant value and over, the maximum value of constant inhibitive quantity is found and stored. When the working quantity becomes greater than the value found by the maximum value of the inhibitive quantity multiplied by the constant value, a bus 3 failure signal is outputted accordingly.

Description

[Detailed description of the invention] A. Industrial applications The present invention relates to a busbar protection relay device.

B. Summary of the Invention The present invention calculates the amount of operation and amount of suppression from the secondary current of a current transformer, and during failure detection when the amount of operation exceeds a certain value, constantly determines and stores the maximum value of the amount of suppression, and calculates the amount of suppression when the amount of operation is A bus fault signal is output when the value becomes larger than the maximum value of the suppression amount multiplied by a certain value.

C. The conventional technology bus protection relay device uses the judgment formula 0 (t) KR (t)> by multiplying the scalar sum of the absolute value of each line operating amount and each line current connected to the bus by a constant value (suppression rate K). When 0 is established, the bus protection relay is activated. However, if the bus-bar external fault current is large and the DC component superimposition ratio is large, the current transformer may undergo transient saturation, and the above determination formula may hold true at the time of the bus-bar external fault.

For this reason, the applicant previously proposed in Japanese Patent Application No. 61-112183 that the maximum value RHAx of the suppression amount R(t) during a certain period of time at the time of a failure in which the amount of operation exceeds a certain value is stored, and the amount of operation 0 ( When the judgment 2 〇 (t) -KRMAx>o is established between t) and the maximum value R''X of the suppression amount,
We have proposed a system that outputs a judgment output for internal bus faults to prevent bus protection relays from malfunctioning due to external bus faults.

D. Problems to be Solved by the Invention However, in this busbar protection relay device, the maximum value RMAX of the suppression amount stored in the storage element is determined for a predetermined period before and after the time when the operation fflo(t) exceeds a certain value. Because it belongs to
If the bus external fault current continues, malfunction may occur.

The present invention has been made in view of the above problems of the prior art, and its purpose is to provide a bus protection relay that does not malfunction due to an external failure of the bus.

E. Means for Solving the Problems In order to achieve the above object, the busbar protection relay device of the present invention includes a calculation element that calculates the amount of operation and the amount of suppression from the secondary current of the current transformer, and a calculation element that calculates the amount of operation and the amount of suppression from the secondary current of the current transformer, and the amount of operation that is a constant value. A storage unit that stores the maximum value of the suppression amount for a predetermined period of time when a system failure occurs, and a calculation unit that outputs a bus fault signal when the operating amount becomes larger than the maximum value of the suppression amount multiplied by a certain value. The storage unit is characterized in that the storage unit constantly determines and stores the maximum value of the suppression amount during the detection of a failure in which the amount of operation exceeds a certain value.

F. action The calculation element is based on the secondary current of the current transformer. Calculate.

A system failure is detected when the amount of power 0(t) exceeds a certain value.

The storage unit constantly determines and stores the maximum value RM■ of the suppression amount during the detection of a system failure when the operation amount 0(t) is equal to or greater than a certain value.

? The arithmetic section calculates the operation amount from the arithmetic element o (B and the maximum value RMAx of the suppression amount from the storage section, using the formula O(t) - KRMA
Make a determination that X〉0. Since the maximum value R'4Ax of the suppression amount is the maximum value during system failure detection, the above-mentioned judgment formula will not be satisfied and the bus protection relay will not malfunction due to an external failure of the bus.

G. Example Examples will be described with reference to the drawings.

In Figure 1, la and lb are the power sources of the power system, and 2a~
2d is a line, 3 is a bus bar, 4a to 4d are current transformers for detecting the current of lines 2 and 2d, and 5a to 5d are circuit breakers inserted in lines 2a to 2d.

6 is each line current I■ detected by the current transformers 4a to 4d.
This input converter 6 converts the current into an appropriate value for performing calculations necessary for the bus protection relay device. The output 7 converted by the input converter 6 is input to a motion amount calculation element 8 and a suppression amount calculation element 9, which calculate the motion amount 0(1) and the suppression fflR(t). The following equation is used to obtain the operation amount 0 (t) and the suppression amount R (t).

However, I+ indicates the current vector value of the line current i, and the absolute value sign indicates the effective value of the current vector value.

Reference numeral 12 denotes a failure detection unit, which manually inputs the O(t) output lO of the motion amount calculation index 8, and outputs a failure detection signal 13 when this value exceeds a certain value. l4 is a suppression amount maximum value storage unit, and R (t) output 11 of the suppression amount calculation element 9 and the failure detection unit 1.
The failure detection signal 13 from 2 is input, and the failure detection signal l
3, the maximum value RMAx of the suppression amount is always determined and stored during the failure detection from about 200 ms before the failure detection time.l6 is the bus protection relay lock signal output part;
When the failure detection signal l3 is input, the bus protection relay lock signal is input for only 1 to 1.5 cycles. This is because when the transient saturation of the current transformer 4 is strong, the maximum value of the suppression amount occurs I cycle after the failure detection signal l3 is output, so the bus protection relay is locked while the maximum value of the suppression amount is obtained. This is because it is necessary.

18 is a bus protection relay calculation unit, and the operation amount calculation element 8 is 0.
(t) RMAX of output lO and suppression amount maximum value storage unit 15
Output 15 is input and the following equation is calculated.

0(t)-KRMAx>o If this equation holds true, a bus failure detection signal l9 is output. However,
The circuit breaker 5 trip signal 2l is output from the logic circuit 20 under the condition that the bus bar protection relay lock signal l7 is not present.

In FIG. 2, according to the present invention, at the time of a bus external failure,
The maximum value RMAx of the suppression amount for the operation amount 0(t) and the suppression amount R(t) is RMA X l.

Therefore, the determination formula o (t) - KRI''AX>O does not hold true. On the other hand, according to the invention of the prior application, the maximum value RI''Ax of the suppression amount is RMAX2, so K =0.8, the above-mentioned judgment formula is established at point B, and the bus protection relay malfunctions. In addition,
In the conventional determination formula O(t)-KR>O, the determination formula holds true at point A, resulting in a malfunction.

H. Effects of the Invention The present invention is configured as described above, and the maximum value of the suppression value used in the determination formula for internal bus failure is the maximum value of the suppression amount that is constantly determined and stored during system failure detection. Therefore, there is no possibility that the judgment formula will be satisfied and the bus protection relay will operate erroneously due to an external failure of the bus.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing the amount of operation, the amount of suppression, and the maximum value of the amount of suppression. 2...Line, 3...Bus bar, 4...Current transformer, 5...
- Breaker. 2 people outside

Claims (1)

[Claims] (1) a calculation element that calculates the operating amount and suppression amount from the secondary current of the current transformer; and a storage unit that stores the maximum value of the suppression amount for a predetermined period in the event of a system failure in which the operating amount exceeds a certain value; and an arithmetic unit that outputs a bus fault signal when the amount of operation is greater than the maximum value of the suppression amount multiplied by a certain value, and the storage unit is configured to store a failure signal when the amount of operation exceeds the certain value. A bus protection relay device characterized in that during detection, the maximum value of the suppression amount is always determined and stored.