JPS63154014A - 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] [Objective of the Invention] (Field of Industrial Application) The present invention has a function of testing the connection direction between an instrument current transformer that obtains a zero-sequence current of a power system and a protective relay device. This relates to protective relay devices.

(Prior art) Generally, a protective relay is a current transformer (hereinafter referred to as CT).
It is operated by current and voltage supplied from a potential transformer (hereinafter referred to as PT). Therefore, when operating the protective relay device, it is necessary to fully confirm that the connection direction between the CT, PT and the protective relay device is correct. That is, if the connection direction is incorrect, there is a risk that the protective relay will malfunction or malfunction. For this reason, when starting the operation of the protective relay device, it is common to conduct a connection direction test (hereinafter referred to as direction test) between the PC, CT and the protective relay device.

An alternative method for directional testing is the use of directional relays (
For example, there are methods for operating short-circuit distance relays, short-circuit direction relays, ground fault direction relays (for example, Denki Shoin, Electric Power Technology Desk Book, 1970, 4-90).

FIG. 8 shows a typical example of direction testing for PT and CT secondary circuits. As the relay element used here, a short circuit distance element shown in FIG. 9 or a short circuit direction element shown in FIG. 10 is used.

In Figure 8, 1 is the power transmission line, 2 is the CT secondary circuit, and 3 is the PT2
In the next circuit, 4 is a relay element, and 5 is a test terminal. The relay element 4 is a digital relay using a microcomputer, and each phase current Sa+'b*'c, each phase K
Pressure V,,#VbN,V,! N, line current 'abp'b
c#'ea and line voltage vab *vba tvea are created using software.

The relay characteristics shown in Figures 9 and 10 are v&b and jab.
It is obtained from the amount of electricity of
(into the shaded area in the figure)], which has the characteristic that the receiver enters the dead area B due to the tidal current. Therefore, if the device is installed on the sending side and does not operate, it becomes clear that the connection direction of the PT secondary and CT secondary is incorrect.

Conversely, if a device is installed on the side of the receiver and it is working, it is similarly determined to be abnormal.

FIG. 11 shows a typical example of directional testing of PT and CT tertiary circuits. The elements used here are generally the earth fault direction elements shown in Fig. 12. 1.3 in Fig. 0 is the same as Fig. 8, and CT2 indicates the case where there is a third-order CT circuit. The secondary CT and tertiary CT are wrapped around the same core. Therefore, as shown in the figure, the a phase of the test terminal 5 is opened, and the dotted lines x, y,
If a residual circuit is formed by connecting z, a zero-sequence current (.) will be artificially generated in the tertiary CT.
. is the same phase as engineering. On the other hand, the 3rd PT7 is always
However, in order to operate the relay element 4 having the characteristics shown in FIG. There is a need to. As mentioned above, the direction in which this zero-phase voltage v0 is applied is applied taking into consideration that the current of the phase with an open phase and the direction of (.) are in the same phase.
T Like the second order, V considering the tidal current. The determination is made by applying t'' and checking the operation of the relay element 4.

(Problems that Goseki tries to solve) In the directional test method described above, first PT.

Testing of CT and secondary circuits can be easily performed, and errors are unlikely to occur during testing. In other words, in this case, since power flow is used, there is no need to change the wiring using test terminals, etc. This is because it can be confirmed in the regular operating state.

However, in the case of PT and CT tertiary circuits, as mentioned above, P
↑Compared to the case of CT 2nd order, it is more complicated to change the wiring connections for both PT 3rd order and CT 2nd order, and the zero-sequence voltage V. In order to give this to the test power supply as a simulated input,
There is also a possibility of erroneous judgment due to incorrect connection of the test power supply, etc. For example, the CT tertiary is connected to the device in the opposite direction, and the zero-sequence voltage ■. If also applied in the opposite direction, the CT tertiary connection is determined to be normal, and the erroneous CT tertiary connection will not be discovered by the direction test.

The present invention has been made to solve the above-mentioned problems, and provides a protective relay device that enables easy and reliable directional testing of instrument current transformers that obtain zero-sequence current. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a first means for selecting an arbitrary phase in a power system, and a phase of a zero-sequence current and a voltage of each phase or a line activated by the first means. The second means compares the phase of at least one of the voltages between the two, and the third means performs a direction test using the result of the second means.

(Function) A phase comparison is made between the current selected by the first means and each phase voltage or line voltage, and the direction test is performed using the result, so there is no mistake in the connection direction.

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

FIG. 1 is a block diagram of an embodiment of a protective relay device according to the present invention, and the reference numerals in the figure correspond to those in FIG. 11. 4-
1 is a digital relay device, and the direction test function is realized by the software of the microprocessor housed inside this device. The configuration of the digital relay device will be explained with reference to FIG.

In FIG. 2, 41 is an input converter, and the electrical quantity D0 of the protected part (each phase current <, sb, s, each phase voltage v,
vb, ve, zero-sequence voltage v0. Input the zero-sequence current j0),
In proportion to this, nine electrical quantities D1 are output. Reference numeral 42 is a data converter (DAU), which samples the above-mentioned electrical quantity at a predetermined period and then outputs nine data D2 ('
&1jb1y'61*v1*Vl)1tV6ieV)1
*<61) t Output. 43 is a processing unit (CPU)
By inputting the above data, each relay element (short circuit relay element) is calculated.

ground fault relay element, etc.) and the direction test function according to the present invention, and outputs an output D5 in accordance with the processing results. This output D5 may be a single output.

There may be multiple outputs depending on the processing content. The structure of this relay is similar to that of a general digital relay, so a detailed explanation will be omitted.

FIG. 3 is a functional block diagram showing the processing contents of the direction test function within the processing device. In FIG. 3, 431 is a phase selection means, for example, as shown in FIG.
If the zero-phase current (.) is to be artificially generated by opening the a phase, select the C phase and activate the phase detection means 432t with the output E1.Similarly, the b # cm When the phase is open, as described above, output Eb#E outputs b.
The phase detection means 433 and the @phase detection means 434 are activated. And phase selection means 431 with a digital relay.
To realize this, a process is performed to read information such as a switch or tap for selecting a phase from input 4.

Next, the characteristics of the phase detection means will be explained. in short,
If any phase is opened, an artificially generated zero-sequence current 10 flows through the tertiary CT, and this current has a constant relationship with each phase voltage. That is, the following formula holds true during normal times.

N, I, = N2i, + N, <0
・・・・・・(1) N, I, = N24. +N,
i.・・・・・・(2) N, Icg N
2<c+ N, s.・・・・・・(3)
However, N, : Number of windings on the primary side N2: Number of windings on the secondary side N, : Number of windings on the tertiary side Here, if the C phase is open as shown in Figure 1, (1
) Since 1=0 in the equation, the following equation holds true.

N, I, = N, ff10...
...(4) For the b phase and C phase, (2) * (s) holds true. Similarly, when the b phase and the C phase are opened, the following formulas are established.

N,Ib=N,<. ......(5
) N, I. =N5s0...
...(6) From the above equation, the artificially generated io and the feed current corresponding to nine phases with an open phase are in the same phase. In addition, since the phase voltage of the system and the sending power flow are in the same phase direction during normal times, the sending power flow of the phase 10 and the phase that is open are in the same phase direction. Depending on the state of the system, the above two quantities may have a phase difference of several tens of magnitude, but they will never be in opposite phase. Therefore, for example, the C phase phase detection means 432 is as follows.

tV(2)(ψ−θ)≧O・・・・・・(7) a However, the phase difference between ψ:10 and vl θ: Adjusted depending on system status phase (usually 3P or less) The b-phase and C-phase are similarly realized below.

i ovbColt (ψ−θ)≧0...
...(8) iove■(ψ-θ)≧0 ...
(9) Taking a digital relay as an example, the above nine operations correspond to calculating the inner product of i and V, and this operation can be easily performed (for example, details can be found in the 41st (Refer to Vol. 4, Digital Relay, p. 45).

On the other hand, when the current is on the receiving side, the directions of ■ and 10 are opposite, so equations (7) to (9) do not hold. and 4
32 to 434 each produce an output of F −F when formulas (7) to (9) are satisfied.

a C FIG. 4 (&) shows an operating characteristic diagram when the formula (7) is established, that is, when the relay device is installed on the feeding power flow side and the C phase is open. FIG. 4(b) shows an operating characteristic diagram when the equation (7) does not hold, that is, when the relay device is installed on the power flow side of the receiver and the C phase is open.

Therefore, by each phase detection means 432 to 434,
It can be confirmed that the tertiary CT is connected in the normal direction. In other words, if the outputs F1 to Fc are not output when it is on the sending current side, or conversely, if the receiving side is on the current side but there are outputs F1 to Fc, it means that the connection is not in the correct direction. I understand. The output means 436 which is output via the OR circuit 435 is for checking the outputs of F1 to Fc, and can be realized by energizing a relay, lighting by a light emitting diode, or by using a light emitting diode.

FIG. 5 is a flowchart of rounding that implements the above means.

Stay7'4m has C phase, 4b has 1@, 4c
Now select each C phase. When the C phase is selected in the Stella 7'4m, the process moves to the Stella f4d, and the phase is detected using the above formula (7). When the B phase is selected in step 4b, the process moves to Step 4e, and the phase is detected using the above formula (8). ), and when C phase is selected in step 4c, Stella f4t
Moving on, phase detection is performed using equation (9).

After performing phase detection using each of the above formulas, each Stella f 4
Go to g, 4h, and 41, judge the result, and perform (7) to (
9) If any of the equations holds true, the result is output at the result output 4j. Thereafter, the controller returns to Stella 7'4m and repeats the above process 9 times.

As described above, according to this embodiment, the direction of the next connection of CTa can be easily confirmed only by the open-phase operation of any phase. The above equations (7) to (9) are examples of detecting a phase difference, and other detection methods may be used as long as the phase difference can be detected.

Therefore, as another example of the phase detection means, phase comparison between the zero-sequence current (.

i,'/,6 am (tp -6-30
...-on or (.V6 ccm (ψ-θ+9
00) ......α force or (V (2)(
ψ−θ+210') ・・・・・・(2) C
It is possible to similarly derive the a b and C phases. However, θ is an arbitrary value. The sixth factor is an operation characteristic diagram for the case of equation 11.

In each of the above embodiments, for the relay device, CT 2
Next and I'? Although nine cases have been described in which input from the third order is introduced, the present invention is not limited to this.

That is, each phase current and zero-phase voltage are not particularly necessary for realizing the function according to the present invention, and only the PT secondary and CTa orders may be input.

In the embodiments described above, the case where a third-order CT is used is explained as a configuration for obtaining a zero-sequence current, but a residual circuit can be formed by connecting with the dotted line in FIG. 7 to obtain a zero-sequence current. Good too. In other words, the zero-sequence current (or phase current A) is in phase with the zero-sequence current, that is, the tidal current!

Since a current having the same phase as is obtained, the direction test can be easily carried out by the same process as the determination using equations (7) to (9).

〔Effect of the invention〕

As explained above, according to the present invention, after a zero-sequence current is artificially generated by the connection operation of the CT secondary circuit, and a phase comparison is made between the zero-sequence current and the phase voltage or line voltage. Since I configured it to perform a direction test using the output,
It is possible to confirm the connection direction of CT and PT, allowing accurate testing.

[Brief explanation of the drawing]

@ Figure 1 is a block diagram of an embodiment of the protective relay device according to the present invention, Figure 2 is a configuration diagram of the digital relay device, Figure 3 is a functional block diagram showing the processing contents of the direction test function in the processing device, FIG. 4 is an operating characteristic diagram, FIG. 5 is a flowchart showing processing contents when each phase is selected and phase comparison processing is performed, FIG. 6 is an operating characteristic diagram of another embodiment, and FIG. 7 is an operating characteristic diagram of another embodiment. The configuration diagram of the embodiment, Figure 8 is an example configuration diagram of the conventional device, Figure 9 is the characteristic diagram of the short-circuit distance element, Figure 10 is the characteristic diagram of the short-circuit direction element, and Figure 11 @ is the characteristic diagram of the conventional loading direction test. Representative example diagram,
FIG. 12 is a characteristic diagram of the earth fault direction element used in FIG. 11. 2...CT secondary circuit 4-1...Digital relay device 5...Test terminal

Claims (1)

[Claims] In a protective relay device that performs a test to confirm the connection direction between an instrument current transformer that obtains zero-sequence current from the power system and a protective relay, the first step selects any phase of the power system described above.
means, a second means activated by the first means to compare the phase of the zero-sequence current and at least one phase of each phase voltage or line voltage, and using the result of the second means. A protective relay device comprising: third means for conducting a direction test.