JPS596723A - Protecting relaying device - 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 The present invention relates to a relay device used for protecting a transformer.

A common ratio differential relay device (
(hereinafter referred to as DfRY) is conveniently used.

This type of DfRY is constructed as shown in FIG. In FIG. 1, lO is a transformer, and current transformers 11fi and 1ltl are provided at the input and output terminals of this transformer 10.
2 and is input to the vector sum detection section 13. The output of the scalar sum detection section 12 is sent to the ratio setting section 14 and the first rectification section 11.
5 are sequentially applied to the minus input terminal of the first comparing section 16. The output of the vector sum detection section 13 is applied to the positive input terminal of the first comparison section 16 via the second rectification section 17 . The first comparator 16 outputs Iy of both human power and supplies the output to the first level detector 18 made of a Schmitt trigger etc.4.The output of the first level detector 1g is supplied to the drive unit 20a of the contact 19fi. be done.

The output of the vector sum detection section 13 is the fundamental wave component component I-1.
It is supplied to the first filter 21fi which passes the second harmonic component If2, and the second filter 21b which passes the second harmonic component If2. The output that has passed through the first filter 21a is output to the third rectifier 22.
The signal is applied to the plus input terminal of the second comparator 23 via.

On the other hand, the output that has passed through the second filter 21b is given to the suppression rate setting section 25 via the 8g4 rectifier 24. The output of this setting section 25 is supplied to the minus input terminal of the second comparison section 23. The output of the second comparison section 23 is supplied to the drive section 20b of the contact 19b via the Ig2 level detection section 26.

Only when the AND condition of the contacts i9n and t9b is satisfied, an output as a protective relay is obtained between the terminals 27 a e 2 fb.

Next, to describe the operation of the conventional tilt protection relay device, the scalar phase IR (corresponding to the passage IIl, flow) obtained from the output of the scalar phase detection section 12 is taken as the suppression amount.

The vector sum (xd) (corresponding to the difference current) obtained at the output of the vector sum detection section 13 is the operating amount. In FIG. 1, the 11m2 level detecting section 18.26 operates immediately when the input value exceeds a predetermined level, and supplies the output to the driving sections 20a and 20b. 2 as above
When two level detecting sections 18°26 are provided, for example, even if the first level detecting section 18 sends out the operating output at the excitation inrush tm when the transformer is turned on and the contact 19fi turns on, the second harmonic component If2 If the second level detecting section 26, which is suppressed by the above, is not operated, the contact 19b remains off. Therefore, the connecting device is the terminal 27a.

27b, no malfunction notification is sent. However, in the past, the criterion for the second harmonic determination element was generally set to about I 12/2 ft 0.15, and since voltage transformation was common, even in the above case, a malfunction output was sent out. I didn't.

However, due to improvements in transformer core materials and changes in structure, the second harmonic component (If2) in the excitation inrush current when the transformer is turned on and the first wave when the fundamental wave component (I11) is turned on. There are some transformers in which the ratio is close to 0.1.1 With such a ratio, the relay device will operate when the excitation inrush current comes. In other words, unnecessary operation outputs are sent out. Although countermeasures against this problem have been considered, if this value is set too low, there is a drawback that, in the event of an internal fault in the transformer, the operating time will be delayed due to harmonic components contained in the fault current (particularly at the initial stage of the fault). In addition, in order to increase the suppression rate by Ifz, a second harmonic bus filter 21b with a large Q is required, resulting in a disadvantage that not only the stability decreases but also the determination time is delayed.

Furthermore, there is also a means for locking the operations of all phases if the drive unit 20b of the element 1' of any one of the three phases is inoperative. However, this method complicates the configuration and reduces operational reliability, and if there is a ground fault in any phase when the transformer is turned on, the ground fault occurs and the drive m of the non-fault phase is interrupted. 20b may cause the outputs of all phases to be locked. For this reason, the operating time of the relay device becomes longer, and there is a possibility that fault removal may be delayed.

This invention was made in view of the above circumstances.

The purpose of the present invention is to provide a highly reliable impurity-preservation relay device that does not malfunction even when exposed to currents, can reliably protect against internal failures of transformers, has a simple configuration, and is highly reliable. .

An embodiment of the present invention will be described below with reference to the drawings, in which the same parts as in FIG. 1 are denoted by the same reference numerals.

In FIG. 2, the output of the operating value setting section 28 is supplied to the second minus input terminal of the second comparing section 23.

The second comparator 23 derives the difference between the fundamental wave component (Ifl) and the 1s2 harmonic component (Ifz) multiplied by the suppression rate and the operating value setting amount. The derived difference is supplied to the integration circuit section 29 and integrated. The second level detection section 26 detects that this integral value has reached a predetermined level, and the drive section 26 detects that the integral value has reached a predetermined level.
b and turns on contact 19t+.

Next, the operation of the above embodiment will be described using FIGS. 3A and 3B.

31i1A, B is the 1c motion theory f for the excitation inrush current
2 This is about an inrush current that becomes /, f, = O, lS at the fourth wave. In wc3 diagram B, the constant is 5.
It becomes 64. Ift is the fundamental wave component included in the rush current, and the first wave is the minimum operating value. Assuming that there is 0.08 times the input, Ifz = 0.089 x engineering (1 = 0.08
This means that the second harmonic component of 9×8×0 was included. The constant is set by the suppression rate setting section 25, and is set to =5.64 as described above. At the time of input, the operation limit is reached at /k,=o,is. This operating limit is the fourth wave in FIG. 3A.

When the setting output of the suppression rate setting section 25 and the setting output of the operating value setting [2B are input to the minus input terminal of the second comparison section 23, the output becomes the shaded portion shown in FIG. 3B. This output becomes an input to the integration circuit section 290 and is integrated there. If the integral constant is determined so that the relay device does not cause unnecessary operation based on the value input to the integral circuit section 29, the response when a fault current of the same magnitude as the first wave of the magnetizing inrush current flows is as follows. The result will be as shown in Figure 4B. That is, @4Ig
The time when the area of the shaded area of lB and the area of the shaded area of FIG. 3B become equal is the operating time. This operating time is the fourth
From Figure B, it is approximately 17 mB.

When the time constant of the integrator circuit section 290 is determined as described above, the operating time characteristic becomes an inverse time characteristic as shown in the GS diagram, and the minimum operating value is calculated. With 8 times the input, it becomes about 171] days. If it is configured to have such an anti-time characteristic,
A relay device is obtained that has a small second harmonic component (without the first unnecessary operation) and operates at a high speed of 30 m5 for a transformer fault current of five times the minimum operating value.

It is well known that the peak value of the first-wave inrush current increases as the transformer capacity decreases, but the attenuation rate of the peak value increases over time as the transformer inrush current decreases. on the other hand.

Actual measurement results and simulations of the second harmonic content show that the smaller the transformer capacity, the greater the rate of increase in 1''/□7. When considered in relation to the area of the shaded part of , the vertical erosion of the area of the shaded area becomes longer.Also, as time passes, the attenuation of the upper Ift is large and the increase in KIf2 is large, so the point where (Ift-KIf2) intersects with KIf2 is large. In other words, the time for which the amount of operation and the amount of suppression become equal) becomes shorter, and the length of the diagonal triangle in the horizontal direction becomes smaller.

On the other hand, if the transformer capacity is large, the peak value of the first wave will be small and If will also be small, so (If
-KIf2) becomes smaller. Therefore, although the length of the diagonal triangle mentioned above in the vertical direction becomes smaller, the attenuation of the force f1 over time also becomes smaller. Therefore, the increase in If2 also becomes smaller, and the length of the triangle in the diagonal area in the lateral direction becomes longer.

As mentioned above, the difference in area of the triangle shown in the shaded area in FIG. 3B due to the difference in transformer capacity is small. If the time constant of the integral circuit section 290 is determined based on the current example, there will be no unnecessary operation even with the excitation inrush current of all transformers! A device is obtained. Figure 3B shows an example of inrush ta when the residual magnetic flux is assumed to be quite large for a small capacity transformer of about 15 MVA.

If the integral time constant is set so as to prevent unnecessary operations to this extent, it is thought that unnecessary operations will not occur even in most transformer excitation inrush* and a.

FIG. 6 shows another embodiment of the invention, in which the same parts as in FIGS. 1 and 2 are designated by the same reference numerals. In the embodiment shown in FIG. 6, the first comparison section 16, the second rubel detection section 18, the contact 19a and the drive section 20a are omitted, and the output of the first rectification section 15 is inputted to the negative input terminal of the second comparison section 23. This is what I did. With this configuration, the circuit configuration can be greatly simplified.

As described above, according to the present invention, the operation amount of the fundamental wave component of the vector sum, the suppression amount of the second harmonic component thereof, and the setting amount of the operation value setting section are supplied to the comparison section, Since the difference between these values is obtained and this value is integrated by the integrating circuit, the following advantages can be obtained.

Even if I set it to 0.15, it doesn't work when I turn on the transformer! Never work,.

Despite having the above-mentioned features, due to the inverse time-limiting characteristic that the time limit becomes faster as the fault current Id increases, sufficient transformer protection coordination can be achieved against internal faults in the transformer. .

C, the fault current is 5 times the minimum operating value (approximately 1.5 times the rated current)
Since a high-speed operation of 30 m5 can be obtained with a total of 30 m5, transformer failures can be reliably removed at high speed.

2. Unnecessary operations can be prevented when the transformer is turned on even when the aspect of the excitation rush current changes depending on the size of the transformer capacity.

E. Suppression due to the second harmonic can be determined independently for each phase, so the transformer protection relay device for each phase can be configured independently for each phase, making it possible to simplify the circuit configuration and increase reliability. It can also improve sexual performance.

Since the suppression method is independent of each phase, even if a ground fault occurs when the transformer is turned on, the fault can be quickly removed.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing a conventional ratio differential relay device for protecting a transformer, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 A and B% 4A and 4B and FIG. 5 are waveform diagrams and characteristic diagrams for explaining the operation of the above embodiment, and FIG. 6 is a block diagram showing another embodiment of the present invention. 12... Scalar sum detection unit, 13... Vector sum. 23... Second comparing section, 26... Integrating circuit section, 26.
...Second level detection section, 19b...Contact, 20fi.
··Drive part.

Claims (2)

[Claims] (1) The first output of a ratio differential relay element whose suppression amount is the scalar sum of current transformer outputs at the transformer terminals and whose operating amount is the vector sum, and the operating amount is the fundamental wave component If+ of the vector sum. , the second output of the second harmonic content determination element with the second harmonic component If2 as the suppression amount; Relay 1 that sends the relay output when the AND condition of the second output is satisfied! In the device, the operation amount of the fundamental wave component of the vector sum, the suppression amount of its second harmonic component, and the setting amount from the operation value setting section are respectively input, and the output is the difference value of the six amounts, and this Protection characterized in that a value is integrated by an integrating circuit section having a predetermined time constant, and a level detection section detects that the integrated value has reached a predetermined level to obtain the second output. Relay device. (2) The integral time constant is set at the time of turning on the transformer,
Engineering. is an operating value, K is a constant, t is I fl-KIf2=I
. 2. The protective relay device according to claim 1, wherein the time period is set to 1.