JPS6087616A - Ratio differential 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 [Technical Field of the Invention] The present invention relates to a ratio differential relay device that protects multi-terminal systems such as power transmission lines and busbars from small current ranges to large currents.

[Technical background of the invention and its problems]・ Ru.

The IJI diagram shows an example of the configuration of a conventional display line relay device for protecting two terminals. Figure 2 is a diagram showing an example of the ratio characteristics of the display line relay device obtained with the configuration shown in Figure 1. The ratio in the large current range is greater than the ratio in the small current range, taking into account errors due to main CT saturation, etc. A material having enlarged broken line characteristics is used.

In FIG. 1, the A terminal current IA and the B terminal current IB are converted into appropriate values by auxiliary current transformers IA and IB, respectively, and then the vector sum derivation circuit 2 converts the differential amount Id (
ΣI) is reduced by the scalar sum derivation circuit 3 to the suppression amount ΣII+
Derive. The suppression amount derived by the scalar sum derivation circuit 3 is multiplied by 1 as a suppression coefficient by the first suppression circuit 5A, and multiplied by the suppression coefficient xt (>xt) by the second suppression circuit 5B.
Adder circuit 6A, respectively.

Differential amount IId+ rectified by the aftermath rectifier circuit 4 at 6B
(lΣII), that is, the operation amount, and the low-pass filter circuits 7A, 7B and the level detection circuit 8A.

8B and outputs them respectively.

1ΣII by the first ratio characteristic circuit of the dashed-dotted line portion 12A.
-, ΣIII≧0... (1) is determined,
Obtain the ratio characteristic of the straight line part a in FIG.
o-K ・'・(2) (KOp Kt ic, p K
t is a constant) to obtain the ratio characteristic of the second straight line portion.

The AND circuit 11 obtains the ratio characteristic of the broken line characteristic as shown in FIG. ing.

In an external accident like point F in Figure 2, the first ratio characteristic (
The straight line part a) changes from the inactive state to the active state, and the second ratio characteristic (
Straight line b) responds to return from the operating state. 9I
If the operation of the ratio characteristic No. 41 is faster than the recovery time of the second ratio characteristic, a malfunction will occur. For this reason, an operating delay circuit 9 is provided for time-coordinating the above-mentioned re-characteristics. On the other hand, time coordination is performed by the operation delay circuit 10 in case the fault recovers from a 1-point external fault to a 0-point fault.

As mentioned above, since the conventional method consists of two elements, an element having the first ratio characteristic and an element having the second ratio characteristic, the circuit configuration becomes large, and the AN of the two elements
1 from condition D! Since electric characteristics are obtained, time coordination between the two elements is required, and this has been an obstacle to increasing the operating time of the relay.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and is a high-speed ratio differential relay device that has a simple configuration and eliminates the need for time coordination between ratio characteristics in a small current range and ratio characteristics in a large current range. is intended to provide.

[Summary of the invention]

By configuring the structure so that the maximum amount of suppression among the two amounts of suppression corresponding to the ratio characteristics in the small current region and the ratio characteristics in the large current region is compared with the operating amount, the ratio characteristics such as the two in Figure 2 C can be achieved. get.

[Embodiments of the invention]

(One Embodiment) FIG. 3 shows an embodiment according to the present invention. First, the input terminal current IA and B terminal current IB will be explained from the circuit configuration of this embodiment.
is converted to an appropriate value by auxiliary current transformers IA and IB,
It is introduced into both the vector sum circuit 2 and the scalar sum circuit 3. The output of the vector sum circuit 2 is subjected to aftereffect rectification by an aftereffect rectification circuit 4. On the other hand, the output of the scalar sum circuit 3 is introduced into the first five suppression circuits and the second suppression circuit 5B, and the respective outputs are introduced into the maximum value detection circuit 13, and the detected maximum suppression amount and the total The output of the wave rectifier circuit 4, that is, the amount of operation, is calculated by the adder circuit 6. The output of the adder circuit 6 passes through a low-pass filter circuit 7 and a level detection circuit 8, and then becomes a final output from an output circuit 11.

Next, the effect will be explained. In Figure 3, A terminal current IA is converted to an appropriate value by auxiliary current transformer IA, and B
Terminal current IB is similarly converted to an appropriate value by auxiliary current transformer IB. The vector sum circuit 2 calculates the amount of operation (differential fi
) Id=Σ is obtained, and the scalar sum circuit 3 obtains the suppression amount Σ1Il=IIAl+1tBl. The amount of suppression obtained by the scalar sum circuit 3 is the amount of suppression obtained by the first suppression circuit 5.
Depending on the person, the amount of suppression will be 1ΣIII, and depending on the second suppression circuit 5B, the amount of suppression will be l I l-. The maximum value detection circuit 13 selects a large amount of ΣIII or 2Σllll-. In the first ratio characteristic (small current range characteristic), the characteristic equation is 1ΣII- and ΣIII≧0, which is the characteristic of straight line a in FIG.

In the second ratio characteristic (large current range characteristic), 1Σ1t(
KtΣIII-K)≧KO 1゛, 1ΣII-, and ΣIII≧, 0-, resulting in the characteristic of the straight line in FIG.

In Figure 2, the first ratio characteristic (small current range characteristic) and the second
(Large current range characteristic At the intersection n of the sides, the amount of suppression is Σl I l = 2Σllll-, in the current range larger than n point, 2ΣIII K>KrΣIII, in the current range smaller than n point, ΣrIl Since -K<KlΣIII, a characteristic is obtained in which the shaded area in FIG. 2 is the operating range.

The suppression amount detected as described above is calculated by the addition circuit 6 as the operation amount 1Σ11, and the output of the addition circuit 6 is smoothed by a low-pass filter, the level is detected by the level detection circuit 8, and the output circuit 11 This will be the final output.

According to this embodiment, the suppression amount is 1ΣIII and 2Σl I
Since the ratio characteristics shown in Fig. 2 are obtained by taking the maximum amount of suppression in l - as the amount of suppression, there is no need for time coordination of the two ratio characteristics as in the past, and a ratio differential relay device with high speed operation can be used. In addition, the circuit configuration is simple.

(Other Embodiments) Although the above description has been made regarding a two-terminal system, it goes without saying that the same can be implemented for systems with three or more terminals.

Furthermore, although the case where there are two ratio characteristics has been described, the same effect can be obtained when there are three ratio characteristics as shown in FIG. Figure 4 a, b.

In order to obtain three ratio characteristics with C, as shown in FIG. If the maximum value of is set as the amount of suppression, the fourth characteristic of 4° can be obtained.In this way, it can be configured by simply adding the third suppression circuit 5, making it extremely compact. For example, it can be similarly applied to a case where the ratio characteristics have three or more ratio characteristics.

Furthermore, although the case where a scalar sum is used as the suppression amount has been described, the same effect can be obtained by using other methods such as a maximum value suppression method in which the maximum value of each terminal current is used as the suppression amount.

Not only display line relay device but also FM current differential relay device,
It can also be applied to other ratio differential relay devices such as busbar protection devices.

〔Effect of the invention〕

As described above, according to the present invention, there is no need for time coordination between the first ratio characteristic (small current range) and the second ratio characteristic (large current range), high-speed operation is preferred, and the amount of suppression is reduced. Since the maximum value of always acts as a restraint, there is no possibility of malfunction due to an external accident, and furthermore, the internal circuit configuration is simplified and a ratio differential relay device that can be downsized can be obtained.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional display line relay device, and Figure 2 is a diagram of a conventional display line relay device.
3 is a diagram showing an embodiment of the present invention, FIG. 4 is a ratio characteristic diagram of the display wire relay device having three ratios, and FIG. 5 is a ratio characteristic diagram of the display wire relay device shown in the figure. 4 is a configuration diagram of an indicator line relay device for obtaining the characteristics shown in FIG. 4. FIG. IA, IB...Auxiliary current transformer 2...Vector sum circuit i...Scalar sum circuit 4...Full wave rectifier circuit 5A, 5B, 5C...Suppression circuit 6...Addition circuit 7. ...Low pass filter circuit 8...Level detection circuit 9...Operating delay circuit 10...Operating delay circuit 11...Output circuit 12A...-first ratio element 12B...th Ratio element 13 of 2...Maximum value detection circuit (73j-7) Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An operation amount derivation circuit that obtains the current of each terminal of the protected system and generates an operation amount according to the sum of each terminal current, and a suppression amount derivation circuit that performs a predetermined calculation on each terminal current to generate a suppression amount. The ratio difference is characterized in that the amount of suppression is a suppression amount corresponding to at least two or more different suppression rates, and the ratio difference is responsive to a magnitude relationship between a maximum suppression amount of these suppression amounts and the amount of operation. Dynamic relay device.