JPS6226245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protective relay device, and more particularly to a protective relay device with improved reset characteristics.

A relay device, whether digital or analog, is one that determines the magnitude relationship between the operating amount V ₁ derived from its input and the set value V ₂ , and provides an output when the former V ₁ is greater than the latter V ₂ It is. In other words, when the operating amount V ₁ changes as shown in Figure 1 with the passage of time t due to changes in the system conditions that are input to the relay device, the output between t ₁ and _{t 3} where V ₁ > V ₂ give. Here, time t ₀ is the time of accident occurrence, t ₂ is the time of accident removal, generally the time T ₁ between t ₀ - _{t 1} is called the operating time, and the time T ₂ between t ₂ - _{t 3} is called the recovery time. It is. As is clear from this figure, which shows when the amount of operation is large and when it is small, there is a tendency that the larger the amount of operation, the shorter the operation time and the longer the recovery time. Note that the delay in the change in the amount of movement is due to the time constant etc. in the process of deriving the amount of movement. In this way, since there is a time delay in the recovery of the relay device, there is a risk of malfunction when the outputs of two or more relay devices that are always on and always inactive are combined for ultimate protection. .

As an example, FIG. 2 shows a plurality of linear elements R ₁ to _{R 4}
If there is an accident within the diagonal line (R ₁ to R ₄₎
This shows the protection area when giving the final output to (all operating). In the figure, the horizontal axis is resistance, and the vertical axis is reactance, and it is assumed that the current is always at point _P1 , and due to an accident, it moves to point _P2 , which is outside the protected area.

When it is at the _P1 point, only _R2 is always inactive, and when it is at the _P2 point, only _R1 is inactive.
Since the other R ₃ and R ₄ are in operation in any state, considering only the operation of R ₁ and R ₂ , as shown in Figure 3, R ₂ is in operation after the accident occurrence time t ₅ . It becomes operational within a relatively short time. but,
As shown in Figure 1, R ₁ takes time to recover (the larger the amount of movement before t ₅ ), and R ₂ movement (t ₆ )
After that, all the elements are in the operating state until the return of _R1 ( _t7 ), and it is determined that the accident is within the operating range, and the final output is given. This is clearly a malfunction.
To avoid this, allow sufficient time for confirmation after the accident occurs.
Although it is possible to provide T ₀ , this is not preferable because protection in the event of an internal accident will be delayed.

In view of the above, an object of the present invention is to provide a protective relay device with improved recovery characteristics. Specifically, after the relay device operates, the return time is shortened by making the difference between the set value and the operating amount small.

In the first method of the present invention, after confirming that the operating amount V ₁ has reached a predetermined level V _L that is greater than or equal to the set value V ₂ , the set value is set to V ₂ ′ (V ₂ ′>V ₂ ). , performs a high-speed return. The present invention described below includes:
Although it is possible to implement the present invention using either a digital device or an analog device, since a digital device is easier to implement, an example of a digital device will be shown as an example. Although the relay device may be of any principle or system, a distance relay device will be described here.

First, a distance relay device inputs the system voltage V〓 and the system current I〓, and uses a predetermined setting impedance Z ₀ to calculate the operation amount V ₁ = (I〓Z〓 ₀ −V〓) I〓Z〓 ₀ is determined and compared with the set value _V2 . In a digital device, the instantaneous values v _t1 and i _t1 of the voltage and current at the same point in time that are sampled at a predetermined period are used to calculate the fourth
This is accomplished as shown in the diagram. First, in block 11, the product i _t1 of i _t1 and a predetermined settling impedance Z ₀ is
In the addition block ₁₂ , the difference between _{it1 Z0} and _vt1 is calculated.In the product block 13, ( _{it1 Z0} - _vt1) is calculated.
₁ ) and i _t1 Z ₀ . 14 is a filter that removes only the fluctuation component from the output of the product means.
The filter output is the operating amount _V1 . Reference numeral 15 denotes an addition block which calculates the difference between V ₁ and the set value V ₂ and provides an operational output when the difference is a positive value, and an inactive output when it is a negative value. The above portion is an example of digitally realizing a distance relay device, and in the present invention, the return characteristic can be improved by simply adding blocks 16 and 17 to this. First, the determination section 16 is provided on the output side of the filter 14, and the
The difference between the output V ₁ of 4 and a predetermined level V _L is calculated. If the output V ₁ -V _L is positive, the level changing unit 17 sets the set value V ₂ to V ₂ ′ (V ₂ ′>V ₂ ), and if it is negative, it remains V ₂ .

This is illustrated in Fig. 5. When the operating amount is V ₁ (V _L > V ₁ ), the set value is set to V ₂ ', so the return is made to time t ₃ '', and the return time is T ₂ ''. becomes.

Since the return time without correction to V ₂ ' is T ₂ , it is clear that the return time is improved. No correction is made when it is less than V ₂ ', such as V ₁ '. According to the present invention described above, the recovery time can be shortened even when the amount of movement is large, so while preventing malfunctions in the event of an external accident as described in FIGS. It can be an action.
In other words, according to the present invention, the return point of the linear element _R1 is
t ₇ ′, and in this case, an erroneous output is given between t ₆ − t ₇ ′, but the confirmation time T ₀ ′ at this time is equal to T ₀ of the conventional method.
It's shorter and better. Therefore, the operation in the event of an internal accident
It can be faster than when T ₀ . Although the above example shows an example in which the set value level is switched in two stages, the same effect can be obtained even if the setting value level is switched in a plurality of stages depending on the amount of operation.

The second method of the present invention is to limit the maximum value of the operating amount to a predetermined value while keeping the set value fixed, and this embodiment is shown in FIG. 16 is a limiter provided after the stacking means 13, and limits the maximum value thereof. The limiter may be installed in the following positions, but in this case, the input signal becomes a rectangular signal, which is not preferable in terms of integration. Since the filter itself has an integral function, there is a delay due to the time constant of the filter after the filter input changes until the limiter output changes at the time of recovery, and this does not contribute to improving the recovery characteristics. In the case of the position, the maximum value of the filter input is limited, and as a result, the maximum value of the filter output does not exceed a predetermined value, and in this case, there is almost no delay at the time of recovery. This method can also improve the return characteristics to the same extent as the first method. Note that it is also possible to combine the first method and the second method.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the recovery characteristics of a conventional protective relay device, FIGS. 2 and 3 are diagrams explaining the problem of malfunction in the event of an external accident when determining protection using a plurality of relay elements, Figure 4 is an embodiment of the present invention;
The figure is a return characteristic diagram when using the circuit in Figure 4,
FIG. 6 is a diagram showing another embodiment of the present invention. 12, 15...addition section, 13...product section, 14...
...filter.

Claims (1)

[Claims] 1. A first means for deriving the operation amount V ₁ through a filter that removes fluctuation components after integrating the input from the power system, and an output V ₁ of the means and a set value V _{2 .} In a protective relay device comprising a second means that compares the values and provides an operating output when V ₁ > V ₂ , the difference between the operating amount V ₁ and the set value V ₂ is made small when the device is operated. A protective relay device characterized in that a third means is added to shorten the recovery time of the protective relay device. 2 The third means means that when the operating amount V ₁ of the first means is larger than the predetermined value V _L , the set value V ₂ is changed to V ₂ ′ (V ₂ ′>
2. The protective relay device according to claim 1, wherein V ₂ , V ₂ ′≦V _L . 3. The protective relay device according to item 1, wherein the first means includes a limiter that limits the integrated value before the filter.