JPH09149539A - Differential relay - Google Patents

Abstract

PURPOSE: To eliminate the possibility of malfunction by sampling at specified sampling intervals the amount of electricity in proportion to currents obtained at respective terminals in a protective section where differential protection is to be provided, converting the sampled amount of electricity into digital, and handling an ordinary digital operation type relay that produces operating output as a hardware mechanism based on the result. CONSTITUTION: The value of a difference function f(d) is calculated by means of a differential function calculating means using a specified plural number of pieces p of differential current data Dd , difference in sampling point from one another. Suppression data Dr is calculated by means of a suppression data calculating means using respective terminal current data D1 sampled at the same time. The value of a suppression function f(r) is calculated by means of a suppression function calculating means using a specified plural number of pieces p of suppression data Dr , different in sampling time from one another. Then the value of the difference function f(d) and the value of the suppression function f(r) are compared with each other by means of a comparing means. If the value of the differential function f(d) is smaller by a specified value than the value of the suppression function f(r), the comparing means is caused to produce arresting output, and a differential relaying means provides such control as to arrest operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a digital operation type differential relay device used for a bus of a power substation or the like.

(Prior Art) In a differential relay, an error of the current transformer becomes a problem because the iron core of the current transformer is saturated by a direct current component of the fault current in the event of an external accident. Particularly in the case of bus bar protection, fault currents that have flowed in from many terminals of the bus bar often gather and flow out in one terminal. In such a case, the current flowing out of the terminal has a large value, and the current transformer is likely to be saturated. Since the currents of the other inflowing terminals have relatively small values, saturation of the current transformer is unlikely to occur, and in many cases it does not saturate at all. In this case, the differential current (the sum of the secondary currents of the current transformer, but the direction of the current is positive in the direction of flowing into the bus) becomes a large value and malfunctions despite an external accident. As a countermeasure against this, there is a differential relay that takes measures against saturation of the current transformer. That is, Japanese Examined Patent Publication Sho 57-50130
No. 1 has a significantly large suppression amount when the sum of the absolute values of the terminal currents (total by scalar) is multiplied by a constant of 1 or less and the absolute value of the differential current (vector sum) is subtracted. It occurs. This will be described with reference to the drawings. FIG. 2A is a diagram showing an example of measured waveforms of the primary current I _p and the secondary current I _s of the current transformer when the current transformer is saturated. As shown in the figure, a period in which the secondary current I _s is not saturated and causes almost no error and a period in which the secondary current I _s is saturated and causes a significant error are repeated for each cycle of the alternating current. Be done. A secondary current is shown the waveform I _s terminal fault current flowing in the external accident, when a current transformer terminal fault current flows did not all saturated, differential current I _d
The waveform of is as shown in FIG. Further, the sum of the absolute values of the terminal current is as shown in FIG I _r. As shown in the figure, in the period in which the secondary current I _s has no error, the value of the differential current I _d is almost zero, while the sum of absolute values I _r is large. By generating a large amount of suppression during this period and storing this, a malfunction can be prevented even if the differential current I _d has a large value. However, when an internal accident occurs during an external accident, there is a drawback that the operation is significantly delayed. FIG. 3 is a diagram showing an example of a waveform in this case, where the current I _i is the sum of the currents flowing into the bus, the current I ₀ is the current at the terminal where the fault current flows during an external fault, and the I _d is the differential current. And is equal to the accident point current at the internal accident point. I _r is the sum of the absolute values of the terminal current. Time t ₁
An internal accident occurred in and before that it was an external accident. When an internal accident occurs at the phase shown in the figure, the fault point current (= differential current I _d ) becomes a full offset waveform having a large DC component as shown in the figure. Assuming that an external accident is at a close range, the amount of change in current after the internal accident occurs (Thevenin's law)
Most of them return to the external accident point. Therefore, there is no change in the sum of inflow currents I _i , and the outflow end current I ₀ has the waveform shown in the figure in which the alternating current component before the occurrence of the internal accident is canceled by the alternating current component. Due to such a current waveform, the sum I _r of the absolute values of the terminal currents has the illustrated waveform. The sum of absolute values I _r during the period when the differential current I _d is small due to the direct current component
Is large and a large amount of suppression is stored during this period, it cannot operate until the DC component is attenuated. As described above, the Japanese Patent Publication No. 57-50130 does not malfunction even when the current transformer is extremely saturated. However, if an internal accident occurs during an external accident as described above, depending on the accident current waveform, It has a drawback that the operation is significantly delayed.
In the case of busbar protection, the occurrence of an internal accident during an external accident occurs, for example, when the circuit breaker fails to break and is damaged when the external accident is interrupted, and is not always rare. In view of the above situation, Japanese Patent Application No. 61-120909 (hereinafter referred to as the prior application) was filed. This prior application is based on the differential current I
Difference between a plurality of predetermined numbers of data of the differential current data (or equivalent data) D _d obtained by sampling _d at predetermined time intervals and converting it into digital data. Using the difference function f (d)
Is calculated, and the operation of the differential relay means is blocked on the condition that this value is sufficiently smaller than the suppression value f (r). This is one which can sufficiently solve the above-mentioned problems in the embodiment described in the prior application.

(Problems to be solved by the invention) However, in the embodiment of the prior application, the suppression value f (r) is sampled at the maximum absolute value of the differential current data sampled in a predetermined period, or at the same time. The sum of the absolute values of the terminal current data is the maximum value among those sampled during a predetermined period, and the predetermined period is one cycle or more. Therefore, in the case of the suppression value f (r) of the magnitude of the difference function f (d), it is sufficiently small in the non-saturation period when the saturation of the current transformer occurs in the external accident, but the difference in the case of the internal accident is small. In the sample near the peak value of the dynamic current I _d, the value is not so large as seen in the example of 7.7%. Therefore, in order to prevent the operation of the differential relay unit from being judged by the internal accident that the magnitude of the difference function f (d) is sufficiently smaller than the suppression value f (r), sufficient attention should be paid to the design and manufacture. There was a need. The present invention has been made in view of the above points, and provides means for improving the suppression value f (r) (referred to as a suppression function f (r) in the present invention) of the embodiment of the prior application, The magnitude of the difference function f (d) at the time of an accident is prevented from becoming so small as to the suppression value f (r), so that a more stable operation can be obtained.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, an electric quantity proportional to a current obtained from each terminal of a protection section for performing differential protection is sampled at a predetermined sampling interval θ _d and converted into digital data. The above problem is solved by using an ordinary digital operation type relay which produces an operation output according to the result of processing the digital data as a hardware mechanism and performing the following processing. The processing content will be described with reference to the drawings. FIG. 1 is a diagram showing the basic configuration of the processing of the present invention. That is, a plurality of predetermined number p of differential current data (data obtained from the differential current I _d or data D _j (j obtained from each terminal current in the protection section) at different sampling times by the difference function calculating means in the process 1 are used.
= 1 to n, where n is the sum of the number of terminal currents) D _d, and the value of the difference function f (d) is calculated. In addition, the suppression data calculation unit of the process 2 calculates the suppression data D _r using each terminal current data D _j sampled at the same time, and the suppression function calculation unit of the process 3 calculates a plurality of predetermined numbers p of different sampling times.
The value of the suppression function f (r) is calculated using the suppression data D _r of. Next, the value of the difference function f (d) is compared with the value of the suppression function f (r) by the comparison means of the process 4, and the magnitude of the difference function f (d) is more predetermined than the magnitude of the suppression function f (r). When smaller than the relation, this comparison means produces a blocking output (blocking signal S ₂ or blocking function f (s)). The differential relay means of the process 5 is controlled so as to block the operation by the blocking output of the comparing means of the process 4 so that it can operate when there is no blocking output. The outline of each processing described above will be described below. The difference function calculating means in the process 1 is arranged such that the predetermined sample interval θ _s (generally θ
equal to the _d, but calculates a difference value function f (d) by using the mutual difference in the differential current data D _d of theta _s ≠ theta _d with sample time different predetermined number p of can without a) is there. The difference function f (d) represents the change situation of the p pieces of differential current data D _d by one function,
When the change is small, that is, when the mutual difference is small, the value of the difference function f (d) is small, and various functions can be used as long as the difference function f (d) is small. An example of the difference function f (d) is shown below.

f (d) = D _dm , D _{d (m−1)} , ... Absolute value of difference between maximum value and minimum value of D _{d (m−p + 1)} ………… (1) f (d) = | S _dm | + | _{Sd (m-1)} | + ... + | _{Sd (m-p + 2)} | ... (2) And D _dm , D _{d (m−1)} , D _{d (m−p + 2)}
, And D _{d (m-p + 1)} is the latest, one before the latest,
It is the value of the differential current data D _d at the time of sampling (p−2) times before the latest and (p−1) times before the latest.

f (d) = | S _dm |, | S _{d (m−1)} |, ... | S _{d (m−p + 2) |} maximum value (4) Equation (1) above is the differential of the predetermined number p. The absolute value of the difference between the maximum value (the one in the most positive direction) and the minimum value (the one in the most negative direction) of the current data D _d is used as the difference function f (d), and is expressed by the equation (2) and The equation (4) is one in which the sum or the minimum value of the absolute values of the differences between the values of the adjacent differential current data D _{d at} the sampling times is used as the difference function f (d). It does not matter which of these expressions is used, and when the change in the value of the differential current data D _d is small, another expression can be used as long as the magnitude is small. The suppression data calculation means of the process 2 calculates the suppression data D _r using each terminal current data D _j sampled at the same time, and an example thereof will be shown below.

Maximum value of D _r = | D _j | (6) The above is for calculating one suppression data D _r ,
Equation (5) is the sum of the absolute values of each terminal current data D _j (where D _j is each of the terminal current data D ₁ , D ₂ ... D _j ), and equation (6) is each terminal current. It is the maximum absolute value of the data D _j . The suppression data D _r is 2 as shown in the following example.
There can be one suppression data D _r1 and D _r2 .

However, (D _j ) _p is the value of only the negative one of the terminal current data D _j corrected to zero, and (D _j ) _n is the current of each terminal whose positive value is corrected to zero. It is the value of the data D _j . In the above formula (7), D _r1 is the sum of the positive ones of the terminal current data D _j , and D _r2 is the sum of the negative ones of the terminal current data D _j . Further, in the equation (8), D
_r1 is the maximum value of each value of zero and the terminal current data D _j, D _r2 is zero and the minimum value of each value of each terminal current data D _j (most value in the negative direction). Suppression data D _r
Can be more, examples of which are given below.

D _r1 = D ₁ , D _r2 = D ₂ ... D _rn = D _n ............ (9) Expression (9) is obtained by calculating each terminal current data D _j (= D ₁ , D ₂ ...
All of D _n ) are used as the suppression data D _r1 , D _r2 ... D _rn . In this case, Process 3 is not necessary for the present invention, but this case is also included in the present invention. The suppression data D _r1 , D _r2 ...
D _rl is a plurality of terminal current data D _j (j = 1)
To n) are used by adding some of them, for example, D _r1 = D ₁ + D ₂ , D _r2 = D ₃ + D ₄ or D _{r (l + 1 )} , D
_{r (l + 2)} ... D _{r (l + k)} is the individual terminal current data D _j (j = 1 to n) as it is, for example, D _r1 =
It is used as D ₁ , D _r2 = D ₂ . Above (5), (6), (7), (8), (9) and (10)
The expression suppression data can reach the goal using either. In addition, when the value of the current passing through the protection section due to an external accident is large, it has the property of becoming large, and other equations can be used as long as this is the case. Processing 3
The suppression function calculation means of is for calculating the value of the suppression function f (r) by using the mutual difference of a predetermined number q of suppression data D _{r having} different sampling times of a predetermined sampling interval θ _s ,
The situation of the change of q pieces of suppression data D _r is represented by one function, and when the change of the suppression data D _r is small, that is, when the change of the terminal current is small, the suppression function f
It has a character that the value of (r) becomes small. First, an example of the suppression function f (r) will be shown for the case where the suppression data D _r is one, that is, the case of the expression (5) or (6).

f (r) = D _rm , D _{r (m−1)} , ... Absolute value of difference between maximum value and minimum value of D _{r (m−q + 1)} (11) f (r) = | S _rm | + | S _{r (m-1)} | + ... | S _{r (m-q + 2)} | ... (12) f (r) = | S _rm | + | S _{r (m-1)} |, ... | S _r Maximum value of _{(m−q + 2)} | (13) And D _rm , D _{r (m−1)} ... D _{r (m−q + 1)
Are} the values of the suppression data D _r at the latest sampling, one before the latest, and (q−1) times before the latest, respectively. In the above equation (11), the absolute value of the difference between the maximum value and the minimum value of the predetermined number of suppression data D _r is the suppression function f (r),
The equations (12) and (13) use the sum or maximum of the absolute values of the differences between the adjacent suppression data D _{r at} the sample times as the suppression function f (r). These (11), (1
The expressions (2) and (13) can achieve the purpose regardless of whether the suppression data D _{r of the} expression (5) or (6) is used. Next, when the suppression data D _r is plural, that is, (7),
Suppression function f in the case of equation (8), (9) or (10)
An example of (r) is shown.

f (r) = f (r1) + f (r2) + ... (15) The maximum value of f (r) = f (r1), f (r2) + ... (16) However, f (r1), f (r2) + ... _Are auxiliary functions of the first, second ... _Obtained from the suppression data D _r1 , D _r2 ... Of the first, second ... First example
The auxiliary function f (r1) of is shown.

f (r1) = D _r1m , D _{r1 (m−1)} , ... Absolute value of difference between maximum value and minimum value of D _{r1 (m−q + 1)} (17) f (r1) = | S _r1m | + | S _{r1 (m-1)} | + ... + | S _{r (m-q + 2)} | ... (18) f (r1) = | S _r1m |, | S _{r2 (m-1)} |, ... + | Maximum value of S _{r (m−q + 2)} | (19) And D _r1m , D _{r1 (m−1)} ... D
_{r1 (m−q + 1)} is the latest suppression data D _r1 at the time of the sample, one before the latest and (q−1) times before the latest
Is the value of The second and the following auxiliary functions f (r2) ... Are respectively (17), (1) using the second and the following suppression data D _r2 .
The same calculation as in the equation (8) or (19) is performed. The comparison means of the process 4 compares the value of the difference function f (d) and the value of the suppression function f (r), and generally, the blocking signal S ₂ is generated when the following expression is satisfied.

f (d) <K ₁ f (r) + K ₂ ……………… (21) f (d) <K ₁ f (r) and the maximum value of K ₂ ………… (22) However, K ₁ and K ₂ are positive constants, the value of K ₁ is, for example, about 0.1 to 0.5, and the value of K ₂ is lower than the sensitivity (minimum operating value) of the differential relay. Further, depending on the blocking method, the value of the blocking function f (s) in the following equation may be output.

f (s) = K ₁ f (r) −f (d) (23) The blocking output is held for about 1 cycle. Further, the equations (21) to (23) are the difference function f described above.
(D) and the suppression function f (r) are all calculated with a positive value such as the absolute value of the difference as described above. If the value of each function is the difference itself and a negative value is included, use the magnitude of each function, that is, the absolute value (21).
~ Equation (23) is applied. As the differential relay means of process 5, generally the same one as the differential relay means of the conventional differential relay is used. In the conventional differential relaying means, the amount of operation f (0) obtained from the differential current data D _d is a constant value or the amount of suppression of a value proportional to the value obtained from each terminal current data D _i. It operates when it becomes larger than f (b). This means is disclosed, for example, in JP-A-59-204421.
Since it is publicly known as an issue or the like, detailed description thereof will be omitted. There are various means for controlling such an operation of the differential relay means so as to be blocked by the blocking output of the comparison means, and examples thereof will be shown below.

(I) The generation of the operation output of the differential relay means is prohibited by the blocking signal S ₂ .

(II) The value of the operation amount f (0) is set to zero or a small value that makes the operation impossible due to the blocking signal S ₂ .

(III) The value of the suppression amount f (b) is set to a large value that renders it inoperable due to the blocking signal S ₂ .

(IV) When the value of the blocking function f (r) is positive, the suppression amount f
Suppression by the blocking function f (r) is added to (b).

Further, in the case of the present invention, the differential relay means does not use the differential current data D _d as in the conventional case, but a predetermined period (for example, 1) after the equation (21) or (22) is not satisfied. It is also possible to make it operate by detecting only the elapse of (cycle), and the objective can be achieved in this way as well. The predetermined sample interval theta _s of predetermined sample interval theta _s and suppression function calculation means of the difference function calculating means above, it is preferable to equally, it is also possible to vary in a range not giving any trouble to the operation and effect. Further, these predetermined sample intervals θ _s do not necessarily have to be equal to the predetermined sample intervals θ _d of the original data, and for example, θ _s =
It is possible to use the original data step by step as 2θ _d , θ _s = 3θ _d, etc. Further, the predetermined number p in the difference function calculation means and the predetermined number q in the suppression function calculation means
It is preferable to use the same number, but it is also possible to use different numbers within a range that does not hinder the working effect.

(Operation) The operation of the present invention will be described first with reference to the drawings regarding an external accident. When the current transformer is not saturated due to an external accident, the differential current I _d has an extremely small value, and the differential current data D _d hardly changes. Therefore, the difference function f (d)
The value of is almost zero even if any of the expressions (1), (2), and (4) is used. During this period, the value of the suppression function f (r) becomes a large value by using any one of the above equations (11) to (19) due to the fault current passing through each terminal. Therefore, the equation (21) or (22) is satisfied in the comparison means 4, or the blocking function f (s) of the equation (23) becomes a large positive value and the operation of the differential relay means 5 is blocked. It Next, a case where the current transformer is saturated due to an external accident will be described. In this case, as will be described later, the value of the difference function f (d) becomes significantly smaller than the value of the suppression function f (r) once per cycle, and a blocking output is obtained in the comparison means 4 during this period. Since this blocking output is held for about 1 cycle or more, the operation of the differential relay means 5 is blocked.
The phenomenon in which the value of the difference function f (d) becomes significantly smaller than the value of the suppression function f (r) once per cycle will be described below. FIG. 4 shows the current waveform when the fault current flows out from one terminal at the time of an external accident, the current transformer at that terminal is severely saturated by the direct current component, and the current transformer at the inflowing terminal is not saturated and the present invention. FIG. 6 is a diagram showing an example of a response of the device of FIG. In the figure, I _i , I _0, and I _d are the waveforms of the sum of the secondary currents of the current transformer at the inflow terminal, the secondary current of the current transformer at the outflow terminal, and the differential current, respectively. The current I ₀ is shown as −I ₀ with the positive and negative polarities reversed for the sake of comparison. This current −I ₀ is originally equal to the current I _i , but has a waveform shown in the figure due to saturation. Due to this saturation, the waveform of the differential current I _d is shown in the figure, but at times t ₁ , t ₂ , t _3, and t ₄ , which are the non-saturation periods of the current transformer that appear once in one cycle, the differential current I _d appears.
The change in _d is slight. Difference function f in the illustrated current waveform
Examples of (d) and the suppression function f (r) are shown by a solid line and a broken line, respectively. In this example, the predetermined sample interval θ _s is set to 30 ° of the sine waveform of the power system frequency, and the predetermined sample numbers p and q are set to 3
And then (hereinafter, all unless otherwise indicated described in this value), the difference function f (d) (1) formula, and each inhibition data _{D r} and inhibition function f (r) (5) and Formula (11) This shows the case where As shown in the figure, the value of the difference function f (d) is almost zero before the accident starts, and this state continues until the end of the unsaturated period of the current transformer at time t ₁ . Further, the value of the difference function f (d) becomes a remarkably small value at each latter stage of the non-saturation period at the times t ₂ , t ₃ and t ₄ . During these non-saturation periods, the changes in the currents I _i and −I ₀ are large as shown in the figure,
In the latter part of the non-saturation period, the value of the suppression function f (r) becomes significantly larger than the value of the difference function f (d). Therefore, even if the value of the constant K _{1 in} the equations (21) to (23) is set to about 0.1, the blocking output (the signal S ₂ or the blocking function f (s)) is obtained.
Is definitely obtained. As described above, blocking the output for each non-saturation period of the current transformer at time t _2, t ₃ and t ₄ when subsequently and before occurrence of the accident until the end of time t ₁ appears once per cycle can be obtained. The figure shows the generation state of the blocking signal S ₂ when the constant K ₁ is 0.2 and the constant K ₂ is a remarkably small value. In this case, since the blocking output is continued during each saturation period, no malfunction occurs. Next, the difference function f
FIG. 4 shows the state of occurrence of the signal S ₂ when (d) and the suppression function f (r) are changed from the above and the respective values and constants K ₁ and K ₂ are the same as above. 5 to 9 for the period around time t ₂ (the non-saturation period of the current transformer is short and the blocking output is most unlikely to occur). Each figure shows the difference function f (d), the suppression data D _r, and the suppression function f.
(R) is as follows. Although only f (r1) is shown below for the auxiliary function,
Other auxiliary functions below (r2) have the same formula as f (r1).

In any case, the value of the difference function f (d) becomes a significantly small value in the latter half of the time t ₂ , and at this time, the value of the suppression function f (r) is significantly larger than the value of the difference function f (d). Since it becomes the value, the blocking output is surely obtained, and this is repeated in other non-saturation periods. In each of FIGS. 5 and 6, the suppression function D _r is the same as in FIG.
(D) and the suppression function f (r) are (2) or (4), respectively.
Shown is the case where the formula and (12) or (13) are changed to
FIG. 7 to FIG. 9 are obtained by changing the suppression data D _r and the suppression function f (r) while keeping the difference function f (d) as in FIG. Even if the difference function f (d) of FIGS. 7 to 9 is changed to the expression (2) or the expression (4) and the auxiliary function f (r1) and others are changed to the expression (18) or the expression (19), Although omitted, the blocking output is surely obtained as well. That is, when the predetermined numbers p and q are 3, the values of the expressions (2) and (18) are in the range of 1 to 2 times the values of the expressions (1) and (17), respectively. The values of the equations (19) and (19) are in the range of 1/2 to 1 times the values of the equations (1) and (17), respectively, and the values in each figure change in this range and the constant K _{1 is set} to 0.1. As a degree, the blocking output can be reliably obtained. Although an example of the waveform of the suppression function f (r) when the suppression data D _r is the expression (6), (8), or (10) is omitted in the above, it will be described. In general application, the number of terminals from which an accident current flows due to an external accident is about 1 to 2 terminals. Assuming that the current transformer at the outflow terminal is saturated to the same degree, an example of the sum of the secondary current waveforms of the current transformer at the outflow terminal is the same as that in which the sign of the current −I ₀ in FIG. 4 is changed. Considering the case of flowing out from two terminals, the maximum absolute value of each terminal current is the current −I in the figure.
It is never smaller than 1/2 of the absolute value of ₀ . Here, focusing on the non-saturation period of the current transformer, for example, time t ₂ ,
The maximum absolute value of each terminal current data D _{j in} equation (6) is ¼ of the sum of the absolute values of each terminal current data D _{j in} equation (5).
It never gets smaller. Therefore, the suppression data D
Suppression function f in the latter half of the non-saturation period when _r is the equation (6)
The value of (r) does not become smaller than 1/4 of the value when the suppression data D _r is _expressed by the equation (5). The value of the suppression function f (r) in the latter part of the non-saturation period in FIGS. 4 to 6 is the difference function f.
It is a sufficiently large value with respect to the value of (d), and the value of the suppression function f (r) shown in the figure is 1 when the constant K ₁ is about 0.1.
Even if it becomes / 4, the blocking output can be surely generated, and the blocking output can be sufficiently generated even if the suppression data D _{r is set} to the expression (6). Further, when the suppression data D _r1 and D _r2 are expressed by the equation (8), the suppression function f in the latter half of the non-saturation period
The value of (r) does not become smaller than 1/4 of the case where the suppression data D _r1 and D _r2 are expressed by the equation (7), and the blocking output can be reliably generated. (10) of the inhibition data D _r uses the terminal current data D _j as inhibition data D _r1 to D _rl by adds the respective terminal current data Some of terminals, each terminal current in the remaining terminal The data is used as it is as the suppression data _{Dr (l + 1) to} Dr _{(l + k)} , but the normal data is added to a non-power supply terminal (a terminal having no power supply on the side opposite to the terminal) or a weak power supply equivalent to this. Limited to terminals. Since the current of the non-power supply terminal is a remarkably small value unless there is an accident outside the terminal, when there is no accident outside the added terminal, the contribution to the suppression function f (r) is Almost none. Further, when there is an accident outside the added terminals, the current of the non-power supply terminals except the outflow current can be ignored, and thus the waveform of the added data is almost the same as the waveform of the individual data. Therefore, even if the value of the suppression function f (r) is calculated after adding the data of each terminal, the value is almost the same as the value of the suppression function f (r) calculated from the data of each terminal. From such a relationship, as long as the data of the non-power supply terminals are added, even if the suppression data D _{r of the} expression (10) is used, it is the same as the case of FIG. 9 using the suppression data D _{r of the} expression (9). Respond to. As described above (5) to (19)
Regardless of whether the suppression data D _r and the suppression function f (r) described in the equation are used, a sufficient blocking output can be generated by an external accident accompanied by current transformer saturation. Next, the response to an internal accident will be described. 10 to 16 show the difference function f (d) and the suppression function f for the waveforms of various differential currents I _d at the time of an internal accident.
The aspect of the value of (r) is shown. Each figure shows the waveform of the differential current I _d ,
This is a case where the difference function f (d), the suppression data D _r , the suppression function f (r), and the auxiliary function f (r1) are set as follows.

The waveform of the differential current I _{d in} FIG. 10 is an example in the case where all the current transformers at the inflow terminals are not saturated, and a DC component that attenuates is superimposed on the AC current having a sine waveform. Since the currents at the respective inflowing terminals have substantially the same phase, the differential current I _d
The waveform is almost the same as the above, and the amplitude is smaller than Id. The waveform of the differential current I _{d in} FIG. 11 is an example when the fault current flows from only one terminal and the current transformer at that terminal is significantly saturated. There is no example of inflow of fault current from other terminals. The waveform in FIG. 12 is an example in the case where the current transformers of some of the terminals into which the fault current flows are saturated and the current transformers of the other terminals are not saturated. The illustrated current I _i is the sum of the currents at the unsaturated terminals, and the current at each unsaturated terminal has a waveform of I.
_It is similar to _i and the amplitude is smaller than I _i . The current I _i ′ is the sum of the currents at the saturated terminals. The current at the saturated terminals has the same waveform as I _i ′ and the amplitude is smaller than I _i . The differential current I _d is the sum of the currents I _i and I _i ′ and has the illustrated waveform. The difference function f (d) and the suppression function f (r) in FIGS. 10 to 12 are all the difference function f as described above.
(D) is the expression (1), the suppression data D _r is the expression (5), and the suppression function f (r) is the expression (11). The value of the suppression function f (r) is the difference function f ( It does not increase with respect to the value of d), and if the value of the constant K _{1 in} the equation (21) or (22) is set to, for example, about 0.2 to 0.5 or less, no blocking output is generated. The above relationship is obtained because a small change in the value of the differential current data D _d results in a small change in the value of the suppression data D _r . In the waveforms of FIGS. 10 and 11, the waveform of the differential current I _{d and} the waveform of each terminal current I _j are similar, and when the change of the differential current I _d is small, the change of each terminal current I _j is also small. . For this reason,
Even if any of the equations described in [Means for Solving Problems] is used for the suppression data D _r and the suppression function f (r), when the value of the difference function f (d) is small, the suppression function f (r) The value of) becomes small, and the blocking output does not appear. On the other hand, in the vicinity of the time t _{1 in} the waveform of FIG. 12, the current I _i is increasing but the current I _i ′ is decreasing, which reduces the change in the differential current I _d. Therefore, depending on how to select the suppression data D _r and the suppression function f (r),
When the value of the difference function f (d) is small, the value of the suppression function f (r) may be large. Therefore, FIGS. 13 to 16 are intended to explain the response to the waveform of FIG. FIG. 13 shows the modification of the suppression data D _r and the suppression function f (r) with respect to FIG. 12 as described above.
In this case, the value of the suppression function f (r) is the suppression data f (d).
, And therefore no blocking output is produced as in the case of FIGS. FIG. 14 shows the suppression data D _r as described above with respect to FIG. 13 (7).
This is a formula and each terminal current data D _j is used as it is. In this case, the value of the suppression function f (r) is equal to or larger than the value of the difference function f (d). In particular, at time t ₂ shown in the figure, the value of the difference function f (d) is 0.173 times the value of the blocking function f (r), which is considerably small. Therefore, if the constant K ₁ is increased to 0.2, the blocking signal S ₂ is generated at this time t ₂ as shown in the figure. This phenomenon is not desirable,
This is still practical. This will be described below. Period that need to retain blocking signal S ₂ as described above is one cycle, blocking the signal holding period in the case where the holding period as one cycle is as dashed line in Figure 14. The holding of the blocking signal S ₂ that occurred before the accident occurs at time t ₂ as shown in the figure.
It is set so as to be canceled before the generation of the blocking signal S ₂ of 1), and the protection operation can be performed during this period. Further, blocking the signal S ₂ is because after time t ₂ does not occur, again to restore the protection capacity from time t ₂ after one cycle.
If the constant K ₁ is set smaller than 0.173, the time t
_No blocking signal S ₂ is produced at ₂ . As mentioned above,
Even in the case of FIG. 14, it is possible to sufficiently endure the practical use and achieve the purpose. 15 and 16 are different from FIG. 14 in that the difference function f (d) and the auxiliary function f are the same without changing the suppression data D _r .
(R1) ... is changed. In this case, the suppression function f
Although the value of (r) may be larger than the value of the difference function f (d), the situation is improved with respect to FIG. That is, the ratio of the value of the difference function f (d) to the value of the suppression function f (r) at time t ₂ is 0.
269, which is a large value of 0.29 in FIG. 16, and the constant K
Even if 1 is increased to about 0.2, the blocking signal S ₂ is not generated. Next, the case of the difference function f (d), the suppression data D _r, and the suppression function f (r) (not shown) will be described below. 10 to 13 when the predetermined number p is set to 3
In the case of the figure, the difference function f (d) is the expression (2), and the suppression function f
Even if (r) is changed to the expression (12) and the auxiliary function f (r1) is changed to the expression (18), the value of each function is in the range of 1 to 2 times the illustrated case, and the difference function f (d) (4), the suppression function f
Even if (r) is changed to the equation (13) and the auxiliary function f (r1) is changed to the equation (19), the value of each function is in the range of 1 to 1/2 times that in the case shown. Therefore, as long as the constant K _{1 is set} to less than 0.5, the blocking output is not reliably generated. Further, when the blocking data D _{r is set} to the expression (6) instead of the expression (5), and when set to the expression (8) instead of the expression (7), and the blocking function f (r) is set to the expression (15). When the equation (16) is used instead of, the value of the blocking function f (r) becomes smaller than the illustrated value in any case, and there is no fear of generating a blocking output. Also,
When the suppression data D _{r is set} to the expression (10) instead of the expression (9), as long as the addition of the data is limited to the non-power supply terminal as described above, the current of the non-power supply terminal at the time of an internal accident is small. Therefore, even if data is added, there is almost no difference in response. Finally, the case of FIG. 3 in which the external accident is shifted to the internal accident will be described. In the case of the figure, the differential current I _d is the sum of the currents I _i and I ₀ , and the change in the current I ₀ is slight, so the change in the current I _d is almost the same as the change in the current I _i . Therefore, the response after shifting to an internal accident is the same as a general internal accident, and similarly, the blocking output does not occur. As described above, the means of the present invention can surely obtain the blocking output in the event of an external accident even if severe saturation occurs in the current transformer,
An internal accident does not generate a blocking output with certainty, so that an internal accident can be reliably identified and protected.

[First Embodiment] FIG. 17 is a block diagram showing the hardware structure of the first embodiment of the present invention. In the figure, B is a protected bus bar, CB ₁ , CB ₂ , CB ₃ and CB _n are circuit breakers provided at each terminal of the bus bar, and CT ₁ , CT ₂ , CT ₃ and CT _n are terminal currents I of the bus bar. _p1 ~I _pn current transformer for _{inputting, CV 1, CV 2, CV} 3 and CV _n input transducers, DAU data obtainer, CPU processing apparatus, O
U is an output device. Secondary current of each current transformer _CT 1 to CT _n is applied to the input transducer _CV 1 _{~CV n,} the secondary current I
produce an electrical quantity _E 1 to E _n proportional to _s1 ~I _sn. Data acquisition unit DAU is sampled at predetermined time intervals the amount of electricity _E 1 to E _n at the same time, we obtain the value converted into digital data each terminal current data _D j (j = _1~n). The processing device CPU performs arithmetic processing using the terminal current data D _j , and produces an operation signal S ₁ if the operation conditions are met. The output unit OU produces an operating output E ₀ in the presence of the operating signal S ₁ . FIG. 18 is a diagram showing the configuration of the processing of this embodiment.
First, in process 6, the data D _j is _fetched and stored as the latest sample data D _jm . Then, in process 7, the data D _jm
By using, as the basic data, the differential current data D _d and the suppression data D _{r at} the latest sampling data D _dm and D
_rm is calculated by the following equation and stored.

However, D _1m , D _2m , D _3m and D _nm are data D
_This is data for each terminal of _jm . After creating these basic data, the difference function f (d) and the suppression function f are processed in process 8.
(R) is calculated according to the equations (1) and (11), respectively. After this processing, the processing of the comparison means of processing 9 is performed,
Further, the processing of the differential relay means of processing 10 is performed. After these processes, data is rewritten in process 11 and process 6
Return to An example of the rewriting process in the process 11 will be shown for the case where both the sample intervals θ _d and θ _s are set to 30 ° (hereinafter, described as θ _d = θ _s = 30 ° unless otherwise noted).

However, in each equation, X means discarding data, and d and r are positive integer constants. The values of the constants d and r differ depending on the processing contents of the processings 9 and 10, but in the present embodiment, d = 6 and r = 12, and data for half cycle and data for one cycle are stored. Details of the process 9 are shown in FIG. First, in process 9-1, either the equation (21) or the formula (22) is compared. If the formula (21) or (22) is satisfied, the process result of the process 9-1 is set to Y, and if the formula is not satisfied, the result is N. To do. If the processing result of processing 9-1 is Y, processing 9
At −2, the signal S _{2 is set} to 1, and if N, the signal S _{2 is set} to 0, and the process 9 is ended. Details of the process 10 are shown in FIG. First, in process 10-1, the state of the signal S ₂ is checked, and if S ₂ is 0, then in process 10-2, 1 is added to the count value C,
This value is set as a new count value C. If S ₂ is 1, the count value C is corrected to 0 in processing 10-3. After these processes, the count value C is checked in the process 10-4, and if the value is 12, the process 10-5 subtracts 1 from the count value C to obtain a new count value C. Move on to. Then, in process 10-6, the motion amount f (o) is calculated in process 10
The suppression amount f (b) is calculated at -7. Further, in process 10-8, the operation amount f (o) and the suppression amount f (b) are compared, and if the operating condition is present, the processing result is Y, and if not, the processing result is N. If the processing result of the processing 10-8 is Y, the signal S1 is set to 1 in the processing 10-9. When the count value C is not 12 in the process 10-4 and when the process result is N in the process 10-8, the signal S _{1 is set} to 0 in the process 10-10. When the signal S ₁ is 1, the output E ₀ is output to the output device OU of FIG.
And a cutoff is commanded. Processing 10-6 to 10-
The process of No. 8 is known in the conventional differential relay, and the example is shown below. The motion amount f (o) in the process 10-6 and the suppression amount f (b) in the process 10-7 are calculated by the following equations, respectively.

f _{(b) = D rm,} the sum of the absolute value of _{D r (m-1) ...} D maximum ... (29) of _{r (m-11)} (28) Equation data _{D d} between last half-cycle Yes, the expression (29) is the maximum value of the suppression data D _{r for} the past 1 cycle. Further, in the process 10-8, for example, the operation condition is set when the condition of the following equation is satisfied.

f (o) ≧ K ₃ f (b) + K ₄ sum (or maximum value) (30) where K ₃ and K ₄ are positive constants. In the present embodiment, the difference function f (d), the suppression data D _r, and the suppression function f (r) are defined as equations (1), (5), and (11), respectively, and when equation (21) or (22) is satisfied. The blocking signal S ₂ is generated, and when the blocking signal S ₂ is generated, the operation of the differential relay means is prohibited so that the signal S ₁ is not generated. The signal S ₂ is generated only every cycle as described above,
When the signal S ₂ becomes 1, the count value C is set to 0 in the process 10-3, and even if the signal S ₂ becomes 0, the count value C is only incremented by 1 for each sample. Therefore, one cycle is required until the count value C reaches 12 and the prohibition of the differential relay means by the process 10-4 is released, so that the differential relay means does not malfunction due to an external accident.
Further, the differential current data D _d is zero during constant operation, and the suppression data D _r has a slight value due to the load current.
As a result, the equation (21) or (22) is established, the signal S ₂ becomes 1, and the count value C also becomes 0. When an internal accident occurs in this state, the signal S ₂ immediately becomes 0, the count value C becomes 12 after one cycle, and the operation prohibition of the differential relay unit is released to perform the protection operation.

[Second Embodiment] The second embodiment is the processing 1 of the first embodiment.
Only 0 is changed, and FIG. 21 shows processing 10 of this embodiment. In the figure, the same parts as those in FIG. 20 are indicated by the same symbols. Process 10-11 is a process for setting the value of the motion amount f (o) to zero. First, in the same manner as in FIG. 20, processing 10-1 to 10-1
Perform processing 0-4. When the count value C is 12, the processes after the process 10-4 are exactly the same as those in the case of FIG. If the count value C has not reached 12, process 10
After the operation amount f (o) is set to zero at -11, the processes after the process 10-7 are performed as in FIG. In this embodiment, when the count value C is less than 12, the operation amount f (o) is set to zero so that the processing result of the processing 10-8 becomes N, and the signal S _{1 is set} to 0. , At this time the signal S ₁
Is 0 as in the case of the first embodiment. The process when the count value C reaches 12 is the same as the process of the first embodiment. Therefore, the signal S _{1 of} this embodiment is
Corresponds to the embodiment shown in FIG. When the count value C is 12, the operation amount f (o) is not limited to zero, but is changed to a sufficiently small value or the suppression amount f (b) is changed to a sufficiently large value. It is also possible to set the processing result of -8 to N. This means is provided with a means for changing the calculated value of the operation amount f (o) in the process 10-6 or the calculated value of the suppression amount f (b) in the process 10-7 when the count value C is 12. Since it can be realized by, detailed description is omitted for simplicity.

[Third Embodiment] The third embodiment is the processing 1 of the first embodiment.
Only 0 is changed, and FIG. 22 shows the processing of this embodiment. In the figure, the same parts as those in FIG. 20 are indicated by the same symbols.
First, processes 10-1 to 10-4 are performed in the same manner as in FIG. When the count value C is 12, in the process 10-5, 1 is subtracted from the count value C to obtain a new count value C, and then the signal S _{1 is set} to 1. When the count value C is less than 12, the signal S _{1 is set} to 0. The difference between this embodiment and the first embodiment is that when the count value C is 12, processing 10-6 to
The signal S ₁ is directly set to ₁ without performing the processing of 10-8.
And there is a point. This will be described. As described above in the section of means for solving the problem, the signal S ₂ is continuously 0 at the time of an internal accident, so that the count value C becomes 12 when one cycle elapses after the internal accident occurs. Is reached and the signal S ₁ goes to 1. Further, at the time of an external accident, even if the current transformer is saturated, the signal S ₂ becomes 1 once per cycle, and the count value C never reaches 12. During normal operation, the differential current I _d is continuously zero and each terminal current I _j is a load current. This state is similar to an external accident without current transformer saturation, the value of the difference function f (d) is zero, and the suppression function f (r) is a slight value due to the load current. It happens that all the terminal currents I _j become zero and the value of the suppression function f (r) becomes zero, but at this time, the differential current I _d is also zero and the value of the difference function f (r). Is also zero. In either case, the equation (21) or (22) is continuously established, and the signal S ₂ is continuously 1 so that the count value C never becomes 12. As described above, since the count value C reaches 12 only in the internal accident, the signal S ₁
Becomes 1. Therefore, this embodiment can be applied similarly to the first embodiment. In addition, as an intermediate value between the present embodiment and the first embodiment, the expression (30) is used as the suppression amount f (b).
It is also possible to apply as zero. This is the second
0 may be omitted, the suppression amount f (b) may be set to zero, and the first embodiment may be applied. Therefore, detailed description is omitted for simplicity.

[Fourth Embodiment] The fourth embodiment is a modification of the processes 9, 10 and 11 of the first embodiment, which will be described. FIG. 23 is a diagram showing the process 9 of this embodiment. First, in processing 9-4, the blocking function f is calculated by the equation (23).
The value of (s) is calculated, and this value is stored as the value f (s) _m of the calculated blocking function in process 9-5. Next, in process 9-6, the value of f (s) _m is checked. If it is negative, in process 9-7 the value of f (s) _m is corrected to zero, and if it is zero or positive, it is not corrected. With the above, the process 9 is completed. The process 10 of this embodiment is shown in FIG. In the figure, the same parts as those in FIG. 20 are indicated by the same symbols. First, in processing 10-6 and 10-7, the values of the motion amount f (o) and the suppression amount f (b) are calculated as in the case of the first embodiment. Next, in process 10-12, the blocking amount f (t) is calculated by the following equation.

f (t) = f (s) _m , f (s) _(m-1) , ... f (s) _(m-11) maximum value (or sum) (31) where f (s) _{( m-1)} ... f (s) _(m-11) is the value of the blocking function f (s) at the time of sampling 1 ... 11 times before the latest sampling. This value is the maximum value (or the sum of positive values) of the blocking function f (s) in the past one cycle. Further, the comparison processing of processing 10-13 is performed, and if the following expression is satisfied, the processing result is Y, and if not, the processing result is N.

f (o) ≧ K ₃ f (b), K ₅ f (t) and sum of K ₄ (or maximum value) (32) where K ₅ is a positive constant. If the processing result of the processing 10-13 is Y, the signal S _{1 is set} to 1 in the processing 10-9, and N
If so, in process 10-10, the signal S _{1 is set} to 0 and process 10
To end. In process 11, the stop function f (s) _m , f
(S) _(m-1) , ... F (s) _(m-11) The same rewriting as in the case of other data is added to the first embodiment. In the present embodiment, while the first to third embodiments prevent the malfunction of the differential relay means by the blocking signal S ₂ , the malfunction is blocked by the blocking function f (s). In the case of an external accident, the blocking function f (s) is the same as the blocking signal S ₂ is always 1 every cycle.
Is always positive once per cycle. Therefore, (3
The blocking amount f (t) in the equation 1) is also always a positive value. Therefore, if the constant K ₅ in the equation (32) is set to a sufficiently large value, the equation (32) will not hold and the signal S ₁ will not be 1. In the case of an internal accident, the blocking function f (s) is continuously negative, as is the case with the signal S ₂ being continuously 0.
Therefore, the blocking amount f (t) is always zero, and the process 10-
The process of 13 is the same as the process of 10-8 regardless of the value of the constant K ₅ . Therefore, the signal S ₁ becomes 1 as in the case of the first embodiment. As described above, this embodiment is the first
It can be applied in the same manner as the embodiment of. The constant K
_When the value of ₅ is infinite, the effect is exactly the same as the operation of the differential relay means is prohibited by the signal S ₂ .

[Fifth Embodiment] In all of the above embodiments, the blocking output is generated during the continuous operation, and this blocking output is held for one cycle in the process 10. Therefore, even if an internal accident occurs, 1
The differential relay means is inoperable between cycles, causing an operation delay of one cycle. The fifth embodiment is for eliminating this operation delay. The processing of this embodiment is shown in FIG. The figure is the same as FIG. 18 except that the accident initial process of process 12 is added between process 9 and process 10.
The processing other than the processing 12 is the same as that of the first embodiment. Details of the process 12 are shown in FIG. First, processing 13
If an accident is detected, the processing result is Y
If not detected, the processing result is N. If this processing result is Y, the count value C'is checked in processing 12-1. If the count value C'is 1 or less, 1 is added to the count value C'to obtain a new count value C'in process 12-2. Further, in the process 12-3, the count value C used in the process 10 is corrected to 11, and the process 12 is ended. Process 12-
If the count value C'exceeds 1 at 1, the process is continued as it is 12
To end. If the result of the process 13 is N, the count value C'is corrected to 0 in process 12-4 and the process 12 is ended. In these cases, the count value C is not modified. In short, the count value C'is always 0 when no accident is detected in the process 12. When the accident is detected, 1 is added to the count value C ', but when the count value C'is 2, this addition is not performed. Only when the accident is detected and the count value C'is 0 or 1, the count value C in the process 10 is corrected to 11. That is, the count value C is corrected to 11 only at the time of the first and second sampling processes in which the accident is detected. The details of the process 13 are shown in FIG. First, the comparison processing of processing 13-1 is performed, and if the following expression is satisfied, the processing result is set to Y,
If not established, the processing result is N.

Maximum value of | D _j | ≧ K ₆ ……………… (33) However, K ₆ is a positive constant. If the processing result of the processing 13-1 is Y, the count value C ″ is set to 12 in the processing 13-2, the processing result of the processing 13 is set to Y, and the accident detection state is set. If the processing result of the processing 13-1 is N. For example, process 13-
The count value C ″ is checked in 3, and if C ″ ≧ 1, processing 13
At -4, 1 is subtracted from the count value C "to obtain a new count value C", and the processing result of the processing 13 is set to Y. If the count value C ″ is less than 1, that is, 0 in the process 13-3, the process result of the process 13 is set to N. At this time, the count value C ″ is not changed. Through the above processing, the value of the constant K ₆ is set to the absolute value of each terminal current data when the load current is maximum | D
_{When the} value is slightly larger than the maximum value of _{j 1} |, the expression (33) does not hold during continuous operation. In addition, in the case of normal internal accidents and external accidents that may cause current transformer saturation, (33)
The expression is satisfied once in one cycle, and the processing result of processing 13-1 is Y. When the processing result of the processing 13-1 becomes Y, 1
During the cycle, the count value C ″ is 1 or more and the processing result of the processing 13 becomes Y. Therefore, in a normal internal accident and an external accident in which there is a risk of current transformer saturation, the processing result of the processing 13 continues to be Y. The overall response of this embodiment will now be described. The processing of this embodiment is performed at the first and second sampling times (hereinafter, this sampling time is f1 and f2, respectively) when the accident is detected. Only the processing (referred to as “sample”) is different from that of the first embodiment. Since the count value C is 11 in the processing at the time of sampling, the signal S
_{If 2} is 0, the count value C becomes 12 in the process 10-2, and the processes from the process 10-5 onward are performed. If the signal S ₂ is 1, the count value C is returned to 0 in processing 10-3. At the time of sampling after the time of sampling f2, the processing is performed in the same manner as in the first embodiment, and when the signal S ₂ becomes 0, 1 is successively added to the count value C. That is, in the processing at the time of f1 and f2 sampling at the initial stage of the accident detection, the processing of the processing 10-5 and thereafter is immediately performed if the signal S ₂ is 0 regardless of the previous signal S ₂ . If the signal S ₂ is 1 at the time of f2 sampling, the subsequent processing is the same as in the first embodiment, and the signal S ₂
It takes one cycle for the count value C to reach 12 even if the value becomes 0, and during this period, the processing from the processing 10-5 is not performed and the signal S _{1 is set} to 0. In the case of an external accident, the rise of the differential current I _d lags behind the rise of each terminal current as shown in FIG. During this time the signal _{S 2} is 1, the signal _{S 2} in the process at least f1 and f2 Sample 1
It is. Therefore, the differential relay unit does not malfunction in the processing at the time of sampling f1 and f2, and does not malfunction in the processing after the sampling of f2 as in the first embodiment. In the case of an internal accident, the differential current I _d rises simultaneously with each terminal current. Therefore, the signal S ₂ becomes 0 at least at the time of f2 sampling, and the processings of the processing 10-5 and below are performed, and the processing result of the processing 10-8 becomes Y, and the signal S 2 becomes
₁ becomes 1 and the protection operation is performed. As described above, in this embodiment, only at the time of f1 and f2 sampling at the initial stage of accident detection,
When the signal S ₂ is 0, the count value C is set to 11 to cancel the holding of the state of 1 of the signal S ₂ so that an internal accident can be protected at a high speed without a delay of 1 cycle. is there. The above-mentioned means for adding the accident initial processing of the processing 12 can be applied to the other second and third embodiments, and similarly, the internal accident can be protected at high speed without malfunctioning in the external accident. It can be transformed. Note that the processing 13-1 of the present embodiment detects that the value of the suppression data D _{r in} the expression (6) has become a certain value or more, but instead of this, the suppression data D _{r in the} expression (5) is used. _{Alternatively} , even if the maximum value of the suppression data D _r1 and −D _{r2 in} the equation (7) is detected to be a certain value or more, the accident state can be detected similarly.

[Sixth Embodiment] The sixth embodiment provides a second means capable of protecting an internal accident at a high speed.
This embodiment is different from the first embodiment only in the processing 9, and the details of the processing 9 are shown in FIG. In the process 9 of FIG. 28, the accident detection of the process 13 is first performed. If an accident is detected and the processing result is Y, the count value C'is checked in processing 9-8, and if C '= 1, the processing after processing 9-1 is the same as that of the first embodiment (FIG. 19). Do the same. Process 9-
If the count value C'is not 1 in step 8, the count value C'is incremented by 1 in step 9-9 to obtain a new count value C '.
The signal S _{2 is set} to 0 in processing 9-3. If no accident is detected in process 13 and the process result is N, process 9-1
The count value C ′ is corrected to 0 by 0, and the signal S is processed by processing 9-3.
_{Set 2} to 0. In the process 9 of the present embodiment, the signal S ₂ is 0 when the accident detection is not performed, and the count value C ′.
Is set to 0. At the time of f1 sampling in which an accident is detected, the count value C'is 0, so the count value C'is maintained, and the signal S ₂ remains 0. Since the count value C'is 1 at the time of f2 sampling, the process 9-
The processing after 1 is performed. That is, the processing after the processing 9-1 is performed and the signal S ₂ can be 1 at the time of f2 sampling after the accident detection and at the sampling after that, and when the accident detection is not performed and the signal is sampled at the f1. S ₂ is set to 0. The reaction of this embodiment will be described. The signal S ₂ is always 0, but the differential current I _d is also extremely small. Therefore, the signal S ₁ is 0 because the processing result of the processing 10-8 in FIG. In the event of an external accident,
The differential current I _d is at least f2 even if the current transformer is saturated.
It does not stand up until the time of sampling, and therefore the process 10-
As for the processing result of 8, the state of N is maintained. Further, since the processing result of processing 9-1 is Y when f2 is sampled, the signal S
₂ becomes 1. Therefore, the processing after the sampling of f2 is the same as that in the first embodiment, and the signal S ₁ never becomes 1. At the time of an internal accident, the processing result of the processing 9-1 is N after the time of f2 sampling. Therefore, the signal S ₂ is 0 continuously before the accident, the count value C of the process 10 is 12 continuously at the stage where the process 10-4 is performed, and the process 10-8 is continuously performed during this period. . Processing 1
In 0-8, since the processing result is Y immediately after the occurrence of the internal accident, high speed operation is possible. As described above, in this embodiment, the state in which the accident detection is not performed and the f immediately after the accident detection are performed.
At the time of one sample, the signal S ₂ is prohibited from becoming 1 so that the internal accident can be protected at a high speed without delay of one cycle. Such means can be applied to the second embodiment as well, and similarly, it is possible to protect the internal accident at a high speed without causing malfunction in the external accident. In the above fifth embodiment, f2 sample time and signal S ₂ when subsequent samples was made to hold the state signal S ₂ is 1 when 1. Further, in the sixth embodiment, the signal S ₂ can be 1 at the time of sampling f2 and the time of sampling thereafter. The sample time to perform these controls at the beginning of the accident detection should be changed within a range that does not exceed the non-saturation period (t _{1 in} FIG. 4) of the current transformer at the beginning of the external accident. I will get it.

[Seventh Embodiment] The seventh embodiment provides a third means capable of protecting an internal accident at a high speed.
The processing of this embodiment is shown in FIG. The drawing is the same as FIG. 18 except that the data correction processing of processing 14 is added after processing 7. In this embodiment, the process 14 is added and the process 9 is performed.
Is the same as that of the first embodiment except that it is changed as described below. Details of the process 14 are shown in FIG. First, process 13
If the accident is detected and the processing result is Y,
The process 14 is ended as it is. If no accident detection is performed in process 13 and the process result is N, processes 14-1 and 14
-2, the values of the data D _dm and D _rm are corrected to zero, and the process 1 is performed.
4 is ended. The comparison means of the process 9 performs the same process as in the first embodiment except that the constant K ₂ is used as the negative constant in the equation (21). The absolute value of the constant K ₂ should be small enough,
The value of the suppression function f (r) at the time of an accident can be ignored. In this embodiment, the difference function f (d) and the suppression function f
(R) is calculated using only the data after the accident is detected.
Before the accident is detected, the value of all the data used is zero, and the constant K _{2 in the} equation (21) is negative, so the signal S ₂ is 0. Therefore, in case of an internal accident, immediately take action 10-1.
3 is performed and the signal S _{1 is set} to 1 to protect at high speed. In an external accident, the signal S ₂ becomes 1 at the same time when the accident is detected, and the malfunction of the differential relay unit due to the saturation of the current transformer is prevented. As described above, in this embodiment, the difference function f (d) and the suppression function f (r) are calculated using only the data after the accident is detected, so that the vehicle can be protected at a high speed during an internal accident. . Similar means are applicable to the second and fourth embodiments, as well as to be able to protect internal accidents at high speeds. In the fourth embodiment, the value of the blocking function f (s) in the equation (23) is zero before the accident detection. Therefore, the prevention amount f (t) of the equation (31) is calculated only from the data after the accident is detected, and the internal accident does not become positive from the early stage of the accident, so that it is possible to protect at a high speed.

[Eighth Embodiment] In the eighth embodiment, the process 7, current 13 and process 11 of the fifth embodiment are changed as follows. In the process 7, in addition to the data D _dm and D _rm of the equation (24), the data D _pm and D _nm are calculated by the following equation and stored.

However, (D _jm ) _p and (D _jn ) _p are respectively corrected to the values of only the negative one and the positive one of the data D _jm at the latest sampling of each terminal current data D _j to zero. The data D _pm and D _nm are the sum of the positive and negative terminal current data D _jm at the latest sample, respectively. Details of the process 13 of this embodiment are shown in FIG.
First, in the process 13-5, the value of the data D _dm is checked, and if the following expression is satisfied, the processing result is set to Y, and if not, the processing result is N.
And

| _Ddm | ≧ K ₈ (36) However, K ₈ is a positive constant. If the processing result of the processing 13-5 is Y, the count value C ″ is set to 12 in the processing 13-7, and the processing result of the processing 13 is set to Y. If the processing result of the processing 13-5 is N, the processing is performed. The change amount of 13-6 is detected. If the following expression is satisfied, the processing result is Y, and if not, the processing result is N.

Maximum value of D _pm and −D _nm ≧ K ₉ {(D _{p (m−1)} , D _{p (m−2)} ... Maximum value of D _{p (m−12)} ) and (−D _{n (m−1) ), -D n (m-2} ) ... sum or maximum value ............... (37 maximum value} and _{K 10} of _{-D n (the} maximum value of _{m -12)))} However, _{K 9} is 1 or more , And K ₁₀ is a positive constant.
If the processing result of the processing 13-6 is Y, the count value C ″ is set to 36 in the processing 13-8, and the processing result of the processing 13 is set to Y. If the processing result of the processing 13-6 is N, the processing is performed. Thirteen
-3, the count value C ″ is checked, and if C ″ is 1 or more, 1 is subtracted from the count value C ″ to obtain a new count value C ″ in process 13-4, and the process result of process 13 is set to Y. . If the count value C ″ is less than 1 in process 13-3, that is, 0, the process result of process 13 is set to N without changing the count value C ″. In process 11, the following process is added to the first embodiment.

The difference between the response of this embodiment and the fifth embodiment is that the processing 1
Only the accident detection process of No. 3 will be described below.
In the process 13-5, the differential current data D _dm has the constant value K.
_When it becomes ₈ or more, the count value C ″ becomes 12, and the processing 1
Processing for one cycle 13 regardless of the processing result of 3-6
The processing result of is Y, and an accident detection state is set. Therefore, when the differential current I _d is generated due to an internal accident or an external accident accompanied by saturation of a current transformer, (3
Since the expression (6) is established, the accident detection state continues until the differential current I _d ceases to flow periodically. When the accident current passes through the protected section due to an external accident or an internal accident, the value on the left side of equation (37) becomes larger than the similar value before that,
Expression (37) is established. As a result, the processing result of processing 13-6 becomes Y. The formula (37) is established when the maximum values of the latest data D _pm and -D _pm are compared with the same data for one cycle before that and the magnitude exceeds a predetermined condition. Always holds. However, it will not be established within one cycle after the accident. Therefore, the processing result of processing 13-6 becomes Y immediately after the occurrence of the accident and becomes N within one cycle. However, since the count value C ″ is corrected to 36 in processing 13-8, the processing result of processing 13 is 3
Holds Y between cycles. Since the response is as described above, the processing result of the processing 13 becomes Y in the internal accident until after the accident is recovered until the accident is recovered. In the case of an external accident, the processing result of the processing 13 becomes Y at the same time as the occurrence of the accident, but soon the processing result of the processing 13-6 becomes N. If the differential current I _d that can be satisfied does not flow, the processing result of the processing 13 becomes N. Generally, when severe current transformer saturation occurs due to an external accident, the differential current I _d flows within 3 cycles after the occurrence of the accident. In such a case, the processing result is Y continuously. However, in this embodiment, the processing result of processing 13 is Y and it is necessary to enter the accident detection state in the case of an internal accident and in the case where the current transformer causes severe saturation due to an external accident. Even in the case of the embodiment, there is no problem in application. In the present embodiment, the processing 13-5 can be other means. The first example is to perform the processing of the following equation.

| D _dm | ≧ K ₁₁ The sum (or maximum value) of K ₈ f (b) and K ₈ ... (40) However, f (b) uses the equation (29) and K ₈ is a positive constant. . This is a slight suppression amount K ₁₁ f in the equation (36).
(B) is added, and a response similar to that of the equation (36) is performed unless the constant K ₁₁ is increased. The second example is to perform undervoltage relay processing in processing 13-5. Due to this processing, the hardware configuration is shown in FIG.
An input converter CV _v similar to CV _{1 to} CV _n is added, and this input converter CV _v is connected to a secondary circuit of an instrument transformer whose primary side is connected to the bus B. The output output electric quantity E _v of the input transformer CV _v is applied to the data acquisition unit DAU and converted into voltage data D _v . This data D _v is fetched in process 6 like other data, and is rewritten in process 11 like differential current data D _d . In process 13-5, using this voltage data D _v , the undervoltage relay process shown in the example below is performed, and if the following formula is satisfied, the process result is set to Y.

However, K ₁₂ is a constant. The equation (41) is for detecting that the integrated value of the absolute value of the piezoelectric data D _v during the half cycle becomes equal to or less than the constant value K ₁₂ . It is well known that this equation can detect a voltage drop phenomenon, and therefore a detailed description is omitted for simplicity. Further, as the undervoltage relay process, there are various means other than the formula (41), and these can be used as well. The undervoltage relay process of this example operates normally in a normal internal accident and an external accident in which there is a risk of transformer saturation, and the processing result is Y. Therefore, the process 13-5 can be similarly applied as the undervoltage relay process instead of the formula (36). Since the undervoltage relay process usually detects an accident with a delay of 0.5 to 1 cycle or less,
If Process 13-5 is an undervoltage relay process, Process 1
The count value C ″ of 3-8 is corrected to about 12. Process 1
Similarly, 3-6 can be other means. That is, the process 13-6 is for detecting an increase in the current at the time of an accident without delay, and various modifications can be implemented within this range. That is, the expression (37) uses the maximum value of the data D _p of the positive sum of the terminal current data and the data −D _{n in} which the sign of the sum of the negative ones is changed, and this value is the maximum value in the past 1 cycle. It is to detect an increase with respect to. On the other hand, for example, by detecting the increase of the data D _r of the expression (5) or the expression (6), the increase of the current can be detected without delay, and it is used similarly to the expression (37). be able to. Further, the means for detecting the increase can be variously modified as well as compared with the data for the past one cycle. Further, the process 13-6 can be made to detect not only the increase in the current but also the change. Detection using data such as data of, for example, (5) or (6) data Dr or the maximum value of the data _{D p} and -D _n, of this change, these data 1 / 2,1,
It can be performed by comparing with data such as 3/2 or 2 cycles before. Also, each terminal current data D
It is also possible to detect the change in current by comparing _j with the data before each 1 or 2 cycles or with the data of 1/2 or 3/2 cycles before being changed in sign. . A device that detects a change in current operates not only when the current increases but also when the current decreases due to accident recovery. However, the operation at the time of recovery from an accident is similar to the case where the recovery from the accident detection is slightly delayed, and there is no problem in application. The accident detecting means described above can be used not only in the fifth embodiment but also in other embodiments using the accident detecting means.

[Ninth Embodiment] In each of the above embodiments, the difference function f (d) is the expression (1), the suppression data D _r is the expression (5), and the suppression function f is
Only the equation (11) is used for (r).
Since the other components can be implemented more easily than the above-described embodiment, detailed description thereof will be omitted for simplicity. That is,
In order to use the difference function f (d) as the expression (2) or (4), the function processing of the processing 8 is replaced by the expression (1) instead of the expression (2) or (4).
You only need to use the formula. The suppression data D _r is (6),
(7), (8), (9) or (10),
The calculation of the data of each formula may be performed in the basic data creation process of process 7, and this data may be processed in the data rewrite process of process 11 in the same manner as in the first embodiment. Further, the suppression function f (r) is set to the expression (12) or (13), or the auxiliary function f (r of the expression (17), (18), or (19) is used.
In order to obtain the suppression function f (r) of the equation (15) or (16) using 1) or the like, after calculating the necessary suppression data D _r in the process 7 as described above, the auxiliary function f (r1) For example, the suppression function f (r) may be performed in the function calculation process of process 8.

[Tenth Embodiment] The tenth embodiment differs from the first embodiment only in the function calculating process of process 8 and the comparing means process of process 9. That is, in process 8, the function of the following equation is calculated.

f (d) = | D _dm −D _{d (m−1)} | ……………… (42) f (r) = | D _rm −D _{r (m−1)} | ………… ( 43) Formula (42) is defined by formula (1), where the predetermined number p is 2,
Eqs. (2) and (4) are the same, and Eq. (43) is a predetermined number p
(11), (12) and (1
It is equal to the expression 3). Details of the process 9 are shown in FIG.
First, the process 9-1 is performed by the equation (21) or (22) as in the first embodiment. If this processing result is Y,
The count value C'is checked in processing 9-13. If the count value C'is ₂ , the signal S _{2 is set} to 1 in the process 9-2. If the count value C'is not 2, in process 9-14, 1 is added to the count value C'to obtain a new count value C ', and process 9
The signal S _{2 is set} to 0 at -3. The processing result of processing 9-1 is N
In this case, the count value C'is corrected to 0 in processing 9-15, and the signal S _{2 is set} to 0 in processing 9-3. The above processing is performed when the processing result of the processing 9-1 is Y continuously.
The signal S _{2 is set} to 1 while the Y state continues from the second time, and the signal S _{2 is set} to 0 in other cases. In the case of the present embodiment, even if the current transformer is saturated due to an external accident, the difference between the maximum value and the minimum value of the three values of the differential current data D _d is the fourth value.
As shown by the difference function f (d) in the figure, it becomes almost zero, so that the value of the difference function f (d) in the expression (42) becomes almost zero at least twice. Thereby, the processing 9-1
The processing result of becomes 1 at least twice consecutively, and the signal S
₂ becomes 1. Further, in the case of an internal accident, the difference function f of the equation (42) is applied to the sample near the peak of the differential current waveform.
The value of (d) may be zero. However, this phenomenon is 2
In the next sample (42)
The value of the difference function f (d) in the equation becomes sufficiently large. Therefore, the processing result of processing 9-1 does not become Y twice in a row,
The signal S ₂ never becomes 1. As described above, the present embodiment does not produce a blocking output in an internal accident, and certainly produces a blocking output in an external accident, and is applicable similarly to the other embodiments. As in this example,
When the formula (21) or (22) is satisfied a plurality of times in succession, the means for outputting the blocking output can be appropriately applied even when the predetermined number p is 3 or more. Further, when the blocking function f (s) of the equation (23) is derived with the predetermined number p set to 2,
From the values of the functions of equations (42) and (43), the blocking function f
Although (s) is obtained by the equation (23), the value of the blocking function f (s) actually used in the differential relay unit of the process 10 is, for example, the minimum value of the equation (23) at the time of two consecutive samples. The value. This is at least once per cycle in the event of an external accident
The value of the difference function f (d) decreases remarkably continuously,
Therefore, while the value of the blocking function f (d) continuously increases, the value of the blocking function f (s) becomes small while the difference function f (d) is small but not continuous at the peak of the waveform during an internal accident. This is because there is something that happens. Obtaining the value of the blocking function f (s) from the plurality of values in the equation (23) in this way can be appropriately applied even when the predetermined number p is 3 or more.

[Eleventh Embodiment] In the above embodiment, a predetermined number p of data used for calculation of the difference function f (d) and the suppression function f (r) are continuously sampled at the sampling interval θ _s. It is to be individual data. However, this is processed using the difference function f (d) and the suppression function f (r) obtained from the combination of arbitrary p data in more than p data sampled continuously, and either If the combination outputs a blocking output, it can be used as the blocking output of the process 9. To simplify this means, for example p
Assuming that = 3 and each of the functions is calculated by using any three pieces of data among the four pieces of data, the following means can be considered. That is, first, three pieces of data are selected from the four pieces of data to obtain the value of the difference function f (d), and further three pieces of data are combined to obtain the value of the successive difference function f (d). The minimum value of the values of these difference functions f (d) is calculated, the suppression function f (r) is calculated using the three pieces of data that have given these minimum values, and then the processing is performed using the values of these functions. 9 is performed. In addition, the maximum value of the four differential current data D _d is excluded 3
The difference function f (d) and the suppression function f (r) are respectively obtained from two combinations of the three pieces of data and the three pieces of data excluding the minimum value, and the presence or absence of the inhibition output is checked for both, and the inhibition output is obtained in any one of them. If is obtained, there is also a method of using it as the blocking output of the process 9. In this case, the change in the differential current data D _d is small for at least three consecutive data at the time of an external accident, and a blocking output is obtained, and at the time of an internal accident, it is small for two data but large for the other one data. So 3 consecutive
A blocking output similar to the case where the number of samples is used is obtained.

[Twelfth Embodiment] In the twelfth embodiment, the hardware configuration and the processes 6 and 11 are different from those of the above-described respective embodiments. FIG. 33 shows the hardware configuration of this embodiment. In the figure, the same parts as those in FIG. 17 are indicated by the same symbols. Also CB, C
Those having the same main character such as T but different subscripts such as 4, 5, 6 indicate that they are similar devices. PT is an instrument transformer, and DF is a differential circuit. The difference between this embodiment and the above-described embodiments is as follows.

(I) A differential circuit DF is formed, and the differential current I _d is converted into an electric quantity E _d by the input converter CV _d to obtain the data acquisition unit DAU.
Add to

(Ii) The voltage of the bus bar B is applied to the input converter CV _v via the instrument transformer PT to be converted into the electric quantity E _v , which is applied to the data acquisition unit DAU.

(Iii) The secondary circuits of the current transformers CT ₅ and CT ₆ and CT ₇ and CT ₈ are respectively connected in parallel, and the sum of the secondary currents is applied to the input converters CV ₅ and CV ₆ , respectively, so that electrical Quantity E
₅ and E ₆ and added to the data acquirer DAU.

Due to the above differences, the differential current data D _d is directly obtained from the electric quantity E _d . Therefore, unlike the above-described embodiments, the calculation of the differential current data D _d is omitted in the process 6. Further, the data D _v from the electric quantity E _v is _fetched in the process 6 and rewritten in the process 11. This data is the 8th
This is used when the undervoltage relay process such as the equation (41) is performed in the accident detection process 13 as described in the embodiment of FIG.
The difference in the processing from the first embodiment is as described above. In this embodiment, the data D _{1 to} D ₆ obtained by converting the electric quantities E _{1 to} E ₆ into digital data are acquired and used as the terminal current data D _j . The data D ₅ and D ₆ are data of the sum of the currents of the two terminals, respectively, but in the case of acquiring the data of the sum of the currents of some of the terminals in this way, they are also called the respective terminal current data in the present invention. In the data of the sum of the currents of some terminal acquires as the terminal current data D _j, in principle limited only in the case of non-power terminal (or terminal equivalent thereto) as the data D ₅ and D ₆ To be In the case of a non-power supply terminal, the current at the time of an accident other than the case where an accident occurs outside the terminal and the accident current flows out can be ignored with respect to the currents of other terminals. Therefore, except when the fault current flows, the contribution to the suppression function f (r) is almost the same whether the individual data of the terminal current or the summed data is used. When the fault current flows out, the waveform of the sum current is almost the same as the waveform of the individual current. Therefore, the value of the suppression function f (r) obtained using the data of the sum current is the individual current. It is almost the same as the value of the suppression function f (r) obtained by using the data of. From such a relationship, even if the data of the sum of the currents of some terminal in accordance with the circumstances of the guard interval acquired as respective terminal current data D _j, when acquiring the respective terminal current data D _j individually to Almost the same suppression function f (r)
Is obtained and is similarly applicable.
Further, the differential current data D _d is directly obtained from the differential current I _d as in this embodiment only by changing the obtaining means of the differential current data D _d . As described above, even if the hardware configuration of each embodiment is as shown in FIG. 33, it can be applied in exactly the same manner as the hardware configuration of FIG.

[Thirteenth Embodiment] In all of the above embodiments, the output electric quantity (E ₁ ) of the input converter (CV ₁ or the like) is almost faithfully transmitted without removing the DC component of the input current.
This can be obtained as the output electricity quantity of only the AC component with the DC component removed. Even if the direct current component is removed, there is almost no change in the differential current data D _d during the converter non-saturation period during an external accident, and a sufficient blocking output can be generated during this period.
Moreover, in the internal accident including the DC component, the change of each data is slightly different from the case where the DC component is not removed. But,
This influence is the differential current data D _d and each terminal current data D
Since it appears substantially in _j , it can be applied in substantially the same manner as the above-mentioned embodiments.

[Others] The method of the accident initial processing described in the fifth to eighth embodiments of the present invention is not limited to the present invention, and a blocking output is always generated by the load current, and this blocking output continues for a while even after an internal accident occurs. It can be applied to all differential relays.
An example of such a differential relay device is the above-mentioned Japanese Patent Publication No.
7-50130 and the like. In addition, the various suppression functions f (r) described in the present invention are not limited to the present invention and can be applied to other differential relays. In that example, the differential current data D _d is operated when it has a waveform that spans both positive and negative waves, and the suppression function f (r) is involved in the determination of the level for detecting whether the data D _d is positive or negative. Let It is also possible to detect and block a period in which the value of the differential current data D _d is significantly smaller than the suppression function f (r).

[Effects of the Invention] As described above, the present invention is not likely to malfunction even if saturation of a current transformer occurs due to an external accident, and operates reliably in an internal accident. Even if the above occurs, there is no fear of causing a delay in operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention, FIG. 2 is a diagram showing current waveforms when a current transformer is saturated, and FIG. 3 is a diagram showing current waveforms when an internal accident follows an external accident, Fig. 4 shows the current waveform when the current transformer is saturated due to an external accident and the response diagram of this device. Figs. 5 to 9 show the response diagrams when the difference function, the suppression function and other conditions are changed. FIG. 10 is a diagram showing the response of the present invention when the current transformer is not saturated due to an internal accident, and FIG. 11 is a diagram of the present invention when the fault current flows through only one terminal and the current transformer is saturated due to the internal accident. FIG. 12 to FIG. 1 showing the response
FIG. 6 is a diagram showing the reaction of the present invention when the current transformers of some terminals into which the fault current flows due to an internal accident are saturated and the current transformers of other terminals are not saturated, and FIG. 17 is a diagram of the present invention. FIG. 18 shows a hardware configuration of the first embodiment, FIG. 18 shows a processing flow of the first embodiment of the present invention, and FIG. 19 shows details of processing 9 of the first embodiment of the present invention. Flow chart, FIG. 20 is a flow chart showing the details of the process 10 of the first embodiment of the present invention, FIG.
FIG. 22 is a flow chart showing details of the process 10 of the second embodiment of the present invention, FIG. 22 is a flow chart showing details of the process 10 of the third embodiment of the present invention, and FIG. FIG. 24 is a flow chart showing details of processing 9 of the fourth embodiment, and FIG.
25 is a flowchart showing the details of the process 10 of the embodiment of the present invention, FIG. 25 is a flowchart showing the process of the fifth embodiment of the present invention, and FIG. 26 is the details of the process 12 of the fifth embodiment of the present invention. 27 is a flow chart showing the details of process 13 of the fifth embodiment of the present invention, and FIG. 28 is a flow diagram showing the details of process 9 of the sixth embodiment of the present invention. FIG. 7 is a flow chart showing the processing of the seventh embodiment of the present invention, and FIG. 30 is the seventh embodiment of the present invention.
FIG. 31 is a flow chart showing details of the process 14 of the embodiment of the present invention, FIG. 31 is a flow chart showing details of the process 13 of the eighth embodiment of the present invention, and FIG. 32 is the process 9 of the tenth embodiment of the present invention. FIG. 33 is a flow chart showing the details of the above, and FIG. 33 is a view showing the hardware configuration of the twelfth embodiment of the present invention. B ... bus CB ₁ to CB n _... breaker CT ₁ ~
CT _n ... Current transformer PT ... Instrument transformer CV _{1 to} CV _n , CV _v and C
V _d ... Input converter DAU ... Data acquisition device CPU ... Processing device O
U: Output device

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[Procedure amendment]

[Submission date] March 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Deleted

Claims (1)

[Claims] Each terminal current I _j (j = 1 to n) is sampled at a predetermined time interval, each terminal current data D _j obtained by converting this into digital data is acquired, and each terminal current data D _j is added. , Differential current data D _d , or differential current I _d at each of the terminals is sampled at predetermined time intervals and converted to digital data to create differential current data D _d. An operation amount for calculating a sum of absolute values of differences between two data values adjacent to each other at a sample time of the data generating means and a plurality of predetermined numbers of the differential current data D _{d having} different sample times, and set as an operation amount. Calculation means, a suppression amount calculation means for calculating a suppression amount value from the maximum value of the differential current data D _d sampled in a predetermined period of one cycle or more, and when the operation amount value is smaller than the suppression amount value A comparison means that produces a blocking output, Differential relay device comprising more becomes possible with differential relay means is suppressed to prevent the operation by blocking the output of the comparison means.