JP2001061226A - Digital protection relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable predictions and high-speed decision. SOLUTION: An A/D converter 2 converts an analog amount, sampled at an interval of a constant time into digital amount, to set it as input data rows. A sum-of-products voltage computing part 3 computes the output data rows An, m with a computing formula shown in the Fig., using input data rows Vm and data rows Vm-1 among the input data rows Vm. A coefficient in and a coefficient μn of the computing equation shown in the Fig. are determined, so as to have a constant gain in each output data row An, m and a phase difference, when the input data rows Vm are the data corresponding to the normal sine wave. A shorted voltage discriminating part 4 outputs an operation decision as a shorted voltage, if the output data rows An, m are inputted and a maximum value among the absolute values of its data becomes a set value Vset or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital protection relay used for protection of a power system and the like, and is mainly applied to an undervoltage relay, an overcurrent relay, a current differential relay, a current compensation undervoltage relay, and the like. The present invention relates to a digital protection relay.

[0002]

FIG. 19 shows an example of a conventional digital protection relay.

[0003] In FIG. 19, an A / D converter 2 converts a system voltage value into digital data by inputting a system voltage value at fixed time intervals. The converted digital data is arranged in order and stored in a data table. For example, when sampling is performed at intervals of 30 electrical degrees, the sine wave voltage waveform F1 is represented as 12 data in one cycle as shown in FIG. 20, and this is generally called an input data sequence.

The amplitude calculating section 21 calculates according to an algorithm for calculating the amplitude of a sine AC voltage, and generally has two types, an addition type and a product type, as shown in FIG.

[0005] First, in the addition type, a sine wave is subjected to phase-increasing rectification, converted into direct current, and its amplitude is obtained. This includes an area method according to the equation (6-1) and a binary addition method according to the equation (6-2).

The product form calculates the sum of products of the instantaneous sine wave values and calculates the amplitude. The amplitude square method shown in the equation (6-3) is a typical example. This is an electrical angle of 9
This is to calculate the sum of squares of the two data separated by 0 °. Further, as shown in FIG. 22, a continuous two-sample operation method by the equation (6-4) or a (6-5)
There is a continuous three-sample operation method using an equation.

The operation determining section 22 compares the amplitude value obtained by the amplitude calculating section 21 with a predetermined set value, and outputs an operation determination output to the outside.

FIG. 23 is a diagram showing an operation range in the case of an undervoltage relay. In FIG. 23, when the voltage of the amplitude value falls within the illustrated operating range, an operation determination is output.

FIG. 24 shows the operating range of the undervoltage relay with current compensation corresponding to FIG.

In general, in a current system in which the power supply behind the installation point of the relay greatly changes, it is impossible to detect all the faults in the protection section by using the undervoltage relay or the overcurrent relay alone. If the power source behind is very small and almost no current flows at the time of failure, the overcurrent relay does not operate. In such a case, the failure detection or the failure phase can be detected by the undervoltage relay.However, if the undervoltage relay has a large power supply behind it and the voltage drop at the installation point of the failure relay is small, the failure will not occur. It cannot be detected. Under such system configuration conditions, an undervoltage relay with current compensation is generally applied as a fault detection relay.

In the operating range shown in FIG.
When the relationship of the expression 6) holds, and the voltage of the amplitude value falls within the frame of the so-called motion field shape, the operation is determined.

V _RY -IZ ≦ V _SET (6-6) V _RY : voltage I: current Z: predetermined impedance V _SET : set value

[0013]

However, the above-mentioned conventional digital type protective relay has a problem in terms of high-speed performance and a tendency to respond.

For example, the amplitude square method shown in the equation (6-3) in FIG. 21 calculates the square value of the amplitude of the input amount from the square of the input amount or addition / subtraction of the product. The term of the product of the wave and the distortion component appears, and the effect of the distortion of the original waveform is greatly expanded.The effect of the product term differs depending on the magnitude and phase of the distortion. It was necessary to study each time, the prospect of the response tendency was poor, and there was a problem in applying a relay.

To avoid this, for example, a rectified average value according to the equations (6-1) and (6-2) in FIG. 21 is used. In this case, since there is no product term in each data, the above problem is solved. However, this method requires a so-called data window that requires data of a half cycle of the fundamental wave. That is, since a wide data window is required, it is difficult to quickly detect a system abnormality.

As described above, the conventional technology cannot overcome the contradictory conditions of increasing the speed and increasing the influence of distortion.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a digital protection relay which is less affected by distortion, has excellent visibility of response tendency, and can operate at high speed. And

[0018]

According to a first aspect of the present invention, there is provided an apparatus for generating an input data sequence as a digital data sequence from sampling data of an input electric quantity, comprising: a first coefficient data corresponding to a second coefficient data; A first coefficient data and a second coefficient data obtained by multiplying the first coefficient data by the latest input data sequence for each of the plurality of coefficient sets; And second operation data obtained by multiplying the latest input data sequence by a past input data sequence to the first input data to generate operation data obtained by adding the second operation data to the first operation data. A digital type comprising: means for generating and outputting a corresponding plurality of output data strings; and means for outputting an operation determination based on the data size of the plurality of output data strings generated and output from the means. In the protection relay, the first coefficient data and the second coefficient data of the plurality of coefficient sets are formed by the plurality of output data strings when the input data string is waveform data corresponding to a steady sine wave. Each waveform has a predetermined peak value that is substantially equal, and the waveforms are determined so as to have a predetermined phase angle difference from each other. According to this means, the first operation data and the second coefficient data obtained by multiplying the latest input data sequence and the first coefficient data for each of a plurality of coefficient sets, and the input data sequence past the latest input data sequence Are added to the second operation data obtained by multiplying the data to generate an output data sequence for each of a plurality of coefficient sets. When the monitoring target is normal and the input electric quantity of the stationary sine wave is input, the waveforms of the output data strings have substantially equal peak values, and the output data strings have a predetermined phase difference from each other. Is output. On the other hand, when the monitored object becomes abnormal and the input electric quantity of the stationary sine wave changes suddenly, the peak value of each subsequent output data string changes suddenly and an operation determination is output. As described above, first, since the operation is determined based on only two pieces of data detected in a short time, the latest input data string and the past input data string, high-speed determination can be performed. Therefore,
Since the data of the half cycle of the fundamental wave is used as in the related art, the operation cannot be determined unless the time is half the cycle, and the operation determination is delayed. However, this can be solved by the present invention. Secondly, conventionally, the influence of the distortion of the waveform to be monitored is increased due to the use of the amplitude square algorithm or the like, which causes a malfunction. Squaring of the amplitude waveform, no influence of waveform distortion and less malfunction. Third, the conventional
Since the tendency of the distortion to malfunction due to the magnitude and phase of the distortion of the input waveform is different, it is impossible to predict how to deal with the distortion, and there is a surface lacking reliability. Since the amplitude square method is not used, it is not affected by the magnitude or phase of the distortion of the input wave. That is, according to the first aspect of the present invention, the peak value of each output data sequence is sequentially output with a phase difference.
When the input waveform to be monitored suddenly changes, a sudden change in the output data sequence corresponding to the suddenly changing input waveform can appear in the next output data sequence, and the abnormality can be immediately detected and the operation can be determined.

According to a second aspect of the present invention, in the digital protection relay according to the first aspect, the means for creating an input data string creates an input data string obtained by digitally filtering sampling data.
According to this means, in addition to the function of claim 1, the data obtained by digitally filtering the input amount is used as the input data sequence. Claim 1 after removing
The invention can be applied in the same manner as in the invention of (1).

According to a third aspect of the present invention, there is provided means for generating an input data sequence as a digital data sequence from sampling data of an input electric quantity, wherein a plurality of first coefficient data and corresponding second coefficient data are defined as one coefficient set. A first set of data, a second set of coefficient data obtained by multiplying the first coefficient data and the latest input data sequence for each of the plurality of coefficient sets, and a past input from the latest input data sequence. Means for generating the operation data obtained by associating the second operation data obtained by multiplying the data sequence with the first operation data and outputting a plurality of output data sequences corresponding to each of a plurality of coefficient sets; Means for outputting an operation determination based on the data size of a plurality of output data strings output from this means, wherein the first coefficient data of the plurality of coefficient sets and When the input data sequence is waveform data corresponding to a specific waveform, the second coefficient data has a predetermined peak value in which each waveform formed by the plurality of output data sequences is substantially equal, and each waveform has They have a predetermined phase angle difference from each other. According to this means, when the input amount is not a stationary sine wave but a specific input waveform, it can be applied in the same manner as the first aspect of the invention by changing the coefficient set.

According to a fourth aspect of the present invention, there is provided the first to third aspects.
In the digital protection relay described above, the means for outputting the operation judgment is to judge the operation based on the relationship between the maximum value of the absolute value of each data of the plurality of output data strings and a predetermined set value, or The operation is determined based on the relationship between any one of the absolute values of the output data sequence and the predetermined set value, or the operation determination is performed based on the relationship between all the data in the plurality of output data sequences and the predetermined set value. It was made. According to this means, it is possible to use an optimal operation determination method according to the situation of the monitoring target.

According to a fifth aspect of the present invention, there is provided a means for creating a main input data sequence as a main digital data sequence from sampling data of a main input electric quantity, and a first coefficient set corresponding to the first coefficient data and the second coefficient data. And a first main operation data obtained by multiplying the first coefficient data by the latest main input data sequence for each of the plurality of coefficient sets, the second coefficient data, and the latest The second main operation data obtained by multiplying the previous main input data sequence from the main input data sequence and the second main operation data correspond to the first main operation data to generate main operation data obtained by adding Means for outputting a plurality of main output data strings corresponding to each set; means for forming a slave data string as a slave digital string from sampling data of the slave input electric quantity; and the slave data created by the means. Means for digitally filtering a plurality of coefficient sets, and a plurality of coefficient sets each including the first coefficient data and the corresponding second coefficient data as one coefficient set. The first
First compensation calculation data obtained by multiplying the coefficient data by the latest compensation input data sequence, a second compensation data obtained by multiplying the second coefficient data by a compensation input data sequence that is earlier than the latest compensation input data sequence. Means for generating compensation operation data obtained by adding the two compensation operation data to the first compensation operation data and generating and outputting a plurality of compensation output data strings corresponding to the plurality of coefficient sets; Means for producing a first determination data sequence obtained by subtracting a positive rectification value of the compensation data sequence from an output data sequence, and a second determination data sequence obtained by subtracting the main data sequence from a negative rectification value of the compensation data sequence. A determination data generation unit having a determination data sequence generation unit; and an operation determination is performed based on the first determination data sequence and the second determination data sequence generated by the determination data generation unit. Means, wherein each of the first coefficient data and the second coefficient data of the plurality of coefficient sets includes waveform data of the main input data sequence and the sub data sequence corresponding to a stationary sine wave. In this case, each of the waveforms formed by the plurality of main output data strings and the plurality of compensation output data strings has a substantially equal predetermined peak value, and the respective waveforms have a predetermined phase angle difference from each other. It is intended to have. According to this means, the same algorithm as in the first aspect of the present invention is applied to the case where the voltage which is the main input amount is compensated by the current which is the auxiliary input amount, and the compensation input corresponding to the compensation vector from the auxiliary input amount. A data sequence is generated, an output data sequence and a compensation data sequence are generated for each of the main input data sequence and the compensation input data sequence, and the corresponding output data sequence is generated from the output data sequence. The determination is made based on the maximum value of the data sequence obtained by subtracting the output data sequence corresponding to the data sequence obtained by subtracting the positive rectified value of the compensation data sequence and the negative rectified value of the plurality of compensation data sequences. This makes it possible to provide a relay that has a good response tendency and that can operate at high speed even when applied to a monitoring target in which the power supply behind changes greatly.

According to a sixth aspect of the present invention, in the digital protection relay according to the fifth aspect, a value of a compensation data string obtained by using one coefficient set among a plurality of coefficient sets is all zero. A plurality of coefficient sets are determined. According to this means, one set of coefficients is added to the invention of claim 5, and the value of the compensation data sequence corresponding to the set of coefficients is set to a value that is always zero. As a result, an infinite set, that is, a characteristic close to a continuous characteristic can be obtained with a small number of coefficient sets, and the calculation load can be reduced while maintaining high speed and linearity.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of an undervoltage relay according to a first embodiment of the present invention.

The undervoltage relay 100A includes an A / D converter 2, a product-sum voltage calculation unit 3, and an undervoltage determination unit 4. Note that illustration and description of commonly used means such as an insulating transformer, an input filter, and a memory for storing data after A / D conversion are provided in front of the A / D converter 2 are omitted.

Here, the A / D converter 2 converts the analog amount sampled at fixed time intervals into a digital amount, and sequentially converts the digital amount converted at the sampling time into a data memory similar to that described with reference to FIG. And an input data sequence. For example, when sampling is performed at an electrical angle of 30 ° of a sine AC voltage, an input data sequence is represented as 12 data in one cycle, and is sequentially generated and output at each sampling time.

The product-sum voltage calculating unit 3 among the input data sequence v _m for each sampling point, with the input data sequence v _m and the input data sequence v _m-1, output by the arithmetic expression shown in FIG. 1 The data sequence A _{n, m} is calculated, and the coefficient λ _n
The coefficient mu _n, when the data input data sequence v _m corresponds to the steady sinusoidal, with a constant gain in the output data array A _{n, m} (constant peak value), and different phases (A predetermined phase difference from each other).

The undervoltage judging section 4 receives the output data string _{An, m} which is sequentially output and makes the maximum value of the absolute values of the data of the output data string _{An, m} equal to or less than the set value _Vset. For example, an operation determination is output as an undervoltage.

[0030] In the above configuration, by means not shown, is introduced AC voltage v, the analog AC voltage is sampled at regular time intervals by the A / D converter 2 is converted into a digital quantity v _m. Here, referred to digital quantity v _m and the input data sequence, subscript m or m-1, etc. represents the number of sample point of time in accordance with conventional. That, v _m in the case of marked input data sequence v _m is representative generally _{v m-1, v m-} 2, the sample values ... etc.

Next, the input data sequence v _{m is} sent to the product-sum voltage calculation unit 3.
Is input, and the following (1-1) is output by the product-sum voltage calculation unit 3.
The following operation is performed by the expression to calculate N output data strings _{An, m} .

A _{n, m} = λ _n v _m + μ _n v _{m -1} (1-1) n = 1 to N

Here, for example, if n = 3, the following (1)
-2) It is determined by the equations (1-4).

When n = 1, A _1m = λ ₁ V _m + μ ₁ V _{m -1} (1-2) When n = 2, A _2m = λ ₂ V _m + μ ₂ V _{m -1.} ... (1-3) When n = 3 A _3m = λ ₃ V _m + μ ₃ V _{m -1} (1-4) Thereby, three output data strings A _1m , A _2m and A _3m are created.

The coefficient lambda _n and coefficient mu _n described above, when the input data sequence v _m is stationary sinusoidal fundamental wave, the output data sequence A _{n, m} is constant regardless of the gain to n, for example, This is N sets of coefficient sets that are 1 and have different phases. Note that such a coefficient λ _n and a coefficient μ _n are calculated by the following equation (1-
It is obtained in advance by the expressions 5) and (1-6).

[0036] _{λ n = cosα n -μ n cosψ} ····· (1-5) μ n = -sinα n / sinψ ····· (1-6) but α _n is A _{n, m} of v phase angle relative to _m , ψ is the angle that represents the sampling interval with reference to the fundamental wave

Here, the above equation (1-5) and (1-6)
The establishment of the equation will be described.

For example, the input data sequence _Vm and the input data sequence V
_m-1 is in the relationship shown in FIGS. 2 and 3, and these are represented by the following equations (1-7) and (1-8). In this case, conditions are considered to obtain v in the equation (1-9) in which the gain is the same and the phase is advanced by α. Note that, for simplicity of description, the expression (1-1) is represented by A in the following expression (1-10).

V _m = sin ωt (1-7) v _m-1 = sin (ωt−ψ) (1-8) v = sin (ωt + α) = sin ωt cosα + cos ωt sinα (1-9) A = λv _m + μv _m-1 (1-10)

First, when the equations (1-7) and (1-8) are substituted into the equation (1-10), A becomes the following equation (1-10).

A = λsin ωt + μsin (ωt−ψ) = λsin ωt + μsin ωt cosψ−μsin ωt cosψ = (λ + μcosψ) sin ωt−μsin ωt cosψ (1-11)

A of the equation (1-11) and v of the equation (1-9)
Must be equal, the following equations (1-12) and (1-13) are obtained by comparing the coefficients of both equations.

Λ + μcosψ = cosα (1-12) −μcosψ = sinα (1-13)

From the above equations (1-12) and (1-13), the following (1) corresponding to the above equations (1-5) and (1-6) is obtained.
−14) and (1-15) are obtained.

Λ = cosα−μcosψ (1-14) μ = −sinα / sinψ (1-15)

For example, when the phase angle v = 30 ° between v _m and v _m−1 , and the coefficients obtained by the above equations (1-14) and (1-15) are obtained, when α = 0 °, λ _{1 = cos0-μ 1 cos30 μ 1} = -sin0 / sin30 ····· (1-16) α = 15 for _{°, λ 2 = cos15-μ} 2 cos30 μ 2 = -sin15 / sin30 ····· (1-17) When α = 30 °, λ ₃ = cos30-μ ₃ cos30 μ ₃ = −sin30 / sin30 (1-18). From (1-16) to (1-18) Output data string A
₁ m, A ₂ m, and A ₃ m are obtained, and a data file F1 as shown in the table of FIG. 3 is created. As a result, as shown in FIG.
Gain relative angle alpha _n 1 different for output data array A
Waveforms a, b, and c in which _{n and m} are plotted can be generated.

Next, the output data string _{An, m} is inputted to the undervoltage judging section 4, where the judgment is made according to the equation (1-19), and the maximum of the absolute values of the N output data strings _{An, m} is obtained. If the value is equal to or less than the set value _Vset, it is determined that an undervoltage is present, and an operation determination is output.

Max | A _{n, m} | ≦ V _set (1-19) n = 1 to N

Next, FIG. 5 is a diagram showing the operation of the undervoltage relay 100A according to the first embodiment of the present invention.
Is the input AC voltage v, (B) is the output data sequence _{An, m} , (C)
Indicates a determination amount Max | A _{n, m} |, and (D) indicates an output.

Here, before the time t = t0, it indicates that the input AC voltage v is a stationary sine wave, and the corresponding output data sequence _{An, m} is the output data sequence having six data. The columns are plotted so that they overlap at each time. In a steady state before time t = 0, the amplitude is 1, and
The phases are shifted (15 °) from each other. Note that, here, a case where N = 6 is shown as an example in the above-described equation (1-1), but the value of N is not limited to 6.

That is, the absolute values of the six data in the output data string at each time are sequentially output so as to have the maximum amplitude value (peak value). Then, the determination amount Max | A of (C)
_{n, m} | is a plot of the maximum value of the absolute value of the output data sequence _{An, m} , and the value is about 1 at time t <t0.
The output corresponding to this is "0".

Next, at time t = t0, the input AC voltage v of (A) decreases rapidly from a maximum amplitude value of 1 to 0.6, the input data sequence v output data array in response to rapid change in _m A _n, Any data of _m is reduced sharply.

In FIG. 5, when the amplitude of n = 5 reaches a peak value at time t1, and further at time t2, the output data sequence A _{n, m}
Is less than or equal to the set value Vset of about 0.8 or less. As a result, the output of (D) becomes "1", and the operation determination is output.

Here, about 1 or about 0.6 means that the peak value of each of the plurality of output data strings _{An, m} is 1 or 0.6, and the maximum value is replaced with an adjacent output data string for a short period of time.
It means that it is slightly smaller than the peak value, that is, there is some ripple. This ripple decreases as the number N of sets of output data strings increases, and a value of N according to the ripple that is practically allowable is used.

The time between time t0 and time t2 is a short time of about two samples. The reason is that the data used as the data window shown in the equation (1-1) is two samples. In addition, for the sake of simplicity, this figure omits the functions of an A / D converter and a pre-analog filter which are usually used. Actually, there is a delay as compared with this explanation. The analog filter does not essentially affect the present invention as long as the analog filter does not impair the matters specifying the present invention.

FIG. 6 is a block diagram showing another embodiment of the undervoltage relay according to the first embodiment of the present invention.

In FIG. 6, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and the main differences from FIG. 1 and FIG.
The configuration of the under-voltage determining section 4 is different from that of the under-voltage determining section 4A.
It was that. Specifically, the undervoltage determination section 4A
Makes a determination according to the following equation (1-20), and if the absolute value of each output data sequence _{An, m} is equal to or less than the set value _Vset, it is determined that there is an undervoltage, and the operation is determined.

∩ {| A _{n, m} | ≦ V _set } = 1 (1-20) n = 1 to N

As described above, according to the first embodiment of the present invention, since the so-called data window has two samples, high-speed operation is achieved. Further, since each of the plurality of output data strings _{An, m} constituting the determination amount is based on the linear operation of the input data string, as is apparent from the equation (1-1), the influence of distortion is The gain and phase of the component can be generally evaluated independently of the other components, and it is not necessary to examine individual conditions one by one.
Further, the influence of interference with other components does not increase abnormally.

FIG. 7 is a configuration diagram of an overcurrent relay according to a second embodiment of the present invention.

The overcurrent relay 100B includes an A / D converter 2
And a digital filter 7 and a product-sum current calculator 3B.

[0062] Here, A / D converter 2 is for converting an analog quantity into a digital quantity i _m by sampling at regular time intervals. Digital filter 7, and generates an input data sequence j _m performs filtering processing.
The product-sum current calculation unit 3B performs a calculation according to a calculation formula shown to generate and output an output data string.

[0063] In the above configuration, the alternating current i is introduced into the A / D converter 2, an analog quantity sampled at regular time intervals by the A / D converter 2 is converted into a digital amount i _m.

Next, the digital filter 7, the input data sequence j _m by the digital weight i _m is the following equation (2-1)
It is said.

[0065] _{j m = i m -i m-} 1 ····· (2-1) The input data sequence j _m is equivalent to the input data sequence in the first embodiment.

Next, the input data string j _m is calculated by
B, the output data sequence B _{n, m} by the following equation (2-2)
It is said.

B _{n, m} = λ _n j _m + μ _n j _m−1 (2-2) n = 1 to N

Specifically, the following equation (2-3) and (2-
4) Two output data strings are generated by the equation.

B _1m = λ ₁ j _m + μ ₁ j _{m -1} (2-3) B _2m = λ ₂ j _m + μ ₂ j _m-1 (2-4)

Here, the coefficients λ _n and μ _n are the same coefficients as in the first embodiment. Note that N = 2 is an example for simplifying the description, and is not necessarily limited to 2.

Next, two output data strings B _{n, m} are output to the overcurrent judging section 9 and the maximum value of the absolute value Max | B _{n, m} | An overcurrent is determined.

Max | B _{n, m} | ≧ I _set (2-5) n = 1 to NN = 2

Here, I _set is a set value, and is a coefficient determined in consideration of a required operation value, a gain determined from the equation (1-19) and the coefficients λ _n and μ _n .

FIG. 8 shows the operation of the second embodiment. The upper stage (A) shows the alternating current i, and the input current i shown in FIG.
It consists of the fundamental wave represented by the equation (2-6) and dc.

When t <0, i = 0, and when t ≧ 0, i = 1.5I _set {sin (ωt + β) −sinβ} (2-6)

In the above equation (2-6), ω is the fundamental wave angular frequency,
β is a desired phase and is π / 2 as an example. The amplitude is, for example, 1.5 times the set value _Iset . Although the term −sin β meaning dc originally has a decay time constant, since the vicinity of t = 0 is to be considered, approximately no decay is assumed.

[0077] (B) in FIG. 8, samples the input current i, a data string i _m converted A / D (2-1) digital filtering data sequence by formula, that is, the input data sequence j _m, the basic Since the wave gain is about 1/2, it is simply shown as doubled in the figure. Note that the data sequence i _m is the waveform
It is omitted because it can be inferred from i.

In FIG. 8, when the determination value Max | B _{n, m} | reaches the set value I _set at t = t ₁ , the overcurrent determination unit 9 outputs. The determination amount Max | B _{n, m} | further increases and t = t ₂ to
the 1.5I _set more than in the period of t _3. This is due to a transient phenomenon of the digital filter 7, which is a so-called overshoot.
That is, it means that the sensitivity is more than necessary. this is,
For example, it can be prevented by means such as inserting a time delay. Alternatively, it is also possible to easily take a means such as changing the delay time depending on the magnitude of the determination amount.

The example of FIG. 8 shows a generation phase in which such an overshoot is greatest. Also,
This Figure 8 shows the case of 1.5 times the amplitude setting value I _{The set,} it is sufficient to prevent the influence of the overshoot only if the amplitude is equal to or less than the set value I _{The set,} necessary delay time is shown It may be smaller than t ₃ -t ₂ .

As described above, in the second embodiment, by inserting the digital filter for removing the dc component inevitably accompanying the change in the current, the data window of the determination amount becomes three samples, and the first embodiment has Compared to the two samples of the form, the data window for operation determination is wider, but the data window is still sufficiently narrow. Further, by preventing the influence of the overshoot, a slight delay occurs, but sufficient high-speed operation can be realized. The first is about linearity
It can be almost the same as the embodiment.

In FIG. 8, since N = 2 for the sake of simplicity, the ripple of the judgment amount is large. However, if necessary, the ripple can be reduced by increasing N as needed. However, in the case of the present embodiment, when the determination amount once exceeds the set value, the influence of the ripple can be eliminated by means such as extending the output.

FIG. 9 is a configuration diagram of an overcurrent relay showing another embodiment of the second embodiment of the present invention.

In FIG. 9, the same reference numerals as those in FIG. 7 indicate the same or corresponding parts. In FIG. 9, the A / D converter 2 or the digital filter 7 and the like are the same as those in FIG. Omitted.

FIG. 9 is different from FIG. 7 in that the judgment is made based on the maximum value of the absolute values of the plurality of output data strings. In FIG. 9, the overcurrent judging section 9B uses the following equation (2-7). The absolute value of each output data string must be greater than or equal to the set value.
= 1 to N, it is determined that an overcurrent has occurred.

∪ {| B _{n, m} | ≧ I _set } = 1 (2-7) n = 1 to N

The equivalent relation between the maximum value and the logical sum or the equivalent relation between the maximum value and the logical product explained in the first embodiment is the same in the following embodiments. is there.

As described above, according to the second embodiment, a data string obtained by digitally filtering a DC component that always occurs with a change in current is used as an input data string. The effect can be realized.

It is to be noted that digital filtering is not necessarily limited to only DC component removal, and similar effects can be obtained with respect to other distortion components. Also, in the present embodiment, an example of an overcurrent relay has been described,
A well-known differential relay or a ratio differential relay is an overcurrent relay in a broad sense, and can be similarly applied. Further, the ratio differential relay can be similarly applied to generation of a so-called suppression amount in a ratio differential relay.

FIG. 10 is a partial configuration diagram of an overcurrent relay according to a third embodiment of the present invention.

FIG. 10 shows a configuration similar to that of FIG.
The A / D converter 2 and the digital filter 7 in FIG. 7 have substantially the same configuration, and are not shown.

The product-sum current calculation unit 3C corresponds to the product-sum current calculation unit 3B shown in FIG. 7, and the coefficients ξ _n and η _n are different from the coefficients λ _n and μ _n. The output data sequence C _{n, m of the} expression becomes B _{n, m} .

C _{n, m} = ξ _n j _m + η _n j _m−1 (3-1) n = 1 to N, where coefficients ξ _n and η _n are shown in the first embodiment ( 2-
The coefficients [lambda] _m and [mu] _{m in the} expression (2) have the relationship of the following expression (3-2).

Ξ _n = λ _n / v _n , (3-2) η _n = μ _n / v _n , n = 1 to Nv _n are other coefficients, the description of which will be described later. Things.

The overcurrent judging unit 9C is the same as the overcurrent judging unit 9 in FIG. 7 except that the output data string C _{n, m} is input instead of the output data string B _{n, m} .

The operation of the overcurrent relay of the present embodiment configured as described above will be described with reference to FIGS.

First, the input current i and the input data string j _m in FIG. 11 are almost the same as those in FIG. 8 and are the case of the generated phase in which the overshoot becomes maximum.

Next, the relationship between the output data sequence C _{n, m} and the output data sequence B _{1, m of} the second embodiment _, and the equations (3-3) and (3-3)
The coefficient v _n with the expression 4) is as follows.

C _{1, m} = B _{1, m} / ν ₁ = B _{1, m} /1.0 (3-3) C _{2, m} = B _{2, m} / ν ₂ = B _{2, m} / 1.9 ・ ・ ・ ・ ・ ・ ・ (3-4) ν ₁ = 1.0, ν ₂ = 1.9

The coefficient ν _n is a value for preventing the overshoot described with reference to FIG. 8. Since no overshoot occurs in the output data sequence B _{1, m} , it is assumed that ν ₁ = 1, and the stationary value for B _{2, m} Since 1.9 times overshoot is obtained, ν ₂ is set to 1.9.

Thus, the output data strings C _{1, m} and C _{2, m}
Do not overshoot together.

[0102] In FIG. 11, determination amount at time t ₁ after Max | C _{n, m} | but there is a time period equal to or less than the set value I _{The set,} there illustrated by continued output by slight stretching, etc. . These are well-known means and are not shown in FIG.

On the other hand, FIG. 12 shows a response waveform under the condition that the generated phase and the amplitude are different from FIG.
In the case of FIG. 12, C _{2, m} is compared with the output data string C _{1 , m.}
Rises quickly, which contributes to a faster rise of the determination amount.

As described above, according to the third embodiment, since there is no overshoot of the determination amount, an output can be generated immediately when the determination amount exceeds the set value, as described in the second embodiment. Since there is no need to insert delays,
Higher speed operation can be achieved.

FIG. 13 is a configuration diagram of a current compensation undervoltage relay according to a fourth embodiment of the present invention.

The current compensating undervoltage relay 100D has an A /
It comprises a D converter 14, a compensation input data generator 15, a product-sum voltage calculator 16, a decision amount generator 17, and a current compensation undervoltage determiner 18.

[0106] Here, A / D converter 14, which converts a is the voltage v and the main data sequence current i is従入force was sampled at regular time intervals v _m and secondary data string i _m main input amount It is. Note that the main input amount or the sub input amount is not necessarily limited to one each. For example, it is possible to use the phase of the voltage or current of 3-phase power system as an input quantity, Toka the line voltage and v _m, the known input variables, such as the delta current is i _m.

[0107] compensation input data string generation unit 15, the A / D converter 14 to input sub data train i _m, the following (4-1)
Generating a compensation input data sequence u _m according to formula.

[0108] _{u m = K (i m -i} m-1) ····· (4-1) where, K is a coefficient for determining the degree of current compensation.

[0109] product sum voltage calculation unit 16, (1-1) similar to the formula output data array A _n, to generate a _m, compensation input data sequence u compensation from _m by (4-2) formula data train H Generate _{n and m} .

[0110] _{H n, m = λ n u} m + μ n u m-1 ····· (4-2) n = 1~N where the coefficient lambda _n and mu _n of equation (1-1) The same value as in the case is used.

The determination amount generator 17 calculates the equation (4-3) and the equation (4-4) based on the output data sequence _{An, m} and the compensation data sequence Hn _{, m.}
The determination data strings D _{n, m} and E _{n, m} are generated by the equations.

D _{n, m} = A _{n, m} − (H _{n, m} ) ₊ ... (4-3) E _{n, m} = (H _{n, m} ) ₋ −A _{n, m.} (4-4) n = 1 to N Here, (H _{n, m} ) ₊ and (H _{n, m} ) ₋ are rectified values of the compensation data sequence H _{n, m in} the positive direction and the negative direction, respectively. It represents.

That is, the judgment data string D in the above equation (4-3)
_{n, m} means a value obtained by subtracting a value equal to H _{n, m} from the output data sequence A _{n, m} when the compensation data sequence H _{n, m} is positive, and becomes zero when negative, and the latter is , The value is equal to H _{n, m} when the compensation data sequence H _{n, m} is negative, and is zero when it is positive. Therefore, the judgment data sequence D _{n, m} is _calculated from the output data sequence A _{n, m} from the compensation data sequence H _{n
, m} minus the positive rectification value,
E _{n, m} is the output data string from the negative rectified value of the compensation data string H _{n, m}
A _{n, m} is subtracted. When the compensation data string is zero, the rectified value is not affected, so that the result is the same regardless of which side is included.

The current compensation undervoltage judging section 18 calculates (4-5)
According to the formula, an output is generated when the maximum value of the determination data strings D _{n, m} and E _{n, m} is equal to or less than the set value V _set .

Max {D _{n, m} , E _{n, m} } ≦ V _set (4-5) n = 1 to N

FIG. 14 shows the operation of the current compensation undervoltage relay according to the fourth embodiment of the present invention configured as described above.
This will be described with reference to FIG.

FIG. 14 is a phase characteristic diagram showing the operating range of the voltage vector V corresponding to the main input amount with the current vector I corresponding to the sub input amount as a phase reference. FIG. 14 shows the number N of pairs for convenience of explanation. FIG. 15 shows a virtual phase characteristic when is set to infinity, and FIG. 15 shows a phase characteristic when the number of sets N is set to 12 as an example.

FIG. 14 is represented by one curve, and FIG. 15 is substantially the same as FIG. 14, except that the characteristic has a bulge due to a slight uncertain range.

[0119] Figure 14 is a curve b - b - Hani - E - consists DOO, a so-called playground shape characteristic, the line segment OP compensation vectors corresponding to the compensation input data sequence u _m, the line segment indicated by the broken line b - E is a line segment passing through the origin O and perpendicular to the compensation vector OP, and a line segment Loni similarly indicated by a broken line is a line segment passing through the point P at the tip of the compensation vector and perpendicular to the compensation vector OP.

The curve ero and the curve niho are line segments, the curve low hanni and the curve haute ii are semicircles having the center at each point P and the origin O and both having a radius of the set value _Vset. It is shown that.

FIG. 14 shows, as described above, the number of sets N
Is set to infinity, the left side of the expression (4-5) is
Judgment data sequence when coefficients λ _n and μ _n are continuously changed
This is the maximum value of D _{n, m} and E _{n, m} .

The expression (4-5) is, by definition, the following (4-6)
Equation (4-7) can be rewritten.

When H _{n, m} is positive Max {A _{n, m} −H _{n, m} , −A _{n, m} } ≦ V _set (4-6) When H _{n, m} is negative Max {A _{n, m} , H _{n, m} −A _{n, m} } ≦ V _set (4-7)

The left side of the above equation (4-6) is the data sequence v _m
−u _m and v _m are continuously shifted with the gain kept constant, and the decision data sequence D _{n, m} = A _{n, m} −H _{n, m} and E _{n, m} = −A
_n, D _{n, m} and E _n in H _n, range _m are positive when the _m, equal to the maximum value of _m. Equation (4-7) can be considered similarly. Therefore, _{assuming that} the vector V is in phase with the compensation vector OP, when the compensation data string H _{n, m} is positive, the output data string A
_{Since n and m} are also positive, the judgment data string E _{n, m} = −A _{n, m} becomes negative, and only the judgment data string _{An, m−} H _{n, m} is valid in the equation (4-6). , OP plus the set value _Vset is one point on the characteristics.

On the other hand, when the vector V is in the opposite phase to the compensation vector OP _, only −An _{, m} is valid, so that a point equal to the origin 0 set value V _set is one point on the characteristic. Become.

Next, in the range of the E-to-H, the phase of the vector V is delayed by π / 2 to 3π / 2 with respect to the compensation vector OP, and the judgment data sequence En _{, m} = −An _{, m} is the compensation vector OP
Corresponds to a range in which the phase is shifted from 0 to ± π / 2.

From the above description, at each point of time during which the compensation data string H _{n, m} is positive, the judgment data string -An _{, m} always takes a peak value at any of n, and the equation (4-5) The left side is the peak value, that is, the value corresponding to the amplitude | V | of the vector V. Similarly, during the period when the compensation data string Hn _{, m} is negative, the left side of the equation (4-7) has a value corresponding to the amplitude | V |. That is, in this range, the amplitude | V | is equal to or less than the set value _Vset , that is, a semicircle having the radius _Vset with the origin O as the center.

Next, the range of the low frequency is determined by the judgment data sequence.
D _{n, m} and the compensation data string H _{n, m} are exchanged, and the point P with respect to the origin O is
Is a semicircle with the point P as the center and the radius _Vset as the center, considering the same as described above.

Next, in the range of yellow and niho, the maximum of the output data sequence _{An, m} or the output data sequence -A _{n, m at} the time when the compensation data sequence H _{n, m} = 0 is obtained. The value becomes the maximum value of the expression (4-6) or (4-7). Assuming that the phase difference between the compensation vector OP and the vector V is θ, this value is | V | × | sin
In this range, the determination formula (4-5) becomes the following formula (4-8), which is a line segment.

| V | × | sin θ | ≦ V _set (4-8)

FIG. 15 shows N = 12 as an example of a finite number of sets.
In the characteristic diagram in the case of, the bulging of the uncertain region due to the finite number of sets is shown. The reason is that, in the case of a finite number of sets, the value on the left side of the decision formula is a discrete value, and therefore it is near | V | or | V | × | sinθ | as described above. It is not a value. But,
If the uncertainty area is sufficiently small as in this example, there is no practical problem. The above description shows the so-called static characteristics, and the dynamic characteristics can be carried out in the same manner as in the first embodiment, so that the details are omitted.

As described above, according to the fourth embodiment, it is well known that a current compensation undervoltage relay having static characteristics is suitable for detecting an abnormality in a power system in which a power supply behind changes. Is omitted, but it is clear that the present embodiment has the same effects as the first embodiment in terms of high speed and good visibility of characteristics.

FIG. 16 is a configuration diagram of a current compensation undervoltage relay according to a fifth embodiment of the present invention.

In FIG. 16, the same reference numerals as in FIG. 13 showing the fourth embodiment denote the same or corresponding parts, and the present embodiment is obtained by adding some elements to the fourth embodiment. D converter 14 and compensation input data generator 15
Is omitted for common use. The product-sum voltage calculation unit 16
Also, the determination amount generation unit 17 is the same as that in FIG. 13, and internal details are omitted.

The line-segment-determination-quantity generating section 19 sets the coefficient set such that the (N + 1) -th compensation data string is always zero, that is, the coefficient set λ _{N + 1} and Calculate μN _{+ 1} . H _{N + 1} , _m = λ _{N + 1} u _m + μ _{N + 1} u _m-1 ≡0 (5-1) When the above-described coefficient sets λ _{N + 1} and μ _{N + 1} are calculated, Using this coefficient set, a determination data sequence D _{N + 1, m} and E _{N + 1, m} are generated.

The coefficient sets λ _{N + 1} and μ _{N + 1} are, for example,
It can be calculated by the formulas (5-2) and (5-3), but can also be calculated by a well-known sequential calculation method or the like based on the compensation data sequence Hn _{, m} (n = 1 to N). it can.

[0137] _{λ N + 1 = -u m-} 1 {(u m-1 -u m) 2 + 2u m u m-1 (1-cosψ)} -1/2 ····· (5-2) _{μ N + 1 = u m {} (-u m-1 + u m cosψ) 2 + u m 2 sin 2 ψ} -1/2 ····· (5-3)

The judgment data strings D _{N + 1, m} and E _{N + 1, m} are (4-
This is the same as the expression (2), but since H _{N + 1, m} ≡0 as described above _{, the} values of the following expressions (5-4) and (5-5) are obtained. D _{N + 1, m} = λ _{N + 1} v _m + μ _{N + 1} v _m-1 ... (5-4) E _{N + 1, m} = −D _{N + 1, m.} (5-5)

The current compensation undervoltage judging section 20 determines that the number of sets N is N
Except for +1, the operation is the same as that of the current compensation undervoltage determination section 18.

Note that, in comparison with the fourth embodiment, the number of sets is
Although N + 1 is assumed, there is no problem even if it is generally described as N if the fifth embodiment is considered alone.

FIG. 17 and FIG. 1 show the operation of the current compensation undervoltage relay of the fifth embodiment configured as described above.
8 will be described.

FIG. 17 shows a static characteristic diagram when the number of sets is N = 6 in the fourth embodiment for convenience of comparison, and FIG. 18 shows a corresponding static characteristic diagram in the fifth embodiment. It is. In FIG. 17, since the number of sets is N = 6, the bulge of the uncertain region is larger than that of N = 12 in FIG. 15, but the other two are the same.

FIG. 18 shows an example of the fifth embodiment.
This shows the characteristics when the (N + 1) = seventh determination data string is added in addition to N = 6.

In this case, the swelling of the uncertain region in the range of the yellow and the niho is eliminated, and a line segment is formed. The reason for this is that in the fourth embodiment, the cause of the occurrence of the uncertain region is a discrete value characteristic based on a finite number of sets, but in this embodiment, the compensation data string H _{N + 1, m} becomes zero. Since the coefficient set is calculated and used, the line segment is not a discrete value but has a continuous value characteristic similar to that of FIG.

As described above, in the fifth embodiment, in addition to the same effects as those of the fourth embodiment, the operation processing amount is reduced with a small number of coefficient sets, and the operation is stabilized by the characteristic with a small operation load and a small uncertain region. Operation can be obtained.

[0146]

As described above, according to the present invention, a malfunction due to the influence of distortion is extremely small, a response tendency and an outlook for a malfunction are good, and a high-speed determination can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an undervoltage relay according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for an operation algorithm of the undervoltage relay of FIG. 1;

FIG. 3 is a diagram illustrating an input data sequence and an output data sequence in FIG. 1;

FIG. 4 is a waveform diagram of an output data string with respect to an input amount in FIG. 1;

FIG. 5 is a diagram showing the operation of the undervoltage relay of FIG. 1;

FIG. 6 is a configuration diagram of an undervoltage relay showing another embodiment of the first embodiment of the present invention.

FIG. 7 is a configuration diagram of an overcurrent relay showing a second embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation of the overcurrent relay of FIG. 7;

FIG. 9 is a configuration diagram of an overcurrent relay showing another embodiment of the second embodiment of the present invention.

FIG. 10 is a configuration diagram of an overcurrent relay showing a third embodiment of the present invention.

11 is a diagram showing a first operation of the overcurrent relay of FIG.

FIG. 12 is a diagram showing a second operation of the overcurrent relay of FIG.

FIG. 13 is a configuration diagram of a current compensation undervoltage relay according to a fourth embodiment of the present invention.

FIG. 14 is a diagram illustrating a first static characteristic of the current compensation undervoltage relay of FIG. 13;

FIG. 15 is a diagram illustrating a second static characteristic of the current compensation undervoltage relay of FIG. 13;

FIG. 16 is a configuration diagram of a current compensation undervoltage relay according to a fifth embodiment of the present invention.

FIG. 17 is a diagram illustrating a first static characteristic of the current compensation undervoltage relay of FIG. 16;

18 is a diagram illustrating a second static characteristic of the current compensation undervoltage relay of FIG. 16;

FIG. 19 is a configuration diagram showing an example of a conventional digital protection relay.

20 is a diagram illustrating a digital protection relay provided in FIG. 19; FIG.
FIG. 4 is a diagram illustrating the operation of the / D converter.

FIG. 21 is a first explanatory diagram for describing a general amplitude value calculation algorithm.

FIG. 22 is a second explanatory diagram for describing a general amplitude value calculation algorithm.

FIG. 23 is an operation range diagram of the undervoltage relay.

FIG. 24 is an operating range diagram of the current compensation undervoltage relay.

[Explanation of symbols]

 2, 14 A / D converter 3, 16 Sum-of-product voltage calculation unit 3B, 3C Sum-of-product current calculation unit 4 Undervoltage calculation unit 4A Undervoltage judgment unit 9, 9B, 9C Overcurrent judgment unit 15 Compensation input data sequence generation unit 17 judgment amount generation unit 18, 20 current compensation undervoltage judgment unit 19 line segment judgment amount generation unit 21 amplitude calculation unit 22 operation judgment unit 100A undervoltage relay 100B, 100C overcurrent relay

Claims (6)

[Claims] 1. An apparatus comprising: means for creating an input data string as a digital data string from sampling data of an input electric quantity; and a plurality of coefficient sets each including a first coefficient data and a corresponding second coefficient data as one coefficient set. Then, the first input data obtained by multiplying the first coefficient data and the latest input data sequence for each of the plurality of coefficient sets, the second coefficient data, and the past input data from the latest input data sequence. A second operation data obtained by multiplying the data sequence with the second operation data is made to correspond to the first operation data to generate operation data obtained by addition, and a plurality of output data sequences corresponding to each of the plurality of coefficient sets are generated and output. A digital protection relay comprising: means for outputting an operation determination based on the data size of the plurality of output data strings generated and output from the means; and The first coefficient data and the second coefficient data are, when the input data sequence is waveform data corresponding to a stationary sine wave, a predetermined peak value in which each waveform formed by the plurality of output data sequences is substantially equal. And wherein the waveforms are determined so as to have a predetermined phase angle difference from each other. 2. The digital protection relay according to claim 1, wherein the means for creating the input data string creates an input data string by digitally filtering the sampling data. 3. A means for generating an input data string as a digital data string from sampling data of an input electric quantity, and a plurality of coefficient sets in which the first coefficient data and the corresponding second coefficient data are one coefficient set. Then, the first input data obtained by multiplying the first coefficient data and the latest input data sequence for each of the plurality of coefficient sets, the second coefficient data, and the past input data from the latest input data sequence. A second operation data obtained by multiplying a data sequence is associated with the first operation data to generate operation data obtained by addition, and a plurality of output data sequences corresponding to each of the plurality of coefficient sets are generated and output. And a means for outputting an operation determination based on the data size of the plurality of output data strings generated and output from the means. Each of the first coefficient data and the second coefficient data of the set has a predetermined peak in which each waveform formed by the plurality of output data strings is substantially equal when the input data string is waveform data corresponding to a specific waveform. A digital protection relay having a predetermined value and a predetermined phase angle difference between the waveforms. 4. The method according to claim 1, wherein the output of the operation determination is performed based on a relationship between a maximum absolute value of each data of the plurality of output data strings and a predetermined set value. The operation is determined based on the relationship between any one of the absolute values of the output data sequence and a predetermined set value, or the operation is determined based on the relationship between all the data of the plurality of output data sequences and the predetermined set value. The digital protection relay according to any one of claims 1 to 3, characterized in that: 5. A means for creating a main input data sequence as a main digital data sequence from sampling data of a main input electric quantity, and a plurality of coefficient sets each including a first coefficient data and a corresponding second coefficient data as one coefficient set. The first main operation data, the second coefficient data, and the latest main input data sequence obtained by multiplying the first coefficient data and the latest main input data sequence for each of the plurality of coefficient sets. The second main operation data obtained by multiplying the main input data sequence in the past and the second main operation data are made to correspond to the first main operation data, and main operation data obtained by addition is generated to correspond to each of the plurality of coefficient sets. Means for outputting a plurality of main output data strings; means for creating a slave data string as a slave digital string from sampling data of the slave input electric quantity; and digitally converting the slave data string created by this means. Means for creating a compensation input data string by filtering, and a plurality of coefficient sets each including the first coefficient data and the corresponding second coefficient data as one coefficient set. The first compensation data obtained by multiplying the first coefficient data by the latest compensation input data sequence, the second coefficient data, and the compensation input data sequence past the latest compensation input data sequence are multiplied. Means for generating the compensation operation data obtained by adding the second compensation operation data obtained in correspondence with the first compensation operation data and generating and outputting a plurality of compensation output data strings corresponding to each of the plurality of coefficient sets; Means for creating a first determination data string obtained by subtracting a positive rectification value of the compensation data string from the main output data string; and a means for subtracting the main data string from a negative rectification value of the compensation data string. No. Determination data generation means having means for generating a determination data sequence; and means for performing an operation determination based on the first determination data sequence and the second determination data sequence generated by the determination data generation device. Wherein the first coefficient data and the second coefficient data of the plurality of coefficient sets are the same when the main input data sequence and the sub data sequence are waveform data corresponding to a stationary sine wave. The waveforms formed by the plurality of main output data strings and the plurality of compensation output data strings have predetermined peak values that are substantially equal, and the respective waveforms are determined to have a predetermined phase angle difference from each other. A digital protection relay, characterized in that: 6. A digital coefficient set according to claim 5, wherein a plurality of coefficient sets are determined so that the value of a compensation data sequence obtained by using one coefficient set among the plurality of coefficient sets becomes zero. Type protection relay.