JP2989190B2 - Negative phase digital filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a negative-phase-separation digital filter used for a protection relay device of a power system (Prior Art) Short-circuit of a three-phase power system Or to protect against ground faults,
A protection relay using an electric quantity (voltage or current) for the negative phase is used. The purpose of the present invention is to detect an accident with a much higher sensitivity than a general relay such as a distance relay when a high-resistance ground-fault or distant accident such as a tree contact occurs.

There has been provided a digital relay for calculating the negative phase component electric quantity data from the sample values of the electric quantities of the three phases and protecting the data by using the data.

(Problems to be Solved by the Invention) The conventional apparatus has a large frequency error generated from the positive phase component of the input electric quantity, and the negative phase electric quantity (hereinafter, referred to as the error output rated value when the rated positive phase electric quantity is added). The ratio (hereinafter referred to as the positive-sequence error ratio) to the output (hereinafter referred to as the rated negative-sequence output) when the rated negative-sequence electric quantity is added is 5%.
When the percentage changes, it reaches about 3%.

Although this value does not seem to be very large, it is often necessary to respond to a negative-sequence electrical quantity of around 1% of the rated negative-phase electrical quantity. With a positive-sequence error ratio of 3%, the protection ability cannot be exerted when the frequency fluctuates.

An object of the present invention is to significantly improve the positive-sequence error ratio, and to reduce the positive-sequence error ratio by 0.1% when the power meter and the right frequency change by 5%.
It is an object of the present invention to provide a digital anti-phase component filter which can be improved to about% or less.

[Configuration of the Invention] (Means for Solving the Problems) FIG. 1 shows the configuration of the present invention. In FIG, 1 is a phase of the electric quantity of 3-phase power system _{a, b,} c _(a sequentially positive phase, _{b, c} by the data acquisition unit, hereinafter the case of collectively E
Are sampled at a frequency cycle that is a natural number times (for example, 12 times) the power system rated frequency, and the sampled values are converted into digital data (collectively indicated by D). 2 and 3 to calculate each first and second reversed phase data D ₁ and D ₂ by reverse-phase data calculating means. 4
In synthesizing means synthesizes the reversed phase data D ₁ and D _2, and calculates a third reverse phase data Dn shown in the following equation.

D _n = K ₁ D ₁ + K ₂ D ₂ (1) (where K ₁ and K ₂ are real constants) This data D _n is used for protection calculation of the protection relay device and the like.

In FIG. 1, for convenience of explanation, the data D ₁ and D ₂ are calculated and then the data D _n is calculated. However, without calculating the data D ₁ and D ₂ , the combined data of the formula (1) is used. D _n can be calculated.

In similar data to those calculated by the data D ₁ and D ₂ are conventional reversed phase data calculating means, a composite value of the data of at least two different sampling time of the data D, represented by the following formula .

D ₁ = K ₁₁ D ₁₁ + K ₁₂ D ₁₂ + (K ₁₃ D ₁₃ ) ... (2) D ₂ = K ₂₁ D ₂₁ + K ₂₂ D ₂₂ + (K ₂₃ D ₂₃ ) ... (3) However, K ₁₁ , K ₁₂ , K ₁₃ , K ₂₁ , K ₂₂ and K ₂₃ are real constants,
D ₁₁ , D ₁₂ , D ₁₃ , D ₂₁ , D ₂₂ and D ₂₃ are respectively at time t ₁₁ ,
At time t ₁₂ , t ₁₃ , t ₂₁ , t _22, and t ₂₃ , it is data or a composite value of data obtained by sampling the electric quantities ₁₁ , ₁₂ , ₁₃ , ₂₁ , ₂₁ , _22, and ₂₃ of the individual phases in the electric quantity at time t.
_11, t ₁₂ and t ₁₃ are different time, the time t _21, t ₂₂ and t ₂₃ are different times.

Electric quantity _11-23, constant K ₁₁ ~K ₂₃ and sampling time
the choice of t ₁₁ ~t ₂₃ will be described. Where the quantity of electricity ₁
And ₂

(However, θ ₁₂ , θ ₁₃ , θ ₂₂ , and θ ₂₃ are sample time differences t ₁₂ −t ₁₁ , t ₁₃ −t ₁₁ , t ₂₂ −t ₂₁ , and t ₂₃ −t, respectively.
₂₁ is a value represented by the electrical angle of the power system rated frequency. For example, t ₁₂ −t ₁₁ is positive when t ₁₂ is later than t ₁₁ . Y is a frequency variation rate of the electric quantity and is represented by the following equation. ) The difference between the electric quantities ₁₁ to ₂₃ , the constants K _{11 to} K ₂₃ and the sample times θ _{12 to} θ ₂₃ is obtained when the frequency fluctuation rate Y is zero.
The electric quantities ₁ and _{2 in the} equations (4) and (5) are selected in the same manner as the normal negative phase component calculating means so that each of them is proportional to only the negative phase component _{n of the} electric quantity. At this time, the electric quantities ₁ and ₂ are represented by the following equations.

₁ = _{n1 n} ... (7) ₂ = _{n2 n} ... (8) (However, _n1 and _n2 are complex constants.) As a result of the above, when only the positive phase component _p is considered when Y ≠ 0 Considering the case where the frequency variation rate Y is not zero, the electric quantities ₁ and ₂ are represented by the following equations.

_{1 = p1 p ...... (9)} 2 = p2 p ...... (10) ( however, a function of _p1 and _p2 each Y, both when Y = 0 becomes zero.) Sample time t ₁₁ and t difference and (1) the constant K ₁ and K ₂ of formula ₂₁ is defined as (9) and (10) the following equation from a function _p1 and _p2 of.

(However θ ₂₁ is the time to sample time t ₂₁ is delayed from t ₁₁ t ₂₁
−t ₁₁ is a value expressed by the electrical angle of the power system rated frequency),
However, even under the above conditions Are excluded.

(Operation) First, the relationship between Expressions (2) and (4) will be described.
(2) data D ₁₂ of the expression is data sampled at a time delayed by the sample time theta ₁₂ in electrical angle of the electric power system nominal frequency than t ₁₁ data D _11. If this delay is represented by the electrical angle of the frequency of the electrical quantity, it becomes (1 + Y) θ ₁₂ . An electrical angle (1 + Y) data D ₁₂ to the quantity of electricity ₁₂ and the sample at the time t ₁₂ later than theta ₁₂ only time t _11, the quantity of electricity ₁₂ (1
+ Y) θ ₁₂ only advances quantity of electricity Equal sampled the data at the time t ₁₁ a. Similarly (2) electric quantity data D ₁₃ is the advanced quantity of electricity ₁₃ by (1 + Y) theta ₁₃ of formula Equal to the sample data to the time t ₁₁ a.

From the above, the data D ₁ in equation (2) is the electric quantity _{1 in} equation (4)
Equal to the sample data to the time t ₁₁ a. Similarly, the data D ₂ of the expression (3) is obtained by converting the electric quantity ₂ of the expression (5) to the time t _21.
Equal to the sampled data.

The time t ₂₁ is because it is (1 + Y) θ ₂₁ delayed by time from the time t _11, the data D ₂ that samples the electrical quantity ₂ to time t ₂₁ is proceeded electric quantity ₂ only (1 + Y) θ ₂₁ Electricity Equal to the sample data to the time t ₁₁ a.

Therefore, the data D _n of the equation (1) is an electric quantity _{e of the} following equation.
Equal to the sample data to the time t ₁₁ a.

Under the condition that the frequency fluctuation rate Y is zero, the electric quantities ₁ and _{2 in the} equations (4) and (5) are proportional only to the negative phase component _n of the electric quantity E as shown in the equations (7) and (8), respectively. So the amount of electricity
_e is Becomes

As described above, under the condition of Y = 0, the data D _n is sample data of only the negative phase electric quantity _n , and the positive phase electric quantity _p
And the component of zero phase component electric quantity ₀ is not included. Thus data D _n is the output data of the reverse-phase digital filter. If the electric quantity does not include the negative phase component,
_{Since n} is zero, the data D _n is always zero regardless of the sample time.

Next, the frequency error which is the main feature of the present invention will be described.

When the frequency fluctuation rate Y is not zero, the electric quantities ₁ and ₂ cause errors with respect to the equations (7) and (8).
This error can be considered in the following three cases.

Negative phase error: Error proportional to negative phase component _n Positive phase error: Error proportional to positive phase component _p Zero phase error: Error proportional to zero phase component _o When the positive phase component of the electric quantity is large and the negative phase component and the zero phase component are small, the object is to respond to the negative phase component with high sensitivity. In such a case, the influence of the positive phase component error is significantly greater than other errors, and the object of the present invention is to reduce the positive phase component error. Therefore, the effect of reducing the positive phase component error will be described.

The positive phase errors of the electric quantities ₁ and ₂ are expressed by equations (9) and (10), respectively. Although functions _p1 and _p2 of the frequency variation rate Y is not insubstantial, positive phase component _p is time sufficiently larger than the reversed phase _n is a large value for the reversed phase _n.

When the positive phase error of electric quantities ₁ and ₂ is expressed by equations (9) and (10), respectively, the positive phase error of equation (14) is Since K ₁ , K ₂ and θ ₂₁ in the equation (16) are selected in the relation of (11), E _e in the equation (16) is And the absolute value of _e is Becomes Here, when the frequency variation rate Y usually 0.05 range to be considered, the theta ₂₁ to 60 ° of normal _{value, | e | ≒ 0.0524K 1 p1} p | ...... (19) (19) , and the electric quantity only 5 per cent with respect to the positive phase error of K _{1 1} K _{1 p1 p.}

Positive phase error data D _n of the present invention (18) or (19)
A sample value of the formula, for example, as compared the conventional reversed phase digital filter of the sample value of the electrical quantity K _{1 1} data, significantly smaller positive phase component error. Further, the frequency variation rate Y
Is zero, the output of the electric quantity _e in the negative phase of _e is (15)
From the formula Where K ₁ , K ₂ and θ ₂₁ are given by equation (12), And the electric quantity _e hardly contains the reverse phase component.
The combination of ₁ and ₂ that satisfies such conditions is not used.

Such a combination is expressed by, for example, the equations (4) and (5). It is assumed that.

In this case, since ₂ = ₁ , _n1 = _{n2 in} equations (7) and (8), and _p1 = _p2 in equations (9) and (10). From these conditions, K ₁ , K ₂ and θ ₂₁ are determined under the conditions of equation (11). Then, the positive phase error of the electric quantity _e can be reduced. However, since _−n1 / _n2 is also −1, the expression (12) is established, and the output of the electric quantity _{e in} the opposite phase is lost, so that it cannot be used.

(Example) A first example of the present invention will be described with reference to the drawings. Second
The figure shows an embodiment of the hardware configuration of the present invention, wherein 5 is a data acquisition device and 6 is a processing device. The data acquisition device 5 inputs the electric quantities _a , _b, and _c of each phase a, b, and c of the three-phase AC, samples them at a cycle of 12 times the rated frequency, and outputs the sampled values to the digital data D _a respectively. , D
Convert to _b and D _c . Processing device 6 to the arithmetic processing by using the digital data, calculates the reversed phase data D _n.
The processing device 6 without outputting the data D _n to the outside, further subjected to protective relay calculation using the data D _n and other data, there is also a case of outputting a signal based on the result. The configuration shown in FIG. 2 is exactly the same as a generally used digital operation type protection relay, and therefore, detailed description is omitted for simplicity.

Next, the processing of this embodiment will be described. In this embodiment, (2)
And using the data D ₁₁ , D ₁₂ , D ₂₁ and D ₂₂ of the equation (3), and calculating the difference between the sample times shown in relation to the respective data, the equations (4), (5) and (11). The values shown in the electrical angle of the rated frequency and the respective constants of the equations (1), (2) and (3) are as follows.

D ₁₁ = D _c −D _a , D ₁₂ = D _a −D _b , D ₂₁ = D _a −D _b , D ₂₂ = D _b −D _c , θ ₁₂ = θ ₂₂ = θ ₂₁ = −60 °, K ₁ = K ₂ = K ₁₁ = K ₁₂ = K ₂₁ = K ₂₂ = 1 (24) The one shown in the equation (24) conforms to the matter described in (Means for solving the problem) This will be described first.
Data _Da , _Db and _Dc are electric quantities _a , _b and _c , respectively.
(4) and (5)
The quantities of electricity ₁ and ₂ in the equation are as follows.

(However, the symbol ^Represents ε ^jθ , and _ca , _ab and _bc are each _c
- _{a, a} - _b and _b - to denote the _c, shown in the same manner. The terms in equations (25) and (26) are represented by symmetric components.

Where _p , _n and _o are the positive phase components based on the a phase, respectively.
The negative phase component and the zero phase component.

So that Becomes

From the equation (28), the electric quantities ₁ and ₂ in the equations (25) and (26) are represented by the following symmetric components.

Therefore, the quantity of electricity when the quantity of electricity is only the positive phase component _p
The values _1p and _2p of ₁ and ₂ are as follows.

Further, the values _1n and _1n of the electric quantities ₁ and ₂ when the electric quantity E is only the negative phase component _n and the frequency variation rate Y is zero.
_2n is as follows.

According to equations (29) and (30), the values of the functions in equations (9) and (10) are Therefore, _p1 and _fp2 become zero when Y = 0. Also, in equation (11) And the values of K ₁ , K ₂ and θ ₂₁ in equation (24) conform to equation (37).

The constants _n1 and _{n2 in the} equations (7) and (8) are (3
From equations 3) and (34), Is Therefore, the condition of equation (12) is not satisfied.

As described above, the expression (24) conforms to the items described in (Means for Solving the Problems).

Next, a specific processing procedure of this embodiment will be described with reference to the drawings. FIG. 3 is a flowchart showing the data processing of this embodiment. When the process is started, the latest sample values D _am , D _bm and D _cm of the electric quantities _a , _b and _c are acquired and stored in _a process 7. Subsequently, the preliminary operation of processing 8 and the data D _{n of} processing 9
After the calculation and the data update in the process 10, the process returns to the process 7.

In process 8, the following data D _bcm , D _cam and D _abm are calculated.

In the process 10, the stored data group is updated as follows.

(However, D _m is a collective representation of data D _am , D _bm , D _cm , D _bcm , D _cam , D _abm and data D _nm to be described later.) That is, data D _m is D _{(m -1)} , D _(m-1) becomes D _(m-2) ……, D
_(m-11) is updated to _{D (m-12), D} (m-12) is rejected. The respective data D _(mn) than data D _m, a (1 + Y) n30 ° before the sample data in the frequency of the input electrical quantities.

In process 9, data D _nm is calculated by the following equation and stored.

_{D nm = D cam + 2D ab} (m-2) + D bc (m-4) ...... (34) data D _nm obtained in this calculation if you each data, the difference between the constants and the sample time and (24) (1) equal to the most recent sample value of expression data D _n.

Next, the function of the present embodiment will be described. Data D _n is equal to the sample value of the electric quantity _e as shown in equation (14). In the present embodiment, the respective constants of the equation (14) are K ₁ = K ₂ = 1, θ ₂₁ = −60 °,
Electric quantities ₁ and ₂ are expressed by equations (29) and (30), respectively. Rewriting equations (29) and (30), Therefore, the quantity of electricity _e is as follows.

If Y = 0, equation (37) becomes Next, the power _e is the reversed phase _n The value is doubled. This is the correct value of the electric quantity _e , and the value of the equation (38) when _n is the rated value is the rated negative-phase output of _e .

When Y ≠ 0, _e has an error proportional to the positive phase component _p and an error proportional to the negative phase component _n . The magnitude of the error E _gp proportional to the positive phase component is And when the frequency fluctuation rate Y is 0.05, Becomes

In this case, the positive-sequence error ratio (the ratio of the error output to the rated negative-phase output when the rated positive-phase electric quantity is added) G _p is Becomes

Size E _gn errors proportional to reversed phase is E _gn ≒ 6E _n sinY30 ° ...... (42), Y = 0.05 when _{E gn ≒ 6 × 0.0262E n ......} (43) next to this Output magnitude E _e ((38)
(Absolute value of equation) (negative phase error ratio) G _n
Is Becomes

The conventional device is for obtaining a sample value of the quantity of electricity _{1 in} the equation (35), for example, and when Y = 0 Becomes

The magnitude E _gp of the positive phase error when Y ≠ 0 is And Y = 0.05 Becomes The positive-sequence error ratio G _p in this case is Becomes

(41) the value of the positive phase error ratio G _p of the embodiment shown in equation 0.
092% is remarkably smaller than the value of 3.03% in the equation (48) of the conventional device. This effect is when the magnitude E _n of the reversed phase is significantly small with respect to the positive-phase component of the magnitude E _p, it may well understand considering the case for example of a E _n = 0.05E _p. In this case, the ratio of the magnitude of the positive phase error output to the correct negative phase output is G _p = 3.03%
In it reached 60.6% in G _p = 0.092% only 1.84%.

Note that the negative phase component error ratio of 3.03% in this embodiment does not generally cause a problem because the correct negative phase component output is 100%.

In this embodiment, each constant is set as shown in equation (24).
Each constant Other values having the relationship of only the values of the data D _n , D _1, and D _{2 in} equations (1), (2), and (3) only change the entire divisor on the right side. This has the same effect as in the case of the expression.

A second embodiment of the present invention will be described. The second embodiment differs from the first embodiment only in the contents of the processings 8, 9, and 10 in FIG. 3, and therefore, only the different parts will be described.

In process 8, the following data D _aom , D _bom and D _com are calculated and stored.

The process 10 is the same as the first embodiment except that the contents of the stored data group are different.

In the processing 9, the data D _nm is calculated and stored by the following formula. D _nm = D _com + 2D _{ao (m−2)} + D _{bo (m−4)} (50) The calculated value is obtained by calculating the difference between the sample times and the rated frequency. , The data of equations (1), (2), and (3) and the respective constants are as follows.

D ₁₁ = D _c −D _o , D ₁₂ = D _a −D _o , D ₂₁ = D _a −D _o , D ₂₂ = D _b −D _o , θ ₁₂ = θ ₂₂ = θ ₂₁ = −60 °, K _{1 = K 2 = K 11 =} K 12 = K 21 = K 22 = 1 ...... (51) where The equation (51) will be described. Data D _a , D _b , D _c and D _o
Are data obtained by sampling the electric quantities _a , _b , _c and their zero-phase components _o , respectively, so that the electric quantities ₁ and _{2 in the} equations (4) and (5) are as follows.

From the relationship of equation (27), Therefore, the quantity of electricity when the quantity of electricity is only the positive phase component _p
The values _1p and _2p of ₁ and ₂ are as follows.

The values _1n and _2n of the electric quantities ₁ and ₂ when the electric quantity E is only the reverse phase component _n and Y = 0 are as follows.

From the expressions (56) and (59), the values of the functions in the expressions (9) and (10) are Becomes These values are zero when Y = 0, and (1
1) In the formula And the values of K ₁ , K ₂ and θ ₂₁ in equation (51) conform to equation (37).

The constants in equations (7) and (8) are (58) and (5)
9) From formula Because Therefore, the condition of equation (12) is not satisfied.

As described above, Expression (51) conforms to the items described in (Means for Solving the Problem).

Next, the positive phase error ratio of the present embodiment will be described. In this embodiment, the respective constants of the equation (14) are K ₁ = K ₂ = 1 θ ₂₁ = −60 °, and the outputs of the electric quantities ₁ and _{2 by} the positive-phase sub-quantity _p are (56) and (57). ), The positive phase error output _gp based on the positive phase electric quantity _p in the electric quantity _e is as follows.

The value of the electric quantity _e when Y = 0 is (14), (5
From equations (8) and (59) and the function of the constant, the following is obtained.

Therefore, the positive-sequence error ratio G _p is calculated from the values of the coefficients in equations (64) and (65) as follows: And when Y = 0.05, And has the same effect as the first embodiment.

In this embodiment, each constant is set as in equation (51). Has the same effect, except that the entire divisor of the right side of the data D _n , D ₁ and D ₂ of the equations (1), (2) and (3) only changes. It is.

The differences between the third embodiment and the first embodiment will be described. This embodiment is different from the first embodiment in that processes 8 and 9 are performed.
Only the processing contents of and 10 are different.

In processing 8, the data D _bcm , D _cam and D _abm ,
And calculate and store the data D _aom , D _bom and D _com of the equation (49). In the process 10, the data group is updated in the same manner as in the first embodiment except that the stored data group is different.

In process 9, data D _nm is calculated by the following equation and stored.

This calculated value is a value obtained by expressing the difference between the sample times by the rated frequency, each data of the equations (1), (2), and (3) and each constant as the following equation (69).

D ₁₁ = D _c −D _a , D ₁₂ = D _a −D _o , D ₂₁ = D _a −D _o , D ₂₂ = D _b −D _a , θ ₁₂ = θ ₂₂ = θ ₂₁ = −30 ゜ K _{1 = K 2 = K 11 + K} 22 = 1 Equation (69) will be described. (69)
The electric quantities ₁ and _{2 in the} equations (4) and (5) are as follows.

From the relationship of equations (27) and (28) Therefore, the electric quantity is the value _1p of the electric quantities ₁ and ₂ when only the positive phase component _p is considered when Y ≠ 0.
_2p is as follows.

Further, the electric quantity is only the reverse phase component _n when Y = 0, and the values _1n and ₁ of the electric quantities ₁ and ₂ when Y = 0.
_2n is as follows.

From the expressions (74) and (75), the values of the functions in the expressions (9) and (10) are Becomes These values are zero when Y = 0, and (1
1) In the formula, And the values of K ₁ , K ₂ and θ ₂₁ in equation (69) conform to equation (37).

The constants in equations (7) and (8) are (76) and (7)
7) From the formula, Because And the condition of equation (12) is not satisfied.

As described above, the condition of the expression (69) conforms to the matter described in (Means for Solving the Problem).

Next, the positive phase error ratio of the present embodiment will be described. In this embodiment, since the respective constants of the equation (14) are K ₁ = K ₂ = 1, θ ₂₁ = −30 °, the positive-phase component error output _gp based on the positive-phase component electric quantity _p in the electric quantity _e is become that way.

The value of the electric quantity _e when Y = 0 is (14), (7)
6) and (77) and the above constants yield the following.

Therefore, the positive-sequence error ratio G _p is calculated from the coefficients of equations (82) and (83). In the case of Y = 0.05, G _p = 4 × 0.0131 ² = 0.069% (85), which is slightly better than the first and second embodiments.

In this embodiment, each constant is set as in equation (69). Other values having the relationship of only the data D _n , D _1, and D _{2 in} equations (1), (2), and (3) only change the entire divisor of the right-hand side. ) Has the same effect as the expression.

The differences between the fourth embodiment and the first embodiment will be described. This embodiment is the same as the first embodiment except that the process 8 in FIG. 3 is omitted and the processes 9 and 10 are different. In processing 10, the data group is updated in the same manner as in the first embodiment except that the stored data group is different.

In processing 9, the data group D _nm is calculated and stored by the following equation.

D _nm = D _cm− 2D _{b (m−2)} + 3D _{a (m−4)} −2D _{c (m−6)} + D _{b (m−8)} (86) This calculated value is obtained by calculating the difference between the sample times. The value indicated by the rated frequency, each data and each constant of the equations (1), (2), and (3) are as follows.

D ₁₁ = D _c , D ₁₂ = D _a , D ₁₃ = D _b , D ₂₁ = D _b , D ₂₂ = D _a , D ₂₃ = D _c θ ₁₂ = θ ₁₃ = −120 °, θ ₂₁ = θ ₂₂ = Θ ₂₃ = −60 °, K ₁₁ = K ₁₂ = K ₁₃ = K ₂₂ = 1, K ₂₁ = K ₂₃ = −1, K ₁ = 1, K ₂ = 2 (87) explain. According to equation (87), (1)
The latest calculated data D _nm of the formula data D _n is as follows.

D _nm = D _1m + 2D _{2 (m−2)} (88) Calculation data D _1m and D _{2 (m} used for the data D _nm of the data D ₁ and D ₂ of the equations (2) and (3) _-2) are as follows.

D _1m = D _cm + D _{a (m-4)} + D _{b (m-8)} …… (89) D _{2 (m-2)} = −D _{b (m-2)} + D _{a (m-4)} −D _{c (m-6)} …… (90) Substituting equations (89) and (90) into equation (88) gives (86)
Expression.

Under the condition of equation (87), the electric quantity of equations (4) and (5)
₁ and ₂ are as follows.

From the relationship of equation (27), Therefore, the electric quantity is the value _1p of the electric quantities ₁ and ₂ when only the positive phase component _p is considered when Y ≠ 0.
_2p is as follows.

Further, the electric quantity is only the reverse phase component _n when Y = 0, and the values _1n and ₁ of the electric quantities ₁ and ₂ when Y = 0.
_2n is as follows.

From the expressions (95) and (96), the values of the functions in the expressions (9) and (10) are Becomes These values are zero when Y = 0, and the ratio between the two functions is as follows under the condition that Y is about 0.1 or less.

Therefore, in equation (11) And the values of K ₁ , K ₂ and θ ₂₁ in equation (87) conform to equation (37).

The constants in equations (7) and (8) are (97) and (9)
8) From formula So that And the condition of equation (12) is not satisfied.

As described above, the condition of Expression (87) conforms to the matter described in (Means for Solving the Problem).

 Next, the positive phase error ratio of the present embodiment will be described.

Since each constant of the equation (14) is K ₁ = 1, K ₂ = 2, and θ ₂₁ = −60 °, the positive-phase component error output _gp due to the positive-phase component electric quantity _p in the electric quantity _e is (95 ) And (96) are as follows.

From the relationship of sin ² Y60 ゜ = 4sin ² Y30 ゜ cos ² Y30 ゜ = 4sin ² Y30 ゜ −4sin ⁴ Y30 式 Becomes

The value of the quantity of electricity _e when Y = 0 is (14),
From the relationship between the equations (97) and (98) and the constant, the following is obtained.

Therefore, the positive-sequence error ratio G _p is obtained from the coefficients of equations (105) and (106) as follows: (107) and Y = 0.05 And has the same effect as the first embodiment.

In this embodiment, each constant is set as shown in equation (87). Other values having the relationship of (1), (2), and (3) have the same effect, except that the entire coefficient on the right side of D _n , D _1, and D ₂ in formulas (1), (2), and (3) changes.

[Effects of the Invention] As described above, according to the present invention, it is possible to realize a negative-sequence digital filter in which the positive-sequence error ratio is significantly reduced when the frequency fluctuates.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of an antiphase digital filter according to the present invention, FIG. 2 is a block diagram showing a hardware configuration of an embodiment of the present invention, and FIG. It is a flowchart which shows. 1 ... Data acquisition means, 2,3 ... Negative phase component calculation means 4 ... Synthesis means, 5 ... Data acquisition apparatus, 6 ... Processing apparatus, 7 ... Data acquisition processing, 8 ... Preliminary calculation processing, 9: reverse phase data calculation processing, 10: data update processing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takayuki Matsuda, Inventor, 1-3-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. (72) Akira Yoshida 1-3-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo TEPCO Co., Ltd. (72) Inventor Hiroshi Saito 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu plant (72) Inventor Fumio Ando 1-18-17 Nishishinbashi, Minato-ku, Tokyo Toshiba Engineering Corporation

Claims (5)

(57) [Claims] A first method for sampling digital quantity (voltage or current) of each of three phases of a three-phase power system at a cycle of a frequency which is a natural number times the rated frequency of the power system to obtain digital data.
Means, and using the digital data, the first reversed-phase component data D ₁ of the electric quantity and the first
D _n = K ₁ D ₁ + K ₂ D ₂ (where K ₁ and K ₂ are constants of real numbers) obtained by combining the reversed phase component data D ₁ and the second reversed phase component data D ₂ different from An anti-phase digital filter comprising a second means, wherein the first and second anti-phase component data D ₁ and D ₂ are each a composite value of data of at least two different sample times represented by the following equations: in _{and, D 1 = K 11 D 11} + K 12 D 12 + (K 13 D 13 + ...) D 2 = K 21 D 21 + K 22 D 22 + (K 23 D 23 + ...) ( where, K _11, K _{12, K 13, K 21,} K 22, and K ₂₃ are real _{constants, D 11, D 12, D} 13, D 21, D 22, D 23 each time t _11, t
_12, t _13, electric quantity _{11, 12} containing the t _21, different phases of electrical quantities in the t ₂₂ and t _{23, 13, 21, 22} and
₂₃ or the composite value of the sampled data) and the constants K ₁₁ , K ₁₂ , (K ₁₃ ...), K ₂₁ , K ₂₂ , (K ₂₃
…) Is the following equation when the quantities of electricity ₁ and ₂ are (However, θ ₁₂ and θ ₁₃ are differences t ₁₂ −t ₁₁ between sample times.
And t ₁₃ −t ₁₁ , θ ₂₂ and θ ₂₃ are the differences between each sample time.
The t ₂₂ -t ₂₁ and t ₂₃ -t ₂₁ a value representing an electrical angle of the rated frequency of the power system, for example t ₁₂ -t ₁₁ is defined to be positive if t ₁₂ lags t _11. Since the electric quantity is only the inverse phase component n when the predetermined frequency fluctuation rate Y = 0, in this case, ₁ = K _n1 n and ₂ = K _n2 n, where K _n1 and K _n2 are Complex constants other than zero) Assuming that only the positive phase component p is considered when the frequency fluctuation rate Y ≠ 0 is predetermined, ₁ = fp ₁ p and ₂ = fp ₂ p (however, fp ₁ and fp ₂ Is a function of Y that becomes zero when Y = 0), and the difference θ ₂₁ between the constants K ₁ and K ₂ and the sample time is And A negative-phase-sequence digital filter characterized in that it does not cause a difference. 2. The electric quantity of each of the three phases is a,
b, the data when the _{c D 11, D 12, D} 21 and D ₂₂ are each an electrical quantity c-a, a-b, a-b and b-c of the sample value a is the relationship of each constant K ₁₁ / _{K 12 = K 21 / K 22} , a _{K 2 / K 1 = K 11} / K 21, and the sample time of the data D _12, D ₂₁ and D ₂₂ is in the electric power system nominal frequency than the sampling time of the data D ₁₁ 2. An anti-phase component digital filter according to claim 1, wherein said filters are at 60 DEG, 60 DEG and 120 DEG respectively. 3. The electric quantity of each of the three phases is a,
The data D ₁₁ , D ₁₂ , D _21, and D ₂₂ are sample values of the electric quantities excluding the zero-phase components from the electric quantities c, a, a, and ▼, respectively, where b and c are the values. Are K ₁₁ / K ₁₂ = K ₂₁ / K ₂₂ , K ₂ / K ₁ = K ₁₁ / K ₂₁ , and the sampling time of data D ₁₂ , D ₂₁ and D ₂₂ is more power than the sampling time of data D ₁₁ 2. The negative-phase-sequence digital filter according to claim 1, wherein the system rated frequencies are 60 °, 60 ° and 120 ° respectively. 4. The electric quantity of each of the three phases is a,
When b and c, the data D ₁₁ , D ₁₂ , D ₂₁ and D ₂₂ are the electric quantities c−a and the electric quantities excluding the zero phase from a, respectively,
is the electric quantity excluding the zero-phase component from a, and ba, and the relationship between the constants is And the sample times of the data D ₁₂ , D ₂₁ and D ₂₂ are respectively 30 °, 30 ° and 60 ° before the sample time of the data D _{11 in} the rated power system frequency. The negative phase digital filter described. 5. The electric quantity of each of the three phases is a,
Data D ₁₁ , D ₁₂ , D ₁₃ , D ₂₁ , D ₂₂ when b and c
And D ₂₃ are electric quantities c, a, b, b,
a, a c, the relationship of each constant _{K 11: K 12: K 13} = 1: 1: 1 K 21: K 22: K 23 = -1: 1: -1 K 2 / K 1 = 2K 12 / a K _22, and the data _{D 12, D 13, D 21} , D 22 and each 120 ° sample time of D ₂₃ is in the electric power system nominal frequency than the sample time of the data D _11, 240 °, 60 °, 120 ° , And 1
2. The negative-phase digital filter according to claim 1, wherein the angle is 80 degrees before.