JP6399974B2 - Protection relay device - Google Patents

Description

  The present invention relates to a protection relay device for protecting a power system such as a power transmission line, a distribution line, and a power device.

  In the protection relay device, various electric quantities are calculated using a current signal or a voltage signal sampled at a constant cycle time corresponding to an electrical angle determined at a rated frequency. For example, on page 111 of Non-Patent Document 1 ("Protective Relay System Engineering" Electrical Society), in the case where the sampling period corresponds to 30 ° of electrical angle, 3 sampling periods before (that is, 90 ° before electrical angle) An arithmetic expression for calculating an amplitude value and a phase difference is shown using the above data.

  In the above arithmetic expression, when the frequency of the power system is the rated frequency, the data before three sampling periods are correctly 90 degrees before the electrical angle. However, when the frequency deviates from the rated frequency, an error occurs because the data before three sampling periods are not correctly 90 degrees before the electrical angle. As a result, the protection relay characteristics are affected. Therefore, it is necessary to correct the calculation formula so that an accurate calculation result can be obtained even when the frequency of the power system deviates from the rated frequency.

For example, Japanese Patent Laid-Open No. 5-49151 (Patent Document 1) discloses an amplitude value calculation method that is not affected by a frequency shift. Specifically, from the digital value Im sampled at a predetermined time of the input electric quantity, and two digital values Im-j and Im + j that sandwich this Im in time series and are shifted by the same time before and after. Calculation of Im ² −Im−j × Im + j is performed. Further results to the Im ² - by multiplying the correction value corresponding to the ratio of the ^{{Im 2 (Im-j +} Im + j) 2/4}, the final amplitude value is calculated.

Japanese Patent Laid-Open No. 5-49151 Japanese Patent Laid-Open No. 1-227613

Supervised by Yoshifumi Ohura, "Protective Relay System Engineering", First Edition, The Institute of Electrical Engineers of Japan, March 15, 2002, p.111

  The calculation method described in Japanese Patent Laid-Open No. 5-49151 (Patent Document 1), which is not affected by the frequency shift, is specialized for amplitude value calculation. There is a problem that cannot be applied. Therefore, there is a need for a method that can be applied to any type of relay calculation without requiring a particularly complicated calculation as compared with a conventional relay calculation method that does not consider the influence of frequency deviation.

  The present invention has been made in consideration of the above-mentioned problems, and the object thereof is to execute a relay operation without being affected by a frequency shift for any kind of relay operation. Is to provide a protective relay device.

  In one aspect, the present invention is a protection relay device, and includes an analog / digital conversion unit, a difference / addition calculation unit, an amplitude value calculation unit, a phase delay data calculation unit, and a relay calculation unit. The analog / digital conversion unit generates time series data of the electric quantity by sampling the electric quantity representing the alternating current or the alternating voltage detected in the electric power system at a constant period and converting it into a digital value. The difference / addition calculation unit calculates the difference amount and the addition amount between the digital value of the current electric quantity and the digital value of the electric quantity n sampling periods before the current time (n is an integer of 1 or more) for each sampling of the electric quantity. By calculating, time series data of each of the difference amount and the addition amount is generated. The amplitude value calculation unit calculates the amplitude value of the electric quantity using a plurality of data including the current time among the electric quantity time-series data for each sampling of the electric quantity, and each time-series data of the difference amount and the addition amount The amplitude value of each of the difference amount and the addition amount is calculated by performing the same calculation as the calculation of the amplitude value of the electric quantity. The phase lag data calculation unit multiplies the digital value of the current electric quantity by the first coefficient and the digital value of the electric quantity one sampling period before the current time by the second coefficient for each sampling of the electric quantity. By calculating the sum with the value, the digital value of the electric quantity obtained by delaying the phase by the set angle from the current electric quantity is calculated. Said 1st coefficient and 2nd coefficient are represented using each amplitude value of the electric quantity calculated at the present time, difference amount, and addition amount. The relay calculation unit performs the relay calculation using the digital value of the electric quantity obtained by delaying the phase calculated by the phase delay data calculation unit.

  According to the present invention, since the digital value of the electric quantity whose phase is accurately delayed by the set angle is calculated and used for the relay calculation, the relay calculation can be executed without being affected by the frequency shift. Furthermore, since the set angle can be set arbitrarily, it can be applied to any kind of relay calculation.

It is a figure for demonstrating the connection of a protection relay apparatus and an electric power grid | system. It is a block diagram which shows the hardware constitutions of the protection relay apparatus of FIG. 2 is a block diagram illustrating a functional configuration of the protection relay device according to Embodiment 1. FIG. It is a flowchart which shows operation | movement of the digital input process part of FIG. It is a vector diagram which shows the relationship between the data used for the calculation in each step of FIG. In the protection relay device of Embodiment 2, it is a vector diagram which shows the relationship between the data used for the calculation in a digital input process part. 6 is a flowchart illustrating an operation of a digital input processing unit in the protection relay device according to the second embodiment. FIG. 10 is a block diagram showing a functional configuration of a protection relay device according to a third embodiment. It is a flowchart which shows operation | movement of the digital input process part of FIG. It is a vector diagram which shows the relationship between the data used for the calculation in each step of FIG.

  Hereinafter, each embodiment will be described in detail with reference to the drawings. The same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

<Embodiment 1>
FIG. 1 is a diagram for explaining a connection between a protection relay device and a power system.

  As shown in FIG. 1, a current transformer (CT) 2 and a voltage transformer 3 (VT: Voltage Transformer) are installed in a transmission line 1 of the power system. Although the power transmission line 1 is for three-phase alternating current, in FIG. 1, it is simplified and shown by one line. A current transformer 2 and a voltage transformer 3 are provided for each phase of the transmission line 1.

  The protection relay device 10 is connected to the current transformer 2 and the voltage transformer 3. The current transformer 2 converts the current flowing through the transmission line 1 into a current having a magnitude suitable for input to the protection relay device 10. The current converted by the current transformer 2 is input to the protection relay device 10. Similarly, the voltage transformer 3 converts the voltage of the power transmission line 1 into a voltage having a magnitude suitable for input to the protection relay device 10. The voltage converted by the voltage transformer 3 is input to the protection relay device 10.

[Hardware configuration of protection relay device]
FIG. 2 is a block diagram showing a hardware configuration of the protection relay device of FIG. Referring to FIG. 2, protection relay device 10 includes an input conversion unit 11 including auxiliary transformers 12_1, 12_2,... And a digital relay unit 13.

  The input conversion unit 11 is an input unit to which the current signal of each phase output from the current transformer 2 in FIG. 1 and the voltage signal of each phase output from the voltage transformer 3 in FIG. 1 are input. Each auxiliary transformer 12 converts the current signal and the voltage signal from the current transformer 2 and the voltage transformer 3 into a signal having a voltage level suitable for signal processing in the digital relay unit 13.

  The digital relay unit 13 includes analog filters (AF) 14_1, 14_2,..., Sample hold circuits (S / F: Sample Hold Circuits) 15_1, 15_2,. A digital (A / D: Analog to Digital) converter 17. The digital relay unit 13 further includes a CPU (Central Processing Unit) 18, a RAM (Random Access Memory) 19, a ROM (Read Only Memory) 20, a digital input (D / I: Digital Input) circuit 21, and a digital An output (D / O: Digital Output) circuit 22 and a bus 23 for connecting these components are included.

  Each analog filter 14 is a low-pass filter provided for removing aliasing errors during A / D conversion. Each sample and hold circuit 15 samples and holds the signal that has passed through the corresponding analog filter 14 at a predetermined sampling frequency. The multiplexer 16 sequentially selects the voltage signals held in the sample hold circuits 15_1, 15_2,. The A / D converter 17 converts the signal selected by the multiplexer into a digital value. The CPU 18 controls the overall operation of the protection relay device 10. The RAM 19 and ROM 20 are used as the main memory of the CPU 18. The ROM 20 uses a non-volatile memory such as a flash memory, and can store a program and / or a setting value for the user to determine relay characteristics in accordance with the system. The digital input circuit 21 and the digital output circuit 22 are interface circuits when the CPU 18 communicates with the outside of the protection relay device 10.

[Functional configuration of protection relay device]
FIG. 3 is a block diagram illustrating a functional configuration of the protection relay device according to the first embodiment. Functionally, the protection relay device 10 includes an analog circuit 30, an A / D conversion unit 31, a digital input processing unit 32, a relay calculation unit 33, and a digital output unit 34.

  The analog circuit 30 corresponds to the input conversion unit 11 and the analog filter 14 shown in FIG. Specifically, the analog circuit 30 insulates the current transformer 2 and the voltage transformer 3 from the internal circuit of the protection relay device 10, and the current signal and voltage input from the current transformer 2 and the voltage transformer 3, respectively. The signal is converted into an internal signal inside the protection relay device 10. Further, the analog circuit 30 removes a high frequency signal included in the current signal and / or the voltage signal by the analog filter 14.

  The A / D converter 31 corresponds to the sample hold circuit 15, the multiplexer 16, the A / D converter 17 and the like of FIG. Specifically, the A / D converter 31 sequentially converts the current signal and the voltage signal processed by the analog circuit 30 into digital. The digitally converted current signal and voltage signal are input to the digital input processing unit 32 at the next stage.

  The functions of the digital input processing unit 32 and the relay calculation unit 33 are realized by the CPU 18 operating according to a program stored in the ROM 20 in advance. The digital input processing unit 32 uses the digitally converted current signal and voltage signal to generate data used when performing various protection relay calculations in the relay calculation unit 33 in the next stage. In the case of this embodiment, the digital input processing unit 32 includes a data storage unit 40, a difference / addition calculation unit 41, an amplitude value calculation unit 42, a trigonometric function calculation unit 43, and a phase lag data calculation unit 44. Including. Specific arithmetic processing of these components will be described with reference to the flowchart of FIG.

  The relay calculation unit 33 performs various relay calculations using the data input from the digital input processing unit 32. For example, the relay calculation unit performs a phase difference calculation and an amplitude value calculation as described in Non-Patent Document 1. The relay calculation unit 33 determines whether or not a failure has occurred in the power system based on the relay calculation result. When the relay operation unit 33 determines that a failure has occurred, the relay operation unit 33 drives the next-stage digital output unit 34 (corresponding to the digital output circuit 22 in FIG. 2) to thereby provide an appropriate circuit breaker (see FIG. (Not shown). When the circuit breaker operates in response to this open signal, the detected fault site is disconnected from the power system.

[Operation of digital input processor]
FIG. 4 is a flowchart showing the operation of the digital input processing unit of FIG. The digital input processing unit 32 in FIG. 3 generates data used for relay calculation in the relay calculation unit 33 using the digitally converted current signal and voltage signal. For example, the digital input processing unit 32 generates 90 ° phase delay data necessary for the amplitude value calculation and the phase difference calculation. At this time, the generated 90 ° delayed phase data is characterized in that the value takes into account the influence of the frequency shift of the power system. Hereinafter, a specific description will be given with reference to FIGS. 3 and 4. Hereinafter, the AC voltage and AC current detected in the power system are collectively referred to as an electric quantity. An electric quantity (voltage value V _m and / or current value I _m ) sampled and digitized at each sampling period is referred to as an electric quantity digital value.

(1. Accumulation of sample data)
First, the data storage unit 40 (for example, corresponding to the RAM 19 in FIG. 2) converts the amount of electricity (voltage signal and / or current signal) digitally converted by the A / D conversion unit 31 for a certain time (that is, from the present time). 4) from the digital value V _mn of the electric quantity before the n sampling period to the digital value V _m of the current electric quantity) (step S100 in FIG. 4). That is, the data storage unit 40 generates time-series data of the digital value V _m of electricity. The sampling period at this time may be an arbitrary period such as 30 °, 22.5 °, or 36 ° in terms of electrical angle. The number of samples n is determined according to the number of samples necessary for calculation in the digital input processing unit 32 and the relay calculation unit 33. Since the digital value of the latest electric quantity at the present time is stored in the form of being overwritten on the digital value of the oldest electric quantity, n + 1 pieces of data V _m , V _m−1 , and n + 1 data before the current sampling period are always obtained. .., V _n are stored in the data storage unit 40.

  Note that the A / D converter 17 in FIG. 2 actually performs A / D conversion every shorter cycle (for example, 3.75 ° in terms of electrical angle), and the data after A / D conversion is converted into the above-described data. What is time-averaged at each sampling period is used for calculation in the digital input processing unit 32.

(2. Calculation of difference and addition)
The differential-adder 41, each electrical quantity sampled, using data from the digital value V _m and two sampling periods before the electric quantity of 2-point digital value V _m-2 of the electrical quantity at the present time A difference operation and an addition operation are performed. That is, the difference / addition calculation unit 41 uses the difference amount D _m and the addition amount S _m as follows:
D _m = − (V _m −V _m−2 )… (1)
S _m = V _m + V _m-2 (2)
Is calculated (step S110). Data storage unit 40, the above difference amount D _m and the addition amount S _m, only accumulating time period required for subsequent operation (step S120). That is, the data storage unit 40, generates the time-series data of each of the difference amount D _m and the adding quantity S _m.

(3. Calculation of amplitude value)
Next, for each sampling of the electric quantity, the amplitude value calculation unit 42 calculates the electric quantity amplitude value AV _m using the electric quantity digital value V _m at a plurality of time points including the present time among the electric quantity time-series data. Calculate. Further, the amplitude value calculation unit 42 performs the same calculation as the amplitude value calculation of the electric quantity on each time series data of the difference quantity D _m and the addition quantity S _m , thereby calculating the difference quantity D _m . calculating the amplitude value AS _m amplitude value AD _m and the addition amount S _m (step S130). Here, the amplitude value AS _m amplitude value AD _m and the addition amount S _m of the difference amount D _m, exchanges when the respective time-series data of the difference amount D _m and the addition amount S _m viewed as a sampling data of the AC signal It means the amplitude value of the signal.

For the above-described amplitude value calculation, a calculation method is adopted in which the amplitude value is constant regardless of the phase angle at the sampling time if the AC input has no distortion. For example, the method described in JP-A-1-227613 (Patent Document 2) is used. This document describes a digital value V _m of an electric quantity at a predetermined time, a digital value V _mx of an electric quantity before the x sampling period, a digital value V _my of an electric quantity before the y sampling period, and a digital value V _my before the z sampling period. Using the electric quantity digital value V _mz (where z = x + y), the product of the electric quantity digital value V _mx and the electric quantity digital value V _my , the electric quantity digital value V _m and the electric quantity digital A method for performing an amplitude value calculation of an electric quantity based on a difference from a product with a value V _mz is disclosed. Specifically, the square root of the absolute value of the difference is calculated.

Hereinafter, the amplitude value calculation unit 42 uses the calculation formula in the case of x = y = 1 and z = 2 among the calculation formulas described in JP-A-1-227613 (Patent Document 2). An operation is performed (the values of x, y, and z are not limited to the above values). In this case, the amplitude value AV _m , the amplitude value AD _m , and the amplitude value AS _m are
AV _m = K * √ (| V _m-1 * V _m-1 −V _m * V _m-2 |)… (3)
AD _m = K * √ (| D _m-1 * D _m-1 −D _m * D _m-2 |) (4)
AS _m = K * √ (| S _m-1 * S _m-1 −S _m * S _m-2 |) (5)
It is expressed as Here, √ (A) represents the square root of A, and | A | represents the absolute value of A. “*” Is used as a multiplication symbol. The coefficient K depends on the frequency, but is a value common to the above equations (3), (4), and (5). Therefore, the coefficient K can be eliminated by taking the ratio of any two of the above equations (3), (4), and (5). In the flowchart of FIG. 4, the description of the coefficient K is omitted for simplicity.

(4. Calculation of trigonometric function of electrical angle θ)
Next, the trigonometric function calculation unit 43 calculates a trigonometric function of the electrical angle θ (angular displacement θ per sampling period) corresponding to the sampling period (step S140). Specifically, the trigonometric function calculation unit 43
cosθ ＝ AS _m / (2 * AV _m )… (6)
sinθ = AD _m / (2 * AV _m )… (7)
tanθ ＝ AD _m / AS _m … (8)
The cosine, sine, and tangent of the electrical angle θ are calculated as follows. The reason why the trigonometric function of the electrical angle θ is obtained according to the above formula will be described later with reference to FIG.

(5. Calculation of phase lag data considering frequency deviation)
Next, the phase lag data calculating unit 44 calculates a phase lag value V _m ∠ (−φ) by a desired angle φ from the current digital value V _m of electricity (step S150). For example, the phase delay data calculation unit 44 calculates a value V _m ∠ (−90 °) whose phase is delayed by 90 ° from the current digital value V _m of electricity.
V _m ∠ (-90 °) ＝ V _m-1 / sinθ−V _m / tanθ… (9)
Calculate according to By substituting the equations (7) and (8) into the above equation (9), the 90 ° phase delay data V _m ∠ (−90 °) is
V _m ∠ (-90 °) ＝ V _m-1 * 2 * AV _m / AD _m −V _m * AS _m / AD _m … (10)
It is expressed.

  The reason why the 90 ° phase delay value can be calculated using the above equation (9) will be described later with reference to FIG. Further, a method of calculating data whose phase is delayed by an arbitrary angle φ will be described later with reference to FIG.

Here, for example, if the electrical angle corresponding to the sampling period is 30 °, it is exactly 30 ° in the case of the rated frequency. However, when the frequency deviates from the rating, the electrical angle corresponding to the sampling period is not exactly 30 °, but becomes an angle depending on the frequency. For this reason, for example, if the 90 ° phase delay data necessary for the phase difference calculation is simply used as the value V _m−3 before 3 sampling periods, the phase delay will be 90 ° when the frequency deviates from the rated value. An error occurs. On the other hand, by using the 90 ° phase delay data calculated according to the above formula (9) or (10), 90 ° phase delay data can be accurately obtained from the present time without being affected by the frequency fluctuation.

[Explanation using vector diagram]
FIG. 5 is a vector diagram showing a relationship between data used for calculation in each step of FIG. Hereinafter, the voltage vector will be described, but the same relationship holds for the current vector. In the following description, for the sake of simplicity, the same reference numerals are used for the instantaneous values and vectors of the electric quantity V _m , the difference quantity D _m , and the addition quantity S _m .

Vector diagram of FIG. 5 (A) shows a voltage vector V _m the current, 1 sampling period before the voltage vector V _m-1, of two sampling periods before the relationship between the voltage vector V _m-2. For each sampling period, the voltage vector is displaced by an angle θ corresponding to one sampling period. FIG. 5A further shows a difference vector D _m = − (V _m −V _m−2 ). From FIG. 5 (A), the relationship between the amplitude value AV _m amplitude value AD _m and the voltage vector V _m of the difference vector D _m is
AD _m = 2 * AV _m * sinθ (11)
It is expressed.

The vector diagram of FIG. 5B shows the relationship between the voltage vectors V _m , V _m−1 , V _m−2 and the addition vector S _m = V _m + V _m−2 . From FIG. 5 (B), the relationship between the amplitude value AV _m amplitude value AS _m and the voltage vector V _m of add vector S _m,
AS _m = 2 * AV _m * cosθ (12)
Represented by From the equations (11) and (12), the trigonometric function of the electrical angle θ shown in the aforementioned equations (6), (7), and (8) is derived.

The vector diagram of FIG. 5C shows a method of constructing a 90 ° phase lag vector V _m ∠ (−90 °) by a linear sum (primary combination) of the voltage vector V _m and the voltage vector V _m−1. It is for explanation. As shown in FIG. 5C, a vector V _m ∠ (−90 °) having a phase delay of 90 ° using scalars k ₁ and k ₂ is
V _m ∠ (-90 °) ＝ k ₂ * V _m-1 −k ₁ * V _m … (13)
It can be expressed as.

Here, the sides of the triangle formed by the vector k ₂ * V _m−1 , the vector k ₁ * V _m , and the vector V _m ∠ (−90 °) are k ₂ * AV _m−1 and k ₁ , respectively. * has a size of AV _m, and AV _m, since AV _m = AV _m-1, the ratio of the length of each side, k _2: k _1: represented by 1. Therefore, by the sine theorem,
1 / sinθ = k ₁ / sin (90 ° −θ) = k ₂ / sin90 °… (14)
Holds. That is,
1 / sinθ = k ₁ / cosθ = k ₂ (15)
Is established. From this, the coefficients k ₁ and k ₂ are
k ₁ = cosθ / sinθ = 1 / tanθ (16)
k ₂ = 1 / sinθ (17)
And given. By substituting the above equations (16) and (17) into the equation (13), the above equation (9) is derived. As is apparent from the above calculation process, the phase lag vector V _m ∠ (−90 °) is not affected by the frequency fluctuation.

[Calculation Method of Vector V _m ∠ (−φ) Delayed by Arbitrary Phase φ]
The vector diagram of FIG. 5D shows a vector V _m ∠ (−φ) delayed by a phase φ from the voltage vector V _m by a linear sum (primary combination) of the voltage vector V _m and the voltage vector V _m−1. Shows how to configure. As shown in FIG. 5D, using the scalars k ₃ and k ₄ , the vector V _m ∠ (−φ) of the delayed phase φ is
V _m ∠ (-φ) = k ₄ * V _m-1 −k ₃ * V _m … (18)
It can be expressed as.

Here, the sides of the triangle formed by the vector k ₄ * V _m−1 , the vector k ₃ * V _m , and the vector V _m ∠ (−φ) are k ₄ * AV _m−1 and k ₃ *, respectively. have a size of AV _m, and AV _m, since AV _m = AV _m-1, the ratio of the length of each side, k _4: k _3: represented by 1. Therefore, by the sine theorem,
1 / sinθ = k ₃ / sin (φ−θ) = k ₄ / sin (180 ° −φ)… (19)
Holds. From this, the coefficients k ₃ and k ₄ are
k ₃ = sin (φ−θ) / sinθ = (sinφ * cosθ−cosφ * sinθ) / sinθ
= Sinφ / tanθ−cosφ… (20)
k ₄ = sinφ / sinθ… (21)
It becomes.

By substituting the above equations (20) and (21) into equation (18),
V _m ∠ (-φ) = V _m-1 * sinφ / sinθ−V _m * (sinφ / tanθ−cosφ)… (22)
Is obtained. Furthermore, by substituting Equations (7) and (8) into Equation (22) above,
V _m ∠ (-φ) = V _m-1 * sinφ * 2AV _m / AD _m −V _m * (sinφ * AS _m / AD _m −cosφ)… (23)
Is obtained. In this way, an operation for phase shifting the vector V _m to an arbitrary angle is possible.

[effect]
As described above, according to the first embodiment, even if the input data deviates from the rated frequency, it is possible to accurately calculate the instantaneous value of the vector having a phase delayed by 90 ° from the current time. By using the instantaneous value of this accurate 90 ° delayed phase vector, it is possible to obtain a phase difference calculation or amplitude value calculation result that does not affect the frequency shift. Furthermore, an instantaneous value of a vector delayed by an arbitrary phase angle φ from the current time can be obtained by the same calculation method, and can be used for relay calculation.

  Further, the above calculation can be performed regardless of the sampling period (electrical angle θ). Therefore, not only in the case of a standard 30 ° electrical angle, a sampling cycle such as 22.5 ° (sampling frequency 16 times the rated frequency) or 36 ° (sampling frequency 10 times the rated frequency) is used. The applied protection relay can perform the amplitude value calculation and the phase difference calculation by the same calculation. Thereby, there is an advantage that it is not necessary to change the arithmetic algorithm in accordance with the sampling period.

<Embodiment 2>
In the first embodiment, a method of obtaining a current or voltage vector that is 90 ° phase lag or a phase lag by an arbitrary angle φ from the current time using the current current or voltage vector and the current or voltage vector two sampling periods before the current sampling time. explained. In the second embodiment, the current or voltage vector at the current time and the current or voltage vector one sampling period before are used, and the current or voltage delayed by 90 ° phase delay and an arbitrary phase angle φ without depending on the sampling frequency. An arithmetic expression capable of obtaining a voltage vector is provided.

[Calculation formula for 90 ° phase lag data]
FIG. 6 is a vector diagram illustrating a relationship between data used for calculation in the digital input processing unit in the protection relay device according to the second embodiment. Hereinafter, the voltage vector will be described, but the same relationship holds for the current vector.

Vector diagram of FIG. 6 (A) is a voltage vector V _m the current, one sampling period before the voltage vector V _m-1, the difference vector E _m = - the relationship between the (V _m -V _m-1) It is shown. From FIG. 6 (A), the relationship between the amplitude value AV _m amplitude value AE _m and the voltage vector V _m of the difference vector E _m is
AE _m = 2 * AV _m * sin (θ / 2)… (24)
Represented by

Vector diagram of FIG. 6 (B) illustrates the voltage vector V _m of current, the 1 sampling period before the voltage vector V _m-1, the relationship between the add vector _{T m = V m + V m} -1 . FIG from 6 (B), the relationship between the amplitude value AV _m amplitude value AT _m and the voltage vector V _m of the adding vector T _m,
AT _m = 2 * AV _m * cos (θ / 2)… (25)
Represented by Here, the electrical angle between the current voltage vector V _m and the voltage vector V _m−1 one sampling period before is θ.

From the above formulas (24) and (25),
cos (θ / 2) ＝ AT _m / (2 * AV _m )… (26)
sin (θ / 2) ＝ AE _m / (2 * AV _m )… (27)
Is obtained. Furthermore, by using the above formulas (26) and (27) and the double angle formula of the trigonometric function,
sinθ = 2 * sin (θ / 2) * cos (θ / 2) = 2 * (AE _m / 2 * AV _m )) * (AT _m / (2 * AV _m )
= AE _m * AT _m / (2 * AV _m * AV _m )… (28)
cos θ = 2 * ((cos (θ / 2)) ² −1) = 2 * (AT _m / 2 * AV _m ) * (AT _m / (2 * AV _m ) −1
= AT _m * AT _m / (2 * AV _m * AV _m ) −1 (29)
tanθ = (AE _m * AT _m / (2 * AV _m * AV _m )) / (AT _m * AT _m / (2 * AV _m * AV _m ) -1)
= AE _m * AT _m / (AT _m * AT _m −2 * AV _m * AV _m )… (30)
Is obtained.

As described with reference to the vector diagram of the above-described FIG. 5 (C), the voltage vector V _m from 90 ° phase lag of the voltage vector V _m ∠ the current (-90 °) is in the above-mentioned formula (9) Represented. Therefore, by substituting the above equations (28) and (30) into equation (9), the voltage vector V _m ∠ (−90 °) with a 90 ° phase delay is
V _m ∠ (-90 °) ＝ V _m-1 / sinθ−V _m / tanθ
= V _m-1 * 2 * AV _m * AV _m / (AE _m * AT _m ) −V _m * (AT _m * AT _m −2 * AV _m * AV _m ) / (AE _m * AT _m )… ( 31)
Can be calculated.

  FIG. 7 is a flowchart showing the operation of the digital input processing unit in the protection relay device of the second embodiment. Hereinafter, with reference to FIG. 3 and FIG.

First, the data accumulating unit 40 converts the amount of electricity (voltage signal and / or current signal) digitally converted by the A / D conversion unit 31 for a certain time (that is, the digital value V of the amount of electricity before the n sampling period from the present time). ₍ from _mn to the current digital value V _m of electricity) is accumulated (step S200 in FIG. 7). That is, the data storage unit 40 generates time-series data of the digital value V _m of electricity.

The differential-adder 41, each electrical quantity sampled, using data from two points of the digital values V _m-1 digital value V _m and one sampling period before the electric quantity of electric quantity of current Difference calculation and addition calculation are performed (step S210). The difference amount E _m and the addition amount T _m are
E _m = − (V _m −V _m−1 )… (32)
T _m = V _m + V _m-1 (33)
It is expressed as Data storage unit 40, a differential amount E _m and the addition amount T _m, by accumulating time period required for subsequent operation (step S220). That is, the data storage unit 40, generates the time-series data of each of the differential amount E _m and the addition amount of T _m.

Next, for each sampling of the electric quantity, the amplitude value calculation unit 42 calculates the electric quantity amplitude value AV _m using the electric quantity digital value V _m at a plurality of time points including the present time among the electric quantity time-series data. Calculate. Further, the amplitude value calculation unit 42 performs the same calculation as the amplitude value calculation of the electric quantity on each time series data of the difference quantity D _m and the addition quantity S _m , thereby calculating the difference quantity E _m . calculating the amplitude value AT _m amplitude value AE _m, and the addition amount T _m (step S230). For the amplitude value calculation, a calculation method is adopted in which the amplitude value is constant regardless of the phase angle at the sampling time if the AC input has no distortion. Specifically, using the method described in Japanese Patent Application Laid-Open No. 1-227613 (Patent Document 2), for example, the same calculation as that described in Expressions (3) to (5) is performed.

  Next, the trigonometric function calculation unit 43 calculates a trigonometric function of the electrical angle θ (angular displacement θ per sampling) corresponding to the sampling period (step S240). The arithmetic expressions of the trigonometric functions are shown in the above expressions (28) to (30).

Next, the phase lag data calculation unit 44 calculates a phase lag value V _m ∠ (−90 °) by 90 ° from the current digital value V _m of electric quantity according to the above equation (31) (step S250). .

[Calculation formula for data delayed by an arbitrary phase angle φ]
A voltage vector V _m ∠ (−φ) whose phase is delayed by an angle φ from the current voltage vector V _m is given by the above-described equation (22). The above equation to equation (22) (28), by substituting (30), the angle φ by a phase lag voltage Bekutoruru V _m ∠ (-.phi) is
V _m ∠ (-φ) = V _m-1 * sinφ / sinθ-V _m * (sinφ / tanθ-cosφ)
= V _m-1 * sinφ * 2 * AV _m * AV _m / (AE _m * AT _m )
−V _m * (sinφ * (AT _m * AT _m −2 * AV _m * AV _m ) / (AE _m * AT _m ) −cosφ) (34)
Can be calculated.

  As described above, in the second embodiment, the current or voltage vector at the current time and the current or voltage vector before one sampling period are used, and the current or voltage vector is delayed by 90 ° from the current time without depending on the sampling frequency. And an arithmetic expression for generating a current or voltage vector whose phase is delayed by an arbitrary phase angle φ is provided. Similar to the case of the first embodiment, this arithmetic expression is not affected by frequency fluctuations, and has higher responsiveness than the case of the first embodiment.

<Modification of Embodiments 1 and 2>
In the first embodiment, a method of calculating phase delay data that does not depend on frequency fluctuations using a difference amount and an addition amount between a digital value of the current electric quantity and a value two sampling periods ago is shown. In the second embodiment, The method of calculating phase delay data that does not depend on the frequency variation using the difference amount and the addition amount between the digital value of the current electric amount and the value before one sampling period is shown. By using the same concept, a phase delay that does not depend on frequency variation using the difference amount and the addition amount between the digital value of the current electric quantity and the value before n sampling periods (n is an integer of 1 or more). Data can be calculated. However, since it is desirable that the phase before the n sampling period is less than 180 ° from the present time, when the electrical angle corresponding to the sampling period is θ and the frequency variation is 10%, the above n is n *. It is necessary to satisfy the relationship of θ ≦ 160 ° (≈180 ° * 90%). However, as n increases, the responsiveness deteriorates. Therefore, n = 1 or n = 2 is desirable for practical use.

<Embodiment 3>
For example, in the change width detection relay calculation, the difference between the digital value of the current electric quantity and the digital value of the electric quantity several cycles before (for example, the digital value of the electric quantity two cycles before) is changed. By detecting whether or not, a change in current or voltage is detected. In such a relay, when the frequency is the rated frequency and there is no change in the power system, the digital value of the current quantity of electricity and the digital value of the quantity of electricity before p cycles (p is an integer of 1 or more) Although the difference is 0, if the frequency deviates from the rated value, an error due to the frequency deviation occurs in the difference result, which becomes a cause of erroneous detection.

  In the third embodiment, since the frequency deviates from the rated frequency, for example, an arithmetic method capable of correcting a phase shift that occurs in a digital value of an electric quantity two cycles before is provided. Hereinafter, it will be described in detail with reference to the drawings.

[Configuration and operation of digital input / output unit]
FIG. 8 is a block diagram illustrating a functional configuration of the protection relay device according to the third embodiment. The protection relay device 10 of FIG. 8 differs from the protection relay device 10 of FIG. 3 in that the digital input processing unit 32 further includes a phase shift correction unit 45. Assuming that the phase shift amount from two cycles before (generally before p cycles) to the present time is α, the phase shift correction unit 45 is a digital of the electric quantity (voltage signal and / or current signal) two cycles before the current time. For the value V _m-2c , a value V _m-2c ∠ (α) obtained by correcting the phase shift angle α is calculated. A specific calculation method will be described later with reference to the flowchart of FIG. In the above notation, for example, when the electrical angle θ corresponding to the sampling period is 30 °, c representing the number of samples in one cycle is c = 12, and the electrical angle θ is 22.5 ° C = 16. One cycle corresponds to an electrical angle of 360 °.

  Further, the protection relay device 10 of FIG. 8 is different in the calculation contents of the difference / addition calculation unit 41 and the calculation contents of the phase delay data calculation unit 44. These different points will be described later with reference to the flowchart of FIG. Since the other points of FIG. 8 are substantially the same as those of FIG. 3, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

FIG. 9 is a flowchart showing the operation of the digital input processing unit of FIG. Hereinafter, with reference to FIG. 8 and FIG. 9, a method for correcting a phase when a phase shift occurs in the digital value of the electric quantity several cycles before due to the frequency shift will be described. In the following, a method of correcting the digital value V _m-2c of the electric quantity two cycles before will be described, but not limited to the correction of the phase shift of the digital value V _m-2c of the electric quantity two cycles before, generally before the p cycle. The present invention can also be applied to the correction of the phase shift of the digital value V _m-pc of the electrical quantity (p is an integer of 1 or more).

(1. Accumulation of digital value of electricity)
First, the data storage unit 40 calculates the amount of electricity (voltage signal and / or current signal) digitally converted by the A / D conversion unit 31 for a predetermined time (from the digital value V _{mn of the} amount of electricity before the n sampling period from the present time). (To the digital value V _m of the current electric quantity) is accumulated (step S300 in FIG. 9). That is, the data storage unit 40 generates time-series data of the digital value V _m of electricity. The number of samples n is determined according to the number of samples necessary for calculation in the digital input processing unit 32 and the relay calculation unit 33.

(2. Calculation of difference and addition)
Next, the difference / addition calculation unit 41, every time the amount of electricity is sampled, the digital value V _m of the current amount of electricity, and 4 cycles before that which is twice the cycle before phase correction (generally 2p cycles before) The difference calculation and the addition calculation are performed using the data of two points of the digital value V _m-4c of the electric quantity. That is, the difference / addition calculation unit 41 determines the difference amount G _m and the addition amount W _m as follows:
G _m = − (V _m −V _m−4c )… (35)
W _m = V _m + V _m-4c (36)
Is calculated (step S310). Further, the difference / addition calculation unit 41 sets the difference amount D _m between the current digital value V _m of the electric quantity and the value V _m−2 before two sampling periods as
D _m = − (V _m −V _m−2 )… (37)
Is calculated. Data storage unit 40, the above difference amount D _m and the differential amount G _m and the addition amount W _m, only accumulating time period required for subsequent operation (step S320). That is, the data storage unit 40 generates time series data of the difference amount D _m , the difference amount G _m , and the addition amount W _m .

(3. Calculation of amplitude value)
Next, for each sampling of the electric quantity, the amplitude value calculation unit 42 calculates the electric quantity amplitude value AV _m using the electric quantity digital value V _m at a plurality of time points including the present time among the electric quantity time-series data. Calculate. Further, the amplitude value calculation unit 42 performs the same calculation as the above-described amplitude value calculation of the electric quantity on each time series data of the difference amount D _m , the difference amount G _m , and the addition amount W _m . , the amplitude value AD _m of the difference amount D _m, to calculate the amplitude value AW _m amplitude value AG _m, and the addition amount W _m of difference amount G _m (step S330). Here, for the amplitude value calculation, a calculation method is adopted in which the amplitude value is constant regardless of the phase angle at the sampling time if the AC input has no distortion. For example, the method described in JP-A-1-227613 (Patent Document 2) is used. If the same arithmetic expression as the above-described expressions (3) to (5) is used,
AV _m = K * √ (| V _m-1 * V _m-1 −V _m * V _m-2 |)… (38)
AD _m = K * √ (| D _m-1 * D _m-1 −D _m * D _m-2 |) (39)
AG _m = K * √ (| G _m-1 * G _m-1 −G _m * G _m-2 |)… (40)
AW _m = K * √ (| W _m-1 * W _m-1 −W _m * W _m-2 |)… (41)
It is expressed. The data accumulating unit 40 accumulates these amplitude values as much as necessary for the subsequent calculation.

(4. Detection of sudden change in current or voltage)
Next, the amplitude value calculator 42 determines whether or not the current or voltage of the power system has suddenly changed due to the occurrence of a failure in the power system (step S340). When the current or voltage changes suddenly, the phase and amplitude of the input electric quantity change suddenly, so that each amplitude value calculated in step S330 is different from the previous value. Therefore, the amplitude value calculation unit 42 determines whether or not the absolute value of the difference between the current amplitude value and the amplitude value of 1 to 2 cycles before is greater than or equal to the determination value,
｜ AV _m −AV _mj ｜ ＞ M1… (42)
｜ AD _m −AD _mj ＞＞ M2… (43)
｜ AG _m −AG _mj ＞＞ M3… (44)
｜ AW _m −AW _mj ＞＞ M4… (45)
It is determined that either of the above holds. Here, m−j indicates a digital value of the electric quantity j cycles before the present time, and a value of about 1 to 2 cycles is generally selected as j. Determination values M1, M2, M3, and M4 are generally set to values that can detect a change of about several percent of current rating or voltage rating. Actually, it is not necessary to determine all the above four formulas, and any one of them may be determined.

  If any of the above equations (42) to (45) is established, the amplitude value calculator 42 proceeds to the next step S360 without executing step S350 for calculating the next angle. . The reason why the angle calculation of the next step is not executed when a sudden change in current or voltage is detected is as follows. First, when the quantity of electricity (current and / or voltage) changes suddenly, the amplitude value and phase of the quantity of electricity also change suddenly, so that the phase shift amount α due to frequency fluctuation cannot be evaluated correctly. Second, even if there is a frequency change, the change is relatively slow due to the inertia of the generator, so the calculation using the digital value of the electric quantity, the angle θ, and the phase shift amount α before the sudden change is detected. This is because there is no practical problem even if it is performed.

(5. Calculation of trigonometric function of phase shift amount α and electrical angle θ)
Next, the trigonometric function calculator 43, the amplitude value AD _m, the amplitude value AG _m of difference amount G _m of the amplitude value AV _m, difference amount D _m of the digital values V _m of the electric amount calculated in step S330, and addition by using the amplitude value AW _m quantity W _m, it calculates a trigonometric function of the electrical angle α indicating the phase shift amount of the digital values V _m of the electric quantity between two cycles (step S350). Specifically, the trigonometric function calculation unit 43
cosα ＝ AW _m / (2 * AV _m-2c )… (46)
sinα = AG _m / (2 * AV _m-2c )… (47)
Then, cosine and sine are calculated for α for phase shift. Further, the trigonometric function calculation unit 43 calculates the sine of the electrical angle θ corresponding to one sampling period,
sinθ = AD _{m + 1-2c} / (2 * AV _m-2c )… (49)
Calculate according to Here, the phase shift amount α depends on the frequency of the input data. In the above equation, the amplitude value AV _m-2c of the electric quantity two cycles before is used for the calculation. However, when the electric quantity (current or voltage) is not in a sudden change state, that is, AV _m-2c = AV _m is almost established. Therefore, there is no particular problem even if the current amplitude value AV _m of the electric quantity is used in the calculation.

(Calculation of 6.90 ° phase lag data)
Next, for each sampling of the electric quantity, the phase lag data calculation unit 44, the digital value V _m-2c of the electric quantity two cycles before the current time, and the digital value V _{m +} of the electric quantity one sampling period after that. _1-2c is used to calculate a value V _m−2c ∠ (−90 °) delayed in phase by 90 ° from the digital value V _m−2c of the electric quantity two cycles before the current time (step S360). Specifically, the phase lag data calculation unit 44
V _m-2c ∠ (-90 °) ＝ D _{m + 1-2c} / (2 * sinθ)… (50)
Then, a value V _m−2c ∠ (−90 °) with a 90 ° phase delay is calculated.

(7. Correction of phase shift α)
Next, the phase shift correction unit 45 calculates a value V _m-2c電 気 (α) obtained by returning the phase by the phase shift amount α from the digital value V _m-2c corresponding to two cycles before the rated frequency. (Step S370). Specifically, as described in FIG. 10, from the relationship between V _m−2c ∠ (α) and V _m−2c ∠ (−90 °),
V _m-2c ∠ (α) = V _m-2c * cosα−V _m-2c ∠ (-90 °) * sinα… (51)
Holds.

[Explanation using vector diagram]
FIG. 10 is a vector diagram showing a relationship between data used for calculation in each step of FIG. Hereinafter, the voltage vector V _m will be described, but the same applies to the current vector I _m . In the following description, for the sake of simplicity, the same reference numerals are used for the instantaneous values and vectors of the electric quantity V _m , the difference quantity D _m , the difference quantity G _m , and the addition quantity W _m .

The vector diagram of FIG 10 (A) shows a voltage vector V _m at the present time, the previous voltage vector V _m-2c two cycles, four cycles before the relation between the voltage vector V _m-4c. Due to the frequency deviation from the rated frequency, the phase is shifted by α every two cycles. FIG. 10A further shows a difference vector G _m = − (V _m −V _m−4c ). Relationship from FIG. 10 (A), the amplitude value AV _m-2c amplitude value AG _m and the voltage vector V _m-2c of the difference vector G _m is
AG _m = 2 * AV _m-2c * sinα… (52)
Represented by

The vector diagram of FIG. 10B shows the relationship between the voltage vectors V _m , V _m−2c , V _m−4c and the addition vector W _m = V _m + V _m−4c . From FIG. 10 (B), the relationship between the amplitude value AV _m amplitude value AW _m and the voltage vector V _m of the adding vector W _m,
AW _m = 2 * AV _m-2c * cosα… (53)
Represented by

The vector diagram of FIG. 10C shows a voltage vector V _m-2c two cycles before the current time, a vector V _m-1-2c one sampling period before the voltage vector, and a vector V after one sampling period. The relationship with _{m + 1-2c} is shown. Every one sampling period, the voltage vector is displaced by an angle θ. FIG. 10C further shows a difference vector D _{m + 1−2c} = − (V _{m + 1−2c} −V _m−1-2c ). The difference vector D _{m + 1-2c} is a voltage vector V _m-1-2c before one sampling period and a voltage vector V after one sampling period with respect to the digital value V _m-2c of the electric quantity two cycles before the present time. _This is the difference from _{m + 1-2c} . From FIG. 5C, the amplitude value AD _m-2c of the difference vector D _m-2c is 2 * sinθ times the amplitude value AV _{m + 1-2c} of the voltage vector V _{m + 1-2c} .
AD _{m + 1-2c} = 2 * AV _m-2c * sinθ (54)
The relationship holds. Furthermore, by using the above equation (54), the vector V _m-2c ∠ (−90 °) whose phase is delayed by 90 ° from the voltage vector V _m-2c is
V _m-2c ∠ (-90 °) = D _{m + 1-2c} / (2 * sinθ) = D _{m + 1-2c} * (AV _m-2c / AD _{m + 1-2c} )… (55)
Given in. From the equations (52) to (54), the above-described trigonometric equations (46) to (49) are obtained.

Vector diagram of FIG. 10 (D) two cycles before the voltage vector V _m-2c the voltage vector V _m-2c ∠α phase-shifted by an angle alpha, the voltage vector V _m-2c than the present time, the voltage vector It shows a method of configuring by a linear sum (primary coupling) with a voltage vector V _m-2c ∠ (−90 °) whose phase is delayed by 90 ° from V _m-2c . Specifically, from FIG.
V _m-2c ∠ (α) = V _m-2c * cosα−V _m-2c ∠ (-90 °) * sinα… (56)
Holds. By substituting the equations (46) and (47) into the above equation (56), the vector V _m-2c ∠ (α) phase-shifted by the angle α is
V _m-2c ∠ (α) = V _m-2c * AW _m-2c / (2 * AV _m-2c )
−D _{m + 1-2c} * (AV _m-2c / AD _{m + 1-2c} ) * AGm / (2 * AV _m-2c )… (57)
You can calculate with.

In this way, it is possible to correct the phase shift α of the amount of electricity that occurs when the frequency deviates from the rated frequency. Be offset frequency than the rated frequency, it is obtained in a state where the digital value V _m-2c quantity of electricity two cycles before the digital value V _m of the electric quantity of current, the phase shift due to frequency shift are corrected it can.

[effect]
As described above, since the input data deviates from the rated frequency, the phase shift angle α is generated between the digital value of the current electrical quantity and the digital value of the electrical quantity before p cycles (p is an integer of 1 or more) from the current time. Even if it is, it can be easily corrected as follows. That is, the difference amount and the addition amount between the digital value of the electric amount before 2 × p cycles and the digital value of the current electric amount are calculated, and the sine and cosine of the phase shift angle α are calculated based on the difference amount and the addition amount. Ask for. Furthermore, the 90 ° phase from the digital value of the electric quantity two cycles before is calculated from the digital value of the electric quantity one sampling period before and the digital value of the electric quantity after one sampling period before the p cycle. Obtain the digital value of the delayed amount of electricity. The phase shift can be corrected from these calculation results. Therefore, even when the frequency deviates from the rating, it is possible to accurately determine the change between the current time and the previous p cycle.

[Modification]
In the third embodiment, the digital value of the electric quantity at the present time and the digital value of the electric quantity at the time 2 × p cycles before the current time (for example, p = 2) are used to calculate the digital value of the electric quantity before the p cycle from the current time. Means for correcting an error caused by the phase shift angle α in FIG. On the other hand, the phase shift angle in the digital value of the electric quantity before the p cycle using two points of the digital value of the electric quantity at the present time used for the change width detection and the digital value of the electric quantity before the p cycle from the current time. You may make it correct | amend the error resulting from (alpha). In this case, as in the second embodiment, a trigonometric function having an angle α / 2 that is ½ of the phase shift angle α is first obtained, and the trigonometric function of the phase shift angle α is calculated using the double angle formula of the trigonometric function. Try to ask.

Further, in the third embodiment, when calculating a value obtained by delaying the phase by 90 ° with respect to the digital value of the electric quantity before the p cycle (for example, p = 2), it is more than the digital value of the electric quantity before the p cycle. The difference amount D _{m + 1-pc} is calculated using the digital value of the electric quantity before and after one sampling period, and the 90 ° phase lag value is calculated using this difference quantity D _{m + 1-pc.} did. Instead, in accordance with the method shown in the first and second embodiments, the digital value V _m-pc of the electric quantity before the p cycle and the digital value V _m-1-pc of the electric quantity one sampling period earlier than that. You may obtain | require the value 90 degree phase-lag by the linear sum (linear combination).

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Transmission line, 2 Current transformer, 3 Voltage transformer, 10 Protection relay apparatus, 18 CPU, 31 A / D conversion part, 32 Digital input processing part, 33 Relay operation part, 34 Digital output part, 40 Data storage part, 41 addition calculation unit, 42 amplitude value calculation unit, 43 trigonometric function calculation unit, 44 phase lag data calculation unit, 45 phase shift correction unit.

Claims (9)

An analog / digital conversion unit that generates time-series data of the electric quantity by sampling an electric quantity representing an alternating current or an alternating voltage detected in the electric power system at a constant period and converting it into a digital value;
For each sampling of the electrical quantity, by calculating the difference amount and the addition amount between the current digital value of the electrical quantity and the digital value of the electrical quantity n times before the current sampling period (n is an integer of 1 or more) A difference / addition calculation unit for generating time series data of each of the difference amount and the addition amount;
For each sampling of the electric quantity, the amplitude value of the electric quantity is calculated using a plurality of data including the current time among the time series data of the electric quantity, and for each time series data of the difference quantity and the addition quantity An amplitude value calculation unit that calculates the amplitude value of each of the difference amount and the addition amount by performing the same calculation as the amplitude value calculation of the electric quantity;
For each sampling of the electrical quantity, a sum of a value obtained by multiplying the current digital value of the electrical quantity by a first coefficient and a value obtained by multiplying the digital value of the electrical quantity one sampling period before the current time by a second coefficient. A phase lag data calculation unit that calculates a digital value of the electric quantity obtained by delaying the phase by a set angle from the current electric quantity,
The first coefficient and the second coefficient are expressed using amplitude values of the electric quantity, the difference quantity, and the addition quantity calculated at the present time,
Furthermore, the protection relay apparatus provided with the relay calculating part which performs a relay calculation using the digital value of the said electric quantity which delayed the said phase.   The protection relay device according to claim 1, wherein n is 1 or 2.   The amplitude value calculation unit includes a first value that is a current value and a second value that is a value before the x sampling period from the current value for each of the digital value of the electric quantity, the difference amount, and the addition amount. Value, a third value that is a value before the y sampling period before the current time, and a fourth value that is a value before the z sampling period (z = x + y) before the current time, The protection relay device according to claim 1, wherein each amplitude value is calculated based on a difference between a product of the third value and a product of the first value and the fourth value. N is 2;
When the electrical angle corresponding to one sampling period is θ and the amplitude values of the electrical quantity, the difference quantity, and the addition quantity calculated at the present time are AV _m , AD _m , and AS _m , respectively, the electrical angle The sine sin θ, cosine cos θ, and tangent tan θ of θ are
sin θ = AD _m / (2 * AV _m ) (A1)
cos θ = A S _m / (2 * AV _m ) (A2)
tan θ = AD _m / AS _m (A3)
Represented by
When the set angle is φ, using the sine sinφ and cosine cosφ of the set angle φ, the first coefficient is − (sinφ / tanθ−cosφ), and the second coefficient is sinφ / sinθ. The protection relay device according to any one of claims 1 to 3. N is 1;
When the electrical angle corresponding to one sampling period is θ, and the amplitude values of the electrical quantity, the difference quantity, and the addition quantity calculated at the present time are AV _m , AE _m , and AT _m , respectively, the electrical angle The sine sin θ, cosine cos θ, and tangent tan θ of θ are
sin θ = AE _m * AT _m / (2 * AV _m * AV _m ) (A4)
cos θ = AT _m * AT _m / (2 * AV _m * AV _m ) −1 (A5)
tan θ = AE _m * AT _m / (AT _m * AT _m −2 * AV _m * AV _m ) (A6)
Represented by
When the set angle is φ, using the sine sinφ and cosine cosφ of the set angle φ, the first coefficient is − (sinφ / tanθ−cosφ), and the second coefficient is sinφ / sinθ. The protection relay device according to any one of claims 1 to 3. An analog / digital conversion unit that generates time-series data of the electric quantity by sampling an electric quantity representing an alternating current or an alternating voltage detected in the electric power system at a constant period and converting it into a digital value;
For each sampling of the amount of electricity, the difference amount and the addition amount between the current digital value of the amount of electricity and the digital value of the amount of electricity before p cycles or 2 * p cycles before the present time (p is an integer of 1 or more) A difference / addition calculation unit that generates time-series data of each of the first difference amount and the first addition amount by calculating the first difference amount and the first addition amount;
For each sampling of the electric quantity, the amplitude value of the electric quantity is calculated using a plurality of data including the current time among the time series data of the electric quantity, and each of the first difference amount and the first addition amount is calculated. An amplitude value calculation unit that calculates the amplitude value of each of the first difference amount and the first addition amount by performing the same calculation as the amplitude value calculation of the electric quantity for the time-series data;
For each sampling of the quantity of electricity, a value obtained by multiplying the digital value of the quantity of electricity before the p cycle from the current time by a first coefficient and a digital value of the quantity of electricity before the p cycle from the current time with a 90 ° phase delay. A phase shift correction unit that corrects an error caused by the phase shift for the digital value of the electric quantity p cycles before the current time by calculating the sum of the value multiplied by the second coefficient;
The first coefficient and the second coefficient are expressed by using the amplitude value of the electric quantity and the amplitude values of the first difference quantity and the first addition quantity calculated at the present time. ,
Furthermore, a protection relay device comprising a relay calculation unit that performs a relay calculation using the digital value of the electric quantity in which an error caused by the phase shift is corrected. The difference / addition calculation unit calculates, as the second difference amount, a difference amount between the current digital value of the electric quantity and the digital value of the electric quantity two sampling periods before the current time for each sampling of the electric quantity. To generate further time-series data of the second difference amount,
The amplitude value calculation unit performs the same calculation as the amplitude calculation of the electric quantity on the time-series data of the second difference quantity for each sampling of the electric quantity, thereby calculating the second difference quantity. Calculate the amplitude value further,
The protective relay device further includes:
For each sampling of the quantity of electricity, the quantity of electricity before the p cycle from the present time is obtained by multiplying the second difference amount calculated after one sampling period after the time point before the p cycle from the present time by a third coefficient. Bei give a phase delay data calculation unit for calculating a digital value but delayed 90 ° phase,
The third coefficient is calculated using an amplitude value of the electric quantity and an amplitude value of the second difference quantity calculated after one sampling period from a time point before p cycles from the current time point. The protective relay device described in 1. The electrical angle corresponding to one sampling period is set as θ, the amplitude value of the electric quantity calculated before p cycles from the present time is AV _m-pc, and the calculated value after one sampling period from the time point before p cycles from the current time. When the amplitude value of the second difference amount is AD _{m + 1-pc} , the sine sin θ of the electrical angle θ is
sin θ = AD _{m + 1-pc} / (2 * AV _m-pc ) (A7)
Represented by
The protection relay device according to claim 7, wherein the third coefficient is 1 / (2 * sin θ). The phase shift angle between the current amount of electricity and the amount of electricity before the p cycle from the present time is α, and the amplitude value of the amount of electricity calculated before the p cycle from the present time is AV _m-pc. When the amplitude values of the first difference amount and the first addition amount are AG _m and AW _m , respectively, the sine sin α and cosine cos α of the phase shift angle α are
sin α = AG _m / (2 * AV _m-pc ) (A8)
cos α = AW _m / (2 * AV _m-pc ) (A9)
Represented by
The protection relay device according to claim 6, wherein the first coefficient is cos α, and the second coefficient is −sin α.

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