JP2000261954A - Protective and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To interrupt a generator and load control by converting the quantity of electricity of an input into a digital quantity of electricity and fetching it into an arithmetic unit, computing a product and delaying the phase of a sampling data, integrating quantities of AC electricity and finding the inverse tangent of the ratio of two quantities, and performing protection and control on the basis of the difference angle. SOLUTION: Measured voltages and currents are inputted to an arithmetic unit 2. The quantity of electricity of a system is converted into a digital quantity by an analog-to-digital converting part 21. A digital quantity-of-electricity leading-in part 22 takes in the digital quantity of electricity. A product computing part 23-1 computes the product of the two quantities of electricity. A product computing part 23-2 delays sampling data by an electrical angle of 90 deg. and computes its product with a quantity of electricity. An internal product computing part 24-1 and an external product computing part 24-2 perform integration, corresponding to time integer times the half cycle of the quantity of AC electricity, and compute and internal product and an external product. A difference angle computing part 25 finds an inverse tangent from the ratio of the internal product and external product, and finds the phase angle of the quantity of electricity. Consequently, step-out detection can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection / control device for calculating a phase difference between two electric quantities in a power system to determine a step-out.

[0002]

2. Description of the Related Art A conventional protection / control device in a power system uses a digital filter focusing on a specific harmonic. Therefore, when a high-frequency component other than the harmonic is included, an error occurs in the calculation result of the phase difference angle. Therefore, various solutions have been proposed to eliminate such errors.

[0003]

As an example, in a power system or the like, when the phase difference angle of each generator is calculated and used as a determination target for step-out detection, the protection target of the power system is reliably protected and the system is collapsed. It is necessary to detect the phase difference angle of each generator, and to issue a control command for shutting down the generator, limiting the load, and the like, if necessary, in order to prevent the occurrence of the phase difference.

In order to prevent malfunction and malfunction, it is necessary to calculate the phase difference angle of each generator with high accuracy.
However, when high frequency components other than the harmonics assumed in advance are included due to a state change such as a system accident, an error occurs in the calculation of the phase difference angle, resulting in excess or deficiency in generator shutoff, load limitation, and the like. There were things.

[0005] The present invention has been made to solve the above-mentioned problems, and the present invention has been made in consideration of a state change such as a system accident.
Even if high-frequency components other than the harmonics assumed in advance are included, the phase difference angle of each generator can be calculated with high accuracy, so that the generator can be shut down and the load can be limited.・ The purpose is to provide a control device.

[0006]

According to a first aspect of the present invention, there is provided a protection and control device for calculating a phase difference angle between two electric quantities from an electric quantity of an electric power system. First means for converting into a digital electric quantity, second means for taking the digital electric quantity converted by the first means into an arithmetic unit, and using each digital electric quantity taken by the second means Using a first product calculator for calculating a product of two electric quantities and each digital electric quantity taken in by the second means, one sampling data of the two electric quantities is phase-shifted by 90 ° in electrical angle. And a second product calculator for calculating the product of the other quantity of electricity, and a calculation result obtained by the first and second product calculators to calculate an AC quantity of electricity. 1st and 2nd that integrate only the integer part of the half cycle of Fourth means comprising an inner product / outer product calculation unit, fifth means for obtaining an arctangent of a ratio of the two quantities from the two quantities obtained by the fourth means, and a phase difference obtained by the fifth means Sixth means for performing protection and control based on corners is provided.

[0007] The protection and control device according to claim 1 of the present invention converts an analog electric quantity taken into an arbitrary terminal of a power system and passed through an input converter into a digital quantity, and converts a digital electric quantity into an arithmetic unit. Then, the sampling time is shifted, the product of the two quantities is calculated, the result of the calculation is integrated by an integral number of half cycles using the AC electrical angle, and the inverse tangent of the ratio of the result of the calculation is obtained. This result is the phase difference angle of the captured electric quantity, and using this result, it is possible to detect out-of-step with high accuracy without being affected by unexpected harmonics. That is, in the present invention, even when unexpected harmonics are contained in the power system, the phase difference angle of two electric quantities is obtained with high accuracy without being affected by the harmonics.

According to a second aspect of the present invention, in the protection / control device according to the first aspect, the amount of electric power input to the input converter is the amount of electric power input from the own power station. Therefore, after the two digital electric quantities of the own power station of the power system are directly taken into the arithmetic unit by the second means without passing through the transmission system, the product is obtained by the third means, so that the power system of the power system is obtained. The phase difference angle can be obtained only by the amount of electricity at the own end.

According to a third aspect of the present invention, in the protection / control device according to the first aspect, one input electric quantity to the input converter is an input electric quantity from its own electric station, and the other input electric quantity is the other. The input electric quantity was set to the input electric quantity from another electric station. Therefore, the amount of digital electricity at the own power station in the power system and the amount of digital electricity transmitted from other
By taking the product into the calculation unit and calculating the product by the means, the phase difference angle between the electric quantity of the own electric station and the electric quantity of the other electric station in the electric power system can be obtained.

According to a fourth aspect of the present invention, there is provided a protection / control device according to the first aspect, wherein a transmission / reception unit is provided in place of the A / D conversion unit in the arithmetic unit at the own electric station.
Electric quantities from a plurality of other electric stations are input to the transmission / reception unit of the arithmetic unit. For this reason, the digital electric quantity transmitted from any electric station in the power system is taken into the arithmetic unit by the second means, and the product is obtained, so that the phase difference angle of any terminal of the power system can be obtained. It becomes possible.

According to a fifth aspect of the present invention, in the protection / control device according to the first aspect, the interval between the amounts of electricity taken in is set to 15 ° instead of 30 °, and the inner product calculation unit and the outer The product calculation unit was the following equation. Record

(Equation 2) Therefore, by using the sampling data of the digital electric quantity of 15 ° in the AC electric angle calculated by the first means, the sampling time of the two digital electric quantities is shifted to obtain the product, thereby obtaining a finer product. The phase difference angle of two electric quantities can be obtained at time intervals.

According to a sixth aspect of the present invention, in the protection / control device according to the first aspect, the phase difference angle calculating section calculates a ratio of two quantities from the inner product calculating section and the outer product calculating section. Accordingly, the phase difference angle equivalent value is obtained, and the step-out determination unit determines from the phase difference angle equivalent value and the set value. Therefore, the calculation time can be shortened without directly calculating the phase difference angle, for example, by using the ratio of the two quantities obtained by the fourth means for detecting the step-out of the generator in the power system.

[0013]

FIG. 1 is a block diagram showing an embodiment according to [claim 1]. In FIG. 1, 1 is an input converter, 2 is an arithmetic unit, and the arithmetic unit 2 is an A / D conversion unit 21, a digital electricity introduction unit 22, a product calculation unit 23.
-1,23-2, inner and outer product calculating units 24-1 and 24-2, phase difference angle calculating unit 25, and step-out determining unit 26. In this embodiment, a step-out detection unit is shown.

Next, the operation will be described. First, the voltage and current (system electricity) measured at one terminal of the power system are
The data is input to the arithmetic unit 2 via the input converter 1. The system electric quantity taken into the arithmetic unit is converted into a digital quantity by the analog / digital converter 21 to be digital electric quantity data suitable for digital operation. The digital electric quantity introducing section 22 takes in the digital electric quantity converted into a digital quantity by the analog / digital conversion section.

The product calculating unit 23-1 uses the digital electric quantity taken in by the digital electric quantity introducing unit to calculate
The product of the two electric quantities (first product) is calculated (described later).
The product calculating unit 23-2 delays the phase of one sampling data of the two electric quantities by 90 ° of the electric angle by using the digital electric quantity taken in by the digital electric quantity introducing unit, and sets the other electric quantity. The product of the quantity (second product) is calculated (described later).

Further, the inner product calculating section 24-1 has a product calculating section 2
The product of the two electric quantities calculated according to 3-1 (first product)
Is integrated for a time that is an integral multiple of a half cycle of the AC electric quantity, and the inner product of the two electric quantities is calculated. The outer product calculation unit 24-2 calculates the second product calculated by the product calculation unit 23-2.
The electric quantity (the second product) is integrated for an integral multiple of a half cycle of the AC electric quantity, and the outer product of the two electric quantities is calculated.

In the phase difference angle calculating section 25, the inner product calculating section 2
The phase difference angle between the two electric quantities is obtained by calculating the arc tangent from the ratio between the inner product and the outer product calculated by 4-1 and the outer product calculating unit 24-2. Then, the out-of-step determining unit 26 determines out-of-step according to the equation (1) using the calculation amount obtained by the phase difference angle calculating unit. If the phase difference angle δ of the two electric quantities is larger than the set value, a step-out determination result is output.

[Equation 3] δ ≧ set value …………………… (1)

According to the above embodiment, 2
The phase of the product of the electrical quantity (first product) and the sampling data of one of the two electrical quantities is delayed by 90 ° of the electrical angle, and the product of the other electrical quantity (second product) is half the system frequency. By integrating by an integral multiple of the cycle and using the orthogonality of the sine and cosine functions, the effect of harmonic components can be eliminated, and the phase difference angle between the two electric quantities can be determined with high accuracy, and step-out detection can be performed. A protection / control device that can be provided can be provided.

As an example, the phase difference angle is calculated as follows.
This shows the process of determining out-of-step. Assuming the digital electric quantity taken in by the digital electric quantity introducing unit 22 in FIG. 1 as the following equations (2) and (3), electric quantity 1 and electric quantity 2
The case where the phase difference angle is obtained will be described. Where k is 30 °
It is digital electric quantity data of an interval.

V1 (k) = V1 sin ωt (2) v2 (t) = V2 sin (ωt + δ) (3)

Next, a product calculation unit 23-1 and a product calculation unit 23-2
, The following equations (4) and (5) are operated. Here, n is an integer appropriately determined so as to satisfy the required data amount in each of the equations of the inner product / outer product calculating units 24-1 and 24-2.

## EQU00005 ## Product calculation unit 24-1, Vc (kn) = v1 (kn) .v2 (kn) (4) Product calculation unit 24-2, Vs (kn) = v1 (kn-3) .v2 (kn) …… (5)

Further, the inner product calculating unit 24-1 and the outer product calculating unit 2
In 4-2, calculations of the following equations (6) and (7) are performed. Here, integration for one time (180 °) of a half cycle is performed.

(Equation 6)

Next, the phase difference angle calculation unit 25 calculates
The phase difference angle between the electric quantity 1 and the electric quantity 2 is calculated by using the inner product and the outer product C and S calculated in 1, 24-2 as follows (8).
It is calculated as in the formula. Next, the out-of-step determination unit 26 uses the phase difference angle δ calculated by the phase difference angle calculation unit 25 to obtain the following (9)
The step-out determination is performed as in the equation, and if the phase difference angle exceeds the set value, a step-out determination output is output.

Δ = tan ⁻¹ (S / C) (8) δ ≧ Set value (9)

The following is an example in which when harmonics other than the fundamental wave of an alternating current are included, the influence of the harmonics can be eliminated by using the orthogonality of the sine function and the cosine function. Two electric quantities v
The phase (difference) δ between 1 (t) and v2 (t) is calculated. Here, v1 (t) is an AC electric quantity including a harmonic term as in equation (10), and v2 (t) is v1 (t) as in equation (11).
On the other hand, it is an AC electricity amount advanced in phase by δ. Here, t is the period of the AC fundamental frequency, and N is an integer.

V1 (t) = V1 sin ωt + ε sinNωt (10) v2 (t) = V2 sin (ωt + δ) (11)

By multiplying the above equations (10) and (11),
When integrating by an integral multiple of a half cycle, the following (12),
Equation (13) is obtained.

(Equation 9)

[0025]

(Equation 10)

From equations (12) and (13), equation (14) or (15) is obtained.

[Equation 11]

FIG. 2 is a block diagram showing an embodiment of [claim 2]. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, a local configuration is used in which the out-of-step of the generator is determined by using only the amount of electricity at the own end of the power system. Accordingly, the feature of the configuration is only the input v1 to v2 of the own electric station, and the other configurations and operations are the same as those in FIG.

According to the present embodiment, the product is obtained by the digital electricity introduction unit after the data is directly taken into the operation unit without passing through the transmission system, so that the phase difference is obtained only by the electricity at the self end of the power system. The angle can be determined.

FIG. 3 is a block diagram showing an embodiment of [claim 3]. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description will be omitted. In the present embodiment, the amount of electricity at the own end of the power system and the amount of electricity transmitted to the other electric station 3 are introduced, so that the phase difference angle between the own end and the other electric station can be calculated. . Other configurations and operations are the same as those in FIG.

According to this embodiment, the digital electric quantity of the own electric station and the digital electric quantity transmitted from the other electric stations are taken into the arithmetic section by the digital electric quantity introducing section, and the product is obtained. The phase difference angle between the amount of electricity at the own electric station and another electric station in the power system can be obtained.

FIG. 4 is a block diagram showing an embodiment of [claim 4]. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description will be omitted. In the present embodiment, the own electric station has only a transmission receiving unit and an arithmetic unit, introduces the amount of electricity transmitted from any electric station in the power system, and calculates a phase difference angle between any electric stations in the system. It is made possible.

In FIG. 4, reference numeral 10 denotes an electric substation 1 having an input converter 1, an A / D converter 21, and a transmission transmitter 28.
Similarly, reference numeral 40 denotes an electric substation 2, and an input converter 40, A / D
It has a converter 41 and a transmission transmitter 42, each of which is connected to its own electric station via a transmission line. The operation is basically the same as in the above embodiments.

According to the present embodiment, the digital electric quantity transmitted from any electric station in the electric power system is taken into the arithmetic unit by the digital electric quantity introducing unit, and the product is obtained. Can be obtained.

FIG. 5 is a block diagram showing an embodiment of [claim 5]. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description will be omitted. In the present embodiment, the product calculating unit 23-1 and the product calculating unit 23-2 can calculate the phase difference angle at finer time intervals by using 15 ° sampling data of the electric quantity of the system.

As an example, the phase difference angle is calculated as follows.
This shows the process of determining out-of-step. Similarly to [claim 1], the digital electric quantity taken in the digital electric quantity introducing unit 22 in FIG. 5 is assumed as follows, and the phase difference angle between the two electric quantities is obtained. In the product calculation unit 23-1 and the product calculation unit 23-2 shown in FIG. 5, calculations of the following equations (16) and (17) are performed.

## EQU12 ## Product calculation unit 23-1 Vc (kn) = v1 (kn) .v2 (kn) (16) Product calculation unit 23-3 Vs (kn) = v1 ( (kn-6) .v2 (kn) (17)

Here, k is digital electric quantity data at intervals of 15 °, n is an inner product of the following 24-3 and 24-4,
It is an integer appropriately determined so as to satisfy the required data amount in the outer product calculation unit. Further, the inner product calculating unit 24-3 and the outer product calculating unit 24-4 perform the calculations of the following equations (18) and (19). Also in this case, integration for one time (180 °) of a half cycle is performed. Hereinafter, the processes after the phase difference angle calculation unit 25 are the same as those in [Claim 1].

(Equation 13)

According to the present embodiment, product calculating unit 23-1
By calculating the product of the two electric quantities of the two electric quantities using the 15-degree sampling data of the electric quantity of the system in the product calculation unit 23-3, the data can be sampled at a smaller sampling cycle. By the sampling theorem, it is possible to cut up to a higher frequency harmonic.

FIG. 6 is a block diagram showing an embodiment of [claim 6]. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, the phase difference angle calculation unit calculates the ratio between the inner product and the outer product from the ratio of the inner product to the outer product calculated by the inner product calculation unit and the outer product calculation unit without calculating the arc tangent, and calculates the phase difference angle of two electric quantities. This is a configuration having a function of replacing with.

Reference numeral 25 denotes a phase difference angle calculator, which is δ '
= S / C, and the step-out determining unit obtains δ ′ ≧ set value. The out-of-step determination unit performs out-of-step determination as described below using the calculation amount obtained by the phase difference angle calculation unit. Based on the ratio between the inner product and the outer product of the two electric quantities, a step-out determination result is output based on C as follows.

[Equation 14]

Assuming that the magnitudes of V1 and V2 in the equations (10) and (11) are the same, the step-out threshold is set to a set value: 15
Assuming 0 °, the out-of-step determination is performed as follows.

(Equation 15)

According to the present embodiment, the ratio between the inner product and the outer product calculated by the inner product calculating unit and the outer product calculating unit is obtained, thereby calculating the phase difference angle of two electric quantities without calculating the arc tangent. Can be calculated, so that the convenience in the calculation of the step-out detection algorithm is improved.

[0042]

As described above, according to the present invention, since the conventional protection / control device in the power system uses a digital filter focusing on a specific harmonic, the protection / control device other than the harmonic assumed in advance is used. In the case where a harmonic component is included, an error has appeared in the calculation result of the phase difference angle. On the other hand, in the present invention, the sampling point of the two electric quantities converted into digital quantities via the input converter is shifted and the two quantities are shifted. The product is calculated, the result of the calculation is integrated by an integral number of half cycles with the AC electrical angle, and the inner product and outer product of the two electrical quantities are obtained. It is possible to provide a protection / control device that eliminates the influence and calculates the phase difference angle of two electric quantities with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of [claim 1].

FIG. 2 is a configuration diagram showing an embodiment of [claim 2].

FIG. 3 is a configuration diagram showing an embodiment of [claim 3].

FIG. 4 is a configuration diagram showing an embodiment of [claim 4].

FIG. 5 is a configuration diagram showing an embodiment of [claim 5].

FIG. 6 is a configuration diagram showing an embodiment of [claim 6].

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input converter 2 Arithmetic unit 21 A / D conversion part 22 Digital electric quantity introduction part 23 Product calculation part 24 Inner product calculation part, Outer product calculation part 25 Phase difference angle calculation part 26 Step-out determination part 27 Transmission reception part 28 Transmission transmission Part 10 Electric station 1 4 Electric station 2 3 Other electric stations

Claims (6)

[Claims] 1. A protection / control device for calculating a phase difference angle between two electric quantities from an electric quantity of an electric power system, a first means for converting an input electric quantity into a digital electric quantity, and a first means for converting the input electric quantity into a digital electric quantity. The second digital electric quantity taken into the arithmetic unit
Means, a first product calculator for calculating a product of two electric quantities using each digital electric quantity taken in by the second means, and each digital electric quantity taken in by the second means. A second product calculator for delaying the phase of one sampled data of the two electric quantities by an electrical angle of 90 ° and calculating a product with the other electric quantity; A fourth means including first and second inner and outer product calculating units for integrating the calculation result calculated by the first and second product calculating units by an integer part of a half cycle of the AC electric quantity; A fifth means for obtaining an arctangent of a ratio of the two quantities from the two quantities obtained by the means of the fourth means, and a sixth means for performing protection and control based on the phase difference angle obtained by the fifth means. A protection and control device comprising: 2. The protection and control device according to claim 1, wherein the amount of electric power input to the input converter is an amount of electric power input from a local power station. 3. The protection / control device according to claim 1, wherein one input electric quantity to the input converter is an input electric quantity from the own electric station, and the other input electric quantity is an input electric quantity from the other electric station. A protection and control device characterized by being an electric quantity. 4. The protection and control device according to claim 1, wherein a transmission / reception unit is provided in place of the A / D conversion unit in the arithmetic unit at the own electric station, and the electric quantity from a plurality of other electric stations is used. A protection / control device characterized by being input to a transmission / reception unit of an arithmetic device. 5. The protection and control device according to claim 1, wherein the interval between the amounts of electricity taken in is 15 ° instead of 30 °.
A protection and control device, wherein the inner product calculating unit and the outer product calculating unit are represented by the following arithmetic expressions. Note 6. The protection / control device according to claim 1, wherein the phase difference angle calculation unit receives two signals from the inner product calculation unit and the outer product calculation unit.
A protection / control device, wherein a phase difference angle equivalent value is obtained by calculating a ratio of the amounts, and a step-out determination unit makes a determination from the phase difference angle equivalent value and a set value.