JP2008191108A - System for evaluating quality of electric power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for evaluating the quality of electric power which infers the causes for generation of higher harmonics based on electric physical quantities, such as current and voltage of consumers receiving power supply. <P>SOLUTION: This system for evaluating quality of electric power 1A is equipped with harmonic component calculation means 8 for calculating the harmonic components of the measured electrical physical quantity 6 per each measuring place, based on the electric physical quantity 6 that includes at least either one of current and voltage measured on at least one or more places of electric power system, and harmonic components agreement calculation means 10, which cross-checks the harmonic component calculated by the harmonic components calculation means 8, with the data of harmonic component generator DB15 which resulted from association of the harmonic component generator itself with harmonic component of this generator, to calculate the agreement level between the harmonic components calculated by the harmonic component calculation means 8 and the harmonic components of the harmonic component generator DB15 data. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power quality evaluation system that evaluates deterioration of power quality due to harmonics, voltage fluctuation, voltage imbalance, instantaneous voltage drop, and the like generated in a power system.

The degree of power quality is determined by voltage fluctuation, voltage imbalance, instantaneous voltage drop or harmonics generated in the power system. A power quality measurement device or a power quality analysis device that measures or analyzes the degree of power quality is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-298147 (Patent Document 1).
JP 2003-298147 A

  However, there is no power quality evaluation system that estimates the generation factors of harmonics that are one element of power quality based on the collected electrical physical quantities such as the voltage and current of the consumer.

  The present invention has been made in consideration of the above-described circumstances, collects electrical physical quantities such as current and voltage of a consumer who receives power supply from a higher-order power system, and generates harmonics based on the collected electrical physical quantities. Provided is a power quality evaluation system for estimating the cause of occurrence of noise.

  In order to solve the above-described problem, the power quality evaluation system according to the present invention is based on an electrical physical quantity including at least one of a current and a voltage measured at at least one location of the power system. Harmonic component calculation means for calculating the harmonic component of each measurement location, the harmonic component for each measurement location calculated by the harmonic component calculation means, the harmonic generating device and the harmonics of the device Harmonic component coincidence calculation means for calculating the degree to which the harmonic component calculated by the harmonic component calculation means matches the harmonic component of the data by collating with the data corresponding to the component. It is characterized by.

  According to the power quality evaluation system of the present invention, electrical physical quantities such as currents and voltages of consumers who receive power supply from a higher-level power system are collected, and the generation factor of harmonics is estimated based on the collected electrical physical quantities. A power quality evaluation system can be provided.

  In addition, if there are a plurality of measurement points and the direction of the harmonic current flowing through each measurement point is known, the harmonic generation location can be estimated. Further, if the harmonic generation device is configured to be controllable, it is possible to prevent the occurrence of a disaster due to the harmonic by controlling the harmonic generation device when a dangerous situation may occur due to the influence of the harmonic.

  The best mode for carrying out a power quality evaluation system according to the present invention will be described below with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is an explanatory diagram showing an application example of the first power quality evaluation system 1A which is an example of the power quality evaluation system according to the first embodiment of the present invention.

  The first power quality evaluation system 1A is, for example, the quality of power supplied to a load facility 4 that is electrically connected to a feeder 3 of a customer 2 that uses electricity by receiving power from a power system (upper power system). It is a system that evaluates from the viewpoint of distortion. The first power quality evaluation system 1A is realized by, for example, cooperation between a computer as hardware and a program as software that evaluates power quality from the viewpoint of distortion.

  As shown in FIG. 1, a measuring device that acquires electrical physical quantity information (hereinafter referred to as electrical physical quantity information) 6 including at least current and voltage in a feeder 3 electrically connected to a bus 5 of a customer 2. 7 is installed. Based on the electrophysical quantity information 6 acquired from the measuring device 7, the first power quality evaluation system 1 </ b> A estimates the generation factor of the harmonic when the harmonic is superimposed on the current and voltage.

  FIG. 2 is a schematic diagram showing the configuration and functions of the first power quality evaluation system 1A.

  As shown in FIG. 2, the first power quality evaluation system 1A includes harmonic component calculation means 8, data recording means 9, harmonic component coincidence calculation means 10, harmonic estimation means 11 and display as output means. Means 12 are provided.

  The harmonic component calculation means 8 acquires the electrophysical quantity information 6 measured by the measuring device 7 and performs waveform analysis. Then, the harmonic component of the measured electrical physical quantity is calculated. A harmonic is a sine wave having a frequency n times (n is an integer of 2 or more) of the fundamental wave superimposed on the fundamental wave, and the waveform of the electrical physical quantity on which the harmonic component is superimposed is based on the commercial frequency. It is represented by the sum of a fundamental wave as a frequency and each sine wave (harmonic component) whose frequency is n times the fundamental frequency (cycle is 1 / n). In the following description, the fundamental wave is a primary component, the sine wave whose period is 1/2 of the fundamental wave (frequency is twice), the secondary component, and the period is 1/3 of the fundamental wave (frequency is 3 times). A sine wave having a period of 1 / n (frequency is n times) of the fundamental wave is referred to as an n-order component.

  The data recording means 9 is a storage area for recording and storing electronic information. In this data recording means 9, information (hereinafter referred to as an actual harmonic component calculation result) 14 representing the result calculated by the harmonic component calculation means 8 is recorded and stored as necessary. Further, the data recording means 9 stores a harmonic generator DB 15 in which information referred to by the harmonic component coincidence calculating means 10 in the calculation is made into a database (hereinafter abbreviated as DB) in advance. The harmonic generator DB 15 associates various types of harmonic generators that can be the main factors that generate harmonics with information on harmonic components generated by each harmonic generator. That is, when the pattern of the harmonic component is specified, the harmonic generation device can be uniquely specified.

  The harmonic component coincidence calculation means 10 compares the actual harmonic component calculation result 14 with each harmonic component pattern obtained by referring to the harmonic generator DB 15 to calculate the coincidence. Information (hereinafter referred to as harmonic component coincidence calculation result) 16 representing the coincidence calculation result is sent to the harmonic factor estimating means 11.

  Based on the received harmonic component coincidence calculation result 16, the harmonic factor estimating means 11 estimates the harmonic generation device that generates the harmonic component pattern having the highest coincidence as the main factor of the harmonic. And the information (henceforth harmonic factor estimation result) 17 showing an estimation result is sent to the display means 12 as an output means.

  The display unit 12 is a unit that visually displays an evaluation result to a user such as a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), or a PDP (Plasma Display Panel). When receiving the harmonic factor estimation result 17, the display unit 12 displays the content of the harmonic factor estimation result 17 as an image.

  The first power quality evaluation system 1A shown in FIG. 2 includes a display unit 12 as an output unit that outputs necessary information including an evaluation result in a format that can be recognized by the user. Instead of this, for example, other output means such as printing means may be provided. Also, the first power quality evaluation system 1A may not include the display unit 12. That is, the first power quality evaluation system 1A may output only the harmonic factor estimation result 17 to an output unit outside the first power quality evaluation system 1A.

  Next, the operation of the first power quality evaluation system 1A will be described.

  FIG. 3 is a graph schematically showing a voltage waveform for two phases between lines as an example of the waveform of the electrical physical quantity actually measured by the measuring device 7.

  For example, in the power quality evaluation system according to the present invention such as the first power quality evaluation system 1A, information representing the waveform of the electrical physical quantity as shown in FIG. 3 is acquired, and the harmonics are obtained based on the acquired waveform information. The wave component calculation means 8 calculates the harmonic component. Here, the horizontal axis of the graph shown in FIG. 2 is time, and the vertical axis is voltage. Vab is a line voltage between a phase and b phase of three phases (a phase, b phase and c phase), and Vbc is a line voltage between b phase and c phase.

  Vab and Vbc shown in FIG. 3 are ideally sine waves at commercial frequencies. When a harmonic enters into this commercial frequency sine wave (fundamental wave) for some reason (a harmonic is superimposed), Vab and Vbc are said to be distorted.

  FIG. 4 is an explanatory diagram showing an example of the harmonic component calculation means 8 in the first power quality evaluation system 1A.

  The harmonic component calculation means 8 regards the harmonic as the sum of each order component and calculates a component for each order. The harmonic component can be obtained by Fourier transform or the like. As one of the most common methods for calculating harmonic components, Fast Fourier Transform (FFT) is known. Of the FFT, a technique (discrete Fourier transform) for obtaining a harmonic component from a discrete signal is referred to as a discrete FFT.

  The harmonic component calculation means 8 acquires the electrophysical quantity information 6 as a discrete signal sampled at a predetermined time interval from the viewpoint of reducing the information quantity, not as a continuous signal that is temporally continuous. This is to reduce the information amount of the electrophysical quantity information 6. The sampling frequency is an arbitrary frequency higher than the Nyquist frequency (twice the frequency of the fundamental wave) based on the sampling theorem, and is a frequency at which the waveform can be reproduced from the sampled value.

  The harmonic component calculation means 8 includes an FFT processing unit 20 that performs FFT. The FFT processing unit 20 has an FFT function (function to perform fast Fourier transform), and performs discrete FFT on the discrete signal of the electrical physical quantity indicated by the electrical physical quantity information 6 acquired by the FFT function. Then, the harmonic component of the electrical physical quantity based on the electrical physical quantity information 6 is calculated.

  FIG. 5 is an explanatory diagram showing an example of the actual harmonic component calculation result 14 in which the harmonic component calculation means 8 calculates the harmonic component for the electrophysical quantity information 6 shown in FIG. 3, that is, Vab and Vbc. In addition, the vertical axis | shaft in FIG. 5 has shown the harmonic content rate, and the horizontal axis has shown the order of the harmonic.

  The measured harmonic component calculation result 14 shown in FIG. 5 is a component for each order of harmonics calculated by the FFT processing unit 20 of the harmonic component calculation means 8 using the FFT function for Vab and Vbc shown in FIG. (Content). The harmonic content is calculated for each order of harmonics, and is calculated based on the following equation (1).

[Equation 1]
Harmonic content (order) = Harmonic magnitude (order) ÷ Fundamental wave size (1)

  6-9 is explanatory drawing showing the relationship (henceforth a harmonic pattern) with the order of the harmonic which a harmonic generator produces | generates, and its component (content rate). More specifically, FIG. 6 shows a power converter (6-phase), FIG. 7 shows an arc furnace, FIG. 8 shows an air conditioner, and FIG. 9 shows a harmonic pattern in the case where general lighting is an example of a harmonic generator. FIG.

  As shown in FIGS. 6 to 9, the order in which the harmonic content increases is different depending on the device, and the harmonic pattern is different. That is, since the harmonic pattern and the harmonic generation device have a one-to-one relationship, if the harmonic pattern is known, a device having a harmonic pattern having a high degree of coincidence with the harmonic pattern is a harmonic generation device. Can be estimated.

  FIG. 10 is an explanatory diagram showing functions and processing contents of the harmonic component coincidence calculation means 10.

  The harmonic component coincidence calculation means 10 has a normalization calculation processing unit having a function (hereinafter referred to as a normalization calculation function) for normalizing so that the sum of the harmonic components of the actually measured harmonic component calculation result 14 becomes 1. 21 and a function for calculating the degree of coincidence between the result of normalizing the measured harmonic component calculation result 14 and the harmonic component (standardized value) of the harmonic generating device stored in the harmonic generating device DB 15 (hereinafter, A harmonic pattern matching degree calculation processing unit 22 having a harmonic pattern matching degree calculation function).

When the harmonic component coincidence calculation means 10 receives the measured harmonic component calculation result 14, first, the normalization calculation processing unit 21 uses the normalization calculation function to calculate the harmonic component of the measured harmonic component calculation result 14. Standardize so that the total is 1. At the time of normalization, a j-th order component (j is a natural number of 2 or more) after normalization is calculated using the following equation (2).

  In some cases, the maximum order of the harmonic components of the harmonic generation device in the harmonic generation device DB 15 does not match the maximum order of the harmonics in the actually measured harmonic component calculation result 14. In this case, the “total value of harmonic components before normalization” that is the denominator of the above equation (2) is stored in the harmonic generator DB 15 and the harmonic component of the harmonic generator and the actually measured harmonic component calculation result 14 are stored. This is not preferable in calculating the degree of coincidence of harmonic components.

  Therefore, when the maximum order of the harmonic components in the harmonic generator DB 15 and the maximum order of the harmonics in the measured harmonic component calculation result 14 do not match, the maximum order of the harmonics is low. The maximum order of harmonics is made to match. Note that since either maximum order can be determined in advance as a design item, there is no problem in matching the maximum orders.

  FIG. 11 shows an outline of normalization of harmonic components when the maximum order of harmonic components in the harmonic generator DB 15 and the maximum order of harmonics in the measured harmonic component calculation result 14 do not match. It is explanatory drawing which showed.

  FIG. 11 illustrates a case where the maximum order of the harmonic generator harmonic component in the harmonic generator DB 15 is 25th. In the case illustrated in FIG. 11, for example, when the maximum order of harmonics in the measured harmonic component calculation result 14 is up to the 20th order, the standardized maximum order is set to a lower order, that is, the measured harmonic component calculation result. The normalization is performed by extracting harmonic components up to the 20th order, with the 20th order of the maximum order of 14 harmonics being matched. In this case, the denominator of the above equation (2) is the total value up to the 20th order of the harmonic components before normalization.

  Further, in the case opposite to the case shown in FIG. 11, that is, the maximum order of the harmonic generator harmonic component in the harmonic generator DB 15 is higher than the maximum harmonic order in the measured harmonic component calculation result 14. When the frequency is low, it is adjusted to the maximum order of the harmonic components in the harmonic generator DB 15.

  When the harmonic component coincidence calculation means 10 normalizes the harmonic components of the actually measured harmonic component calculation result 14, the harmonic pattern coincidence calculation processing unit 22 then uses the harmonic pattern coincidence calculation processing function to perform the standardization. Normalized harmonic component calculation results (hereinafter referred to as normalized measured harmonic component calculation results) 23 and normalized harmonic components (hereinafter referred to as normalized harmonics) of the harmonic generation device stored in the harmonic generation device DB 15 Harmonic component coincidence is calculated based on 24.

  The harmonic components of the harmonic generator stored in the harmonic generator DB 15 are standardized so that the sum of the harmonic components is 1. For this reason, the harmonic component coincidence calculation means 10 determines the degree of coincidence (hereinafter referred to as a harmonic pattern) between the normalized measurement harmonic component calculation result 23 and the harmonic component of the harmonic generator stored in the harmonic generator DB 15. The degree of coincidence can be calculated.

  In the calculation of the harmonic pattern coincidence, first, the absolute value of the difference between the normalized measurement harmonic component calculation result 23 and the normalized value of the harmonic component of the harmonic generation device in the harmonic generation device DB 15 is calculated for each order. Then, the total value (hereinafter referred to as the normalized difference total value) is calculated as shown in Equation (3).

[Equation 3]
Normalized difference total value = | Second-order component after normalization (measured harmonic component calculation result 14) -Second-order component of harmonic of harmonic generation device | + | Third-order component after normalization (measured harmonic component) Calculation result 14)-Third-order component of harmonic of harmonic generation device + + ... + | n-order component after normalization (measured harmonic component calculation result 14)-n-th order of harmonic of harmonic generation device Component | = | Second-order component of normalized measured harmonic component calculation result 23 -Secondary component of normalized harmonic generation device harmonic component 24 | + | Third component of normalized measured harmonic component calculation result 23-Standard Third-order component of normalized harmonic generator harmonic component 24 | +... N-order component of normalized measured harmonic component calculation result 23 −n-order component of normalized harmonic generator harmonic component 24 | (3)

  When the normalized difference total value is calculated, the harmonic pattern matching degree is calculated based on the calculated normalized difference total value. Since the normalized difference total value and the harmonic pattern matching degree have a certain relationship, the harmonic pattern matching degree can be calculated using the normalized difference total value. Here, the relationship between the normalized difference total value and the harmonic pattern matching degree shown in the above formula (3) and the harmonic component matching degree will be described with reference to FIGS.

  12 to 14 are explanatory diagrams showing specific examples of the calculation of the normalized difference total value, and FIG. 15 is an explanation schematically showing the relationship between the normalized difference total value and the harmonic pattern matching degree. FIG.

  FIG. 12 shows a case where the normalized measured harmonic component calculation result 23 and the normalized harmonic generation device harmonic component 24 completely match. As shown in FIG. 12, when the normalized measured harmonic component calculation result 23 and the normalized harmonic generation device harmonic component 24 completely match, that is, the normalized measured harmonic component calculated result 23 and the standard. When all the order components (third order, fifth order, and seventh order components in FIG. 12) of the harmonic component generator harmonic component 24 coincide with each other, the normalized difference is apparent from the above equation (3). The total value is zero.

  FIG. 13 shows a case where the normalized measured harmonic component calculation result 23 and the normalized harmonic generation device harmonic component 24 do not completely match. As shown in FIG. 13, when the normalized measured harmonic component calculation result 23 and the normalized harmonic generator harmonic component 24 do not completely match (when all do not match), the normalized measured harmonic component Since each order component (third order, fifth order, and seventh order component in FIG. 13) of the calculation result 23 and the normalized harmonic generator harmonic component 24 does not coincide with each other, the normalized difference total value is the sum of all components. Sum and 2

  FIG. 14 shows a case where the normalized measurement harmonic component calculation result 23 and the normalized harmonic generation device harmonic component 24 partially match. As shown in FIG. 14, the normalized difference total value in the case where a certain order component of the normalized measured harmonic component calculation result 23 and the normalized harmonic generator harmonic component 24 match and the other order components do not match. Takes a range between the case shown in FIG. 12 and the case shown in FIG. 13, that is, a range from 0 to 2. If the example shown in FIG. 14 is specifically calculated, the terms of the third-order and seventh-order components that do not match among the terms of the above formula (3) remain, and | 0.6-0 | + | 0-0 .6 | = 0.6 + 0.6 = 1.2.

  FIG. 15 summarizes the results shown in FIGS. 12 to 14. In FIG. 15, the relationship between the normalized difference total value is shown on the horizontal axis and the harmonic pattern matching degree [%] is shown on the vertical axis. ing. As shown in FIG. 15, the normalized difference total value is 0 when the harmonic pattern coincidence is 100% (matches at all orders of the harmonics) and the harmonic pattern coincidence is 0% (all harmonics are coincident). In the case of a mismatch in the order of 2), it can be expressed as a straight line (linear function) connecting 2 to 2.

  However, in actual calculation processing, when the harmonic pattern coincidence is used to represent 0 to 100%, the case where all the orders of the harmonics coincide with each other is set to + 100%, and the case where the orders of the harmonics do not coincide with each other. It becomes clearer whether -100% can be a harmonic generation factor. Therefore, a harmonic component in which all orders are matched (when the harmonic pattern matching degree is 100%) is + 100% and not matched at all (when the harmonic pattern matching degree is 0%) is set to -100%. Introduce the concept of coincidence. The harmonic component coincidence can be expressed by the following equation (4).

[Equation 4]
Harmonic component coincidence (%) = (1−normalized difference total value) × 100 (4)

  FIG. 16 is an explanatory diagram schematically showing the relationship between the normalized difference total value and the harmonic component matching degree. When the normalized difference total value is 0 on the horizontal axis and the harmonic component match [%] is on the vertical axis, the relationship between the two is shown. When the normalized difference total value is 0 (matches in all orders of harmonics) The harmonic component coincidence is 100%, and when the standardized difference total value is 2 (non-coincidence for all orders of harmonics), the harmonic component coincidence is −100%. The harmonic pattern coincidence calculation processing unit 22 calculates the harmonic component coincidence (%) by substituting the calculated normalized difference total value into the above equation (4) and calculating. The calculation result is sent to the harmonic factor estimation means 11 as the harmonic component coincidence calculation result 16.

  FIG. 17 is an explanatory diagram showing functions and processing contents of the harmonic factor estimating means 11.

  The harmonic factor estimating means 11 includes a matching degree rearrangement processing unit 27 as a harmonic matching degree rearranging means for rearranging the display positions of the harmonic generators (harmonic factors) according to the harmonic component matching degree, And a harmonic factor extraction processing unit 28 for extracting a harmonic generation device estimated as a wave factor.

  The coincidence rearrangement processing unit 27 has a function of rearranging the harmonic component coincidence of the harmonic generators according to a rule defined in advance. The degree-of-match rearrangement processing unit 27 rearranges the received harmonic component coincidence of each harmonic generation device in descending order of harmonic component coincidence, for example.

  The harmonic factor extraction processing unit 28 extracts a harmonic generation device estimated as a harmonic factor. When extracting harmonic factors, for example, a threshold is set for the harmonic component coincidence, and a harmonic generator having a harmonic component coincidence exceeding this threshold is selected as the harmonic factor. To be extracted. The harmonic factor extraction processing unit 28 sends the extracted harmonic generation device to the display unit 12 as the harmonic factor estimation result 17. In the harmonic factor extraction processing unit 28, the threshold value to be set and the number of the threshold values can be arbitrarily set according to the display contents.

  18 and 19 are explanatory diagrams showing an example in which the harmonic factor estimation result 17 sent from the harmonic factor estimating unit 11 is displayed on the display unit 12.

  As shown in FIGS. 18 and 19, for example, the harmonic generation devices estimated as the harmonic generation factors are displayed from the left side in descending order of harmonic component coincidence. Also, depending on the threshold value to be set and the normalized measured harmonic component calculation result 23, as shown in FIG. 18, there may be many harmonic generators extracted, for example, 8 items, as shown in FIG. In addition, for example, there are cases where the number of harmonic generation devices extracted, such as three items, is small.

  According to the first power quality evaluation system 1 </ b> A, the electrical physical quantity information 6 is acquired from the measuring device 7 installed in the consumer 2 that receives power supply from the power system, and the power quality information 6 is based on the acquired electrical physical quantity information 6. The power quality can be evaluated from the viewpoint of distortion, which is one factor. Specifically, a reference harmonic pattern (standardized harmonic generation equipment harmonic component 24) is prepared in advance for each equipment that can become a harmonic generation factor, and a standard obtained based on the acquired electrophysical quantity information 6 The harmonic component coincidence degree can be calculated for the normalized measurement harmonic component calculation result 23 and the normalized harmonic generation equipment harmonic component 24 of each device, and a device having a high degree of harmonic component coincidence can be estimated as a harmonic factor.

  The power quality evaluation system 1A performs power quality evaluation according to an execution request from a user or the like, but adds a timer function and repeats calculation of power quality evaluation (estimation of harmonic factors) every predetermined time. The power quality evaluation system 1A may be configured.

  Further, in the power quality evaluation system 1A, it has been described that the harmonic factor estimation result 17 which is the final result is displayed on the display unit 12. It does not preclude displaying the wave component coincidence calculation result 16 and other necessary information.

  Furthermore, in the present embodiment, the power quality evaluation system 1A includes the harmonic factor estimation means 11, but it does not necessarily have to be included. When a harmonic generation device having a certain harmonic component coincidence is not estimated as a harmonic factor, for example, when it is desired to display the harmonic component coincidence for all harmonic generation devices on the display means 12, the harmonic factor is extracted. This is because it is no longer necessary.

  Furthermore, in the present embodiment, the harmonic factor estimation unit 11 includes the matching degree rearrangement processing unit 27, but the matching degree rearrangement processing unit 27 may be independent of the harmonic factor estimation unit 11. . That is, the harmonic factor estimation means 11 does not necessarily need to include the matching degree rearrangement processing unit 27. Furthermore, the power quality evaluation system 1A may not include the harmonic matching degree sorting unit (matching degree sorting processing unit 27). This is because when the harmonic factor estimation result 17 is not rearranged and displayed on the display unit 12 as the output unit, the function of rearranging the harmonic component coincidence of the harmonic generation devices is unnecessary.

[Second Embodiment]
The second power quality evaluation system 1B is configured to calculate the direction of the current flowing through the measuring device 7 in addition to obtaining the electrical physical quantity information 6 from the measuring device 7 and estimating the harmonic factor. An application example of the second power quality evaluation system 1B is basically the same as that of the first power quality evaluation system 1A. In FIG. 1, the first power quality evaluation system 1A is replaced with the second power quality evaluation system 1B. 1 is an explanatory diagram showing an application example of the second power quality evaluation system 1B.

  Further, the second power quality evaluation system 1B has a function of calculating the direction of the current flowing through the measuring device 7 instead of the harmonic component calculation means 8 with respect to the first power quality evaluation system 1A shown in FIG. The harmonic component calculation means 30 which has is provided. That is, the second power quality evaluation system 1B is different in that it includes a harmonic component calculation means 30, a data recording means 9, a harmonic component coincidence calculation means 10, a harmonic estimation means 11, and a display means 12. However, other configurations are not substantially different. Therefore, in the description of the second power quality evaluation system 1B, components that are not substantially different from the components in the first power quality evaluation system 1A are assigned the same reference numerals and description thereof is omitted.

  FIG. 20 is an explanatory diagram showing an example of the harmonic component calculation means 30 provided in the second power quality evaluation system 1B.

  The harmonic component calculation unit 30 includes an FFT processing unit 20 and a current direction calculation processing unit 32 as a harmonic current direction calculation unit having a function of calculating the direction of the current flowing through the measuring device 7. That is, the harmonic component calculation means 30 is configured by adding a function for calculating the direction of the current flowing through the measuring device 7 to the harmonic component calculation means 8 in the first power quality evaluation system 1A.

  The current direction calculation processing unit 32 determines whether the direction of the harmonic voltage of the k-th order (k is a natural number satisfying 2 or more and n or less), which is a harmonic of a certain order, and the direction of the harmonic current are the same direction or the reverse direction. Judgment is made from the phase difference between the vector and the current vector.

  FIG. 21 is an explanatory diagram showing an outline of the calculation of the direction (current vector) of the harmonic current performed by the current direction calculation processing unit 32.

  FIG. 21 shows harmonic k-th order voltage vectors and current vectors (first current vector to fourth current vector). Whether the direction of the current vector is the same or opposite to the voltage vector is determined in the same direction if the phase or lag (phase difference) of the current vector with respect to the phase of the voltage vector is within 90 degrees. When the angle exceeds 90 degrees, it is determined that the direction is opposite. Accordingly, the first current vector and the second current vector shown in FIG. 21 are determined to be in the same direction, and the third current vector and the fourth current vector are determined to be in the reverse direction.

  The harmonic component calculation means 30 stores information indicating the result of the FFT calculated by the FFT processing section 20 and information on the result of the harmonic current direction calculated by the current direction calculation processing section 32 in the data recording means 9, The measured harmonic calculation result 14 is sent to the harmonic component coincidence calculation means 10. The subsequent processing is substantially the same as that of the first power quality evaluation system 1A. However, since the measured harmonic calculation result 14 output from the harmonic component calculation means 30 includes information on the result calculated for the direction of the harmonic current, the display content displayed on the display means 12 includes the harmonic current. The direction information is included.

  According to the second power quality evaluation system 1B, since the direction of the harmonic current is also determined, in addition to the operation and effect of the first power quality evaluation system 1A, the direction of the generation factor of the harmonic is also determined. I can judge. Therefore, the accuracy of estimating the harmonic generation factor can be improved as compared with the first power quality evaluation system 1A.

  In the present embodiment, the case where the harmonic component calculation unit 30 includes the current direction calculation processing unit 32 has been described. However, the current direction calculation processing unit 32 may be independent. That is, you may comprise the 2nd power quality evaluation system 1B which further comprises the current direction calculation process part 32 in 1 A of 1st power quality evaluation systems.

[Third Embodiment]
FIG. 22 is an explanatory diagram showing an application example of the third power quality evaluation system 1C which is an example of the power quality evaluation system according to the third embodiment of the present invention.

  As shown in FIG. 22, the third power quality evaluation system 1 </ b> C has a plurality of power transmission lines 33 and a plurality of power transmission lines 33 (in FIG. 22, 2 as an example). The measuring devices 7a to 7c are installed in the feeders 3a and 3b, respectively, and the physical quantity information 6 is acquired from the measuring devices 7a to 7c to evaluate the quality of the power. In addition, the code | symbol I shown in FIG. 22 shows a harmonic current.

  FIG. 23 is a conceptual diagram showing the configuration and functions of the third power quality evaluation system 1C.

  As shown in FIG. 23, the third power quality evaluation system 1C includes harmonic component calculation means 30, data recording means 9, harmonic component coincidence calculation means 10, harmonic factor estimation means 35, and display means 12. It comprises. The third power quality evaluation system 1C acquires the respective electrical physical quantity information 6 acquired from each of the measuring devices 7a to 7c to estimate the harmonic generation factor, the direction of the harmonic current, and the load that becomes the harmonic generation source. The equipment 4 is specified.

  FIG. 24 is a conceptual diagram showing the configuration and functions of the harmonic factor estimating means 35 provided in the third power quality evaluation system 1C.

  In addition to the matching degree rearrangement processing unit 27 and the harmonic factor extraction processing unit 28 included in the harmonic factor estimation unit 11, the harmonic factor estimation unit 35 generates harmonics from the direction of the harmonic current flowing through the measuring devices 7 a to 7 c. A harmonic generation source specifying processing unit 36 as harmonic generation source estimation means for estimating the generation source is further provided.

  The harmonic generation source identification processing unit 36 narrows down the harmonic generation sources by paying attention to the point that harmonic current flows from the harmonic generation source. For example, when the load facility 4b shown in FIG. 22 has a harmonic generation source, the harmonic current I flows into the upper power system through the feeder 3b via the feeder 3b and the bus 5 or through the feeder 3a. It will flow into the load facility 4a. That is, if the direction of the harmonic current I observed by each of the measuring devices 7a to 7c is known, the harmonic generation source can be narrowed down and the harmonic generation source can be estimated. The harmonic generation source information (harmonic generation source estimation result) 37 estimated by the harmonic generation source identification processing unit 36 is output to the display unit 12 together with the harmonic factor estimation result 17.

  FIG. 25 is an explanatory diagram showing determination logic in the harmonic generation source identification process performed by the harmonic generation source identification processing unit 36.

  The harmonic generation source identification processing unit 36 first identifies a harmonic generation source according to the first harmonic generation source identification logic. The first harmonic generation source specifying logic is a logic that is effective when the harmonic generation is performed at one place. When the harmonic current I measured by each of the measuring devices 7a to 7c is a constant condition, the first harmonic generation source specifying logic is provided at one place. Harmonic sources are identified. For example, the direction of the harmonic current I observed by the measuring device 7a is the bus 5 side (condition 1), the direction of the harmonic current I observed by the measuring device 7b is the bus 5 side (condition 2), and If the direction of the harmonic current I observed by the measuring device 7c is true for all conditions 1 to 3 on the higher power system side (condition 3), the harmonic generation source is specified to be the higher power system. .

  However, the harmonic generation source may not be identified by the first harmonic generation source identification logic. In this case, subsequently, the harmonic generation source is specified according to the second harmonic generation source specifying logic. If the harmonic generation source cannot be specified by the first harmonic generation source specifying logic, it means that there are a plurality of harmonic generation sources.

  According to the third power quality evaluation system 1C, in addition to the operation and effect of the second power quality evaluation system 1B, a harmonic generation source is generated from the direction of the harmonic current I passing through the plurality of measuring devices 7a to 7c. More specific identification such as which equipment is present can be made.

  The third power quality evaluation system 1C further includes a harmonic generation source identification processing unit 36 as a harmonic generation source estimation unit in addition to the matching degree rearrangement processing unit 27 and the harmonic factor extraction processing unit 28. Although the factor estimating means 35 is provided, instead of the harmonic factor estimating means 35, the harmonic factor estimating means 11 (the matching degree rearrangement processing unit 27 and the harmonic factor extraction processing unit 28) and the harmonic generation source estimation. You may make it the structure which comprises a means (harmonic generation source specific process part 36).

[Fourth Embodiment]
FIG. 26 is an explanatory diagram showing an application example of the fourth power quality evaluation system 1D which is an example of the power quality evaluation system according to the fourth embodiment of the present invention.

  The fourth power quality evaluation system 1D includes, in the power system of the customer 2, a power transmission line 33 that connects the higher power system side and the bus 5 and a plurality of feeders 3a (two cases are shown as an example in FIG. 26). , 3b, the measurement devices 7a to 7c are installed, the electrical physical quantity information 6 is acquired from the measurement devices 7a to 7c, and the power quality is evaluated.

  Further, the fourth power quality evaluation system 1D is electrically connected to the load facilities 4a and 4b, and has higher harmonics than the load monitoring devices (not shown) or the harmonic generators in the load facilities 4a and 4b. Information for warning of wave generation (hereinafter referred to as alarm information) 39 and a control signal 40 for controlling the harmonic generator are configured to be transmitted.

  Furthermore, the fourth power quality evaluation system 1D is electrically connected to a monitoring control center 41 that monitors and controls the load facilities 4a and 4b, and is configured to transmit alarm information 39. . Note that symbol I shown in FIG. 26 indicates a harmonic current.

  FIG. 27 is a conceptual diagram showing the configuration and functions of the fourth power quality evaluation system 1D.

  As shown in FIG. 27, the fourth power quality evaluation system 1D includes harmonic component calculation means 30, data recording means 9, harmonic component coincidence calculation means 10, harmonic factor estimation means 35, and display means 12. In addition, an alarm generation processing unit 45 and a control command generation processing unit 46 are further provided.

  The alarm generation processing means 45 transmits a function to generate alarm information 39 and the generated alarm information 39 to the outside of the monitoring control center 41 or the like when the degree of harmonics is higher than a predetermined level (warning level). It has the function to do. Further, the control command generation processing means 46 has a higher harmonic level than an arbitrary fixed level (forced control level), and when there is a harmonic generation device present in the load facilities 4a and 4b in the customer 2, It has a function of generating a control signal 40 for controlling the harmonic generator and a function of transmitting the generated control signal 40 to a control target (a harmonic generator present in the load facilities 4a and 4b or its controller). The forced control level is generally set to a level higher than the warning level.

  The 4th electric power quality evaluation system 1D acquires each electrophysical quantity information 6 acquired from each measuring device 7a-7c, presumes a harmonic generation factor, a harmonic current direction, and a harmonic generation source. . When the degree of harmonics exceeds the warning level, the alarm generation processing unit 45 generates alarm information 39 for warning the generation of harmonics and transmits it to the outside of the monitoring control center 41 and the like. Further, when the harmonic generation source is a device that can be controlled by the customer 2 and the degree of the harmonic exceeds the warning level and exceeds the forcible control level, the control command generation processing means 46 generates the control signal 40. Then, the generation of harmonics is forcibly suppressed by transmitting to the controlled object.

  In order to determine whether it is necessary to generate the alarm information 39 and the control signal 40, it is necessary to determine the degree of harmonics. Therefore, in the fourth power quality evaluation system 1D, the total distortion rate is used as an example of an index indicating the degree of harmonics. The total strain rate is expressed by the following equation (5).

[Equation 5]
Total distortion factor = RMS value only for harmonics ÷ RMS value (5)

  FIG. 28 is an explanatory diagram for explaining the relationship between the time transition of the total distortion rate, which is one index indicating the degree of harmonics, and the generation timing of the alarm information 39 and the control signal 40. In FIG. 28, the horizontal axis represents time, and the vertical axis represents the total strain rate.

In the fourth power quality evaluation system 1D, first, when the total distortion rate which has been changing below the warning level Ra reaches the warning level Ra, the alarm generation processing means 45 causes the time t when the total distortion rate reaches the warning level Ra. _The time counting is started from ₀ until the total distortion rate becomes less than the warning level Ra. When the counted time is equal to or longer than a predetermined time ta (hereinafter, referred to as an alarm occurrence time limit), the alarm generation processing unit 45 generates alarm information 39.

Furthermore, the total harmonic distortion reaches the forced control level Rc rises, the control command generating processing unit 46 time to total harmonic distortion is less than level Rc from time overall strain rate reaches the forced control level Rc t ₁ Start counting. When the counted time becomes equal to or greater than a predetermined time tc (hereinafter referred to as a control signal generation time limit value) set in advance, the control command generation processing means 46 generates the control signal 40.

  According to the fourth power quality evaluation system 1D, the alarm generation processing unit 45 that generates the alarm information 39 and outputs the alarm information 39 when the degree of harmonics exceeds an arbitrarily set warning level is provided. A harmonic generation warning can be issued to the harmonic generation source and its management source. Further, since the control command generation processing means 46 that generates the control signal 40 and outputs the control signal 40 to the forced control target when the degree of harmonics exceeds the arbitrarily set forced control level, it becomes a harmonic generation source. The device can be forcibly controlled to reduce the degree of harmonics or suppress the generation of harmonics.

  Therefore, the fourth power quality evaluation system 1D can issue a warning or forcibly control the estimated harmonic generation source in addition to the operation and effect of the third power quality evaluation system 1C. Therefore, the deterrence of disaster caused by harmonics can be increased as compared with the conventional power evaluation system or the first to third power quality evaluation systems 1A to 1C.

  Although the fourth power quality evaluation system 1D has been described as including the alarm generation processing unit 45 and the control command generation processing unit 46, it is not necessary to include both the units 45 and 46. That is, the fourth power quality evaluation system 1D provided with the alarm generation processing means 45 in the third power quality evaluation system 1C, or the fourth power quality evaluation system 1C provided with the control command generation processing means 46 in the third power quality evaluation system 1C. The power quality evaluation system 1D may be configured.

  As described above, according to the power quality evaluation system according to the present invention, the electrical physical quantity information 6 such as voltage and current of the consumer 2 that receives power supply from the upper power system is collected, and harmonics that are one of power quality are collected. It is possible to estimate the generation factor (the type of the device that is generating) and the generation source (which load facility or higher power system is present). In addition, when it is determined that a hazard such as a disaster has occurred in the load facility 4 due to the influence of harmonics, the harmonic generation device is forcibly controlled to prevent the occurrence of disasters due to the harmonics. be able to.

Explanatory drawing which shows the example of application of the electric power quality evaluation system which concerns on the 1st Embodiment of this invention. Schematic explaining the configuration and function of the power quality evaluation system according to the first embodiment of the present invention. The graph which showed roughly the voltage waveform for two phases between lines as an example of the waveform of the electrical physical quantity which the measurement apparatus measured. Explanatory drawing which shows an example of the harmonic component calculation means in the electric power quality evaluation system which concerns on the 1st Embodiment of this invention. Explanatory drawing which shows an example of the actual harmonic component calculation result which the harmonic component calculation means in the electric power quality evaluation system which concerns on this invention calculated the harmonic component about Vab and Vbc shown in FIG. Explanatory drawing showing the relationship between the harmonic order of the power converter device (6 phases) which is an example of a harmonic generator, and its component (content rate). Explanatory drawing showing the relationship between the harmonic order of the arc furnace which is an example of a harmonic generator, and its component (content rate). Explanatory drawing showing the relationship between the harmonic order of the air-conditioner which is an example of a harmonic generator, and its component (content rate). Explanatory drawing showing the relationship between the harmonic order of the general illumination which is an example of a harmonic generator, and its component (content rate). Explanatory drawing which shows the function and process content of the harmonic component coincidence calculation means of the electric power quality evaluation system which concerns on this invention. Explanatory diagram showing an outline of normalization of harmonic components when the maximum order of harmonic components in the harmonic generator DB does not match the maximum order of harmonics in the measured harmonic component calculation result . Explanatory drawing which showed the specific example of calculation of the normalization difference total value in case the normalized measurement harmonic component calculation result and the normalized harmonic generation equipment harmonic component correspond completely. Explanatory drawing which showed the specific example of the calculation of the normalization difference total value in case the normalized measurement harmonic component calculation result and the normalized harmonic generator harmonic component do not completely match (in the case of complete mismatch). Explanatory drawing which showed the specific example of calculation of the normalization difference total value in case the normalized measurement harmonic component calculation result and the normalized harmonic generator harmonic component partially correspond. Explanatory drawing which showed schematically the relationship between a normalized difference total value and a harmonic pattern coincidence degree. Explanatory drawing which showed schematically the relationship between a normalized difference total value and a harmonic component coincidence degree. Explanatory drawing which shows the function and process content of the harmonic factor estimation means in the electric power quality evaluation system which concerns on the 1st Embodiment of this invention. Explanatory drawing which showed the example of a display of the evaluation result (harmonic factor estimation result) in the electric power quality evaluation system which concerns on this invention. Explanatory drawing which showed the other example of an evaluation result (harmonic factor estimation result) in the electric power quality evaluation system which concerns on this invention. Explanatory drawing which shows an example of the harmonic component calculation means in the electric power quality evaluation system which concerns on the 2nd Embodiment of this invention. Explanatory drawing which showed the outline | summary of the calculation of the direction (current vector) of the harmonic current which the current direction calculation process part of the electric power quality evaluation system which concerns on this invention performs. Explanatory drawing which shows the example of application of the electric power quality evaluation system which concerns on the 3rd Embodiment of this invention. The conceptual diagram which shows the structure and function of the electric power quality evaluation system which concern on the 3rd Embodiment of this invention. The conceptual diagram which shows the structure and function of the harmonic factor estimation means in the electric power quality evaluation system which concerns on the 3rd Embodiment of this invention. Explanatory drawing which showed the determination logic of the harmonic generation source specific process which the harmonic generation source specific process part of the harmonic factor estimation means in the electric power quality evaluation system which concerns on the 3rd Embodiment of this invention performs. Explanatory drawing which shows the example of application of the electric power quality evaluation system which concerns on the 4th Embodiment of this invention. The conceptual diagram which shows the structure and function of the electric power quality evaluation system which concern on the 4th Embodiment of this invention. The relationship between the generation time of the alarm information and control signal generated in the power quality evaluation system according to the fourth embodiment of the present invention and the time transition of the total distortion rate, which is an index indicating the degree of harmonics, will be described. Illustration.

Explanation of symbols

1A, 1B, 1C, 1D Power quality evaluation system 2 Customer 3 (3a, 3b) Feeder 4 (4a, 4b) Load facility 5 Bus 7 (7a, 7b, 7c) Measuring device 8 Harmonic component calculation means 9 Data recording Means 10 Harmonic component coincidence calculation means 11 Harmonic estimation means 12 Display means (output means)
15 Harmonic generator DB
20 FFT processing unit 21 Normalization calculation processing unit 22 Harmonic pattern matching degree calculation processing unit 27 Matching degree rearrangement processing unit 28 Harmonic factor extraction processing unit 30 Harmonic component calculation means 32 Current direction calculation processing unit 33 Transmission line 35 Harmonic Wave factor estimation means 36 Harmonic generation source identification processing unit 41 Monitoring control center 45 Alarm generation processing means 46 Control command generation processing means

Claims (9)

Harmonic component calculation means for calculating a harmonic component of the measured electrical physical quantity for each measurement location based on an electrical physical quantity including at least one of current and voltage measured at at least one location of the power system; ,
The harmonic component calculation unit is configured to collate the harmonic component for each measurement location calculated by the harmonic component calculation unit with the data in which the harmonic generation device and the harmonic component of the device are associated with each other. A power quality evaluation system comprising: a harmonic component coincidence calculating unit that calculates a degree to which the calculated harmonic component matches the harmonic component of the data. The apparatus further comprises a harmonic factor estimating unit that narrows down at least one of a device that is a harmonic generation factor and a device that is not a harmonic generation factor based on a result calculated by the harmonic component coincidence calculation unit. 1. The power quality evaluation system according to 1. The power quality evaluation system according to claim 1, further comprising: a harmonic matching degree rearranging unit that rearranges the results calculated by the harmonic component matching degree calculating unit in a predetermined order. The measurement location is plural, and further comprises a harmonic current direction calculation means having a function of calculating the direction of the harmonic current with respect to the harmonic voltage based on the current and voltage measured at each measurement location. The power quality evaluation system according to any one of claims 1 to 3. Based on the direction of the harmonic current flowing through each measurement location calculated by the harmonic current direction calculation means, the direction of the harmonic generation source is determined, and the harmonic generation source estimation having the function of estimating the harmonic generation source The power quality evaluation system according to claim 4, further comprising means. 6. The electric power according to claim 5, further comprising alarm generation processing means having a function of generating alarm information indicating a warning and transmitting the alarm information to the outside when the degree of harmonics is higher than a predetermined fixed level. Quality evaluation system. If the harmonic generation source estimated by the harmonic generation source estimation means is a self-controllable device and the degree of harmonics is greater than a certain level that is arbitrarily set, the device that becomes the harmonic generation source is forced A control command generation processing unit having a function of generating a control signal to be controlled automatically and transmitting the generated control signal to a device that is the harmonic generation source and a controller that controls the device is provided. Item 7. The power quality evaluation system according to Item 5 or 6. The harmonic component calculation means further comprises a timer function, calculates a harmonic component for each measurement location at a predetermined time, and the harmonic component coincidence calculation means has a predetermined harmonic component calculation means. Harmonic components calculated by the harmonic component calculation means by collating the harmonic components for each measurement location calculated for each time and the data corresponding to the devices generating the harmonics and the harmonic components of the devices. The power quality evaluation system according to claim 1, wherein the power quality evaluation system is configured to calculate a degree of coincidence with a harmonic component of the data. The power quality evaluation system according to claim 1, further comprising output means for outputting necessary information including a calculation result calculated by at least the harmonic component coincidence calculating means in a format that can be recognized by a user.

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