KR20120012591A - Power quality measuring device and evaluating voltage drop using it - Google Patents

Abstract

An apparatus for measuring power quality is provided. The power quality measuring device includes a voltage drop measurement unit for measuring the magnitude and duration of the voltage drop from the acquired voltage data and outputting the voltage drop event as a voltage drop event, and the voltage drop output from the voltage drop measurement unit during the set monitoring period. Collecting the event to calculate the average number of occurrences of the instantaneous voltage drop, and includes a monitoring period estimator for estimating the minimum monitoring period of the instantaneous voltage drop event from the annual average occurrence count calculated according to the required accuracy.

Description

Power quality measuring apparatus and method for analysis of instantaneous voltage drop using

The present invention relates to a power quality measuring apparatus, and more particularly, to a power quality measuring apparatus capable of measuring and analyzing an instantaneous voltage drop generated from a power line, and an instantaneous voltage drop analyzing method using the same.

The purpose of the power business is to provide good quality power to consumers at a low cost. To this end, the utility monitors power quality phenomena such as downtime, regulated voltage retention, and frequency maintenance, which are measures of good quality power supply.

To this end, a power quality measuring apparatus capable of measuring the quality of a power system is used, and a conventional power quality measuring apparatus classifies a power quality phenomenon using acquired voltage or current data and displays the classified results. The operator of the was required to take action based on the displayed results.

However, since the conventional power quality measuring device only displays the classification result of power quality phenomena, operators have an intuitive understanding of each power quality phenomenon.

In addition, in order to derive an analysis such as a tendency of occurrence of the phenomenon from the monitoring result of each power quality phenomenon, there is a problem that a separate analysis and additional work must be performed from the monitoring result.

An object of the present invention is to provide a power quality measuring apparatus including an instantaneous voltage drop analyzing apparatus.

Another object of the present invention is to provide an instantaneous voltage drop analyzing method capable of analyzing a voltage drop phenomenon using a power quality measuring apparatus.

Power quality measuring apparatus according to an embodiment of the present invention for solving the above problems, the instantaneous voltage drop measuring unit for measuring the magnitude and duration of the voltage drop from the acquired voltage data and outputting it as a voltage drop event and set Collecting the instantaneous voltage drop events output from the voltage drop measurement unit during the monitoring period to calculate the average number of occurrences of the instantaneous voltage drop, and to estimate the minimum monitoring period of the instantaneous voltage drop event from the calculated average annual occurrence number according to the required accuracy It includes a monitoring period estimation unit.

The instantaneous voltage drop analysis method according to an embodiment of the present invention for solving the other problem, the step of measuring the magnitude and duration of the voltage drop from the acquired voltage data and outputting the instantaneous voltage drop event, the set monitoring period Collecting the instantaneous voltage drop events during the calculation to calculate the average number of occurrences per year, and estimating the minimum monitoring period of the instantaneous voltage drop events from the calculated annual average number of occurrences according to the required accuracy.

Power quality measuring apparatus and instantaneous voltage drop analysis method of the present invention, by analyzing the occurrence trends and trends for the instantaneous voltage drop phenomenon generated in the power line, it is possible to intuitively understand the results of the administrator to the instantaneous voltage drop phenomenon Immediate action and management of the system becomes easy.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the drawings cited in the detailed description of the invention, a brief description of each drawing is provided.
1 is a block diagram of a power quality measurement system according to the present invention.
FIG. 2 is a configuration diagram of a raw data generating device shown in FIG. 1.
3 is a configuration diagram of the instantaneous voltage drop analyzing apparatus shown in FIG. 1.
4 is an operation flowchart of the instantaneous voltage drop measuring unit shown in FIG. 3.
5 is an operation flowchart of the scatter plot display unit shown in FIG. 3.
6 is an exemplary view illustrating an operation of a scatter plot display unit.
7 is an operation flowchart of the monitoring period estimator shown in FIG. 3.
8 is an exemplary view of a display of an apparatus for measuring power quality.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the embodiments of the present invention, reference should be made to the accompanying drawings that illustrate embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a block diagram of a power quality measurement system according to the present invention.

Referring to FIG. 1, the power quality measuring system 10 may include a power quality measuring device 30 and a management server 40.

The power quality measuring device 30 may include a raw data generating device 31 and an instantaneous voltage drop analyzing device 35.

The raw data generating device 31 measures the voltage signal VS or the current signal IS from the power line 20, for example, the power line 20 of 330V, 220V or 110V on U, V, W, Raw data, that is, raw voltage data VD or raw current data ID for power quality measurement, may be generated and output from the voltage signal VS or the current signal IS.

The instantaneous voltage drop analyzing device 35 analyzes the instantaneous voltage drop generated in the power line 20 from the raw voltage data VD or the raw current data ID output from the raw data generating device 31, and analyzes the voltage drop. The result can be sent to the management server 40.

For example, the instantaneous voltage drop analyzing apparatus 35 may analyze the probability of occurrence of the instantaneous voltage drop occurring in the power line 20, the number of occurrences, or a monitoring period for monitoring the same, and transmit the same to the management server 40.

The management server 40 may display the analysis result transmitted from the voltage drop analyzing apparatus 35 to a manager (or an operator). The manager may perform the measures and management for the instantaneous voltage drop of the power line 20 through the displayed analysis results.

FIG. 2 is a configuration diagram of a raw data generating device shown in FIG. 1.

1 and 2, as described above, the raw data generator 31 generates raw voltage data VD or raw current data ID from a voltage or current signal measured from the power line 20. can do.

However, in the present embodiment, for convenience of description, an example in which the raw data generating device 31 generates and outputs the raw voltage data VD from the voltage signal VS measured from the power line 20 will be described.

The raw data generating device 31 may include a measuring unit 111, a filter 113, an analog-digital converter 115, a signal processing unit 117, and a storage unit 119.

The measuring unit 111 may measure the voltage signal VS from the power line 20. Here, between the measuring unit 111 and the power line 20 is a transformer (not shown) that can drop the voltage flowing in the power line 20 to a voltage of a magnitude that can be processed by the raw data generating device 31 It may be located further.

The filter 113 filters and outputs the voltage signal VS measured by the measuring unit 111, and the analog-digital converter 115 converts the filtered voltage signal VS 'to analog-digital raw data. (VD) can be output.

The signal processor 117 may signal-process the converted signal, that is, raw voltage data VD, and store the signal in the storage 119.

On the other hand, the raw data generating device 31 may be operated when a predetermined period or a manager's request is generated to measure the voltage signal VS from the power line 20 to generate the raw voltage data VD.

3 is a configuration diagram of the instantaneous voltage drop analyzing apparatus shown in FIG. 1.

Referring to FIGS. 1 and 3, as described above, the instantaneous voltage drop analyzing apparatus 35 is provided with respect to the quality of a signal provided through the power line 20, for example, the instantaneous voltage drop, from the provided raw voltage data VD. The analysis may be performed and sent to the management server 40.

On the other hand, the power quality measuring device 30 uses a variety of analysis, for example, a signal flowing in the power line 20 by using the raw voltage data VD or the raw current data ID output from the raw data generating device 31. Various power quality items, such as voltage retention, instantaneous voltage rise, power failure, harmonic analysis, and flicker analysis, may be analyzed. For this purpose, various analysis devices may be further included in addition to the instantaneous voltage drop analysis device 35.

The instantaneous voltage drop analyzing apparatus 35 may include an instantaneous voltage drop measuring unit 210, a scatter plot display unit 220, a monitoring period estimating unit 230, and a reliability evaluation unit 240.

The instantaneous voltage drop measuring unit 210 obtains the raw voltage data VD from the raw data generator 31 and measures the magnitude and duration of the instantaneous voltage drop generated in the power line 20, respectively, and the instantaneous voltage Can be output as a falling event (EV).

For example, the instantaneous voltage drop measuring unit 210 calculates the rms voltage data from the obtained raw voltage data VD, and compares the calculated rms voltage data with the reference voltage data Vref to determine the magnitude and duration of the instantaneous voltage drop. Can be measured and output.

The instantaneous voltage drop measuring unit 210 may include a magnitude measuring unit 211 and a duration measuring unit 213.

In addition, although not shown in the drawing, the instantaneous voltage drop measuring unit 210 merges the measured magnitude of the voltage drop and the duration of the voltage drop to output a merging unit (not shown) that outputs the instantaneous voltage drop event (EV). It may further include.

4 is an operation flowchart of the instantaneous voltage drop measuring unit shown in FIG. 3.

3 and 4, the instantaneous voltage drop measuring unit 210 may calculate the effective value voltage data from the obtained source voltage data VD (S10).

Subsequently, the calculated rms voltage data is compared with the reference voltage data Vref (S20), and the duration of the instantaneous voltage drop is measured according to the comparison result (S30) or the rms voltage data is again obtained from the raw voltage data VD. Can be calculated (S10).

For example, the raw data generating device 31 illustrated in FIG. 1 may output the raw voltage data VD to the instantaneous voltage drop measuring unit 210 for a set time, for example, a constant monitoring period.

The magnitude measuring unit 211 of the instantaneous voltage drop measuring unit 210 calculates the first effective value voltage data, for example, the first effective value voltage data, from the first obtained raw voltage data, for example, the first source voltage data VD, and the reference voltage. It can be compared with data Vref.

As a result of comparison, when the magnitude of the first effective value voltage data is smaller than (or less than) the reference voltage data Vref, the duration of the instantaneous voltage drop may be measured by using the duration measuring unit 213. .

Here, the duration measuring unit 213 may be configured as a counter that can count the time.

However, if the size of the first effective value voltage data is greater than (or exceeds) the size of the reference voltage data Vref, the magnitude measuring unit 211 may output the second source voltage output from the raw data generating device 31. The step of acquiring the data VD and calculating the second effective value voltage data may be repeated (S10).

Meanwhile, when the duration measuring unit 213 measures the duration of the instantaneous voltage drop according to the comparison result, the magnitude measuring unit 211 acquires the second raw voltage data VD to calculate the second effective value voltage data. In operation S40, the calculated second effective value voltage data and the reference voltage data Vref may be compared.

As a result of comparison, when the second effective value voltage data is less than (or less than) the reference voltage data Vref, the duration measuring unit 213 continuously performs the duration measurement of the instantaneous voltage drop (S30) and measures the magnitude. The unit 211 may repeat the operation of acquiring the third raw voltage data VD to calculate the third effective value voltage data and comparing the same with the reference voltage data Vref (S40).

However, if the second effective value voltage data is greater than or equal to (or greater than or equal to) the reference voltage data Vref, the duration measuring unit 213 may end the duration measurement of the instantaneous voltage drop (S50). .

In addition, the magnitude measuring unit 211 may extract the rms voltage data having the minimum magnitude from the rms data calculated during the measured duration of the instantaneous voltage drop and output it as the magnitude of the instantaneous voltage drop (S60).

The instantaneous voltage drop measuring unit 210 may merge the measured duration of the instantaneous voltage drop and the magnitude of the extracted instantaneous voltage drop to output the instantaneous voltage drop event EV (S70).

Here, the reference voltage data Vref may be, but is not limited to, the maximum effective value voltage data, for example, the effective value voltage data dropped by 10% from the effective value voltage data without the instantaneous voltage drop occurring, for example, 0.9 [P.U].

In addition, the instantaneous voltage drop measuring unit 210 may operate during an actual monitoring period, that is, a preset monitoring period, to output one or more instantaneous voltage drop events EV.

Referring to FIG. 3 again, the scatter plot display unit 220 may acquire the instantaneous voltage drop event EV output from the instantaneous voltage drop measurement unit 210 and display the instantaneous voltage drop event EV in a scattered form on a two-dimensional graph.

For example, the scatter plot display unit 220 divides the two-dimensional graph into a plurality of areas according to the set classification criteria Sref and displays the instantaneous voltage drop event EV on the graph, whereby the manager is generated for each of the divided areas. Intuitive understanding of the instantaneous voltage drop event EV can be achieved.

5 is an operation flowchart of the scatter plot display unit illustrated in FIG. 3, and FIG. 6 is an exemplary view illustrating an operation of the scatter plot display unit.

3, 5, and 6, the scatter plot display unit 220 acquires the instantaneous voltage drop event EV output from the voltage drop measuring unit 210 (S110) and one or more classification criteria (Sref). Can be input (S120).

As shown in FIG. 6, the scatter plot display unit 220 may generate a two-dimensional graph including an x-axis and a y-axis, wherein the x-axis of the two-dimensional graph is the duration of the instantaneous voltage drop, and the y-axis is the instantaneous voltage drop. It may be the size of.

In addition, the scatter plot display unit 220 may divide the generated two-dimensional graph into a plurality of areas according to the input classification criteria Sref.

For example, when the input classification criteria Sref is five of X, T, S, Z, and Y, the scatter plot display unit 220 may divide the graph into a plurality of areas according to each classification criteria Sref. .

Here, the classification criterion X represents a section in which the magnitude of the instantaneous voltage drop is 40 to 80% of the maximum value, and a duration of 20 ms to 150 ms.

In addition, the classification criterion T represents a section in which the magnitude of the instantaneous voltage drop is 0 to 40% of the maximum value, and a duration of 20 ms to 600 ms.

In addition, the classification criterion S is a section in which the magnitude of the instantaneous voltage drop is 40 to 80% of the maximum value, and the duration is 150 ms to 600 ms.

In addition, the classification criterion Z represents a section in which the magnitude of the instantaneous voltage drop is 0 to 80% of the maximum value, and a duration of 600 ms to 3 sec.

In addition, the classification criterion Y represents a section in which the magnitude of the instantaneous voltage drop is 80 to 90% of the maximum value, and the duration is 20 ms to 3 sec.

The scatter plot display unit 220 may display the instantaneous voltage drop event EV, which is input on a two-dimensional graph divided into a plurality of areas for each classification criterion Sref, in a scattering format (S130).

The manager may grasp the instantaneous voltage drop occurrence characteristic of the power line 20 for each classification criterion Sref according to the display result of the scatter plot display unit 220, and take countermeasures for the instantaneous voltage drop through this (S140).

Referring back to FIG. 3, the monitoring period estimator 230 may determine the power line from the instantaneous voltage drop event EV output from the voltage drop measurement unit 210 during the actual monitoring period RMP. The annual average number of occurrences of the instantaneous voltage drop of 20) may be calculated, and the minimum operating period MP of the power line 20, that is, the minimum operation period of the instantaneous voltage drop analyzing apparatus 35 may be estimated using the calculated average annual number of occurrences of the instantaneous voltage drop.

7 is an operation flowchart of the monitoring period estimator shown in FIG. 3.

3 and 7, the monitoring period estimator 230 acquires the instantaneous voltage drop event EV output from the voltage drop measuring unit 210 (S210), and the actual monitoring period RMP from the manager. Can be input (S220).

The monitoring period estimator 230 may calculate the annual average number of occurrences of the instantaneous voltage drop from the instantaneous voltage drop event EV and the actual monitoring period RMP (S230).

The annual average number of occurrences of the instantaneous voltage drop may be calculated according to Equation 1 below.

[Equation 1]

Where μ denotes the number of annual average occurrences of the voltage drop, RMP denotes the actual monitoring period, and k denotes the number of instantaneous voltage drop events generated during the actual monitoring period.

Subsequently, the monitoring period estimator 230 may receive an instantaneous voltage drop request accuracy DA, for example, an instantaneous voltage drop occurrence prediction accuracy that is a reference for analyzing the instantaneous voltage drop (S240).

The monitoring period estimator 230 may estimate a minimum monitoring period MP for satisfying the required accuracy DA from the input request accuracy DA and the calculated number of annual average occurrences (S250).

For example, in a power system, the occurrence of an instantaneous voltage drop due to an accident is high. At this time, the occurrence of the accident of the power system follows the Poisson distribution.

Accordingly, the monitoring period estimator 230 may estimate the occurrence probability of the instantaneous voltage drop through Poisson distribution analysis as shown in Equation 2 below.

&Quot; (2) "

Where μ denotes the number of annual average occurrences of the voltage drop, RMP denotes the actual monitoring period, and k denotes the number of instantaneous voltage drop events generated during the actual monitoring period.

In addition, the monitoring period estimating unit 230 may satisfy the required accuracy DA according to Equation 3 below from the annual average number of occurrences of the instantaneous voltage drop and the estimated probability of occurrence of the instantaneous voltage drop. The monitoring period MP can be estimated.

&Quot; (3) "

Where μ is the average number of occurrences of the instantaneous voltage drop, MP is the minimum monitoring period, and ε is the error rate.

The minimum monitoring period MP output from the monitoring period estimator 230 may be displayed together with the result of the instantaneous voltage drop event EV output from the scatter plot display unit 220.

For example, referring to FIG. 8, the scatter plot display unit 220 may output the instantaneous voltage drop event EV and the number of occurrences of the classification criteria Sref, which are displayed in a scattered form on a two-dimensional graph for each classification criteria Sref ( 1, 3).

In addition, the monitoring period estimator 230 may output the annual average number of occurrences, the required accuracy DA and the actual monitoring period RMP calculated for Poisson distribution analysis (4), and the minimum monitoring estimated by using the same The period MP can be output (2).

In this way, the instantaneous voltage drop event EV output from the scatter plot display unit 220 and the monitoring period estimator 230, the number of occurrences per classification criterion Sref, the annual average number of occurrences, the required accuracy DA, and the actual monitoring period RMP. ) And the minimum monitoring period (MP) may be displayed on the management server 40 and the like on one screen and displayed to the administrator.

Therefore, the manager can immediately take action on the instantaneous voltage drop generated in the power line 20.

Referring back to FIG. 3, the minimum monitoring period MP estimated by the monitoring period estimator 230 may be output to the reliability evaluator 240.

The reliability evaluator 240 may evaluate the reliability RA of the annual average occurrence number of the instantaneous voltage drops calculated by comparing and analyzing the estimated minimum monitoring period MP and the actual monitoring period RMP.

Although the contents of the present invention have been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible therefrom. will be. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

10: power quality measurement system 20: power line
30: power quality measuring device 31: raw data generating device
35: voltage drop analysis device 40: management server
210: instantaneous voltage drop measuring unit 110: scatter plot display unit
230: monitoring period estimation unit 240: reliability evaluation unit

Claims (12)

In the power quality measuring device for analyzing the instantaneous voltage drop occurring in the power system,
An instantaneous voltage drop measuring unit measuring the magnitude and duration of the instantaneous voltage drop from the obtained voltage data and outputting the instantaneous voltage drop event; And
Collecting the instantaneous voltage drop event output from the instantaneous voltage drop measurement unit for a set monitoring period to calculate the annual average number of occurrences of the instantaneous voltage drop, and from the annual average occurrence number calculated according to the required accuracy of the instantaneous voltage drop event An apparatus for measuring power quality comprising a monitoring period estimator for estimating a minimum monitoring period. The method according to claim 1,
And a scatter plot display unit configured to display the instantaneous voltage drop event output from the instantaneous voltage drop measuring unit in a scattered form on a two-dimensional graph according to a set classification criterion. The method according to claim 1,
The instantaneous voltage drop measuring unit calculates an effective value voltage data from the voltage data, and compares the calculated effective value voltage data with reference voltage data to measure the magnitude and duration of the instantaneous voltage drop. The method according to claim 3,
And the instantaneous voltage drop measuring unit measures and outputs the time from the time when the effective voltage data becomes less than 90% of the reference voltage data to the time just before the time becomes 90% or more as the duration. The method according to claim 3,
And the instantaneous voltage drop measuring unit measures and outputs the RMS voltage data having the smallest magnitude among the RMS voltage data calculated during the duration as the magnitude of the instantaneous voltage drop. The method according to claim 1,
The monitoring period estimation unit,
And a Poisson distribution analysis to estimate an instantaneous voltage drop occurrence probability from the annual average occurrence number and to estimate the minimum monitoring period that can satisfy the required accuracy from the estimated instantaneous voltage drop occurrence probability. The method according to claim 1,
And a reliability evaluation unit for comparing and analyzing the set monitoring period and the minimum monitoring period to evaluate the calculated reliability of the annual average number of occurrences. In the instantaneous voltage drop evaluation method of the power quality measuring device for analyzing the voltage drop generated in the power system,
Measuring the magnitude and duration of the voltage drop from the acquired voltage data and outputting a voltage drop event;
Calculating the annual average number of occurrences by collecting the instantaneous voltage drop event during a set monitoring period; And
Estimating a minimum monitoring period of the instantaneous voltage drop event from the annual average number of occurrences calculated according to a required accuracy. The method of claim 8, wherein outputting the instantaneous voltage drop event comprises:
Calculating an effective voltage data from the voltage data;
Comparing the calculated RMS voltage data with reference voltage data;
Comparing and measuring the time from the time when the effective value voltage data becomes less than 90% of the reference voltage data to the time just before the size becomes greater than 90% as the duration; And
And measuring and outputting the RMS voltage data having the smallest magnitude among the RMS voltage data calculated during the measured duration as the magnitude of the instantaneous voltage drop. The method according to claim 8,
Estimating the minimum monitoring period of the instantaneous voltage drop event,
Estimating the probability of the instantaneous voltage drop from the annual average number of occurrences using Poisson distribution analysis: and
And calculating the minimum monitoring period that can satisfy the required accuracy from the estimated probability of occurrence of the voltage drop. The method according to claim 8,
And displaying the instantaneous voltage drop event in a scattered form on a two-dimensional graph according to a set classification criterion. The method according to claim 8,
And comparing and analyzing the set monitoring period and the minimum monitoring period, and evaluating the calculation reliability of the annual average number of occurrences.

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