KR20220148698A - Power distribution panel equipped with power quality diagnosing device and method applying fuzzy clustering and voltage sag severity index - Google Patents

Abstract

Disclosed is a device for comprehensively diagnosing a power quality in a distribution board, which is a device for comprehensively diagnosing a power quality in a distribution board. The device comprises: a monitoring means configured to monitor a voltage fluctuation of an input voltage to be diagnosed and transmitted to the distribution board; a processing means configured to record measured values of the input voltage to be diagnosed during a preset monitoring period from a time point when the voltage fluctuation exceeds a fluctuation threshold, create a voltage disturbance scatter plot based on voltage fluctuation amplitudes and fluctuation durations of the measured values, cluster the measured values into at least one cluster by applying a fuzzy clustering algorithm to the voltage disturbance scatter plot, determine at least one medoid by selecting a measured value closest to the center of the cluster among measured values of at least one cluster, and apply a position of at least one medoid of the voltage disturbance scatter plot to a weighted look-up table based on an ITIC curve to calculate a comprehensive power quality diagnosis index; and a display means configured to display a comprehensive diagnosis signal according to the comprehensive power quality diagnosis index.

Description

POWER DISTRIBUTION PANEL EQUIPPED WITH POWER QUALITY DIAGNOSING DEVICE AND METHOD APPLYING FUZZY CLUSTERING AND VOLTAGE SAG SEVERITY INDEX

The present invention relates to a switchgear having an apparatus and method for diagnosing power quality to which fuzzy clustering and a voltage drop severity index are applied. More specifically, the present invention relates to a case in which transient phenomena and harmonics such as instantaneous voltage drop, instantaneous blackout, and instantaneous voltage rise that degrade the quality of power supplied by the switchgear continuously occur, this is shown in the voltage disturbance scatter diagram. It relates to an apparatus and method for comprehensively diagnosing the quality of power supplied to a load by calculating an instantaneous voltage drop severity index to which the harmonic distortion factor (THD) and fuzzy clustering theory are applied.

Power disturbance refers to a phenomenon in which instantaneous power failure, instantaneous voltage drop, voltage rise, surge, etc. occur in the electric power system due to lightning strike, sudden load reduction, electric power line accident, or starting of large electric equipment in the normal state of the power supply. In order to define the power quality of the power system, the above Electromagnetic Disturbance Phenomenon should be measured and evaluated. In this case, voltage, current and frequency characteristics can be mainly used.

In order to suppress the effects of electromagnetic disturbances such as blackouts, voltage fluctuations, instantaneous voltage drops and harmonics on the power system, the Electricity Business Act stipulates the range and duration of voltage fluctuations to be maintained, and overloads and overheats electrical equipment. There are various regulations related to the power system, such as the allowable standard value of harmonics that affect , noise, and the like.

Since the quality of the power supplied to the load is affected by the power supplier involved in the power distribution process in addition to the influence on the switchgear side, disputes may arise as to where the responsibility for damage caused by abnormalities in the quality of the power supplied to the load lies. can In general, since the switchgear side lacks the equipment or technology for quality analysis compared to the power supplier, there may be cases where it may face the limit of proof of responsibility for the deterioration of power quality. Therefore, a device capable of analyzing the power quality of the customer inlet end may be required on the switchboard side as well.

Republic of Korea Patent Publication No. 10-2012-0012591

The technical problem to be solved by the present invention is to provide a power quality comprehensive diagnosis device that enables analysis of the power quality of the customer inlet end even on the switchgear side.

As a means for solving the above technical problem, an apparatus for comprehensively diagnosing power quality in a switchboard according to some embodiments of the present invention includes: a monitoring means configured to monitor a voltage change of a diagnostic target input voltage introduced into the switchboard; Recording the measurement values of the input voltage to be diagnosed measured during a preset monitoring period from the point in time when the voltage fluctuation exceeds the fluctuation reference value, and generating a voltage disturbance scatter plot based on the voltage fluctuation width and fluctuation duration of the measurement values; By applying a fuzzy clustering algorithm to the voltage disturbance scatterplot, the measured values are clustered into at least one cluster, and among the measured values of each of the at least one cluster, the measurement value closest to the cluster center is selected to determine at least one medoid, and the processing means configured to calculate a power quality comprehensive diagnostic index by applying the position of the at least one medoid in the voltage disturbance scatterplot to a weighted lookup table based on an ITIC curve; and display means configured to display a comprehensive diagnostic signal according to the power quality comprehensive diagnostic index. includes

According to another embodiment of the present invention, a method for comprehensively diagnosing power quality in a switchgear, performed by an apparatus for comprehensively diagnosing power quality in a switchgear, includes: monitoring a voltage change of an input voltage to be diagnosed transmitted to the switchboard; recording the measurement values of the input voltage to be diagnosed, which are measured during a preset monitoring period from a point in time when the voltage fluctuation exceeds a fluctuation reference value; generating a voltage disturbance scatter plot based on the voltage fluctuation width and fluctuation duration of the measured values; clustering the measured values into at least one cluster by applying a fuzzy clustering algorithm to the voltage disturbance scatterplot; determining at least one medoid by selecting a measurement value closest to a cluster center from among the measurement values of each of the at least one cluster; calculating a power quality comprehensive diagnostic index by applying the position of the at least one medoid in the voltage disturbance scatter plot to a weighted lookup table based on an ITIC curve; and displaying a comprehensive diagnostic signal according to the power quality comprehensive diagnostic index. includes

According to the apparatus and method for comprehensively diagnosing power quality in a switchgear according to the present invention, clustering is performed by a fuzzy clustering algorithm, so that the medoid can be determined in each cluster, and the medoid is weighted according to where it is located in the voltage disturbance scatterplot. A power quality comprehensive diagnostic index can be calculated by the lookup table. According to the weighted lookup table, not only the instantaneous voltage drop in the voltage disturbance scatterplot, but also the effect of a momentary blackout or instantaneous overvoltage can be comprehensively reflected, so the quality of the power coming from the power supplier to the switchgear can be effectively analyzed.

1 is a view for explaining a power system according to some embodiments.
2 is a view for explaining an apparatus for comprehensively diagnosing power quality in a switchboard of a power system according to some embodiments.
3 is a block diagram illustrating elements constituting an apparatus for comprehensively diagnosing power quality in a switchboard according to some embodiments.
4 to 6 are diagrams for explaining a voltage disturbance scatter plot for calculating a power quality comprehensive diagnostic index according to some embodiments.
7 is a diagram for explaining a process of calculating an instantaneous voltage drop severity index according to some embodiments.
8 is a flowchart illustrating steps constituting a method for comprehensively diagnosing power quality in a switchgear according to some embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is only for specifying the embodiments, and is not intended to limit or limit the scope of rights according to the present invention. What a person of ordinary skill in the art related to the present invention can easily infer from the detailed description and embodiments of the invention should be construed as belonging to the scope of the present invention.

Although the terms used in the present invention have been described as general terms widely used in the technical field related to the present invention, the meaning of the terms used in the present invention is the intention of a technician in the relevant field, the emergence of new technology, examination standards or precedents. It may vary depending on Some terms may be arbitrarily selected by the applicant, and in this case, the meaning of the arbitrarily selected terms will be described in detail. Terms used in the present invention should be interpreted as meanings reflecting the overall context of the specification, not just dictionary meanings.

Terms such as 'consisting' or 'comprising' used in the present invention should not be construed as necessarily including all of the components or steps described in the specification, and when some components or steps are not included, And when additional components or steps are further included, it should also be construed as intended from the term.

Terms including an ordinal number such as 'first' or 'second' used in the present invention may be used to describe various components or steps, but the components or steps should not be limited by the ordinal number. . Terms containing an ordinal number should only be construed for the purpose of distinguishing one element or step from other elements or steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Detailed descriptions of matters widely known to those of ordinary skill in the art related to the present invention will be omitted.

1 is a view for explaining a power system according to some embodiments.

Referring to FIG. 1 , a power system 10 for receiving and distributing power transmitted from a power provider at a power distribution panel is shown. In the power system 10 , transmitted power may be transmitted to a load through a switchboard, and at this time, a device 100 for comprehensively diagnosing power quality in the switchboard may be installed in the switchboard.

In the power system 10 , a power supervisory control and data acquisition (SCADA) system may be formed. In the power system 10 , data exchange between components may be performed using a TCP/IP method or a WiFi method, and power management may be performed through a mobile device.

In the power system 10 , the switchgear may refer to a panel that receives power transmitted from a power provider and distributes it back to a load. The device 100 may be provided for comprehensive diagnosis of the power quality of the power transmitted to the switchgear.

2 is a view for explaining an apparatus for comprehensively diagnosing power quality in a switchboard of a power system according to some embodiments.

Referring to FIG. 2 , in the apparatus 100 for comprehensively diagnosing the power quality in the switchboard of the power system 10 , the monitoring means 110 , the processing means 120 , and the display means 130 may perform their respective functions. have.

The monitoring means 110 may receive a diagnosis target input voltage for power quality diagnosis. The input voltage provided to the monitoring means 110 may be transmission power transmitted from the power system 10 to the switchboard by the power provider. For example, the monitoring means 110 may be an electrical measuring means for measuring the width and duration of voltage fluctuations.

The processing means 120 may process steps for comprehensive power quality diagnosis. The processing means 120 may be an electronic device comprising a general purpose memory/processor structure. The processing means 120 may execute a computer program or application for performing a comprehensive power quality diagnosis. For example, the processing means 120 may consist of a memory such as DRAM, SRAM or SSD and a processor such as a CPU, AP or GPU.

The display means 130 may display at least one comprehensive diagnosis signal of normality, harmonic warning, power quality warning, and danger based on the power quality comprehensive diagnosis index. In addition, the display means 130 may display a warning signal for voltage abnormal events such as instantaneous interruption, instantaneous voltage drop (SAG), instantaneous overvoltage (SWELL), undervoltage (UV) and overvoltage (OV), and , can display a harmonic distortion factor (THD) warning signal. For example, the display unit 130 may be an electronic display unit such as an LCD panel or an LED panel.

3 is a block diagram illustrating elements constituting an apparatus for comprehensively diagnosing power quality in a switchboard according to some embodiments.

Referring to FIG. 3 , the apparatus 100 for comprehensively diagnosing power quality in a switchgear may include a monitoring unit 110 , a processing unit 120 , and a display unit 130 . However, the present invention is not limited thereto, and other general-purpose elements may be further included in the device 100 .

The monitoring means 110 may be configured to monitor the voltage fluctuation of the input voltage to be diagnosed transmitted to the switchgear.

The diagnosis target input voltage may mean a voltage supplied by a power provider in the power system 10 . By monitoring the input voltage to be diagnosed, it can be ascertained when the voltage fluctuation starts.

The processing means 120 may be configured to record measurements of the input voltage to be diagnosed measured during a preset monitoring period from a point in time when the voltage fluctuation exceeds the fluctuation reference value.

For example, the variation reference value may be set to 10% of the normal voltage. When the input voltage to be diagnosed is less than 90% or more than 110% of the normal voltage, it may be determined that the input voltage to be diagnosed exceeds the variation reference value. The preset monitoring period may be preset to an appropriate value as needed, such as 60 seconds (3,600 cycles), 30 seconds (1,800 cycles), or 10 seconds (600 cycles).

When the voltage fluctuation exceeds the fluctuation reference value, the measurement values of the input voltage to be diagnosed may be recorded for a preset monitoring period from the time of the exceeding. The measurements may include a width of the voltage fluctuation in units of PU (Per Unit) and a duration of the voltage fluctuation in units of cycles.

For example, if one measurement value is recorded as (10, 0.85), the measurement value has a voltage 0.85 times the nominal voltage based on the ITIC curve, and the duration of the voltage is 10 cycles. may mean data.

The processing means 120 may be configured to generate a voltage disturbance scatter plot based on the voltage fluctuation width and the fluctuation duration of the measurements.

The voltage disturbance scatterplot may mean a statistical graph that displays measured values recorded during a preset monitoring period from a point in time when the voltage fluctuation exceeds a fluctuation reference value with respect to the voltage fluctuation duration of the x-axis and the voltage fluctuation width of the y-axis. For example, when 99 measurements are recorded during a preset monitoring period, the voltage fluctuation width in PU units and the voltage fluctuation duration in cycles for each of the measurement values may be plotted as 99 points in two dimensions.

The voltage fluctuation duration corresponding to the x-axis of the voltage disturbance scatter plot may be displayed in units of cycles. 1 cycle may mean 1/60 sec. The voltage fluctuation width corresponding to the y-axis of the voltage disturbance scatter plot may be expressed in units of PU (per unit). The PU unit of the y-axis may represent a relative magnitude of a voltage measured by setting the nominal voltage according to the ITIC curve to 1 as 0.9 PU, 0.7 PU, 1.1 PU, or the like. An example of a voltage disturbance scatterplot may be shown with reference to FIGS. 4 to 6 .

The processing means 120 may be configured to apply a fuzzy clustering algorithm to the voltage disturbance scatterplot to cluster the measurements into at least one cluster.

For example, when 99 measurements are included in the voltage disturbance scatterplot, the 99 measurements may be clustered into one, two, three or more clusters. Fuzzy clustering may be a soft clustering method that suggests a probability that a measurement belongs to several clusters, rather than the hard clustering method K-centric clustering in which each measurement exclusively belongs to a specific cluster.

In fuzzy clustering, the number of clusters may be determined to an appropriate number as the clustering results converge as the algorithm progresses. That is, the number of clusters in the clustering result may vary depending on how the measured values of the voltage disturbance scatterplot are distributed.

The processing means 120 may be configured to determine the at least one medoid by selecting a measurement closest to the cluster center from among the measurements of each of the at least one cluster.

When the number of measurements in the voltage disturbance scatterplot is 99 and the 99 measurements are clustered into 3 clusters by fuzzy clustering, a medoid is determined for each of the 3 clusters, so that a total of 3 medoids can be determined. . A medoid may mean a measurement value closest to a cluster center of a corresponding cluster among measurements of each cluster.

The at least one medoid may represent measurements in the voltage disturbance scatterplot. Instead of performing analysis on all measured values, analysis of at least one medoid may be performed, and a comprehensive power quality diagnostic index may be calculated therefrom.

The processing unit 120 may be configured to calculate a power quality comprehensive diagnostic index by applying the position of at least one medoid in the voltage disturbance scatter plot to a weighted lookup table based on the ITIC curve.

For the voltage disturbance scatterplot, a weighted lookup table based on the ITIC curve may be preset. The ITIC (Information Technology Industry Council) curve is an approximate version of the CBEMA power acceptability curve, which indicates a reference threshold for voltage disturbance. It is widely used for

Considering that the farther away from the reference threshold according to the ITIC curve, the greater the effect on the power quality in the voltage disturbance scatterplot, the weight lookup table is calculated by setting different weighted scores for each area where the medoid is located. can be formed. For example, as shown in FIGS. 4 to 6 , a weight lookup table including weights set for each region may be preset.

When the position of at least one medoid is applied to the weighted lookup table, the total power quality diagnostic index may be calculated by summing the added scores corresponding to each medoid.

The power quality comprehensive diagnosis index may mean an index for diagnosing the overall quality of transmitted power. Specifically, in addition to the commonly used instantaneous voltage drop (SAG), an instantaneous voltage rise (SWELL) that exceeds the ITIC curve, an interruption that is less than 10% of the reference voltage, or an overvoltage (OV) or undervoltage (UV) ) can be considered comprehensively, so the quality of power transmitted to the power distribution end can be analyzed through the power quality comprehensive diagnostic index.

The display means 130 may be configured to display a comprehensive diagnostic signal according to the power quality comprehensive diagnostic index.

For example, as will be described later with reference to FIGS. 5 and 6 , when the power quality comprehensive diagnostic index exceeds 0.6, the warning light may be turned on by the display means 130 . In addition, the display means 130 may display a warning signal for warning that a voltage abnormal event determined by the position of at least one medoid in the voltage disturbance scatterplot, or that the harmonic distortion factor exceeds a reference value.

As described above, in the apparatus 100, the power quality comprehensive diagnostic index may be calculated through the processes of generating a voltage disturbance scatterplot, applying a fuzzy clustering algorithm, determining a Meadoid, and applying a weight lookup table. Since the comprehensive power quality diagnostic index can reflect various types of voltage abnormal events other than instantaneous voltage drop (SAG), it can be used to comprehensively analyze the quality of power transmitted from power providers.

Meanwhile, in addition to calculating the power quality comprehensive diagnostic index, the apparatus 100 may analyze a total harmonic distortion (THD) of the input voltage to be diagnosed monitored by the monitoring means 110 .

That is, the processing means 120 may calculate the harmonic distortion factor (THD) of the input voltage to be diagnosed, and if the THD of the input voltage to be diagnosed exceeds the THD reference value, the THD weight is added to the comprehensive power quality diagnostic index. can be further configured. In addition, the display means 130 may be further configured to display a THD warning signal when the THD of the input voltage to be diagnosed exceeds the THD reference value.

Since harmonics also correspond to one factor inducing deterioration of the quality of transmission power, the apparatus 100 may additionally analyze harmonic distortion of transmission power in order to comprehensively analyze the power quality at the receiving/distributing stage. At this time, if it is determined that the input voltage to be diagnosed contains excessive harmonics, a THD weighted score may be added to the comprehensive power quality diagnostic index, so the effect of harmonics may be reflected in the comprehensive power quality diagnostic index. The display means 130 may additionally display a THD warning signal in addition to the existing voltage abnormal event warning signal.

4 to 6 are diagrams for explaining a voltage disturbance scatter plot for calculating a power quality comprehensive diagnostic index according to some embodiments.

Referring to FIG. 4 , there is shown a voltage disturbance scatter plot 400 defining regions of voltage anomaly events based on an ITIC curve.

The voltage disturbance scatter plot 400 may target voltage fluctuations of the input voltage to be diagnosed collected for 60 sec (3,600 cycles), and a log scale may be applied to the duration of the x-axis if necessary. The y-axis of the voltage disturbance scatterplot 400 may indicate voltage fluctuations of measured values as a percentage with respect to a reference voltage.

In the voltage disturbance scatter plot 400, ITIC curves 410 and 420 are indicated by thick solid lines like the SWELL reference curve 410 on the upper side and the SAG reference curve 420 on the lower side, and the ITIC curve 410 is based on Regions of eight voltage anomaly events are shown. The values of the ITIC curve 410, for example, the ITIC SAG reference voltage of 80% when the duration is 3 sec, may then be used in the calculation process of the voltage sag severity index (VSSI). .

Regions 1 to 8 of the eight voltage abnormal events are based on the ITIC curves 410 and 420, the instantaneous voltage drop region 1, the instantaneous voltage rise region 2, the instantaneous power failure region 3, and the instantaneous It may be composed of a voltage drop region 4 , an instantaneous voltage rise region 5 , a temporary blackout region 6 , a temporary voltage drop region 7 , and a temporary voltage rise region 8 . The division of the regions 1 to 8 of the voltage abnormal event may be in accordance with IEEE 1519.

Referring to FIG. 5 , a voltage disturbance scatter plot 500 is shown that displays a weight lookup table in which different weights are set in regions 1 to 8 of voltage abnormal events.

Specifically, in the weight lookup table of the voltage disturbance scatter plot 500, a weight of 0.1 may be assigned to the instantaneous voltage drop region 1, and a weight of 0.05 may be assigned to the instantaneous voltage rise region 2, and A weight of 0.05 may be assigned to the electrostatic region 3, a weight of 0.0 or 0.2 may be assigned to the instantaneous voltage drop region 4, and a weight of 0.1 may be assigned to the instantaneous voltage rise region 5, and , a weight of 0.1 or 0.2 may be assigned to the temporary blackout region 6 , a weight of 0.0, 0.3 or 0.4 may be assigned to the temporary voltage drop region 7 , and a weight of 0.2 may be assigned to the temporary voltage rise region 8 . Weights may be assigned.

In the weight lookup table of the voltage disturbance scatterplot 500, the different weights set in the regions 1 to 8 of the voltage abnormal event are the values of the duration of the x-axis while being farther away from the reference threshold of the ITIC curve. As this value is larger, it may be set to a larger value.

Referring to FIG. 6 , a voltage disturbance scatter diagram 600 is shown for explaining a process of applying at least one medoid m1 to m6 to a weight lookup table.

In the voltage disturbance scatterplot 600, when the weighted score assigned to the regions 1 to 8 of the voltage abnormal event according to the weighted lookup table is applied to at least one medoid m1 to m6, 0.1 in the medoid m1 Points, 0.2 points for Meade (m4), 0.3 points for Meadows (m5), and 0.2 points for Meadows (m6) are added, so that the power quality comprehensive diagnosis index can be calculated as 0.8 points.

When the power quality comprehensive diagnostic index exceeds the reference value, for example, when it exceeds the reference value of 0.6 point, the display means 130 may display the comprehensive diagnostic signal as a danger among safety, warning, and danger.

On the other hand, as an example, even if the power quality comprehensive diagnostic index is calculated as 0.5 and does not exceed the standard value of 0.6, when the harmonic distortion factor (THD) of the input voltage to be diagnosed exceeds the THD standard value, 0.7 points plus the THD weight of 0.2 points are the standard value If it exceeds 0.6, the display means 130 may display the comprehensive diagnosis signal as a danger.

At least one medoid (m1 to m6) may be utilized to determine the type of voltage abnormality event and display a warning signal therefor, in addition to calculating the power quality comprehensive diagnostic index.

That is, the processing means 120, the at least one medoid in the voltage disturbance scatter plot instantaneous power interruption (Interruption), instantaneous voltage drop (Sag), instantaneous overvoltage (Swell), undervoltage (UV) and any voltage of overvoltage (OV) It may be further configured to determine whether it belongs to the region of the abnormal event, and the display means 130 may be further configured to display a warning signal for the voltage abnormal event in the region to which the at least one medoid belongs.

In the regions 1 to 8 of the voltage abnormal event of the voltage disturbance scatterplot 600, only the instantaneous interruption, the instantaneous voltage drop (Sag), and the instantaneous overvoltage (Swell) are displayed, but in a similar manner to the undervoltage (UV) and a region corresponding to the overvoltage OV may be further defined.

In the case of at least one medoid (m1 to m6), the medoids m1 and m6 are located in the instantaneous overvoltage (Swell) region, and the medoids (m4, m5) are located in the instantaneous voltage drop (Sag) region. In response, the display means 130 may display an instantaneous overvoltage (Swell) warning signal and an instantaneous voltage drop (Sag) warning signal.

According to the warning signal display for such voltage abnormal events, in addition to displaying the comprehensive diagnostic signal as serious by comparing the power quality comprehensive diagnostic index with the reference value, what voltage abnormal event is currently occurring can be analyzed by the warning signal. can

7 is a diagram for explaining a process of calculating an instantaneous voltage drop severity index according to some embodiments.

Referring to FIG. 7 , a table 700 is shown for explaining the process of calculating the instantaneous voltage drop severity index (VSSI) in six steps. A voltage sag severity index (VSSI) may be an index for quantifying the effect of an instantaneous voltage sag (Sag) among voltage abnormal events.

With respect to the sag severity index of FIG. 7 , the processing means 120 is configured to calculate a sag severity index indicating how transient or repetitive the sag is for each of the at least one cluster in the voltage disturbance scatterplot. It may be further configured, and the display means 130 may be further configured to display the instantaneous voltage drop severity index together with the comprehensive diagnostic signal.

The instantaneous voltage drop severity index VSSI can numerically indicate whether the voltage drop appears only temporarily or occurs repeatedly in the power system. As will be described later, as VSSI calculated as a value of 0 to 1 is closer to 0, it may indicate that the voltage drop is repetitive, and as it is closer to 1, it may indicate that it is temporary.

Accordingly, when the instantaneous voltage drop severity index VSSI is displayed by the display means 130 , information on whether the voltage drop is temporary or repetitive may be provided to the switchboard side based on the value of VSRI.

According to steps 1 to 6 of the table 700 , the VSSI for at least one medoid of the clustered at least one cluster may be calculated from the measurements plotted as a voltage disturbance scatter plot. For example, when 99 measurements are clustered into 3 clusters by the fuzzy clustering algorithm, 3 VSSIs may be calculated by calculating the index for the medoids of each cluster.

Specifically, in steps 1 and 2 of the table 700, a voltage disturbance scatterplot may be generated by plotting the measured values. In this case, the x-axis of the voltage disturbance scatterplot may be divided into appropriate numerical values, and, if necessary, A log scale may be applied to the x-axis.

과 같이 산출될 수 있다. 즉, V_sag가 ITIC 커브의 임계값 V_ITIC(D)과 동일한 경우 VSI는 0일 수 있고, V_sag가 V_ITIC(D)에서 멀어질수록 심각도 S가 높은 값을 가질 수 있다.In step 3 of the table 700, a severity S corresponding to an intermediate variable for calculating VSSI may be calculated. Severity S(D) of the measured value V _sag in the voltage disturbance scatter plot, for the duration D, which is the x-axis value of V _sag , using the threshold value V _ITIC (D) of the ITIC curve at D,

can be calculated as That is, when V _sag is equal to the threshold V _ITIC (D) of the ITIC curve, VSI may be 0, and the severity S may have a higher value as V _sag is further away from V _ITIC (D).

In step 4 of the table 700, fuzzy clustering may be performed on the measurements to find a medoid from each cluster by clustering the measurements of the voltage disturbance scatterplot. In the fuzzy clustering process, the average (centroid) C _k of each cluster may be calculated based on the weight w _i,k , and the closest measurement to the center C _k may be determined as the medoid of the corresponding cluster. At least one by fuzzy clustering When a medoid is determined from a cluster of , the severity S (medoid) for each medoid can be calculated.

In step 5 of the table 700, S(max) corresponding to the maximum value among the severity S values of each cluster may be calculated.

과 같이 순간전압강하 심각도 지수 VSSI(D)가 산출될 수 있다. 이 때, VS_t 및 VS_0.9PU는 클러스터 임계치의 전압강하 심각도 및 클러스터 임계치 대비 0.9 PU 지점의 전압강하 심각도를 의미할 수 있다.In step 6 of the table 700, using the previously obtained S (medoid), S (max), the formula

The instantaneous voltage drop severity index VSSI(D) can be calculated as In this case, VS _t and VS _0.9PU may mean a voltage drop severity of the cluster threshold and a voltage drop severity of 0.9 PU compared to the cluster threshold.

에 따라 산출할 수 있고, 적어도 하나의 클러스터 각각에 있어서 클러스터 최대값의 심각도 S(max), 클러스터 메도이드의 심각도 S(medoid), 클러스터 임계치의 심각도 VS_t, 클러스터 임계치 대비 0.9 PU 지점의 심각도 VS_0.9PU에 대한 순간전압강하 심각도 지수 VSSI(D)를 다음 수식:

에 따라 산출할 수 있다.That is, the processing means 120 calculates the voltage drop measurement V _sag at a specific duration D of the voltage disturbance scatterplot and the severity S(D) for the ITIC curve threshold V _ITIC (D) by the following equation:

In each of at least one cluster, the severity S(max) of the cluster maximum value, the severity S(medoid) of the cluster medoid, the severity VS _t of the cluster threshold, and the severity VS of the 0.9 PU point relative to the cluster threshold The sag severity index VSSI(D) for _0.9PU is given by the following formula:

can be calculated according to

In the equation of step 6 of the table 700, the denominator may be a constant value according to the section to which the duration D belongs, and the numerator may be the difference between S(max) and S(medoid), so S(medoid) is S(max) ), VSSI(D) may have a lower value.

When S(medoid) is close to S(max), it means that the medoid is located near the maximum value, which means that many measurements are clustered near the maximum value, so VSSI(D) with a low value close to zero may mean that the voltage drop occurs repeatedly. In the same way, a high value of VSSI(D) close to 1 may mean that the voltage drop is temporary.

8 is a flowchart illustrating steps constituting a method for comprehensively diagnosing power quality in a switchgear according to some embodiments.

Referring to FIG. 8 , a method 800 for comprehensively diagnosing power quality in a switchgear may include steps 810 to 870 . However, the present invention is not limited thereto, and other general steps may be further included in the method 800 .

The method 800 may consist of steps processed in time-series by the apparatus 100 for comprehensively diagnosing power quality in a switchgear. Therefore, even if the content is omitted below, the content described above for the apparatus 100 may be equally applied to the method 800 .

The method 800 for comprehensively diagnosing the power quality in the switchgear may be performed by the apparatus 100 for comprehensively diagnosing the power quality in the switchboard.

In operation 810 , the device 100 may monitor the voltage fluctuation of the input voltage to be diagnosed transmitted to the switchboard.

In operation 820 , the device 100 may record the measurement values of the input voltage to be diagnosed measured during a preset monitoring period from the point in time when the voltage fluctuation exceeds the fluctuation reference value.

In step 830 , the device 100 may generate a voltage disturbance scatter plot based on the voltage fluctuation width and fluctuation duration of the measurements.

In operation 840 , the apparatus 100 may apply a fuzzy clustering algorithm to the voltage disturbance scatterplot to cluster the measurements into at least one cluster.

In operation 850 , the apparatus 100 may determine at least one medoid by selecting a measurement closest to the center of the cluster from among the measurements of each of the one or more clusters.

In step 860, the device 100 may calculate the power quality comprehensive diagnostic index by applying the position of at least one medoid in the voltage disturbance scatter plot to the weighted lookup table based on the ITIC curve.

In step 870 , the device 100 may display a comprehensive diagnostic signal according to the power quality comprehensive diagnostic index.

Meanwhile, the method 800 may be recorded in a computer-readable recording medium in which at least one program or software including instructions for executing the method is recorded.

Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and floppy disks. Magneto-optical media, and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like may be included. Examples of program instructions may include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

Although the embodiments of the present invention have been described in detail above, the scope of the rights according to the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention described in the following claims are also present. It should be construed as being included in the scope of rights according to the

10: power system
100: A device for comprehensively diagnosing power quality in the switchgear
110: monitoring means
120: processing means
130: display means

Claims (1)

In a device for comprehensively diagnosing power quality in a switchboard,
monitoring means configured to monitor a voltage fluctuation of the input voltage to be diagnosed transmitted to the switchboard;
Recording the measurement values of the input voltage to be diagnosed, which are measured during a preset monitoring period from the point in time when the voltage fluctuation exceeds the fluctuation reference value,
generating a voltage disturbance scatterplot based on the voltage fluctuation width and fluctuation duration of the measured values;
clustering the measured values into at least one cluster by applying a fuzzy clustering algorithm to the voltage disturbance scatterplot;
Determining at least one medoid by selecting a measurement closest to the center of the cluster among the measurements of each of the at least one cluster,
processing means configured to calculate a power quality comprehensive diagnostic index by applying the position of the at least one medoid in the voltage disturbance scatter plot to a weighted lookup table based on an ITIC curve; And
display means configured to display a comprehensive diagnostic signal according to the power quality comprehensive diagnostic index; A device for comprehensively diagnosing power quality in the switchboard, including:

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