KR100784302B1 - Diagnosis Method And Equipment for Electric Power machinery - Google Patents

Abstract

The present invention relates to an apparatus and method for diagnosing a power device capable of diagnosing aging or abnormality of the power device.

The present invention provides a normal current detector for detecting a current signal having a first magnitude among current signals input from a power device, a fault current detector for detecting a current signal greater than the first magnitude, and a current signal smaller than the first magnitude. A current detector including a high frequency and a notch component detector to divide the channel into a plurality of channels according to the magnitude of the current signal; It characterized in that it comprises a signal processing unit for determining the abnormality of the power device using the current signal divided into the plurality of channels.

Description

Diagnosis Method And Equipment for Electric Power machinery

1 is a block diagram showing an apparatus for diagnosing a power device according to the present invention.

FIG. 2 is a flowchart illustrating a diagnostic method using the diagnostic apparatus of the power device shown in FIG. 1.

    <Explanation of symbols for main parts of the drawings>

110: current detection unit 112: current input unit

114: voltage input unit 120: normal current detection unit

122,132,142: Transducers 124,144,146,148,164: Filter

126,134,150,152: Channel 128,158: Analog to Digital Converter

130: fault current detection unit 140: high frequency and notch component detection unit

156: signal processor 160: voltage detector

162: transformer 166: control unit

168 display unit

The present invention relates to an apparatus and method for diagnosing a power device, and more particularly, to an apparatus and method for diagnosing an aging or abnormality of a power device.

With the development of power electronic technology, various power devices are widely used in various fields such as industry, home, transportation, medical care, and environment.

Such power equipment generates measurable electrical signals in the early and ongoing stages of aging or failure. At this time, the generated electrical signal is not periodic but sporadic and is generated from insulation breakdown of insulator, tree contact of line, failure of underground cable, and arrester failure. The current magnitude of this electrical signal is 10-100mA, and the frequency is distributed between 2-10kHz.

In the event of aging or failure of such power equipment, there is a great possibility of economic and social losses. Accordingly, the conventional power device lowers the possibility of an accident by setting an arbitrary service life and replacing it regularly. However, this method generates significant economic losses compared to identifying and replacing the correct operating state.

Accordingly, in recent years, there is a demand for a technology capable of capturing and diagnosing abnormalities caused by aging or failure of power equipment.

Accordingly, an object of the present invention is to provide an apparatus and method for diagnosing a power device capable of diagnosing aging or abnormality of the power device.

In order to achieve the above object, a diagnostic apparatus for a power device according to the present invention is to detect a current signal having a first magnitude and a current signal larger than the first magnitude of the current signal input from the power device; A fault current detecting unit and a high frequency and notch component detecting unit for detecting a current signal smaller than the first magnitude are provided, and the current detecting unit is divided into a plurality of channels according to the magnitude of the current signal. Characterized in that the signal processing unit for determining the abnormality of the power device.

delete

The steady current detector includes: a first transducer converting the current signal having the first magnitude into a voltage signal; A first filter for removing aliasing included in a signal input from the first transducer; And a normal signal channel to which a signal from which aliasing is removed from the first filter is input.

The fault current detector includes a second transducer converting a current signal larger than the first magnitude into a voltage signal; And a failure signal channel to which the signal converted from the second transducer is input.

The high frequency and notch component detector comprises: a third transducer converting a current signal smaller than the first magnitude into a voltage signal; A second filter for removing fundamental wave components included in a signal input from the third transducer; A third filter which removes aliasing included in the signal input from the second filter and detects a high frequency component; A fourth filter for removing aliasing included in the signal input from the second filter; A high frequency signal channel to which a signal of a high frequency component from which aliasing is removed from the third filter is input; And a notch signal channel to which a signal from which aliasing is removed from the fourth filter is input.

The apparatus for diagnosing the power device may further include a voltage detector configured to detect a voltage signal input from the power device.

The voltage detector includes a transformer for converting a level of the voltage signal; And a fifth filter for eliminating aliasing included in the converted voltage signal.

The diagnostic apparatus of the power device includes a first analog-to-digital converter formed between at least one of the normal signal channel, the fault signal channel, the high frequency signal channel, and the fifth filter and a signal processor; And a second analog to digital converter formed between the notch signal channel and the signal processor, wherein the resolution of the first analog to digital converter is lower than that of the second analog to digital converter.

The signal processor may detect abnormal data using any one of a simple moving average technique, a simple exponential smoothing technique, a shewhart control chart, an EWMA control chart, and a ratio control chart.

In order to achieve the above object, the diagnostic method of the power device according to the present invention comprises the steps of: dividing the current signal into a plurality of channels according to the magnitude of the current signal input from the power device; And determining an abnormality of the power device by using the current signal divided into the plurality of channels.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 1 and 2.

1 is a block diagram showing an apparatus for diagnosing a power device according to the present invention.

The diagnostic apparatus for a power device according to the present invention shown in FIG. 1 includes a current input unit 112 for receiving a current signal, a voltage input unit 114 for receiving a voltage signal, and a current detector 110 for analyzing the input current signal. ), A voltage detector 160 for analyzing the input current signal, analog-to-digital converters 128 and 158 for converting the input analog signal into a digital signal, and a signal processor 156 for detecting abnormal electric signals among the input digital signals. ), A control unit 166 for controlling the power device from the data from the signal processing unit 156, and a display unit 168 for displaying the operation result of the control unit 166.

The current input unit 112 is connected to a current device so that a current signal from the current device is input.

The current detector 110 includes a steady current detector 120, a fault current detector 130, and a high frequency and notch component detector 140.

The steady current detector 120 includes a first transducer 122, a first filter 124, and a normal signal channel 126 connected between the current input unit 112 and the first analog-digital converter 128.

The first transducer 122 converts the normal current signal input from the current input unit 112 into a voltage signal to analyze the current in the normal state of the current device. For example, the first transducer 122 converts the normal current signal of 6 ~ 10A to 5V. The first filter 124 is composed of an anti-aliasing filter that removes the aliasing included in the signal input from the first transducer 122. The normal signal channel 126 supplies a signal de-aliased from the first filter 124 to the first analog to digital converter 128.

The fault current detector 130 includes a second transducer 132 and a fault signal channel 134 connected between the current input 112 and the first analog-digital converter 128.

The second transducer 132 converts the fault current signal input from the current input unit 112 into a voltage signal to analyze the current in the fault state of the current device. For example, the second transducer 122 converts a current signal of about 10 to 100 A greater than the steady state current to 5V. The fault signal channel 134 supplies the signal from the second transducer 132 to the first analog to digital converter 128.

The high frequency and notch component detector 140 includes a third transducer 142, second to fourth filters 144, 146, 148, and a high frequency signal connected between the current input unit 112 and the first and second analog-to-digital converters 128 and 158. Channel 150 and notch signal channel 152.

The third transducer 142 converts a specific current signal input from the current input unit 112 into a voltage signal to detect the high frequency and notch components of the current device. For example, the third transducer 142 converts a 5A current signal smaller than the steady state current to 5V. The second filter 144 includes a notch filter that removes a fundamental wave (eg, 60 Hz) component from a voltage signal input from the third transducer 142. The third filter 146 detects high frequency components included in the signal input from the second filter 144 and removes aliasing. To this end, the third filter 146 is formed by integrating an anti-aliasing filter and a high pass filter. The fourth filter 148 is composed of an anti-aliasing filter that removes the aliasing included in the signal input from the second filter 144. The high frequency signal channel 150 supplies the high frequency signal from which the aliasing is removed from the third filter 146 to the first analog to digital converter 128. The notch signal channel 152 supplies a signal from which the aliasing is removed from the fourth filter 148 to the second analog-to-digital converter 158.

The voltage input unit 114 is connected to a current device so that a voltage signal from the current device is input.

The voltage detector 160 includes a transformer 162 and a fifth filter 164 connected between the voltage input unit 114 and the first analog to digital converter 128.

The transformer 162 changes the level of the voltage signal input from the voltage input unit 114 to analyze the voltage of the current device. That is, the transformer 162 converts a voltage signal of 60 to 65V, for example 63.5V or 100 to 120V, for example 110V, into a voltage signal of 5 to 7V, for example 6V. The fifth filter 164 includes an anti-aliasing filter that removes aliasing included in the signal input from the transformer 162.

The first analog to digital converter 128 converts an analog signal input from the normal signal channel 126, the fault signal channel 134, the high frequency signal channel 150, and the fifth filter 164 into a digital signal. At this time, the first analog-to-digital converter 128 has a resolution of 12 bits or more.

The second analog to digital converter 158 converts an analog signal input from the notch signal channel 152 into a digital signal. At this time, the second analog-to-digital converter 158 has a higher resolution, for example, 16 bits or more than the first analog-to-digital converter 128.

The signal processor 156 uses the digital signals input every second from the first and second analog-to-digital converters 128 and 158 to provide electrical physical quantities such as current rms, voltage rms, current phase, voltage phase, active power, reactive power, and the like. Is calculated every few cycles, for example every two cycles. The signal processing unit 156 updates data such as minimum, maximum, average, and standard deviation of each electrical physical quantity every second. Every second, the controller 166 supplies abnormal data that exceeds the absolute upper limit threshold, the absolute lower limit threshold, or is above the current average value or below the average value.

The controller 166 determines the failure and the aging of the power device based on the data input from the signal processor 156 to control the operation of the power device.

The display unit 168 displays the operation result controlled by the control unit 166, that is, to inform the user of the current state of the power device. Such a display part uses LED, LCD, PDP, CRT, etc., for example.

Meanwhile, the signal processor 156 detects abnormal data through numerical analysis or waveform analysis.

Numerical analysis uses either Simple Moving Average or Simple Exponential Smoothing to analyze voltage unbalance data indicating the tendency of continuous thinking.

Simple Moving Average method finds abnormal data by calculating the average of 2 ~ 5 previous data from current data, predicting the value of next period and comparing it with actual value. Here, the calculation formula of the predicted value of the next period is shown in Equation 1.

The Simple Exponential Smoothing technique gives more weight to recent data. The equation of the Simple Exponential Smoothing technique is shown in Equation 2.

In Equation 2, when the weight of the most recent data is λ (0 <λ <1), the weight of the next data has a relationship of λ (1-λ), λ (1-λ) ² , and λ is Smoothing Factor, Smoothing Constant, and Damping Factor.

Waveform analysis uses upper and lower limits (UCL) and lower limits (LCL) for control using the average and standard deviation of the measured data to distinguish between normal and abnormal conditions. Detect abnormal data in and control it. To do this, waveform analysis uses a Shewhart control chart, an Exponentially Weighted Moving Average (EWMA) control chart, and a proportional control chart.

Shewhart control charts ( X Charts) are effective for recognizing relatively large fluctuations, and set upper and lower limits first with stored data. The calculation of this Shewhart control chart is shown in Equation 3.

EWMA control charts (Exponentially Weighted Moving Average) are effective for recognizing relatively small variations, and the more recent data is weighted, the higher the weight is. The equation of the EWMA control chart is shown in Equation 4.

Where t = 1,2, .... N

Xt: actual measurement data at time t

W = number of data used for calculation

λ: Weight index or braking index (0 <λ≤1)

And a chart is completed by calculating an average value, an upper limit, and a lower limit by Formula (5).

 The proportional control chart (p chart) technique is based on the binomial distribution, which analyzes the abnormal signal from the variation of the voltage rms that indicates the tendency of discrete thinking. The ratio of non-conforming parts of the total population to non-conforming (defined as defective) is defined as the ratio of the number of abnormal data to the number of data in the total population, expressed as a percentage or decimal. To determine whether the voltage sag is measured by measuring the voltage effective value, first, the ratio of the number of data when a predetermined threshold falls within a predetermined period is calculated.

Equation 6 obtains the ratio of the instantaneous voltage drop occurring in one month, and calculates the average for the total number of months observed in Equation 7.

The upper limit value and the lower limit value are calculated by Equation 8 to complete the chart.

Detailed analysis of voltage and current waveform data as described above detects continuous or discrete electrical signals in the event of aging or failure of power equipment, and detects aging or failure of power equipment in advance.

2 is a flowchart illustrating a diagnostic method of a power device according to the present invention.

First, a current signal and a voltage signal from a current device are input to each of the current input unit and the voltage input unit (steps S1 and S2).

The current signal input to the current input unit is classified into a normal current signal, a fault current signal, a high frequency signal, and a notch component detection current signal according to the magnitude and transmitted to the corresponding channel (step S3). The steady current signal passes through a first transducer that converts the signal into a voltage signal, passes through a first filter for eliminating aliasing, and then is transmitted to the normal signal channel. The fault current signal is sent to the fault signal channel after passing through a second transducer that converts the signal into a voltage signal. The high frequency and notch component detection current signal passes through a third transducer that converts the signal into a voltage signal and then through a second filter that removes the fundamental wave component. The signal passing through the second filter is transmitted to the high frequency signal channel through the third filter, and one of the signals passing through the second filter is transmitted to the notch signal channel through the fourth filter. Current signals transmitted to the channel are converted into digital signals by the analog-to-digital converter.

The voltage signal input to the voltage input part is converted into a digital signal by an analog-to-digital converter after passing through a fifth filter for reducing the voltage level and eliminating aliasing.

The digital signal converted to the digital signal is analyzed (step S4), and every second, abnormal data that exceeds the absolute upper limit threshold or the absolute lower limit threshold or exceeds the current average value or the average value is supplied to the controller (step S5). The operation result controlled by the controller is displayed on the display unit (step S6).

As described above, the apparatus and method for diagnosing a power device according to the present invention analyzes the input current signal into a normal signal channel, a fault signal channel, a high frequency signal channel, and a notch signal channel. Accordingly, the diagnostic device and method of the power device according to the present invention can detect abnormal electrical signals generated during aging or failure of the power device, thereby diagnosing abnormality of the power device.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (18)

delete A normal current detector for detecting a current signal having a first magnitude among current signals input from a power device, a fault current detector for detecting a current signal greater than the first magnitude, a high frequency for detecting a current signal smaller than the first magnitude, and A current detector including a notch component detector to divide the channel into a plurality of channels according to the magnitude of the current signal; And a signal processing unit for determining an abnormality of the power device using current signals divided into the plurality of channels. The method of claim 2, The normal current detector A first transducer converting the current signal of the first magnitude into a voltage signal; A first filter for removing aliasing included in a signal input from the first transducer; And a normal signal channel to which a signal from which aliasing is removed from the first filter is input. The method of claim 2, The fault current detector A second transducer for converting the current signal larger than the first magnitude into a voltage signal; And a failure signal channel to which the signal converted from the second transducer is input. The method of claim 2, The high frequency and notch component detection unit A third transducer converting the current signal smaller than the first magnitude into a voltage signal; A second filter for removing fundamental wave components included in a signal input from the third transducer; A third filter which removes aliasing included in the signal input from the second filter and detects a high frequency component; A fourth filter for removing aliasing included in the signal input from the second filter; A high frequency signal channel to which a signal of a high frequency component from which aliasing is removed from the third filter is input; And a notch signal channel to which a signal from which aliasing is removed from the fourth filter is input. The method according to any one of claims 3 to 5, And a voltage detector for detecting a voltage signal input from the power device. The method of claim 6, The voltage detector A transformer for converting the level of the voltage signal; And a fifth filter for eliminating aliasing included in the level-converted voltage signal. The method of claim 7, wherein A first analog-to-digital converter formed between at least one of the steady current detector, the fault current detector, the high frequency detector, and the fifth filter and the signal processor; And a second analog to digital converter formed between the notch component detector and the signal processor. And the resolution of the first analog to digital converter is lower than that of the second analog to digital converter. delete Dividing the current signal into a plurality of channels according to the magnitude of the current signal input from the power device; And determining whether there is an abnormality of the power device by using current signals divided into the plurality of channels. The method of claim 10, Dividing the current signal into a plurality of channels Detecting, by the normal signal detector, a current signal having a first magnitude among the current signals input from the power device; Detecting a current signal larger than a first magnitude among current signals inputted from the power device by a fault signal detector; And detecting, by a high frequency and notch component detector, a current signal smaller than a first magnitude among the current signals input from the power device. The method of claim 11, The detecting of the current signal having the first magnitude in the normal signal detector may include Converting at the first transducer into a voltage signal for the first magnitude current signal; Removing aliasing included in a signal input from the first transducer in a first filter; And a signal from which the aliasing is removed from the first filter is input to a normal signal channel. The method of claim 11, Detecting a current signal larger than the first magnitude in the fault signal detector Converting at the second transducer into a voltage signal for a current signal that is greater than the first magnitude; And inputting a signal converted from the second transducer into a fault signal channel. The method of claim 11, The detecting of the current signal smaller than the first magnitude by the high frequency and notch component detector may include Converting at the third transducer into a voltage signal for a current signal smaller than the first magnitude; Removing fundamental wave components included in a signal input from the third transducer in a second filter; Removing an aliasing included in a signal input from the second filter and detecting a high frequency component in a third filter; Removing aliasing included in a signal input from the second filter in a fourth filter; Inputting a signal of a high frequency component in which aliasing is removed from the third filter, to a high frequency signal channel; And a signal from which the aliasing is removed from the fourth filter is input to the notch signal channel. The method according to any one of claims 12 to 14, And detecting the voltage signal inputted from the power device. The method of claim 15, Detecting the voltage signal Converting the level of the voltage signal in a transformer; And removing from the fifth filter the aliasing included in the level-converted voltage signal. The method of claim 16, Converting an input analog signal into a digital signal using a first analog to digital converter connected to at least one of the normal current detector, the fault current detector, the high frequency detector, and the fifth filter; And converting an input analog signal into a digital signal using a second analog-digital converter connected to the notch component detector and having a higher resolution than the first analog-digital converter. The method of claim 10, Determining the abnormality of the power device is Detecting abnormal data among the data input to the signal channel unit by using any one of a simple moving average technique, a simple exponential smoothing technique, a shewhart control chart, an EWMA control chart, and a ratio control chart. Diagnostic method of power equipment.

Images