KR101362940B1 - Method and apparatus diagnosing earth system - Google Patents

Abstract

An earth system diagnostic apparatus is disclosed. According to a preferred embodiment of the present invention, an apparatus for diagnosing a grounding system, comprising: a power supply for applying a first power source having a first frequency between a main current pole and an auxiliary current pole; And obtain magnitude and phase information of a first frequency component of a current between the main current electrode and an auxiliary current pole, obtain magnitude and phase information of a first frequency component among potentials between a main potential electrode and an auxiliary potential electrode, And a ground impedance calculator for calculating the first ground resistance and the first reactance of the first ground impedance by complex-operating the magnitude and phase information of one frequency component and the magnitude and phase information of the first frequency component among the potentials. do.

Description

METHOOD AND APPARATUS DIAGNOSING EARTH SYSTEM

The present invention relates to a method and apparatus for diagnosing grounding systems, and more particularly, to a method and apparatus for diagnosing grounding systems capable of accurately and integrally diagnosing ground impedance and surge impedance in a live state.

Increasingly industrialized, informationized and urbanized modern societies consume a lot of energy in dense areas. Among the energy consumed, the electric power with the highest convenience of transportation, convenience of use and pollution-free is most widely used. Therefore, stable supply of power has become an important factor throughout the industry.

Grounding is essential for a stable supply of power. Grounding provides a reference potential to the power equipment while simultaneously discharging fault currents that occur during transients, such as breakers in the breaker or inflow of lightning. Therefore, the performance of ground is determined by how quickly the fault current is discharged to earth.

In the past, only ground resistance has been considered as a barrier to current conduction in the commercial frequency concept. Ultimately, the ground resistance is based on the DC component and there is no frequency concept. Diagnosis of the grounding system using only grounding resistance has not been a problem in the midst of lukewarm industrial development. However, considering the fault current caused by the breaker breaking operation and the transient phenomenon such as the inflow of the lightning current, the frequency deviates from the commercial frequency concept, and the high frequency current is generated in most cases. For high frequencies, the reactance component should be considered. Against this background, the concept of “ground impedance” was introduced. The ground impedance may be expressed by Equation 1 below.

(R: ground resistance, X: reactance component of ground impedance)

Equation 1 is an interpretation from the viewpoint of the lumped constant circuit.

Ground impedance is based on an alternating state that includes the concept of frequency, making it easy to understand the transient state and providing a solution to the problem. When the low frequency current is introduced, the capacitive properties of the earth are mainly shown, and at high frequencies, the inductive reactance is mainly shown. However, conventionally, only the magnitude of the ground impedance is measured as the potential / current without considering the phase difference between the potential and the current measured when the ground impedance is diagnosed. If only the magnitude of the ground impedance is measured, since the ground resistance and the reactance component are not diagnosed separately, there is a problem in that the accurate diagnosis of the ground impedance cannot be made. In addition, the conventional diagnostic method has a problem that the capacitance and inductance for determining the reactance component are not known, and thus a comprehensive diagnosis for any frequency cannot be made. That is, in order to diagnose the grounding performance of a specific frequency, it is troublesome to measure the grounding impedance of the specific frequency.

In the case of lightning current, the fault current forms a steep wave and the rate of increase of the inrush current is high. That is, the short head. Therefore, lightning strikes have a serious effect in terms of rising earth potential or destructive insulation even if the amount is small in terms of total energy.

In terms of power stabilization, it is much more important to reduce the ground resistance than to quickly emit a steep wave current that has a serious adverse effect on insulation breakdown or reverse flashover of the power plant. In this case, the ratio of the instantaneous potential rise to the steep wave current is referred to as "impulse impedance" or "surge impedance". Typically, high frequency currents of up to several M Hz exist in steep wave currents. Although the ground rod is about M, the potential and current at the intrusion and end points of the ground rod will be different if the steep wave entering is high frequency. Therefore, the surge impedance should be interpreted as the concept of traveling wave. That is, surge impedance should be interpreted as distribution constant circuit in terms of transmission. In the analysis of the distribution constant circuit, the surge impedance may be expressed by Equation 2 below.

(L: inductance of the grounding system, C: capacitance of the grounding system)

In terms of grounding, another important implication of steep waves is that the method of reducing ground resistance in the ground area generally does not reduce the surge impedance. This is because when a steep wave is injected into a general ground network, for example, a wave length μs, the wide ground network does not all contribute to the reduction of the surge but only a part of the injection point contributes to the reduction of the surge. After all, the steep wave has a large ground area, so the impedance impedance value is not reduced in proportion to the area.

However, in the related art, the surge impedance, which should be interpreted as the distribution constant circuit, was analyzed by the lumped constant circuit using the high frequency sine wave. That is, a high frequency sine wave power supply was applied and surge impedance was measured by electric potential / current. This is a misconception about the concept of surge impedance. In addition, a method of measuring a surge impedance by applying an impulse power supply and using a potential / current has been proposed, but a measurement value of any timing of a nonlinearly changing potential and current measurement value is used to calculate the surge impedance. There was a problem that it would be ambiguous.

That is, conventionally, there is a problem that the diagnosis about the ground impedance and the surge impedance is not made correctly.

In addition, in the related art, since the diagnosis of the grounding system is possible only in the diagonal state, the diagnosis work is very troublesome, and there is a problem that causes inconvenience to the power user.

Accordingly, an object of the present invention is to provide a method and apparatus for diagnosing a grounding system capable of accurately and integrally diagnosing ground impedance and surge impedance in a live state.

Other objects of the present invention will be readily understood through the following description of the embodiments.

In accordance with an aspect of the present invention to achieve the above object, a grounding system diagnostic method is disclosed.

According to a preferred embodiment of the present invention, there is provided a method of diagnosing a grounding system, comprising: applying a first power source having a first frequency between a main current pole and an auxiliary current pole; Obtaining magnitude and phase information of a first frequency component of a current between the main current pole and the auxiliary current pole; Obtaining magnitude and phase information of a first frequency component of a potential between the main potential electrode and the auxiliary potential electrode; And calculating the first ground resistance and the first reactance of the first ground impedance by complex computing the magnitude and phase information of the first frequency component of the current and the magnitude and phase information of the first frequency component of the potential. A method of diagnosing grounding systems is provided that includes a step.

Here, the step of applying a first power source having the first frequency between the main current pole and the auxiliary current pole is performed in a state where the ground system is live, and the first frequency is a commercial frequency in the power system and It may not be an integer multiple of at least one of the frequencies used in the communication facility.

In addition, applying a second power source having a second frequency between the main current pole and the auxiliary current pole; Obtaining magnitude and phase information of a second frequency component of a current between the main current pole and the auxiliary current pole; Obtaining magnitude and phase information of a second frequency component of a potential between the main potential electrode and the auxiliary potential electrode; Calculating the second ground resistance and the second reactance of the second ground impedance by complex computing the magnitude and phase information of the second frequency component of the current and the magnitude and phase information of the second frequency component of the potential, respectively. ; Generating an equation relating to the magnitude of the first reactance and the magnitude relating to the magnitude of the second reactance; And calculating an inductance and a capacitance of the grounding system by combining an expression relating to the magnitude of the first reactance and an expression relating to the magnitude of the second reactance.

Calculating an inductive component of the grounding system by multiplying the inductance by the angular frequency of at least one of the first frequency and the second frequency; And calculating the capacitive component of the grounding system by dividing 1 by the product of the capacitance multiplied by the angular frequency of at least one of the first frequency and the second frequency.

The method may further include calculating a surge impedance of the grounding system by calculating a square root of a value obtained by dividing the inductance by the capacitance.

According to another aspect of the invention, a grounding system diagnostic apparatus is disclosed.

According to a preferred embodiment of the present invention, an apparatus for diagnosing a grounding system, comprising: a power supply for applying a first power source having a first frequency between a main current pole and an auxiliary current pole; And obtain magnitude and phase information of a first frequency component of a current between the main current electrode and an auxiliary current pole, obtain magnitude and phase information of a first frequency component among potentials between a main potential electrode and an auxiliary potential electrode, And a ground impedance calculator for calculating the first ground resistance and the first reactance of the first ground impedance by complex-operating the magnitude and phase information of one frequency component and the magnitude and phase information of the first frequency component among the potentials. A grounding system diagnostic apparatus is provided.

Here, the power supply unit applies a first power source having the first frequency between the main current pole and the auxiliary current pole in a state where the ground system is live, and the first frequency is a commercial frequency and communication in a power system. It may not be an integer multiple of at least one of the frequencies used in the installation.

The power supply unit applies a second power source having a second frequency between the main current pole and the auxiliary current pole, and the ground impedance calculator includes a second frequency of the current between the main current pole and the auxiliary current pole. Obtain the magnitude and phase information of the component, obtain the magnitude and phase information of the second frequency component among the potentials between the main potential pole and the auxiliary potential pole, and obtain the magnitude and phase information of the second frequency component of the current and the second frequency component of the potential Compute the second ground resistance and the second reactance of the second ground impedance, respectively, by complex operation of the magnitude and phase information of the equation, and an equation relating to the magnitude of the first reactance and an equation relating to the magnitude of the second reactance. Generating and linking an equation relating to the magnitude of the first reactance with an equation relating to the magnitude of the second reactance, The method may further include an LC calculator that calculates ductance and capacitance.

The inductance component of the grounding system is calculated by multiplying the inductance by the angular frequency of at least one of the first frequency and the second frequency, and 1 is equal to the capacitance at least of the first frequency and the second frequency. By dividing by one multiplied by the angular frequency, it may further include a reactance calculator for calculating a capacitive component of the grounding system.

The apparatus may further include a surge impedance calculator configured to calculate a surge impedance of the grounding system by calculating a square root of a value obtained by dividing the inductance by the capacitance.

As described above, according to the method and apparatus for diagnosing the grounding system according to the present invention, an accurate diagnosis of the grounding impedance is performed by separately calculating the grounding resistance and the reactance using the magnitude and phase information of the current and potential of the power frequency component. There is an advantage that this can be done.

In addition, according to the method and apparatus for diagnosing the grounding system according to the present invention, the surge impedance is derived by a formula, and thus, there is an advantage in that the accurate diagnosis of the surge impedance is possible.

In addition, according to the method and apparatus for diagnosing the grounding system according to the present invention, since the ground impedance and the surge impedance are diagnosed using a frequency that is not an integer multiple of the frequency used in the commercial frequency and communication equipment in the power system, Diagnosis can be made in the absence of influence. Therefore, there is an advantage that the diagnosis of the ground impedance and the surge impedance is possible in the live state.

1 is a view for explaining a general grounding system diagnostic method.
2 is a functional block diagram of a grounding system diagnostic apparatus according to an exemplary embodiment of the present invention.
3 is a functional block diagram of an operation unit of FIG. 2.
4 is a flow chart illustrating a grounding system diagnostic process in accordance with one preferred embodiment of the present invention.
5 is a functional block diagram of a grounding system diagnostic apparatus according to another embodiment of the present invention.
6 is a functional block diagram of an operation unit of FIG. 5.
7 is a flowchart illustrating a grounding system diagnostic process according to another embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be.

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, a general grounding system diagnostic method will be described with reference to FIG. 1.

1 is a view for explaining a general grounding system diagnostic method.

1 to 10 is a grounding system to be diagnosed, and 17 represents a grounding electrode 17 in the grounding system 10. Hereinafter, the ground electrode 17 in the ground system 10 is referred to as a “main ground electrode”. In the diagnosis of ground, the main ground electrode 17 may be the main current electrode C1 or the main potential electrode P1. The auxiliary current electrode C2 is provided at a considerable distance from the main current electrode C1. The power supply 12 is applied between the main current pole C1 and the auxiliary current pole C2, and the current I flowing between the main current pole C1 and the auxiliary current pole C2 by the applied power supply 12. ) Is measured. The auxiliary potential electrode P2 may move from the main current electrode C1 side to the auxiliary current electrode C2 side between the main current electrode C1 and the auxiliary current electrode C2. In each movement, the potential V between the main potential electrode P1 and the auxiliary potential electrode P2 can be measured. The measured potential can form a profile such as 18. The ground electrode has a constant resistance zone around it which greatly influences the ground resistance. Therefore, when the distance D between the main current electrode C1 and the auxiliary current electrode C2 is sufficiently separated so that the resistance zones of the positive electrode electrodes do not overlap, a section horizontal to the potential profile is formed. When the ground impedance is measured using the potential of this horizontal part, a highly accurate measured value can be obtained. The measured ground impedance may be expressed by the following equation (3).

However, the ground electrode of the power equipment in operation or in the live state always has a ground potential under the influence of the leakage current flowing to the ground in the power equipment or the communication equipment. In fact, the ground potential measured for a power plant in operation contains not only 60 Hz, the fundamental wave, but also components of three harmonics, 180 Hz and five harmonics, 300 Hz. Therefore, in diagnosing grounding in the live state of the grounding system, the effects of leakage currents should be excluded. Details thereof will be described later.

Hereinafter, a grounding system diagnostic apparatus according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 3.

2 is a functional block diagram of a grounding system diagnostic apparatus according to an exemplary embodiment of the present invention. 3 is a functional block diagram of an operation unit of FIG. 2.

The grounding system diagnostic apparatus 100 includes a frequency variable unit 110, a power supply unit 120, a current measurement unit 130, a potential measurement unit 140, an operation unit 150, a storage unit 160, and an output unit ( 170). Hereinafter, it is assumed that the auxiliary potential electrode P2 is installed in a section in which the potential profile is horizontal. Of the four ports included in the grounding system diagnostic apparatus 100, 1 and 2 are respectively the main current pole C1 and the auxiliary current pole C2, and 3 and 4 are the main potential pole P1 and the auxiliary potential pole P2, respectively. Can be connected to.

The frequency variable unit 110 may control the frequency of the power output from the power supply unit 120 based on an external input or preset information. Specifically, the frequency variable unit 110 may control the frequency of the power output from the power supply unit 120 by controlling the switching timing at which the power supply unit 120 generates the square wave. The control of the switching timing may be achieved by adjusting the frequency of the clock to turn on / off the switch included in the power supply 120 in the frequency variable section 110. The frequency variable unit 110 may include a separate processor for controlling the frequency. Herein, the information set in the frequency variable part 110 may specify control information for outputting a plurality of preset frequencies from the power supply unit 120, control information for sequentially decreasing the frequency, control information for sequentially increasing the frequency, and frequency. The section includes a wide width, control information for changing the frequency to a small width, and control information for randomly controlling the frequency if a predetermined condition is satisfied. That is, the form in which the frequency variable unit 110 controls the frequency may be unlimited. The frequency applied to the power output from the power supply unit 120 by the frequency variable unit 110 may be started externally through the output unit 170.

The power supply unit 120 may be positioned between the main current pole C1 and the auxiliary current pole C2 to supply power having a preset frequency. The power supply unit 120 may generate a square wave having an arbitrary frequency by performing a switching operation under the control of the frequency variable unit 110, and filter the same to output a sine wave power having a desired arbitrary frequency. At this time, since the magnitude of the sine wave output through the filtering is reduced, it is possible to amplify the amplitude by installing an amplifier in the output terminal of the filter. In order to measure the ground resistance in the live state, interference with the commercial frequency components of the power system and the frequency components of the communication equipment should be excluded. Therefore, the frequency of the power output from the power supply unit 120 is preferably a frequency that is not an integer multiple of the commercial frequency and / or the frequency of the communication equipment. For example, in the case of Korea, since the commercial frequency is 60 Hz, the frequency of the power output from the power supply unit 120 may be 30 Hz, 150 Hz, or the like. Alternatively, a low frequency of several tens of Hz or a high frequency of several M Hz may be selected as a frequency of the power supplied from the power supply 120 to separately analyze the low frequency or high frequency characteristics. Unlike the above, if the grounding system is diagnosed in an oblique state, there may be no frequency limitation. That is, a frequency having an integer multiple of the commercial frequency and / or the frequency of the communication facility can be used in the diagnosis. Use a frequency that is not an integer multiple of the frequency of the commercial frequency and / or communication equipment, and filter the measured values in the current measuring unit 130 and the potential measuring unit 140 so as not to be an integer multiple of the frequency of the commercial frequency and / or communication equipment. By diagnosing the ground with only the frequency component, the interference by the commercial frequency component can be excluded at the time of diagnosis in the live state. This will be described in detail below.

The current measuring unit 130 may be installed at an output terminal of the power supply unit 120 to measure a current flowing between the main current pole C1 and the auxiliary current pole C2. The current measuring unit 130 may sample the current at a predetermined period in order to modulate the current, which is an analog signal, into a digital signal. Digital information generated by sampling may include magnitude and phase information of a current. At this time, for accurate sampling of the signal, the number of bits allocated to represent the sampling period and the sampled current may be adjusted. At this time, in the case of the diagnosis in the live state, the digital information generated by the current measuring unit 130 includes a component (a commercial frequency and / or a frequency component of the communication equipment) due to the leakage current and the power supplied from the power supply unit 120. Components (frequency components of the power output from the power supply unit 120) may all be included. At this time, only the frequency component of the power output from the power supply unit 120 may be filtered using an analog filter before sampling. In addition, only filtered power frequency components may be sampled and converted into digital information. On the contrary, in the case of the diagnosis in the oblique state, the digital information generated by the current measuring unit 130 includes components by the power supplied from the power supply unit 120 (frequency components of the power output from the power supply unit 120). Only may be included. In this case, analog filtering may be omitted. Digital information about the current generated by the current measuring unit 130 may be stored in the storage unit 160.

The potential measuring unit 140 may be provided between the main potential electrode P1 and the auxiliary potential electrode P2 to measure the potential between the main potential electrode P1 and the auxiliary potential electrode P2. For accuracy of the measurement, the input terminal of the potential measuring unit 140 may have a high impedance. To implement this, a buffer may be provided at the input of the potential measuring unit 140. The potential measuring unit 140 may sample the potential at a predetermined period in order to modulate an analog signal current into a digital signal. The digital information generated by sampling may include magnitude and phase information of the potential. At this time, for accurate sampling of the signal, the number of bits allocated to represent the sampling period and the sampled potential may be adjusted. At this time, in the case of diagnosis in the live state, the digital information generated by the potential measuring unit 140 includes a component (a commercial frequency component and / or a frequency component of a communication facility) and a power supply supplied by the power supply unit 120 due to leakage current. All of the components (frequency components of the power output from the power supply 120) may be included. At this time, only the frequency component of the power output from the power supply unit 120 may be filtered using an analog filter before sampling. In addition, only filtered power frequency components may be sampled and converted into digital information. On the contrary, in the case of the diagnosis in the oblique state, the digital information generated by the potential measuring unit 140 includes components by the power supplied from the power supply unit 120 (frequency components of the power output from the power supply unit 120). Only may be included. In this case, the analogue filtering may be omitted. As will be described later, the phase difference between the current and the potential is used in the calculation of the ground impedance. Therefore, in order to extract the phase difference between the correct current and the potential, the timing to be sampled must be the same. Therefore, the current measuring unit 130 and the potential measuring unit 140 are preferably synchronized by the same clock to perform sampling at the same timing. The digital information about the potential measured by the potential measuring unit 140 may be stored in the storage unit 160.

The calculator 150 may calculate the ground impedance by using magnitude and phase information of current and potential stored in the storage 160. The calculator 150 may include a filter 151, a ground impedance calculator 152, an LC calculator 153, a reactance calculator 154, and a surge impedance calculator 155.

The filtering unit 151 may digitally filter digital information about current and potential stored in the storage 160. In this case, Fast Fourier Tranform (FFT) may be used. Filtering with high sharpness or selectivity Q may be achieved by digital filtering. By filtering, only the frequency component of the power supplied from the power supply 120 may be extracted from the digital information about the current and the potential. Filtering may be omitted when diagnosing the grounding system in an oblique state. Digital information about the filtered current and potential (such as the magnitude and / or phase of the current and / or potential) may be externally initiated as an image or sound by the output unit 170.

The ground impedance calculator 152 may calculate the ground impedance by using digital information of current and potential of the power supplied from the power supply 120. The ground impedance calculated by the ground impedance is expressed by Equation 4 below.

(V = magnitude of potential with respect to power frequency components, θv: phase of potential with respect to power frequency components, I = magnitude of current with respect to power frequency components, θi: phase of current with respect to power frequency components, R: ground resistance, X: reactance component of grounding system, XL: inductive component of grounding system, XC: capacitive component of grounding system)

Here, the calculation method of the ground impedance is not limited, and a complex operation including an operation using a pager may be used.

At least one of the ground resistance (R), the reactance component (X), the magnitude of the ground impedance (V / I), the complex form of the ground impedance (R + jX), the phaser form of the ground impedance, and the like may be provided through the output unit 170. It may be initiated externally. However, even with Equation 4, only the ground resistance R and the reactance component X of the grounding system can be known only by the magnitude and phase of the potential and current for one power source frequency. That is, the inductive component XL and the capacitive component XC of the grounding system are not distinguished and diagnosed, and only the reactance component X in which the inductive component XL and the capacitive component XC are combined may be diagnosed. . Therefore, even if the ground impedance is calculated using harmonics of several M Hz, the diagnosis of the surge impedance cannot be made. In other words, the capacitance and inductance of the grounding system are unknown, so the surge impedance cannot be calculated. We have seen this before. Therefore, for accurate diagnosis of the grounding system, the absolute values of capacitance and inductance of the grounding system must be calculated.

To this end, the grounding system diagnostic apparatus 100 may calculate inductance and capacitance of the grounding system using two power supply frequencies.

In detail, the power supply unit 120 may output a power source having a first frequency f1 and a second frequency f2, and the ground impedance calculator 152 may calculate a ground impedance for each frequency. The calculated ground impedance is as shown in Equations 5 and 6 below.

(First Ground Impedance: Ground Impedance for First Frequency f1)

(Second Ground Impedance: Ground Impedance for Second Frequency f2)

Equation 5 may be converted to Equation 7 below, and Equation 6 may be converted to Equations 7 and 8 below.

In Equations 7 and 8, the first frequency f1 and the second frequency f2 are information obtained through the frequency variable unit 110 and may be known. In addition, the magnitude of the first ground impedance, the magnitude of the second ground impedance, and the ground resistance R may be known as values calculated by the ground impedance calculator 152. In addition, in Equations 7 and 8, only the inductance L and the capacitance C of the grounding system may be unknown.

The LC calculation unit 153 calculates the magnitude of the known first ground impedance, the magnitude of the second ground impedance, the ground resistance R, the first frequency f1, and the second frequency f2 into Equations 7 and 8, respectively. Can be substituted. Then, the LC calculation unit 153 can calculate the inductance L of the grounding system and the capacitance C of the grounding system by combining Equations 7 and 8. The calculated inductance L of the grounding system and the capacitance C of the grounding system may be externally started through the output unit 170.

Through the above process, the ground resistance R, the inductance L of the ground system, and the capacitance C of the ground system can be measured.

The reactance calculator 154 may calculate the inductive component XL of the grounding system using Equation 9 below.

The reactance calculator 154 substitutes f for any one of the frequencies of the power supplied by the power supply 120 in equation 9, and substitutes the inductance L calculated by the LC calculator 153 into L. Inductive component (XL) can be calculated. In addition, the inductive component XL can be calculated using any frequency selected externally to diagnose the grounding system. For example, in order to diagnose the characteristics of the grounding system with respect to the high frequency, the inductive component XL may be calculated using any high frequency input from the outside. Alternatively, the frequency variable unit 110 may vary the frequency using a preset algorithm, and calculate the inductive component XL for each of the changed frequencies. The calculated inductive component XL may be initiated externally through the output unit 170.

The reactance calculator 154 may calculate the capacitive component XC of the grounding system using Equation 10 below.

The reactance calculator 154 substitutes one of the frequencies of the power supplied by the power supply unit 120 into f in Equation 10, and substitutes the capacitance C calculated by the LC calculator 153 into C. The capacitive component (XC) can be calculated. In addition, the capacitive component (XC) can be calculated using any frequency selected externally to diagnose the grounding system. For example, in order to diagnose the characteristics of the grounding system with respect to high frequency, the capacitive component XC may be calculated using an externally input high frequency. Alternatively, the frequency variable unit 110 may vary the frequency using a predetermined algorithm, and calculate the capacitive component XC for each of the changed frequencies. The calculated capacitive component XC may be initiated externally through the output unit 170.

The surge impedance calculator 155 may calculate the surge impedance using Equation 11 below.

The surge impedance calculator 155 may calculate surge impedance by substituting the inductance L and the capacitance C of the grounding system calculated by the LC calculator 153 into Equation (11). The calculated surge impedance may be initiated to the outside through the output unit 170. By accurately calculating the surge impedance, a diagnosis according to the distribution constant circuit can be provided. That is, the grounding system can be accurately diagnosed for the surge that is the traveling wave.

In summary, the present invention makes it possible to diagnose grounding in a live state by using a frequency that is not an integer multiple of the commercial frequency of the power system and / or the frequency of the communication facility. In addition, the present invention provides the magnitude of ground impedance, ground resistance, reactance component of ground impedance, inductive component of ground impedance, capacitive component of ground impedance, capacitance of ground system, inductance of ground system, surge impedance, frequency of ground system. In terms of characteristics, both can be diagnosed. Thus, an optimal grounding system can be realized by designing and managing grounding systems based on such diagnostic parameters.

Hereinafter, a grounding system diagnostic method according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 4. Thereby, the grounding system diagnostic apparatus of FIG. 2 can be embodied more.

4 is a flow chart illustrating a grounding system diagnostic process in accordance with a preferred embodiment of the present invention. In the following, descriptions that overlap with the above description will be omitted or simplified.

First, a first power source having a preset frequency may be supplied between the main current pole C1 and the auxiliary current pole C2 by the power supply 120 (S401). The frequency of the first power source may be controlled by the frequency variable unit 110. The frequency of the first power source may not be an integer multiple of the commercial frequency and / or an integer multiple of the frequency of the communication facility when the grounding system is diagnosed in the live state. The frequency of the first power supply may be unlimited in frequency when the grounding system is diagnosed in an oblique state. Here, the height of the frequency of the first power supply may be unlimited. When trying to diagnose the characteristics of the grounding system for a low frequency, the frequency of the first power supply may be low. In addition, when a characteristic of the grounding system for high frequency is to be diagnosed, the frequency of the first power supply may be high. The first frequency may vary based on preset information. For example, the frequency of the power output from the power supply unit 120 may vary from a low frequency to a high frequency from a high frequency to a low frequency or randomly.

Next, the current flowing between the main current pole C1 and the auxiliary current pole C2 may be measured by the current measurement unit 130 (S402). The current measuring unit 130 may sample the current at a predetermined period in order to modulate the current, which is an analog signal, into a digital signal. Digital information generated by sampling may include magnitude and phase information of a current. At this time, for accurate sampling of the signal, the number of bits allocated to represent the sampling period and the sampled current may be adjusted. At this time, in the case of the diagnosis in the live state, the digital information generated by the current measuring unit 130 includes a component due to leakage current (commercial frequency component, communication equipment frequency component) and the component by the power supplied from the power supply unit 120. (The frequency component of the power output from the power supply unit 120) may all be included. At this time, only the frequency component of the power output from the power supply unit 120 may be filtered using an analog filter before sampling. In addition, only filtered power frequency components may be sampled and converted into digital information. On the contrary, in the case of the diagnosis in the oblique state, the digital information generated by the current measuring unit 130 includes components by the power supplied from the power supply unit 120 (frequency components of the power output from the power supply unit 120). Only may be included. In this case, analog filtering can be omitted. Digital information about the current generated by the current measuring unit 130 may be stored in the storage unit 160.

Next, the first potential between the main potential electrode P1 and the auxiliary potential electrode P2 may be measured by the potential measurement unit 140 (S403). For accuracy of the measurement, the input terminal of the potential measuring unit 140 may have a high impedance. To implement this, a buffer may be provided at the input of the potential measuring unit 140. The potential measuring unit 140 may sample the potential at a predetermined period in order to modulate an analog signal current into a digital signal. The digital information generated by sampling may include magnitude and phase information of the potential. At this time, for accurate sampling of the signal, the number of bits allocated to represent the sampling period and the sampled potential may be adjusted. At this time, in the case of the diagnosis in the live state, the digital information generated by the potential measuring unit 140 includes components by leakage current (frequency components of commercial frequency and communication equipment) and components by power supplied from the power supply unit 120. (The frequency component of the power output from the power supply unit 120) may all be included. At this time, only the frequency component of the power output from the power supply unit 120 may be filtered using an analog filter before sampling. In addition, only filtered power frequency components may be sampled and converted into digital information. On the contrary, in the case of the diagnosis in the oblique state, the digital information generated by the potential measuring unit 140 includes components by the power supplied from the power supply unit 120 (frequency components of the power output from the power supply unit 120). Only may be included. As will be described later, the phase difference between the current and the potential is used in the calculation of the ground impedance. Therefore, in order to extract the phase difference between the correct current and the potential, the timing to be sampled must be the same. Therefore, the current measuring unit 130 and the potential measuring unit 140 are preferably synchronized by the same clock to perform sampling at the same timing. That is, S402 and S403 may be performed at the same time. The digital information about the potential measured by the potential measuring unit 140 may be stored in the storage unit 160.

Next, the digital information about the current and potential stored in the storage 160 may be digitally filtered by the filtering unit 151 (S404). In this case, Fast Fourier Tranform (FFT) may be used. Filtering with high sharpness or selectivity Q may be achieved by digital filtering. By filtering, only the frequency component of the power supplied from the power supply 120 may be extracted from the digital information about the current and the potential. Filtering may be omitted when diagnosing the grounding system in an oblique state. Digital information about the filtered current and potential (such as the magnitude and / or phase of the current and / or potential) may be externally initiated as an image or sound by the output unit 170.

Next, the first ground impedance may be calculated by the ground impedance calculator 152 using digital information of current and potential with respect to the power supplied from the power supply 120 (S405). The calculated first ground impedance is expressed by Equation 5. Here, the calculation method of the ground impedance is not limited, and a complex operation including an operation using a pager may be used. As a result, the magnitude of the ground impedance, the ground resistance, the reactance component, and the like with respect to the first frequency may be extracted. The extracted information may be disclosed to the outside through the output unit 170 and may be stored in the storage unit 160.

In addition, the second power supply step (S406), the second current measurement step (S407), the second potential measurement step (S408), filtering (S409), and the second ground impedance calculation step (S410), to the second frequency The second ground impedance for can be calculated. The second ground impedance is as shown in equation (6). As a result, the magnitude of the ground impedance, the ground resistance, the reactance component, and the like with respect to the second frequency may be extracted. Here, the second power source is a power source having a second frequency, and the second frequency may be any frequency different from the first frequency. The second frequency may also not be an integer multiple of the commercial frequency and the communication equipment frequency. The extracted information may be disclosed to the outside through the output unit 170 and may be stored in the storage unit 160.

Next, the inductance L and the capacitance C of the grounding system may be calculated by the LC calculator 153 (S411). In this case, the LC calculator 153 may use Equations 7 and 8.

Then, by the reactance calculator 154, the inductive component XL and the capacitive component XC of the grounding system can be calculated using the inductance L and the capacitance C of the grounding system ( S412). In this case, the reactance calculator 154 may use Equations 9 and 10.

Next, the surge impedance calculation unit 155 may calculate the surge impedance of the grounding system by using the inductance L and the capacitance C of the grounding system (S413). In this case, Equation 11 may be used. S412 and S413 may be performed simultaneously or at this time.

The process of FIG. 4 may be performed in whole or in part or in whole or in part. For example, only S401 to S405 may be performed to diagnose only the ground impedance for a specific frequency, and S401 to S405 may be repeatedly performed to examine the ground impedance for several frequencies. In addition, only S401 to S403 may be performed, and ground impedance and surge impedance may be calculated by separate equipment or manpower based on the measurement results in S402 and S403.

Hereinafter, a grounding system diagnostic apparatus according to another exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 6.

5 is a functional block diagram of a grounding system diagnostic apparatus according to another embodiment of the present invention. 6 is a functional block diagram of an operation unit of FIG. 5. Like reference numerals are used to refer to like elements as in FIGS. 2 and 3. In the following, descriptions that overlap with the above description will be omitted or simplified.

Grounding system diagnostic apparatus 200 according to another embodiment of the present invention is different in operation of the operation unit 250. Therefore, the operation of the operation unit 250 will be described.

The calculator 250 may include a filtering unit 151, a ground impedance calculator 152, an LC calculator 253, a reactance calculator 154, a surge impedance calculator 155, and a resonance frequency tracker 256. It may include.

The filtering operation of the filtering unit 151, the ground impedance calculation operation of the ground impedance calculation unit 152, the calculation of the capacitive component and the inductive component using the frequency, inductance, and capacitance of the reactance calculation unit 154 are illustrated in FIG. 2. As in the grounding system diagnostics. However, the operation of calculating the inductance and capacitance of the grounding system is different.

In detail, the power supply unit 120 outputs a power source having a preset frequency under the control of the frequency variable unit 110. As described above, the ground impedance calculator 152 may calculate the ground impedance using only the frequency component of the output power. At this time, the ground resistance can be calculated.

The resonant frequency tracking unit 256 may track the resonant frequency with a ground resistance value. The resonance frequency is as shown in Equation 12 below.

(L: inductance of the grounding system, C: capacitance of the grounding system)

As is known, the resonant frequency is the frequency when the impedance becomes equal to the resistance. Therefore, the resonant frequency tracking unit 256 can find the resonant frequency by finding a frequency where the magnitude of the ground impedance calculated by the ground impedance calculator 152 matches the ground resistance. However, the resonance frequency tracking unit 256 may set the frequency when the magnitude of the ground impedance corresponding to a preset ratio of the ground resistance, for example, 101% to 100%, is measured in the range of the tolerance, as the resonance frequency. have. Finding a frequency at which the magnitude of the ground impedance matches the ground resistance may include finding a frequency at which the magnitude of the reactance becomes zero. In addition, the frequency when the magnitude of the ground impedance corresponding to the preset ratio of the ground resistance is measured may include a frequency when the reactance is a preset ratio, for example, when the magnitude of the reactance corresponds to 0 to 0.01. . In detail, the frequency variable unit 110 may vary the frequency at a predetermined period. In this case, the frequency variable unit 110 may gradually increase the frequency, and may gradually decrease the frequency. Alternatively, the frequency may be changed randomly. Alternatively, the frequency variable unit 110 may change the frequency at a somewhat larger interval until the ground impedance corresponds to a preset ratio of the ground resistance, for example, 95%, and the ground impedance may be changed. When belonging to the preset ratio, the frequency may be varied at somewhat smaller intervals. In this case, the ground impedance calculator 152 may calculate the ground impedance every time the frequency is changed. In this case, the calculated magnitude of the ground impedance may be stored in the storage 160 together with the frequency used when the ground impedance is measured. In addition, the resonance frequency tracking unit 256 may compare the magnitude of the ground impedance with the ground resistance. In addition, when the magnitude of the ground impedance is equal to the ground resistance or falls within a preset range, the resonance frequency tracking unit 256 may set the frequency of the power supply used when measuring the ground impedance as the resonance frequency. The tracked resonant frequency may be stored in the storage 160 or may be initiated externally by the output unit 170.

The LC calculation unit 253 may calculate the inductance and capacitance of the grounding system by substituting the resonance frequency tracked by the resonance frequency tracking unit 256 into Equation 12 and combining Equations 7 and 12. have.

The reactance calculator 154 calculates the capacitive and inductive components of the grounding system using the inductance and capacitance calculated by the LC calculator 253, and the surge impedance calculator 155 calculates the surge impedance. Can be calculated

Hereinafter, a grounding system diagnostic method according to another exemplary embodiment of the present invention will be described with reference to FIGS. 5 to 7. Thereby, the grounding system diagnostic apparatus of FIG. 5 can be embodied more.

7 is a flowchart illustrating a grounding system diagnostic process according to another embodiment of the present invention. In the following, descriptions that overlap with the above description will be omitted or simplified.

First, the ground impedance may be calculated by the ground impedance calculator 152 (S701). Matters regarding the calculation of the ground impedance are as described above with reference to FIG. 4.

Next, the resonance frequency may be tracked by the resonance frequency tracking unit 256 (S702). The resonant frequency tracker 256 may find the resonant frequency by finding a frequency at which the ground impedance corresponds to the ground resistance. Alternatively, the resonant frequency tracking unit 256 may set the frequency of the power supply when belonging to a preset ratio of the ground resistance as the resonant frequency. The resonant frequency of the grounding system can also be a major parameter for diagnosing the grounding system. Thus, the resonant frequency may be initiated externally by the output unit 170.

Then, the inductance and capacitance of the grounding system may be calculated by the LC calculator 253 (S703). The LC calculation unit 253 may calculate the inductance and capacitance of the grounding system by substituting the resonance frequency tracked by the resonance frequency tracking unit 256 into Equation 12 and combining Equations 7 and 12. have.

Next, the reactance calculator 154 may calculate the inductive component and the capacitive component of the grounding system (S704). The reactance calculator 154 may calculate the inductive component and the capacitive component by substituting inductance and capacitance into Equations 9 and 10, respectively.

Then, the surge impedance may be calculated by the surge impedance calculator 155 (S705). The surge impedance calculator 155 may calculate the surge impedance by substituting the inductance and capacitance of the grounding system in Equation (11).

The process of FIG. 7 may be performed in whole or in part or in iteration of all or a part thereof. For example, when the ground impedance of the grounding system is to be diagnosed, S701 may be performed alone, or when the resonance frequency of the grounding system is to be diagnosed, S701 and S702 may be performed together, and the inductance and / or Alternatively, when the capacitance is to be diagnosed, S701 to S703 may be performed together.

Meanwhile, the method for diagnosing the grounding system according to the present invention may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

It will be apparent to those skilled in the relevant art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. The appended claims are to be considered as falling within the scope of the following claims.

100: grounding system diagnostic device
110: frequency variable 120: power supply
130: current measuring unit 140: potential measuring unit
150, 250: calculator 151: filter
152: ground impedance calculator 153, 253: LC calculator
154: reactance calculation unit 155: surge impedance calculation unit
160: storage unit 170: output unit
256: resonant frequency tracking unit

Claims (10)

In the method of diagnosing a grounding system,
Applying a first power source having a first frequency between the main current pole and the auxiliary current pole;
Obtaining magnitude and phase information of a first frequency component of a current between the main current pole and the auxiliary current pole;
Obtaining magnitude and phase information of a first frequency component of a potential between the main potential electrode and the auxiliary potential electrode; And
Calculating first ground resistance and first reactance of the first ground impedance by complex operation of magnitude and phase information of the first frequency component of the current and magnitude and phase information of the first frequency component of the potential; Including,
Applying a first power source having the first frequency between the main current pole and the auxiliary current pole,
The grounding system is live,
The first frequency is,
A method of diagnosing grounding systems, characterized in that it is not an integral multiple of at least one of a commercial frequency in a power system and a frequency used in a communication facility.
delete delete delete delete A device for diagnosing a grounding system,
A power supply for applying a first power source having a first frequency between the main current pole and the auxiliary current pole; And
Obtains magnitude and phase information of a first frequency component of a current between the main current pole and an auxiliary current pole, obtains magnitude and phase information of a first frequency component of a potential between a main potential pole and an auxiliary potential pole, and obtains a first of the currents. And a ground impedance calculator for calculating the first ground resistance and the first reactance of the first ground impedance by complex-operating the magnitude and phase information of the frequency component and the magnitude and phase information of the first frequency component among the potentials. ,
The power supply unit applies a first power source having the first frequency between the main current pole and the auxiliary current pole in a state where the ground system is live,
The first frequency is,
A grounding system diagnostic apparatus, characterized in that it is not an integer multiple of at least one of commercial frequencies in a power system and frequencies used in communication facilities.
delete The method according to claim 6,
The power supply unit,
A second power source having a second frequency is applied between the main current pole and the auxiliary current pole,
The ground impedance calculator,
Obtains magnitude and phase information of a second frequency component of a current between the main current pole and an auxiliary current pole, obtains magnitude and phase information of a second frequency component of a potential between a main potential pole and an auxiliary potential pole, and obtains a second of the current Computing the magnitude and phase information of the frequency component and the magnitude and phase information of the second frequency component among the potentials to calculate the second ground resistance and the second reactance of the second ground impedance, respectively,
The grounding is achieved by generating an expression relating to the magnitude of the first reactance and the magnitude relating to the magnitude of the second reactance, and the equation relating to the magnitude of the first reactance and the expression relating to the magnitude of the second reactance. And an LC calculation unit for calculating inductance and capacitance of the system.
The method of claim 8,
By multiplying the inductance by the angular frequency of at least one of the first and second frequencies, an inductive component of the grounding system is calculated, and 1 is equal to the capacitance of at least one of the first and second frequencies. And a reactance calculator for calculating a capacitive component of the grounding system by dividing by the value of the angular frequency.
The method of claim 8,
And a surge impedance calculator configured to calculate a surge impedance of the ground system by calculating a square root of a value obtained by dividing the inductance by the capacitance.

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