KR20180058911A - System for evaluground impedance measurement system - Google Patents

Abstract

According to the present invention, disclosed is a ground impedance evaluation system. According to a specific embodiment of the present invention, the reliability of ground impedance can be increased by deriving the ground impedance with a high signal to noise ratio and interference by calculating the phase and amplitude of a current and a voltage from voltage and current values measured in a ground electrode and a power auxiliary electrode for a sine wave power source of each measurement frequency band which is set. The ground impedance measured based on a comparison result of a plurality of predetermined determination reference values and an average value of the ground impedance derived from the sine wave power source of each measurement frequency band. The stability of a ground system can be fundamentally obtained according to the evaluation result of the ground impedance.

Description

SYSTEM FOR EVALUATION IMPEDANCE MEASUREMENT SYSTEM

The present invention relates to a ground impedance evaluation system, and more particularly, to a ground impedance evaluation system that averages the ground impedances of a plurality of measurement frequency bands and sets a ground impedance and a ground impedance based on a comparison result between an average value of ground impedance and a predetermined reference value. And the safety of the grounding system can be ensured.

Current grounding system performance is evaluated by applying a low frequency current of 1 [kHz] or less to earth. However, transient currents having frequency components of several [kHz] to several [MHz] flow during a ground fault or lightning stroke in a converter, and the rise time of the waveform is also in the range of several hundred [ns] to several [ There is a significant difference from the ground potential rise calculated by one ground resistance.

If a low-frequency current flows into the earth electrode, the influence of the reactance component of the earth electrode is very small, which is measured simply as a resistance component. However, if a surge current such as a surge current and a high-frequency current enter the earth, the influence of the reactance of the earth electrode and the earth capacitance becomes very large It appears as an impedance component.

Therefore, the performance of the grounding system should be evaluated to be broadband considering the low frequency as well as the high frequency components. That is, the conventional ground impedance measuring apparatus measures at a fixed frequency in a low frequency band of 1 [kHz] or less. However, in actual grounding systems, high-frequency currents of several hundred [kHz] to several [MHz] are generated depending on the fault conditions. The measurement of the ground impedance is required.

The applicant of the present invention has applied the ground impedance of a high frequency range, that is, a surge current such as a surge current and a high frequency current to a high impedance component due to the inflow into the ground.

Korean Patent Publication No. 2012-0008823 (Published date 2012.01.01)

SUMMARY OF THE INVENTION The present invention has been made in order to evaluate the ground impedance measured based on the ground impedance in a high frequency range and to evaluate the ground impedance and the safety of the ground system.

A ground impedance evaluation system according to an embodiment of the present invention is a ground impedance evaluation system for measuring a ground impedance of a ground system,

A sinusoidal wave generating unit for setting a plurality of measurement frequency bands and generating a sinusoidal wave power of each of the set measurement frequency bands; An amplification unit for amplifying the input sinusoidal power based on a predetermined amplification degree and then applying current to the current auxiliary electrode embedded in the ground and the earth electrode; A measuring unit for measuring a current from the ground electrode and measuring a voltage indicated by a current applied to the ground from the potential auxiliary electrode; And an evaluation unit for calculating an average value of the ground impedances measured for the sinusoidal power source for each of the plurality of measurement frequency bands, comparing the calculated ground impedance average value with a plurality of predetermined determination reference values, and evaluating the ground impedance and the ground system based on the comparison result .

Preferably, the measuring unit includes an A / D conversion module for converting the original signal detected from the potential auxiliary electrode into a digital form; An I / Q signal detection module for estimating a phase and an amplitude with respect to a voltage and a current using an I / Q demodulation method through a digital signal processing; And an estimation computation module for the estimate and amplitude based on the predefined relational expression for the I / Q signal.

Preferably, the I / Q signal detection module includes a plurality of multipliers for performing frequency conversion on the received original signal by multiplying the measured frequency and the reference signal synchronized with each other by an inphase component and a quadrature component, respectively; And a plurality of low pass filters (LPFs) for removing white noise and interference signals included in the Inphase component and Quadrature component.

Preferably, the evaluating unit may calculate an average value of the ground impedances of the respective measurement frequency bands by the derived average value deriving module; A determination module for determining at least one of good, good, acceptable, and non-acceptable of the ground impedance meter of the ground system based on the average value of the ground impedance for each frequency band to be measured and a plurality of predetermined reference values; And a display module that outputs phase and ground impedance values corresponding to the respective measurement frequency bands in a graph form based on the determination result through the determination module and displays the evaluation result on the ground impedance on the screen.

According to this aspect, in the ground impedance evaluation system according to an embodiment of the present invention, the phase and amplitude of the current and voltage are measured from the voltage and current values measured at the power assist electrode and the earth electrode for the sinusoidal power source of each measurement frequency band The ground impedance having the interference and the high signal-to-noise ratio is derived, thereby improving the reliability of the ground impedance.

According to the present invention, the measured ground impedance is evaluated based on the comparison result between the average value of the ground impedance derived from the sinusoidal power source of each measurement frequency band and a predetermined plurality of judgment reference values, It has an advantage that can be fundamentally secured.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further understand the technical idea of the invention. And should not be construed as limiting.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the overall configuration of a ground impedance evaluation system of the present invention. FIG.
2 is a diagram showing a detailed configuration of a measurement unit of the ground impedance evaluation system of the present invention.
3 is a graph showing an I / Q signal of an original signal measured on a plurality of planes of a measurement unit of the ground impedance evaluation system of the present invention.
4 is a diagram showing a detailed configuration of an evaluation unit of the ground impedance evaluation system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, 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. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention.

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.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have.

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 ground impedance evaluation system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing a configuration of a ground impedance evaluation system S according to an embodiment of the present invention. As shown in the drawing, the sine wave generator 100, the current amplifier 200, the measuring unit 300, (400).

The sine wave generating unit 100 may set a plurality of measurement frequency bands in the frequency band of 65 [kHz] to 1.0 [MHz], and generate a sinusoidal wave power of the set measurement frequency band.

The current amplification unit 200 amplifies the input power up to 30 [Vp-p] and 0.5 [A], and then applies it to the current auxiliary electrode C buried in the ground and the earth electrode E.

The measuring unit 300 measures a current from the ground electrode E and measures the voltage indicated by the current applied to the ground from the potential auxiliary electrode P. [

Meanwhile, the evaluating unit 400 calculates an average value of ground impedances measured by the measuring unit 300 for each of a plurality of measurement frequency bands, compares the calculated ground impedance average value with a predetermined plurality of determination reference values, Impedance and earthing system can be evaluated.

Therefore, it is possible to evaluate the excellent, good, allowable, and non-conforming states of the grounding system based on the ground impedance based on the present invention.

Referring to FIG. 2, the measuring unit 300 includes an A / D conversion module 310, an I / Q signal detection module 320, and a computation module 330.

The measuring unit 300 should measure the amplitude and the phase of the voltage and the current having the variable frequency of 100 Hz to 1 MHz in order to measure the ground impedance.

The measuring unit 300 converts the original signal detected from the potential auxiliary electrode P into a digital signal by the A / D conversion module 310, and then converts the original signal into a digital signal Synchronous demodulation through processing I / Q demodulation can be used to estimate phase and amplitude for voltage and current.

That is, a sine wave having an arbitrary magnitude and phase can be represented on a complex plane using an Inphase component and a Quadrature component as shown in FIG. That is, when the I / Q component is detected, the amplitude and phase of the detected original signal can be calculated.

)의 크기(A) 및 위상(

), 백색 잡음(

), 간섭 신호(

)를 포함할 수 있다. 이에 원신호(

)는 다음식 1을 만족할 수 있다.The original signal in digital form of the A / D conversion module 310 may be transmitted to the I / Q signal detection module 320. In this case, the original signal in digital form is the original signal (

(A) and phase (

), White noise (

), An interference signal (

). Therefore,

) Can satisfy the following expression (1).

.. 식 1

.. Equation 1

)를 수신한 I/Q 신호 검출모듈(320)은 곱셈기(321)(322)측정 주파수와 동기된 기준 신호

와

를 각각 곱하여 Inphase 성분

와 Quadrature 성분

로 주파수 변환한 후 저역통과필터(LPF: 323, 324)를 이용하여 백색 잡음(

), 간섭 신호(

)를 제거하도록 구비될 수 있다.These original signals (

The I / Q signal detection module 320 receives the reference signal 322 synchronized with the measurement frequency of the multipliers 321 and 322,

Wow

And the Inphase component

And quadrature component

Pass filter (LPF) 323 and 324 to convert the white noise (

), An interference signal (

As shown in FIG.

와 Quadrature 성분

는 다음 식 2 및 3을 각각 만족한다.At this time, the frequency-converted Inphase component

And quadrature component

Satisfy the following expressions 2 and 3, respectively.

.. 식 2

.. Equation 2

.. 식 3

.. Equation 3

)과 Q성분의 백색잡음(

)은 원신호 백색 잡음에 기준 신호가 곱하여 진 것이므로 원 신호에 대한 통계적 특성 변화는 없으므로 대역 제한된 부가 잡음 이 존재한다.Here, the white noise of the I component (

) And the white noise of the Q component (

) Is obtained by multiplying the original signal white noise by the reference signal, there is no statistical characteristic change with respect to the original signal, Lt; / RTI >

)과 Q성분의 간섭신호(

)은

주파수 대역만큼 천이되고 이러한 간섭 신호는 LPF(323)(324)를 통과하여 제거될 수 있다.The interference signal of the I component (

) And an interference signal of the Q component (

)silver

Frequency band, and this interference signal can be removed through the LPFs 323 and 324.

을 포함하는 I/Q 신호 ,

는 다음 식 4 및 5를 각각 만족한다.Band limited additional noise

Lt; RTI ID = 0.0 > I / Q & ,

Satisfy the following equations (4) and (5), respectively.

.. 식 5

.. Equation 5

.. 식 6

.. Equation 6

는 LPF(323, 324)에 의해 대역 제한된 부가 잡음으로서, LPF(323, 324)의 대역폭이 충분히 작은 경우 I/Q 신호

,

는 다음 식 7 및 8로 나타낼 수 있다.here,

When the bandwidth of the LPFs 323 and 324 is sufficiently small as the additional noise band-limited by the LPFs 323 and 324,

,

Can be expressed by the following equations (7) and (8).

.. 식 7

.. Equation 7

.. 식 8

.. Equation 8

,

는 연산 모듈(330)로 전달될 수 있다. 연산 모듈(330)은 I/Q 신호

,

와 기 정해진 관계식을 토대로 위상

에 대한 추정치

와 진폭에 대한 추정

를 연산할 수 있다.The I / Q signal

,

May be communicated to the computing module 330. The operation module 330 receives the I / Q signal

,

And based on the predetermined relationship

Estimates for

And amplitude estimates

Can be calculated.

에 대한 추정치

는

관계식으로부터 도출될 수 있고 이에 위상에 대한 추정치

는 다음 식 9로 나타낼 수 있고, 진폭에 대한 추정

는 다음 식 10으로 나타낼 수 있다.Therefore,

Estimates for

The

Can be derived from the relational expression, and an estimate

Can be expressed by the following equation (9), and an estimate of the amplitude

Can be expressed by the following equation (10).

.. 식 9

.. Equation 9

.. 식 10

.. Equation 10

및 진폭에 대한 추정

으로부터 전위의 접지 임피던스를 도출할 수 있으며, 이러한 전압에 대한 위상 및 진폭 및 전류에 대한 위상 및 진폭을 토대로 접지 임피던스를 도출하는 일련의 과정을 당업자에 의해 자명한 사항이다.An estimate of the phase of the measurement unit 300

And amplitude estimates

And a series of processes for deriving the ground impedance based on the phase and amplitude for the voltage and the phase and amplitude for the current are obvious to those skilled in the art.

The ground impedance for any measurement frequency band of the measurement unit 300 may be transmitted to the evaluation unit 400. [

Referring to FIG. 3, the evaluation unit 400 includes an average value derivation module 410, a determination module 420, and a display module 400. The average value derivation module 410 includes a mean value derivation module 410, a determination module 420, (Not shown).

The average value deriving module 410 may be provided to derive an average value of the ground impedances of the respective measurement frequency bands. The average value of the ground impedances of the measurement frequency bands derived by the average value deriving module 410 is determined by the determination module 420 Lt; / RTI >

The determination module 420 may be configured to determine at least one of good, good, acceptable, and non-acceptable of the ground impedance meter of the ground system based on the average value of the ground impedance for each measurement frequency band and a plurality of predetermined reference values.

For example, if the average value Z (t) of the ground impedance is equal to or less than a predetermined first judgment reference value (preferably 10?), It is preferable that the second judgment reference value is less than or equal to a predetermined second judgment reference value 40?) Or less, and it is judged that it is not suitable if the predetermined fourth determination reference value (40?) Is exceeded.

The determination result of the ground impedance may be transmitted to the display module 430. The display module 430 may display the phase and ground impedance values corresponding to the respective measurement frequency bands on the basis of the determination result And the result of the evaluation of the ground impedance can be displayed on the screen.

Therefore, according to the present invention, the measured ground impedance is evaluated on the basis of the comparison result between the average value of the ground impedance corresponding to each measurement frequency band and a predetermined plurality of judgment reference values, and thereby the safety of the ground system is fundamentally .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

By calculating the phase and amplitude of the current and voltage from the voltage and current values measured at the power supply auxiliary electrode and the earth electrode for the sinusoidal power source of the set measurement frequency band, the ground impedance having the interference and the high signal to noise ratio is derived, The evaluation of the measured ground impedance is performed based on the comparison result between the average value of the ground impedance derived from the sine wave power supply of each measurement frequency band and a predetermined plurality of judgment reference values and the evaluation of the ground impedance According to the result, the ground impedance evaluation system which can fundamentally secure the safety of the grounding system can be made to be very accurate in terms of operation accuracy and reliability, further improved in performance efficiency, and the possibility of commercialization or sales of the power system Not only is it obvious enough Because the extent that can be carried to the invention there is industrial applicability.

Claims (7)

1. A ground impedance evaluation system for measuring a ground impedance of a ground system,
A sinusoidal wave generating unit for setting a plurality of measurement frequency bands and generating a sinusoidal wave power of each of the set measurement frequency bands;
An amplification unit for amplifying the input sinusoidal power based on a predetermined amplification degree and then applying current to the current auxiliary electrode embedded in the ground and the earth electrode;
A measuring unit for measuring a current from the ground electrode and measuring a voltage indicated by a current applied to the ground from the potential auxiliary electrode; And
And an evaluation unit for calculating an average value of the ground impedances measured for the sine wave power source for each of the plurality of measurement frequency bands, comparing the calculated ground impedance average value with a plurality of predetermined determination reference values, and evaluating the ground impedance and the grounding system based on the comparison result Wherein the ground impedance measuring system is a ground impedance measuring system.
2. The method of claim 1,
Is a high frequency band in a range of 61 [kHz] to 1.0 [MHz].
The apparatus according to claim 2, wherein the measuring unit
An A / D conversion module for converting the original signal detected from the potential auxiliary electrode into a digital form;
An I / Q signal detection module for estimating a phase and an amplitude with respect to a voltage and a current using an I / Q demodulation method through a digital signal processing; And
And an arithmetic module for estimating an estimated value and an amplitude of the phase based on a predetermined relational expression for the I / Q signal.
The apparatus of claim 3, wherein the I / Q signal detection module
A plurality of multipliers for frequency-converting the received original signal to an inphase component and a quadrature component by multiplying the measured frequency and the reference signal synchronized, respectively; And
And a plurality of low-pass filters (LPF) for removing white noise and interference signals included in the inphase component and the quadrature component.
5. The apparatus of claim 4,
Based on the ratio of the inphase component and the quadrature component passed through the low-pass filter,

Relation to phase

Estimates for

And deriving
Derived phase

Estimates for

Satisfies the following expression (21). ≪ EMI ID = 21.0 >

.. Equation 21
6. The method of claim 5,

The
And the ratio between the magnitude of the measurement signal and the Inphase component and the Quadrature component passed through the low-pass filter, and satisfies the following expression (22).

.. Equation 22
7. The image processing apparatus according to claim 6,
An average value of the ground impedances of the respective measurement frequency bands;
A determination module for determining at least one of excellent, good, acceptable, and non-acceptable of the ground impedance meter of the ground system based on the average value of the ground impedance for each of the measurement frequency bands and a plurality of predetermined reference values; And
And a display module for outputting phase and ground impedance values corresponding to the respective measurement frequency bands in the form of a graph based on the determination result through the determination module and displaying evaluation results of the ground impedance and the ground system on the screen Ground impedance evaluation system.

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