CN106093589B - A kind of pole tower ground resistance Accurate measurement and device - Google Patents
A kind of pole tower ground resistance Accurate measurement and device Download PDFInfo
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Abstract
Include the embedded orientation that grounding body is judged using magnetic field method the invention discloses a kind of pole tower ground resistance Accurate measurement and device;The soil resistivity of soil near grounding body is measured using four-electrode method;Injection Current frequency range is selected according to soil resistivity, measures one group of pole tower ground resistance measured value, measurement result is corrected, obtains the measurement exact value of pole tower ground resistance.The present invention, which provides device and method, can not turn off accurate measurement of the ground lead realization to pole tower ground resistance value, realize vertical cloth pole by burying the judgement in orientation to grounding body first, improve the accuracy of measurement;Secondly by the power frequency to the measurement selection injection of soil resistivity near shaft tower, adaptability of the measurement method to different shaft tower soil environments is improved;Without disconnecting ground lead, the working efficiency of measurement of Grounding Resistance is improved.Calculating for pole tower ground resistance is made measurement error reach minimum, is promoted the accuracy of measurement result using mean value method.
Description
Technical field
The present invention relates to pole tower ground resistance field of measuring technique, more particularly to the accurate side of measurement of a kind of pole tower ground resistance
Method and device.
Background technology
The lightning conducter lightning protection measures one of most basic as transmission line of electricity, both protection circuit from thunder and lightning attack directly, while
The current by pass of lightning current is collectively formed with support shaft tower, earthing or grounding means.Earthing or grounding means is by the grounding body that is embedded in the earth and connects
Ground lead is constituted, and is the most important part of entire current by pass, and ground resistance is the major parameter for weighing earthing or grounding means.Work as thunder
When electric current flows into the earth through current by pass, the pressure drop on earthing or grounding means will make lightning conducter obtain an above earth potential, if ground connection
Resistance, which crosses senior general, causes lightning conducter potential rise height generation back overrating voltage to make line tripping.
Therefore pole tower ground resistance value directly affects the tripping times of transmission line of electricity, has to the operation of power grid vital
Effect.The ground resistance for meeting regulatory requirements is the guarantee safely and steadly to transmit electric power.Therefore accurately and efficiently measuring rod
Tower grounding resistance has important engineering significance.And the pole tower ground resistance measurement method generally used in engineering at present is accurate
Property is not fully up to expectations, and the pole tower ground resistance measurement method generally used in engineering now is mainly the following:
1) three electrode method
Three electrode method is that a kind of widest pole tower ground resistance measurement method is used in current engineering project.This method base
It in voltage and current principle, is measured by the way of arrangement electric current pole tension pole, when measurement, into grounding body, Injection Current is believed
Number I, and the voltage U on voltage pole is measured, pole tower ground resistance value R=U/I is finally obtained, but the premise of this method is in soil
Uniformly and grounding body is counted as under hemispheroidal equivalent condition, and distance of the voltage pole away from grounding body can be obtained by theoretical calculation
Distance than upper electric current pole span grounding body is 0.618, voltage pole is theoretically located at zero-potential point, therefore be also known as the method
0.618 method.
Three electrode method requires to lay measuring electrode along the embedded oriented perpendicular of grounding body in measurement process, however in engineering
In practice, due to factors such as the losses of construction drawing, the embedded orientation of earthing pole is often unknown, therefore vertical cloth pole is generally difficult to
It is accomplished, therefore the accuracy measured is also difficult to completely be ensured.Further, since the electric current of injection grounding body is usually
Power current, therefore disconnection ground lead is needed in measurement process, and in practice, the current by pass of lightning current contains ground connection
Lead, the actual resistance value situation of grounding body can not also be accurately reflected by disconnecting the measurement result of ground lead.And due to measurement process
In need to disconnect shaft tower ground lead, therefore considerably increase the workload of measurement, it is inefficient.
2) high frequency multiple process
Cloth pole mode realizes similar to the high frequency multiple process of three electrode method and does not turn off shaft tower grounding resistance under ground lead
It measures, the principle utilized is to inject 10kHz high-frequency currents to grounding body, since lightning conducter inductance value is much larger than grounding body inductance
Value, when injecting high-frequency signal, most current can pass through ground lead and flow into grounding body, therefore may be implemented to ground connection
The on-line measurement of bulk resistor.
However since different shaft towers, the impedance of grounding body and the induction reactance of shaft tower are not quite similar, the embedded soil of different shaft tower institutes
Soil resistivity it is also different, high-frequency method injection stabilization 10kHz frequency currents the adaptability of shaft tower local environment is also difficult to
It is guaranteed.Therefore, the accuracy of high-frequency method is also to be improved.
3) split-core type meter method
The appearance of nineteen nineties pincerlike meter, which realizes, not exclusively disconnects earthmeter pole tower ground resistance value,
Without arranging electrode when biggest advantage is measurement, that is, it is not necessarily to know the embedded orientation of tower grounding body, as long as split-core type meter is pressed from both sides
On ground lead, just it can measure.Compared with traditional three electrode method for needing cloth pole, this method significantly reduces manpower object
Power improves measuring speed.
And split-core type meter method is highly prone to interfere, therefore due to the principle using electromagnetic induction when measuring pole tower ground resistance
The accuracy of measurement is generally difficult to be guaranteed.Under normal circumstances, split-core type meter method is only in the former base shaft towers stood out from power transformation
Possess higher accuracy in measurement.
In conclusion the major defect that pole tower ground resistance measures at present has:
1. it is indefinite that grounding body buries orientation;
2. needing disconnection ground lead, Injection Current frequency single;
3. not considering the influence of soil resistivity.
Therefore, it is necessary to study a kind of accurate cloth pole and to realize in the case where not turning off ground lead and accurate to measure shaft tower
The method of ground resistance.
Invention content
The purpose of the present invention is a kind of accurate measuring device of pole tower ground resistance of research and methods, realize to tower grounding electricity
The accurate measurement of resistance.This method realizes the judgement that orientation is buried to grounding body, to realization and earthing pole in measurement process
The vertical cloth pole mode in direction;This method, which realizes, does not turn off ground lead measurement, to contain grounding lead in measurement result
The resistance value of line has more accurate measurement result;This method realizes Injection Current frequency by the measurement to soil resistivity
Selection, to different shaft towers have stronger adaptability.This method overcomes the ground resistance measurement method institute generally used
The deficiency having has higher accuracy, is proved to be a kind of accurate feasible, convenient method of measurement.
Below main contents of the present invention are carried out with the analysis in principle:
1, pole tower ground resistance Accurate measurement
(1) pole tower ground resistance buries the detection in orientation
The measuring circuit of this method uses the cloth pole mode of three electrode method, and in order to avoid interference, keep measurement result more accurate
Really, three electrode method requires measuring electrode to be arranged along Grounding Grids direction in measurement process.Due to construction drawing in Practical Project
The reasons such as loss, it is often unknown that grounding body buries orientation.This method proposes a kind of to judge that grounding body buries orientation by magnetic field
Method.
It measures before carrying out, the Injection Current into tower grounding body, the grounded body of electric current diffusing into soil, due to grounding body
Resistance is much smaller than electric resistance of soil, therefore electric current is largely flowed in the embedded direction of grounded body, and electric current can shape in soil surface
At magnetic field, according to electromagnetic field correlation theory it is found that the magnetic induction intensity for burying orientation along grounding body is maximum.Using corresponding detection
Magnetic induction intensity instrument detects soil surface magnetic field, can learn that grounding body buries orientation.This method is through simulation analysis and scene
Experiment is proved to be a kind of feasible method for judging grounding body and burying orientation.
(2) ground lead measurement is not turned off
It is less efficient compared to on-line measurement mode that off-line measurement mode disconnects ground lead, and the current by pass of lightning current
Ground lead is contained, therefore, the accuracy for disconnecting the measurement method measurement result of ground lead is also difficult to be guaranteed, can not
React the most true situation of grounding body.The present invention carries out ground resistance survey using the method for not turning off ground lead on-line measurement
Amount.The electric current of sufficiently large frequency is injected to tower grounding body, shaft tower and lightning conducter induction reactance are more much bigger than grounding body impedance at this time, can
Think that shaft tower part is open, it is achieved that the on-line measurement to ground resistance.
(3) frequency-selecting type measurement method
Traditional high frequency multiple process injects tower grounding body using 10kHz electric currents, and due to different high pressure shaft tower inductance values
The soil resistivity difference of difference, different shaft tower local environments causes grounding body impedance also different, therefore is only injected into 10kHz frequencies
Electric current is not strong for the adaptability of different shaft tower environment, therefore the accuracy of measurement result is also unable to get guarantee.
The present invention carries out the selection of Injection Current frequency using the method for frequency-selecting.The soil of soil near shaft tower is measured first
Resistivity selects the frequency range of Injection Current frequency according to soil resistivity, and one group of frequency in the frequency range is injected to tower grounding body
Rate is calculated and measures resistance value, and calculated measurement result using the method for average, obtains the measured value of pole tower ground resistance.It is logical
It crosses and is compared with the experimental data of three electrode method and split-core type meter method, it is feasible to obtain this method, and measurement result is accurate.
2, the design of frequency-selecting type ground connection shaft tower earth resistance metering device
Frequency-selecting type pole tower ground resistance measuring device is made of field measurement apparatus and central processing module two parts, wherein
Field measurement apparatus includes:Encourage source module, signal acquisition circuit module, central processing module, LCD MODULE, power supply electricity
Road, field measurement apparatus mainly complete data signal acquisition, carry out the calculating of soil resistivity and ground resistance at live shaft tower
The calculating and display of value, the selection of power frequency.
Device uses the cloth pole mode of three electrode method, passes through the electric current frequency of the measurement selection injection grounding body to soil resistivity
The voltage of acquisition, current signal are inputted central processing by rate by signal acquisition module after amplification, filtering, conversion process
Module (microcontroller), which calculates, is tested pole tower ground resistance value, the method for average is used in this calculating process, to make overall calculation miss
It is poor minimum, accurately reflect grounding resistance.
In view of the above analysis, the technical solution adopted by the present invention is:A kind of pole tower ground resistance Accurate measurement, including
Following steps:
1) pole tower ground resistance buries the detection in orientation, and the embedded orientation of grounding body is judged using magnetic field method, so that it is determined that
The cloth set direction of electrode.
2) four-electrode method is utilized to measure the soil resistivity of soil near grounding body.
3) it uses the cloth pole mode of three electrode method to measure the laying of electrode, Injection Current frequency is selected according to soil resistivity
Rate range injects one group of electric current in the frequency range to tower grounding body, calculates separately out one group of resistance value to be measured, and profit
One group of resistance value to be measured is calculated with the method for average, obtains the measured value of pole tower ground resistance.
Specifically, in step 1), the magnetic field method judges that the embedded orientation of grounding body is specially:Into tower grounding body
Injection Current recycles after the grounded body of electric current and soil diffusing through electrode and forms magnetic field in soil surface;It is visited using magnetic field
The distribution situation for surveying instrument detection soil surface magnetic field is that radius measurement is justified apart from decanting point a distances using Current injection points as the center of circle
Magnetic Induction Density Distribution on week, magnetic induction intensity most strength are that tower grounding body buries orientation, point E are denoted as, similarly in distance
On the circumference of decanting point b distances measure magnetic induction intensity distribution, show that tower grounding body bury orientation, be denoted as point F, point E and
The line direction of point F is the embedded orientation of tower grounding body.
In the above-mentioned technical solutions, step 3) is described selects Injection Current frequency range according to soil resistivity, is basis
Following relationship carries out Injection Current frequency range selection:
The determination of the upper limit value of above-mentioned Injection Current frequency range is as follows:
To make impedance ground value close to grounding resistance, grounding body induction reactance part needs as small as possible, 2 π fLx/Rx→ 0,
If Injection Current upper frequency limit value determines that function Δ (f) is:The π fL of Δ (f)=2x/Rx, wherein LxFor tested tower grounding body electricity
Sense, RxTested tower grounding bulk resistor, f are Injection Current frequency, and Δ (f) is that upper limit value determines function.
When i.e. condition is converted into Δ (f) → 0, the requirement accurately measured can be met, simulation calculation can obtain, the value of Δ (f)
Gradually increase with the increase of frequency, but the value of Δ (f) only levels off to 0 can just reduce error, is ensuring measurement result
Under the premise of accuracy, the corresponding frequency values in Δ (f)=0.05 are set as upper frequency limit value, according under different soils resistivity
Ground resistance standard calculates the upper limit value of Injection Current frequency.
The present invention also provides a kind of accurate measuring device of pole tower ground resistance, including excitation source module, signal acquisition module,
Signal pre-processing module, central processing module and display module, the excitation source module pass through to tower grounding body Injection Current
Tower grounding body, electric current pole and excitation source module forming circuit;The output end of excitation source module is connect with centre module;Signal
The input terminal of acquisition module is connect with voltage pole, the output end of signal acquisition module and the input terminal phase of signal pre-processing module
Even;The output end of signal pre-processing module is connected with the input terminal of central processing module;Display module is defeated with central processing module
Outlet is connected.
Technical solution provided by the invention can not turn off accurate measurement of the ground lead realization to pole tower ground resistance value,
Vertical cloth pole is realized by burying the judgement in orientation to grounding body, improve the accuracy of measurement first;Secondly by attached to shaft tower
The power frequency of the measurement selection injection of nearly soil resistivity, improves adaptability of the measurement method to different shaft tower soil environments;
Without disconnecting ground lead, the working efficiency of measurement of Grounding Resistance is improved.Calculating for pole tower ground resistance, using average value
Method makes measurement error reach minimum, promotes the accuracy of measurement result.
Description of the drawings
Fig. 1 is the measuring circuit figure of patent of the present invention;
Fig. 2 is the Distribution of Magnetic Field figure that shaft tower horizontal grounding objects are generated in soil surface;
Fig. 3 is not turn off ground lead to measure pole tower ground resistance physical model;
Fig. 4 is that pole tower ground resistance accurately measures Simplified equivalent model;
Fig. 5 is the circuit diagram that soil resistivity measures;
Fig. 6 is δ (f) with Injection Current frequency f change curves;
Fig. 7 is frequency-selecting type pole tower ground resistance measuring device structure chart.
Specific implementation mode
Technical scheme of the present invention is described further below in conjunction with attached drawing:
1, pole tower ground resistance Accurate measurement, referring to Fig.1, core includes the following steps wiring diagram:
1) magnetic field method is used to judge the embedded orientation of grounding body, so that it is determined that the cloth set direction of electrode;
It measures before work starts, the Injection Current into tower grounding body, is passed through after the grounded body of electric current and soil diffusing
Another electrode recycles and forms magnetic field in soil surface.Due to shaft tower horizontal grounding objects more options rectangular cross-section band steel or
Circular round steel, when electric current flows through grounding body, you can by shaft tower horizontal grounding objects be equivalent to the straight current carrying conductor model of limit for length into
Row calculate, it is equivalent after model it is as shown in Figure 2.It calculates it is found that magnetic induction density B at soil surface any point P (x, y, 0):
In formula, μ is the magnetic conductivity of soil, and I is to measure current effective value, and h is the buried depth of grounding body, For P points and bar
The vertical line angle of tower grounding body both ends line and grounding body, L are the length of grounding body.
It is found that the maximum value of magnetic induction intensity is located at the surface of shaft tower horizontal grounding objects, with the offset of position, magnetic strength
Intensity is answered to be gradually reduced.Using the distribution situation in detection of magnetic field instrument detection soil surface magnetic field, since electric current mainly connects along shaft tower
Ground body is flowed, and is magnetic induction intensity point on radius measurement circumference apart from decanting point a distances using Current injection points as the center of circle
Cloth, magnetic induction intensity most strength are that tower grounding body buries orientation, are denoted as point E.Same method is in the circle apart from decanting point b
The distribution that magnetic induction intensity is measured on week, show that tower grounding body buries orientation, is denoted as point F, point E and the line direction of point F is
For the embedded orientation of tower grounding body.
2) injection high-frequency current avoids disconnecting ground lead in measurement process as electric current is measured, and measurement result includes to connect
Ground lead resistance value improves measurement result accuracy;
Measuring circuit is identical as three electrode method measuring circuit, and boost voltage pole P and auxiliary current pole C are arranged in perpendicular to shaft tower
Grounding body bury orientation direction on, by voltage pole be arranged in potential compensation point (be computed voltage pole P apart from grounding body G away from
0.618 times of the distance of grounding body G with a distance from for electric current pole C, at this time 0) current potential at P is.
High-frequency ac current is injected into grounding body, with the raising of frequency and soil resistivity, the inductive effect of shaft tower
It is more and more obvious, can obtain not turning off ground lead measurement pole tower ground resistance physical model as shown in figure 3, Injection Current isWhereinBy tower grounding body, soil and electric current pole form current loop, andPass through shaft tower, lightning conducter
And the shaft tower of surrounding forms current loop.If the lightning conducter induction reactance of shaft tower both sides to be asked, lightning-arrest line resistance, shaft tower resistance, bar
Tower induction reactance, ground resistance and grounding body equivalent inductive reactance summation are Zeq=j ω Leq+Req, wherein LeqFor lightning conducter equivalent inductance, Req
For lightning conducter equivalent resistance, it is equivalent after circuit model it is as shown in Figure 4.The calculation shows that, tower-footing impedance value change with frequency f
Expression formula:
In formula:LxFor tower grounding body inductance, RxFor tower grounding bulk resistor.
Not turning off the condition that ground lead pole tower ground resistance accurately measures is:
| Z (f) | "=0 (3)
3) it by the measurement to soil resistivity, determines the frequency range of Injection Current, measures one group of pole tower ground resistance
Measured value corrects measurement result, obtains the measurement exact value of pole tower ground resistance.
Soil soil resistivity near grounding body is measured using four-electrode method, measuring circuit as shown in figure 5, using
Four electric current cloth poles, wherein two electrodes of A, B constitute current loop, and two electrodes of C, D are used to measure the potential difference of soil surface,
To which ρ values be calculated using the relationship of voltage and current.
In figure, a1, a2For the spacing of electric current pole A and potential pole C, D, a3, a4For the spacing of electric current pole B and potential pole C, D,
Equally, four electrodes need to carry out cloth pole along same straight line, and the depth of cloth pole is h, is a, cloth pole between each electrode
Depth h be less than 1/20 equal to distance a between each electrode, i.e. h≤a/20, opposite two voltage poles in electric current pole generate
Current potential be:
V1=I the π of ρ/2 (1/a-1/2a)
V2=I the π of ρ/2 (1/2a-1/a)
So the potential difference between two voltage poles is:
V=V1-V2=I the π of ρ/2 a
Therefore deduce that soil resistivity is:
The π aV/I=2 π of ρ=2 aRg (4)
In formula, a is interelectrode distance, RgFor the electric resistance of soil of actual measurement.
As formula (4) it is found that when known to as a, measures the voltage between C, D electrode and flows through the electric current of A, B electrode, you can
To calculate soil resistivity.
According to the soil resistivity measured, high-frequency method measurement request grounding resistance is far longer than grounding body induction reactance value and remote
Much smaller than lightning conducter induction reactance value, i.e.,:
By Rx=10 Ω, Lx=10 μ H, Leq=10mH is substituted into formula (4) and is obtained:
159Hz<<f<<159kHz (6)
Above formula has obtained one than broad Injection Current frequency range, is needed in conjunction with practical measure, by frequency-selecting type bar
The Injection Current frequency range of tower ground resistance primarily determines as 1kHz~15kHz, i.e., within the scope of 1kHz~15kHz every
1kHz is measured.It measures in the range and obtains multigroup frequency values, and handled according to obtained discrete data is measured,
Optimum frequency point is obtained, grounding resistance is solved.
Since under different soil resistivity environment, the standard value of pole tower ground resistance is also not quite similar, if per base shaft tower
Value all use identical standard value, inject the electric current of identical frequency, error can also increase therewith, it is therefore necessary to analysis not
With the Injection Current frequency range of soil resistivity section.
It is 1~15kHz that a preliminary Injection Current frequency range has tentatively been deduced in formula (6), then according to table 1
In ground resistance standard value, by building two mathematical functions, come determine respectively the upper limit value of Injection Current frequency range with
Lower limiting value.
Pole tower ground resistance standard value under 1 different soils resistivity of table
A) determination of Injection Current lower-frequency limit value
If Injection Current lower-frequency limit function δ (f) is:
As δ (f) → 0 in formula (7), you can to meet the accurate measuring condition of formula, therefore, choose frequency-selecting type tower grounding electricity
The canonical parameter that resistance measures brings the formula into, draws out the curve graph that δ (f) changes with frequency f, as shown in Figure 6.
It can be seen that according to the curve when ground resistance standard value changes to 30 Ω from 10 Ω, function δ (f) changes width
It spends and little, when f is in value after 1kHz, the variable quantity of the value of δ (f) is very small, nearly close to zero.In conjunction with determining before
Preliminary frequency range lower limiting value, in different soils electrical resistivity range, the lower limiting value of Injection Current frequency can be set
For 1kHz.
B) determination of Injection Current upper frequency limit value
To make impedance ground value close to grounding resistance, grounding body induction reactance part needs are as small as possible, and (5) are converted
For:2πfLx/Rx→ 0, if Injection Current upper frequency limit value determines that function Δ (f) is:
The π fL of Δ (f)=2x/Rx (8)
When i.e. condition is converted into Δ (f) → 0, the requirement accurately measured can be met.Simulation calculation can obtain, the value of Δ (f)
Gradually increase with the increase of frequency, but the value of Δ (f) only levels off to 0 can just reduce error, is ensuring measurement result
Under the premise of accuracy, set the corresponding frequency values in Δ (f)=0.05 as upper frequency limit value, ensure to have enough frequency bands into
While row frequency-selecting is handled, it can also meet the condition accurately measured.It then can determine under different soils resistivity, Injection Current frequency
The upper limit value of rate.
By a), b) can determine under different soils resistivity, the frequency range of Injection Current frequency-selecting, as shown in table 2.Determine note
After entering current frequency range, 10 groups of different frequencies for selecting frequency range are injected into the known tower grounding body of soil resistivity nearby
Electric current (averagely selecting 10 class frequencys in selected frequency range), measurement of Grounding Resistance value obtains the flat of 10 groups of measurement of Grounding Resistance values
Mean value obtains the accurate measurements of pole tower ground resistance.
Current frequency range is injected under 2 different soils resistivity of table
2, for frequency-selecting type pole tower ground resistance measuring device with reference to Fig. 7, composition and module connection are as follows:The device packet
Include excitation source module 1, signal acquisition module 2, signal pre-processing module 3, central processing module 4 and display module 5, the excitation
Source module 1 passes through tower grounding body, electric current pole C to tower grounding body Injection Current) it is formed into a loop with excitation source module 1;Excitation
The output end of source module 1 is connect with centre module 4;The input terminal of signal acquisition module 2 is connect with voltage pole P, signal acquisition
The output end of module 2 is connected with the input terminal of signal pre-processing module 3;The output end and central processing of signal pre-processing module 3
The input terminal of module 4 is connected;Display module 5 is connected with 4 output end of central processing module.Central processing module 4 is adopted in the present apparatus
With the high-performance microprocessor STM32 of group of STMicw Electronics.
Apparatus of the present invention are a kind of accurate measuring devices of frequency-selecting type pole tower ground resistance, can not turn off ground lead
In the case of accurately measure the grounding resistance of shaft tower, and measurement data is carried out to be processed such that error reaches using the method for average
It is a kind of accurately and efficiently measurement method to minimum.Pass through the electric current frequency of the measurement selection injection grounding body to soil resistivity
The voltage of acquisition, current signal are inputted central processing by rate by signal acquisition module after amplification, filtering, conversion process
Module (microcontroller), which calculates, is tested pole tower ground resistance value, 10 groups calculated frequency-selecting using mean value method in this calculating process
Measurement of Grounding Resistance value result is handled, and to keep overall calculation error minimum, accurately reflects grounding resistance.
Claims (3)
1. a kind of pole tower ground resistance Accurate measurement, which is characterized in that include the following steps:
1) pole tower ground resistance buries the detection in orientation, the embedded orientation of grounding body is judged using magnetic field method, so that it is determined that electrode
Cloth set direction;The magnetic field method judges that the embedded orientation of grounding body is specially:The Injection Current into tower grounding body, electric current warp
It is recycled through electrode after grounding body and soil diffusing and forms magnetic field in soil surface;Soil surface is detected using detection of magnetic field instrument
The distribution situation in magnetic field is magnetic induction intensity point on radius measurement circumference apart from decanting point a distances using Current injection points as the center of circle
Cloth, magnetic induction intensity most strength are that tower grounding body buries orientation, point E are denoted as, similarly in the circumference apart from decanting point b distances
The upper distribution for measuring magnetic induction intensity, show that tower grounding body buries orientation, is denoted as point F, point E and the line direction of point F is
The embedded orientation of tower grounding body;
2) four-electrode method is utilized to measure the soil resistivity of soil near grounding body;
3) it uses the cloth pole mode of three electrode method to measure the laying of electrode, Injection Current frequency model is selected according to soil resistivity
It encloses, injects one group of electric current in the frequency range to tower grounding body, calculate separately out one group of resistance value to be measured, and utilize flat
Equal method calculates one group of resistance value to be measured, obtains the measured value of pole tower ground resistance.
2. a kind of pole tower ground resistance Accurate measurement according to claim 1, it is characterised in that:Step 3) the basis
Soil resistivity selects Injection Current frequency range, is to carry out Injection Current frequency range selection according to following relationship:
3. a kind of pole tower ground resistance Accurate measurement according to claim 2, it is characterised in that:The Injection Current frequency
The determination of rate range is as follows:
Wherein upper limit value:To make impedance ground value close to grounding resistance, grounding body induction reactance part needs as small as possible, 2 π
fLx/Rx→ 0, if Injection Current upper frequency limit value determines that function Δ (f) is:The π fL of Δ (f)=2x/Rx, wherein LxTo be tested shaft tower
Grounding body inductance, RxFor tested tower grounding bulk resistor, f is Injection Current frequency, and Δ (f) is that upper limit value determines function;
When i.e. condition is converted into Δ (f) → 0, the requirement accurately measured can be met, simulation calculation can obtain, the value of Δ (f) with
The increase of frequency and gradually increase, but the value of Δ (f) only levels off to 0 can just reduce error, is ensuring that measurement result is accurate
Under the premise of property, the corresponding frequency values in Δ (f)=0.05 are set as upper frequency limit value, according to the ground connection under different soils resistivity
Resistance standard calculates the upper limit value of Injection Current frequency.
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