CN107632203A - A kind of large ground network earth loop impedance test method for considering earth effect - Google Patents
A kind of large ground network earth loop impedance test method for considering earth effect Download PDFInfo
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Abstract
The invention discloses a kind of large ground network earth loop impedance test method for considering earth effect, multiple voltage pole measurement points are equidistantly spaced from voltage measurement line；Each voltage pole measurement point and the distance of tested ground network edge, and each measured value for the tested mesh grounding impedance that voltage pole measurement point measures are recorded, calculates resistive component value and inductive component value therein；Resistive component curve and its expression formula and inductive component curve and its expression formula are respectively obtained using the method for curve matching according to the data of record；Second order derivation is carried out to resistive component expression formula, obtained extreme point is returned in substitution resistive component expression formula resistive component measured value R (x is calculated0)；Vertical axis intercept L is taken to inductive component expression formula0It is Z so as to obtain the measured value of tested mesh grounding impedance as inductive component measured value0=R (x0)+jL0.The present invention can effectively improve the accuracy of large ground network earth resistance.
Description
Technical field
The invention belongs to mesh grounding testing impedance field, more particularly to a kind of impedance ground that can consider earth effect is surveyed
Amount method, judge for analyzing the actual value of large ground network impedance ground, to improve the accuracy of fieldtesting results.
Background technology
Power system is interconnection wide area (Wide-Area) system being made up of more conductors above and below the ground.Transformer station
(factory) earth mat is the important component of power system subsurface grid, plays working earthing, protective grounding, lightning protection and antistatic
The four big functions such as ground connection.Field measurement transformer station (factory) mesh grounding impedance is to ensure earthed system normal work and meet to be grounded
The important means of application demand.Be advantageous to grasp the operation conditions of earth mat to the accurate measurement of earth mat impedance ground, promote power transformation
Stand (factory) earth mat repair based on condition of component, to reduce power off time and improve power supply reliability suffer from significance.
Because test current with earth mat current potential is to exchange, impedance ground actual measurement value expression is Z=R+jX, contains resistance
Components R and inductive component X.Straight-line method is the main method of testing of current domestic mesh grounding impedance, and its core concept is to utilize
Electric current pole away from earth mat forms tested current loop, recycles rational voltage pole arrangement to compensate the shadow of electric current pole mutual impedance
Ring, also commonly referred to as penalty method or " 0.618 " method.
The influence of the earth can be to the measured result meeting of straight-line method in the earth loop impedance test of large-scale substation (factory) earth mat
Bring greater impact：On the one hand because earth mat laying causes surrounding soil resistivity uneven distribution to be present extensively, with tradition
Straight-line method test it is possible that compensation point be difficult to find accurately or different unwrapping wire paths on the larger situation of test value difference.
Existing grid grounding impedance measurement standard at home《DL/T 475-2006 earthing or grounding means characterisitic parameter measures directive/guide》In to measurement point
The choosing method of (near zero-potential point) is：Voltage pole is that spacing moves three times with the 5% of electric current pole length, measured value three times
Error is considered measurement point within 5%, and this method has significant limitation in actually measuring；On the other hand, large-scalely
The size of net is larger to cause during actual measurement voltage, current feed are parallel collinearly make it that mutually inductance value increases between the two apart from long, the portion
Point mutual inductance value, which can be added on the inductive component of impedance ground, causes measured result bigger than normal.It is using angle-off set or away from method, i.e., logical
Cross increase voltage, the influence of mutual inductance is reduced or eliminated in the method for current feed spacing, can improve the accuracy of measurement result.But
Be in actual measurement some plant stands by site contour limited only unique path can place voltage, current feed, can only adopt
Cut-off collimation method is tested, test error caused by now just needing accurate evaluation and eliminating mutual inductance.Therefore, it is necessary to provide one
Kind can eliminate test error caused by mutual inductance, and then the method that accurate measurement is carried out to earth mat impedance ground.
The content of the invention
The technical problem to be solved in the present invention is：Test error existing for impedance ground is surveyed for traditional line method, is proposed
A kind of new method for the large ground network straight-line method measurement impedance ground for considering earth effect, this method can effectively eliminate electric resistance of soil
The influence of the uneven mutual inductance between test lead of rate, improve the accuracy of field actual measurement results.
Technical scheme provided by the present invention is：
A kind of large ground network earth loop impedance test method for considering earth effect, comprises the following steps：
Step 1, the position for determining electric current pole, electric current pole and the line of tested earth mat are then current measurement line；It is determined that
The voltage measurement line parallel with current measurement line；Multiple voltage pole measurement points are equidistantly spaced from voltage measurement line, are designated as P1
~Pn, P1~PnIt is less than the distance of the position and tested ground network edge of electric current pole with the distance of tested ground network edge；According to
DL/T 475-2006《Earthing or grounding means characterisitic parameter measures directive/guide》, the distance of voltage pole and tested ground network edge should be less than electric current
Pole and the distance of tested ground network edge, present invention point on the basis of 0.618 times of electric current pole with the distance for being tested ground network edge,
Multiple voltage pole measurement points are taken in the range of this at equal intervals, for follow-up cubic spline interpolation.
Step 2, recording the distance of each voltage pole measurement point and tested ground network edge, (i.e. voltage, current measurement line are parallel
Collinear lengths), it is designated as x1~xn, and each measured value for the tested mesh grounding impedance that voltage pole measurement point measures, including electricity
Component and inductive component are hindered (according to DL/T 475-2006《Earthing or grounding means characterisitic parameter measures directive/guide》Specified in three electrode method survey
The measured value of tested mesh grounding impedance is measured, resistance point in the measured value of impedance ground is drawn from the reading of test apparatus
Amount and inductive component size), data record format is as shown in table 1；
The measurement data record table of table 1
| Voltage pole measuring point P | P1 | P2 | P3 | P4 | ……Pn |
| Distance x | x1 | x2 | x3 | x4 | ……xn |
| Resistive component value R | R1 | R2 | R3 | R4 | ……Rn |
| Inductive component value L | L1 | L2 | L3 | L4 | ……Ln |
Step 3, resistive component curve and its expression formula respectively obtained using the method for curve matching according to the record data of table 1
R (x)=Ax3+Bx2+ Cx+D and inductive component curve and its expression formula L=Δs Lx+L0, wherein A, B, C, Δ L and L0It is to intend
Close obtained parameter；Slope Δ L in inductive component curve and its expression formula is voltage, the parallel conllinear unit length of current measurement line
The mutual inductance error of degree, earth mat is bigger, then parallel collinear lengths are longer, and mutual inductance error is just as caused by Δ L × parallel collinear lengths
It is bigger；
Step 4, second order derivation is carried out to resistive component expression formula, obtain second dervative R " (x)=6Ax+2B, second dervative
Extreme pointThe as data point of impedance ground resistive component, return and be calculated in substitution resistive component expression formula
Resistive component measured value is R (x0)；
Step 5, vertical axis intercept L is taken to inductive component expression formula0As inductive component measured value；
Step 6, the measured value for obtaining being tested mesh grounding impedance are Z0=R (x0)+jL0。
Further, in the step 3, it is fitted to obtain resistive component curve and its expression formula R by cubic spline interpolation
(x)=Ax3+Bx2+ Cx+D, linear interpolation are fitted to obtain inductive component curve and its expression formula L=Δs Lx+L0。
The present invention considers the influence of the earth when using the impedance ground of straight-line method measurement large-scale substation (factory) earth mat,
Take the method for second dervative extreme value to efficiently solve by resistive component cubic spline difference to lead extensively because earth mat lays area
Surrounding soil resistivity is caused uneven distribution to be present so that the problem of zero-potential point is difficult to choose when measuring；On the other hand electricity is passed through
The method for feeling component fitting a straight line is effectively rejected because the mutual inductive impedance that longer voltage, current measurement lead parallel coupling obtain misses
Difference.
Beneficial effect is：
The present invention is a kind of optimization and improvement to traditional line method, from earth loop impedance test principle, respectively from electricity
Two angles of resistance component and inductive component eliminate the measurement of traditional line method voltage pole by way of being fitted to measured data
Point is difficult to the difficulty chosen (near zero potential), and can effectively eliminate the parallel conllinear mutual inductance error of voltage, current measurement line
Influence, obtain the inductive component value of earth mat impedance ground in itself, the standard of large ground network earth resistance can be effectively improved
True property.
Brief description of the drawings
Fig. 1 principle of the invention figures.
Fig. 2 surveys certain earth mat resistive component matched curve and expression formula.
Fig. 3 surveys certain earth mat inductive component matched curve and expression formula.
Fig. 4 flow charts of the present invention.
Embodiment
The present invention is described in more detail below in conjunction with the drawings and specific embodiments.
The invention discloses a kind of large ground network earth loop impedance test method for considering earth effect, schematic diagram such as Fig. 1 institutes
Show, comprise the following steps：
Step 1, the position for determining electric current pole, electric current pole and the line of tested earth mat are then current measurement line；It is determined that
The voltage measurement line parallel with current measurement line；Multiple voltage pole measurement points are equidistantly spaced from voltage measurement line, are designated as P1
~Pn, P1~PnIt is less than the distance of the position and tested ground network edge of electric current pole with the distance of tested ground network edge；According to
DL/T 475-2006《Earthing or grounding means characterisitic parameter measures directive/guide》, the distance of voltage pole and tested ground network edge should be less than electric current
Pole and the distance of tested ground network edge, present invention point on the basis of 0.618 times of electric current pole with the distance for being tested ground network edge,
Multiple voltage pole measurement points are taken in the range of this at equal intervals, for follow-up cubic spline interpolation.
Step 2, recording the distance of each voltage pole measurement point and tested ground network edge, (i.e. voltage, current measurement line are parallel
Collinear lengths), it is designated as x1~xn, and each measured value for the tested mesh grounding impedance that voltage pole measurement point measures, including electricity
Component and inductive component are hindered (according to DL/T 475-2006《Earthing or grounding means characterisitic parameter measures directive/guide》Specified in three electrode method survey
The measured value of tested mesh grounding impedance is measured, resistance point in the measured value of impedance ground is drawn from the reading of test apparatus
Amount and inductive component size), data record format is as shown in table 1；
The measurement data record table of table 1
| Voltage pole measuring point P | P1 | P2 | P3 | P4 | ……Pn |
| Distance x | x1 | x2 | x3 | x4 | ……xn |
| Resistive component value R | R1 | R2 | R3 | R4 | ……Rn |
| Inductive component value L | L1 | L2 | L3 | L4 | ……Ln |
Step 3, resistive component curve and its expression formula respectively obtained using the method for curve matching according to the record data of table 1
R (x)=Ax3+Bx2+ Cx+D (example is as shown in Figure 2) and inductive component curve and its expression formula L=Δs Lx+L0(example is as schemed
Shown in 3), wherein A, B, C, Δ L and L0It is the parameter that fitting obtains；Slope Δ L in inductive component curve and its expression formula
For voltage, the mutual inductance error of the parallel conllinear unit length of current measurement line, earth mat is bigger, then parallel collinear lengths are longer, by Δ L
Mutual inductance error caused by × parallel collinear lengths is bigger；
Step 4, second order derivation is carried out to the resistive component expression formula in Fig. 2, obtains second dervative R " (x)=6Ax+2B,
The extreme point of second dervativeThe as data point of impedance ground resistive component, return and substitute into resistive component expression formula
It is R (x that resistive component measured value, which is calculated,0)；
Step 5, vertical axis intercept L is taken to the inductive component expression formula in Fig. 30As inductive component measured value；
Step 6, the measured value for obtaining being tested mesh grounding impedance are Z0=R (x0)+jL0, measurement procedure figure is as shown in Figure 4.
Further, in the step 3, by (progress of Origin softwares) cubic spline interpolation be fitted to obtain resistive component curve and its
Expression formula R (x)=Ax3+Bx2+ Cx+D, linear interpolation are fitted to obtain inductive component curve and its expression formula L=Δs Lx+L0。
It is specific referring to one of the large ground network earth loop impedance test method of the earth effect of present invention consideration shown in Fig. 2, Fig. 3
Embodiment, the resistive component and inductive component of the tested mesh grounding impedance of the embodiment are intended by Origin softwares respectively
Curve description is closed, the resistive component solution point of tested mesh grounding impedance is taken at matched curve second dervative extreme value, inductance point
Measure fitting a straight line vertical axis intercept.
The embodiment formed more than considers the large ground network earth loop impedance test method of earth effect, is demonstrate,proved through on probation
It is bright work well, result of the test it is accurate, design requirement is fully achieved.
Claims (2)
- A kind of 1. large ground network earth loop impedance test method for considering earth effect, it is characterised in that comprise the following steps：Step 1, the position for determining electric current pole, electric current pole and the line of tested earth mat are then current measurement line；It is determined that with electricity The parallel voltage measurement line of flow measurement line；Multiple voltage pole measurement points are equidistantly spaced from voltage measurement line, are designated as P1~Pn, P1~PnIt is less than the distance of the position and tested ground network edge of electric current pole with the distance of tested ground network edge；Step 2, record each voltage pole measurement point and the distance x of tested ground network edge1~xn, and each voltage pole measurement point The measured value Z of its tested mesh grounding impedance measured1~Zn, including resistive component value R1~RnWith inductive component value L1~Ln；Step 3, the data recorded according to step 2 use the method for curve matching to respectively obtain resistive component curve and its expression formula R (x)=Ax3+Bx2+ Cx+D and inductive component curve and its expression formula L=Δs Lx+L0, wherein A, B, C, Δ L and L0It is to intend Close obtained parameter；Step 4, second order derivation is carried out to resistive component expression formula, obtain second dervative R " (x)=6Ax+2B, the pole of second dervative Value pointThe as data point of impedance ground resistive component；By x0Return to substitute into resistive component expression formula and be calculated Resistive component measured value is R (x0)；Step 5, vertical axis intercept L is taken to inductive component expression formula0As inductive component measured value, slope Δ L is voltage, electric current survey Measure the mutual inductance error of the parallel conllinear unit length of line；Step 6, the measured value for obtaining being tested mesh grounding impedance are Z0=R (x0)+jL0。
- 2. the large ground network earth loop impedance test method according to claim 1 for considering earth effect, in the step 3, It is fitted to obtain resistive component curve and its expression formula R (x)=Ax by cubic spline interpolation3+Bx2+ Cx+D, linear interpolation fitting Obtain inductive component curve and its expression formula L=Δs Lx+L0。
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Cited By (5)
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| CN108896825A (en) * | 2018-06-05 | 2018-11-27 | 国网甘肃省电力公司电力科学研究院 | Harmonic wave grid grounding impedance measurement method with vertical grounding electrode or deep-well earth mat |
| CN110308332A (en) * | 2019-07-16 | 2019-10-08 | 国网湖南省电力有限公司 | A kind of grounding net of transformer substation impedance ground detection method, system and medium |
| CN111812407A (en) * | 2020-07-16 | 2020-10-23 | 国网湖南省电力有限公司 | Comprehensive grounding impedance measurement method, system and medium |
| CN113219254A (en) * | 2020-01-21 | 2021-08-06 | 武汉市康达电气有限公司 | Method and device for measuring grounding impedance of grounding grid, electronic equipment and medium |
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| CN103308822B (en) * | 2013-05-07 | 2015-06-24 | 河南理工大学 | Small current earth fault line selection method for radial distribution network |
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| CN104897968B (en) * | 2015-05-14 | 2017-08-08 | 武汉市康达电气有限公司 | Mesh grounding impedance detecting method based on paraphase method of addition |
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| CN108896825A (en) * | 2018-06-05 | 2018-11-27 | 国网甘肃省电力公司电力科学研究院 | Harmonic wave grid grounding impedance measurement method with vertical grounding electrode or deep-well earth mat |
| CN110308332A (en) * | 2019-07-16 | 2019-10-08 | 国网湖南省电力有限公司 | A kind of grounding net of transformer substation impedance ground detection method, system and medium |
| CN113219254A (en) * | 2020-01-21 | 2021-08-06 | 武汉市康达电气有限公司 | Method and device for measuring grounding impedance of grounding grid, electronic equipment and medium |
| CN111812407A (en) * | 2020-07-16 | 2020-10-23 | 国网湖南省电力有限公司 | Comprehensive grounding impedance measurement method, system and medium |
| CN111812407B (en) * | 2020-07-16 | 2022-09-16 | 国网湖南省电力有限公司 | Comprehensive grounding impedance measurement method, system and medium |
| CN113866505A (en) * | 2021-09-17 | 2021-12-31 | 广东电网有限责任公司广州供电局 | Grounding grid on-resistance measurement and grounding grid state evaluation method and system |
| CN113866505B (en) * | 2021-09-17 | 2024-03-01 | 广东电网有限责任公司广州供电局 | Grounding grid on-resistance measurement and grounding grid state evaluation method and system |
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