CN104568719A - Evaluation method of transformer substation grounding grids - Google Patents

Evaluation method of transformer substation grounding grids Download PDF

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Publication number
CN104568719A
CN104568719A CN201510012452.6A CN201510012452A CN104568719A CN 104568719 A CN104568719 A CN 104568719A CN 201510012452 A CN201510012452 A CN 201510012452A CN 104568719 A CN104568719 A CN 104568719A
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grounded screen
ground wire
formula
corrosion
area
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CN104568719B (en
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郭军科
于金山
苏展
卢立秋
郝春艳
邵林
刘鸿芳
其他发明人请求不公开姓名
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State Grid Corp of China SGCC
State Grid Tianjin Electric Power Co Ltd
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State Grid Tianjin Electric Power Co Ltd
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Abstract

The invention relates to an evaluation method of transformer substation grounding grids. The evaluation method comprises the following steps: (1) deriving the thinning speed of metal thickness of a grounding grid by applying the faraday's law; (2) determining the minimal section area Sg of a grounding wire without considering corrosion; (3) determining the minimal section area Sg2 when considering the influence of the corrosion factor; and (4) determining the evaluation years of the grounding grid. According to the method, the calculation process is clear, the accuracy rate is high, and the theoretically powerful support is provided for the safety running of a power system grounding grid.

Description

A kind of appraisal procedure of grounding net of transformer substation
Technical field
The invention belongs to grounding net of transformer substation technical field, especially a kind of appraisal procedure of grounding net of transformer substation.
Background technology
Grounding technology relates to the various problems such as corrosion diagnosis technology and earthing device impact characteristics of the numerical analysis of earthed system electric parameter and optimal design, soil exchangeable base cation analysis, the resistance technology of falling of high soil resistivity, stake resistance scientific measurement, grounded screen.A large amount of documents shows that the main results of grounded screen concentrates on three aspects.One is testing and analyzing and the optimal design of earthed system parameter, not only impedance ground will be considered, also should consider Potential distribution on its step voltage, touch voltage and earth mat, secondly the parameter such as electrical integrity, thermal capacity, corrosion resistance of earth mat should also be considered, general also needs measures the hierarchical model that soil resistivity sets up soil, obtains more accurate Measurement and analysis result and instruct optimal design by numerical analysis.Two is situation and assessments thereof of grounded screen, the security of grounded screen is judged according to grounded screen testing and analysis result, mainly comprise the isoparametric tolerance value of thermal capacity of stake resistance, touch voltage, step voltage and down conductor and grounded screen, with reference to standard both domestic and external, earthed system is carried out to the assessment of security.Three is grounded screen fault monitoring and diagnosis, measures the connectedness of earthed system and the corrosion condition of diagnosis grounded screen, propose corresponding rectification and maintenance measure, for the safe operation of grounded screen provides safeguard by down conductor.
Study effective ground net corrosion to detect and method for diagnosing faults and grounded screen measurability problem, for the correct operation conditions grasping grounded screen, evaluate feasibility and the applicability of various Fault Diagnosis for Grounding Grids algorithm, Timeliness coverage grounded screen hidden danger also takes corresponding measure to have important directive significance, is more conducive to ensureing the people's lives and property and safety.
Have a lot relevant with the defect of earthing device in the electrical hazard of electric system.Trace it to its cause, grounded screen is the buried hidden facility in underground of electric system, and the on-the-spot technical problem underlying exposed is bad connection between the less than normal and grounding body in ground net corrosion, down conductor cross section, and these problems have buried hidden danger all to the fault of electric power.Ground net corrosion is the process of a gradual change, erodes to and to a certain degree namely enters malfunction, and reliability reduces even performance failure, can not meet the requirement of safe operation of power system.China is due to resource, economic dispatch reason, grounded screen material used is mainly plain carbon steel, ground net corrosion presents local corrosion form usually, after there is corrosion grounded screen carbon steel material become fragile, aliquation, loose, thinning, even rupture, so electric power grounding grid seriously corroded is current China electric power grounding grid distinct issues the most.
By the sequence of extent of corrosion, the most seriously corrosion of counterpoise grounding in cable duct, being secondly the corrosion of down conductor, is finally the corrosion of main grounding grid, and etching time is generally 5-20 after putting into operation, and within serious 3 years after putting into operation, namely corrodes.With the distribution of soil resistivity, soil electrochemistry characteristic, microorganism, stray current, weather conditions, the material of use, the difference of the factors such as construction technology and anti-corrosion measure, maximum year corrosion speed is also variant.
Summary of the invention
The object of the invention is, in order to overcome the deficiencies in the prior art, to provide a kind of appraisal procedure of grounding net of transformer substation.
The present invention solves its technical matters and takes following technical scheme to realize:
An appraisal procedure for grounding net of transformer substation, it is as follows that the method comprising the steps of:
(1) apply Faraday's law, derive the thinning speed of thickness of grounded screen metal;
Grounded screen material corrosion process in soil is applicable to Faraday's law: △ m=MQ/zF, and in formula, △ m is lysed metal quality; M is its atomic weight; Q is the electric charge of transfer; Z is the quantivalency of metallic ion; F is Faraday constant, by density p scan following formula be derived:
J A=Q/St=△m/St×zF/M-△s/t×zFρ s/M
In formula, J athat the anode of metallic ion passage divides the current density of reaction: S is the surface area of electrode: t is the time; △ s is the thickness be stripped;
W-f aJ A=△s/t
f a=M/zFρ s=3.2684/z(M/g·mol -1)(g·cm -3s)mm·a -1/mA·cm -2
v=f bJ A=△m/St
f b=M/zF=0.32311/z(M/g·mol -1)g·cm -2·h -1/mA·cm -2
In formula, W is the thinning speed of thickness, and v is the mass loss rate of per surface area;
W=f cv (I)
f c=f a/f b=1/ρ s=8.76((g·cm -3s)mm·a -1/g·cm -2·h -1
Wherein, f a, f b, f cfor grounded screen material reduction coefficient;
By above-mentioned formula (I) and f a, f b, f creduction coefficient can draw the thinning speed of the thickness of grounded screen metal;
(2) when determining not consider corrosion, ground wire minimum sectional area S g;
According to thermal stable condition, when not considering corrosion, ground wire minimum sectional area S g(unit: mm 2) be:
S g1=Ig/c·t e -2(II)
Wherein, in formula Ig be flow through the short-circuit current stationary value of ground wire, thermal stability factor that c is ground wire material, t efor the equivalent duration of short circuit;
(3) when determining to consider the affecting of corrosion factor, ground wire minimum sectional area S g2;
S g2=(A-2×w×n)(B-2×w×n) (III)
Wherein, when grounded screen is round steel type, in formula, A represents grounded screen width, and B represents grounded screen thickness, and n represents the operation time limit, and w represents the thinning speed of grounded screen material, unit: mm/a;
(4) the assessment time limit of grounded screen is determined.
And, for f in described step (1) a, f b, f creduction coefficient, common grounded screen material reduction coefficient is as following table:
And, Ig, c, t in the formula (II) of described step (2) econcrete regulation be:
1. Ig is the short-circuit current stationary value flowing through ground wire, unit: A, for effectively earthed system and low resistance earthing system, considers individual event or two earth short circuit currents; For earth-free, grounding through arc and high resistance grounding system, then consider dissimilarity two earth short circuit currents, Ig, according to system 5-10 development plan, determines by system maximum operational mode, and Ig calculates by substation bus bar short-circuit current maximal value 75%;
2. c is the thermal stability factor of ground wire material, and determine according to the initial temperature of ground wire before the kind of material, performance and maximum permissible temperature and short circuit, steel gets 70, and copper gets 210, and aluminium gets 120;
3. t efor the equivalent duration of short circuit, unit: the system of s, 500kV gets 0.35s; 200kV system gets 0.6-0.7s; 110kV and following electric pressure system failure duration are chosen according to actual conditions, consider that relay protection scheme is close, get the level value 0.6-0.7s that 220kV system is identical.
And described step (4) determines that the concrete grammar of the assessment time limit of grounded screen is:
1. for the grounded screen used, by the enforcement specification of actual grounded screen, with S g2numeric ratio comparatively, get enforcement gauge number, with calculating S gbe worth closest to time n value, draw the assessment tenure of use of actual grounded screen;
2. for when not considering corrosion, the ground wire minimum sectional area S calculated g, by comparing S g1with the S according to not number calculating in the same year g2value, draw this S g1the in-service life-span of design load.
Advantage of the present invention and good effect are:
The present invention is by measuring the average corrosion rate (g/dm of different materials 2a), by measuring anode reaction current density, J a, and then know the thickness of metal-stripping material, by measuring different materials mass loss △ m, and then know the electric charge of transfer.And then know the thickness of metal-stripping material, calculate the thinning speed w of grounded screen material (mm/a), consider the impact of ground net corrosion factor, draw the material specification of grounded screen science, derive the tenure of use of grounded screen.This method computation process is clear, and accuracy rate is high, and the safe operation for electric system grounded screen provides theoretic powerful support.
Embodiment
Be further described the invention process below, following examples are descriptive, are not determinate, can not limit protection scope of the present invention with this.
An appraisal procedure for grounding net of transformer substation, the step of the method is as follows:
(1) apply Faraday's law, derive the thinning speed of thickness of grounded screen metal;
Grounded screen material corrosion process in soil is applicable to Faraday's law: △ m=MQ/zF, and in formula, △ m is lysed metal quality; M is its atomic weight; Q is the electric charge of transfer; Z is the quantivalency of metallic ion; F is Faraday constant, by density p scan following formula be derived:
J A=Q/St=△m/St×zF/M-△s/t×zFρ s/M
In formula, J athat the anode of metallic ion passage divides the current density of reaction: S is the surface area of electrode: t is the time; △ s is the thickness be stripped;
W-f aJ A=△s/t
f a=M/zFρ s=3.2684/z(M/g·mol -1)(g·cm -3s)mm·a -1/mA·cm -2
v=f bJ A=△m/St
f b=M/zF=0.32311/z(M/g·mol -1)g·cm -2·h -1/mA·cm -2
In formula, W is the thinning speed of thickness, and v is the mass loss rate of per surface area;
W=f cv (I)
f c=f a/f b=1/ρ s=8.76((g·cm -3s)mm·a -1/g·cm -2·h -1
Common grounded screen material reduction coefficient and normal potential are as table 1
The reduction coefficient of table 1 metal-metal ion electrochemical reaction
The thinning speed of the thickness of grounded screen metal can be drawn by the reduction coefficient in above-mentioned formula (I) and table 1;
(2) when determining not consider corrosion, ground wire minimum sectional area S g;
According to DL/T 621-1996, the heat-stable calibration of substation grounding device is specified, according to thermal stable condition, when not considering corrosion, ground wire minimum sectional area S g(unit: mm 2) be:
S g1=Ig/c·t e -2(II)
Wherein, in formula for parameter Ig, c, t e -2, provide as follows:
1. Ig is the short-circuit current stationary value (unit: A) flowing through ground wire, for effectively earthed system and low resistance earthing system, considers individual event or two earth short circuit currents; For earth-free, grounding through arc and high resistance grounding system, then consider dissimilarity two earth short circuit currents, Ig according to system 5-10 development plan, should determine by system maximum operational mode, and Ig calculates by substation bus bar short-circuit current maximal value 75%;
2. c is the thermal stability factor of ground wire material, and determine according to the initial temperature of ground wire before the kind of material, performance and maximum permissible temperature and short circuit, usually, steel gets 70, and copper gets 210, and aluminium gets 120;
3. t efor the equivalent duration (unit: s) of short circuit, usually, the system of 500kV gets 0.35s, 200kV system gets 0.6-0.7s, 110kV and following electric pressure system failure duration are chosen according to actual conditions, consider that relay protection scheme is close, the level (0.6-0.7s) that desirable 220kV system is identical;
(3) when determining to consider the affecting of corrosion factor, ground wire minimum sectional area S g2;
S g2=(A-2×w×n)(B-2×w×n) (III)
When grounded screen is round steel type, in formula, A represents grounded screen width, and B represents grounded screen thickness, and n represents the operation time limit (unit: year), and w represents the thinning speed of grounded screen material (mm/a);
(4) for the grounded screen used, by the enforcement specification of actual grounded screen, with S g2numeric ratio comparatively, get enforcement gauge number, with calculating S gbe worth closest to time n value, draw the assessment tenure of use of actual grounded screen; For when not considering corrosion, the ground wire minimum sectional area S calculated g, by comparing S g1with the S according to not number calculating in the same year g2value, draw this S g1the in-service life-span of design load.
Example
Select coastland Q235 steel,
W=f cv,
By calculating w=0.877 (mm/a);
S g1=Ig/ct e -2, the short-circuit current stationary value Ig flowing through earth lead calculates by accounting 220kV transformer station place busbar short-circuit current maxima 75%, and namely Ig gets 46.319 × 0.75=34.74kA, and c gets 70.t e=0.2s。
S g1=Ig/c·t e -2=34.74×10 3/70·0.2 -2=221.94mm 2
N selects 1 year.
S g2=(A-2×w×n)(B-2×w×n)=(6-2×0.877×1)(60-2×0.877×1)
=247.31mm 2
Pass through S g1and S g2comparative analysis, show that this area's grounded screen in-service life-span is 1 year.

Claims (4)

1. an appraisal procedure for grounding net of transformer substation, is characterized in that the method comprising the steps of as follows:
(1) apply Faraday's law, derive the thinning speed of thickness of grounded screen metal;
Grounded screen material corrosion process in soil is applicable to Faraday's law: △ m=MQ/zF, and in formula, △ m is lysed metal quality; M is its atomic weight; Q is the electric charge of transfer; Z is the quantivalency of metallic ion; F is Faraday constant, by density p scan following formula be derived:
J A=Q/St=△m/St×zF/M-△s/t×zFρ s/M
In formula, J athat the anode of metallic ion passage divides the current density of reaction: S is the surface area of electrode: t is the time; △ s is the thickness be stripped;
W-f aJ A=△s/t
f a=M/zFρ s=3.2684/z(M/g·mol -1)(g·cm -3s)mm·a -1/mA·cm -2
v=f bJ A=△m/St
f b=M/zF=0.32311/z(M/g·mol -1)g·cm -2·h -1/mA·cm -2
In formula, W is the thinning speed of thickness, and v is the mass loss rate of per surface area;
W=f cv (I)
f c=f a/f b=1/ρ s=8.76((g·cm -3s)mm·a -1/g·cm -2·h -1
Wherein, f a, f b, f cfor grounded screen material reduction coefficient;
By above-mentioned formula (I) and f a, f b, f creduction coefficient can draw the thinning speed of the thickness of grounded screen metal;
(2) when determining not consider corrosion, ground wire minimum sectional area S g;
According to thermal stable condition, when not considering corrosion, ground wire minimum sectional area S g(unit: mm 2) be:
S g1=Ig/c·t e -2(II)
Wherein, in formula Ig be flow through the short-circuit current stationary value of ground wire, thermal stability factor that c is ground wire material, t efor the equivalent duration of short circuit;
(3) when determining to consider the affecting of corrosion factor, ground wire minimum sectional area S g2;
S g2=(A-2×w×n)(B-2×w×n) (III)
Wherein, when grounded screen is round steel type, in formula, A represents grounded screen width, and B represents grounded screen thickness, and n represents the operation time limit, and w represents the thinning speed of grounded screen material, unit: mm/a;
(4) the assessment time limit of grounded screen is determined.
2. the appraisal procedure of grounding net of transformer substation according to claim 1, is characterized in that: for f in described step (1) a, f b, f creduction coefficient, common grounded screen material reduction coefficient is as following table:
3. the appraisal procedure of grounding net of transformer substation according to claim 1, is characterized in that: Ig, c, t in the formula (II) of described step (2) econcrete regulation be:
1. Ig is the short-circuit current stationary value flowing through ground wire, unit: A, for effectively earthed system and low resistance earthing system, considers individual event or two earth short circuit currents; For earth-free, grounding through arc and high resistance grounding system, then consider dissimilarity two earth short circuit currents, Ig, according to system 5-10 development plan, determines by system maximum operational mode, and Ig calculates by substation bus bar short-circuit current maximal value 75%;
2. c is the thermal stability factor of ground wire material, and determine according to the initial temperature of ground wire before the kind of material, performance and maximum permissible temperature and short circuit, steel gets 70, and copper gets 210, and aluminium gets 120;
3. t efor the equivalent duration of short circuit, unit: the system of s, 500kV gets 0.35s; 200kV system gets 0.6-0.7s; 110kV and following electric pressure system failure duration are chosen according to actual conditions, consider that relay protection scheme is close, get the level value 0.6-0.7s that 220kV system is identical.
4. the appraisal procedure of grounding net of transformer substation according to claim 1, is characterized in that: described step (4) determines that the concrete grammar of the assessment time limit of grounded screen is:
1. for the grounded screen used, by the enforcement specification of actual grounded screen, with S g2numeric ratio comparatively, get enforcement gauge number, with calculating S gbe worth closest to time n value, draw the assessment tenure of use of actual grounded screen;
2. for when not considering corrosion, the ground wire minimum sectional area S calculated g, by comparing S g1with the S according to not number calculating in the same year g2value, draw this S g1the in-service life-span of design load.
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105069202A (en) * 2015-07-22 2015-11-18 国网天津市电力公司 Intelligent laying design method of substation grounding grid
CN105894096A (en) * 2016-04-22 2016-08-24 国家电网公司 Cloud-model-based transformer station grounding grid state evaluation method
CN105675475B (en) * 2015-12-25 2018-10-30 西安科技大学 A kind of ground net corrosion speed grade prediction technique
CN109580463A (en) * 2018-11-22 2019-04-05 国网天津市电力公司电力科学研究院 A method of measurement ground net corrosion degree
CN111048919A (en) * 2019-12-24 2020-04-21 嘉兴恒创电力设计研究院有限公司 Energy station grounding grid in high-soil-resistivity area and resistance reduction optimization method thereof
CN111257794A (en) * 2020-01-20 2020-06-09 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 Transformer substation grounding device thermal stability checking method based on conduction test

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008224405A (en) * 2007-03-13 2008-09-25 Tokyo Electric Power Co Inc:The Corrosion rate evaluating method
CN101315403A (en) * 2007-05-29 2008-12-03 华北电力科学研究院有限责任公司 Ground net corrosion detection method and system
CN103105355A (en) * 2011-11-14 2013-05-15 华北电力科学研究院有限责任公司 Method and device for detecting corrosion of grounding grid of electric transmission line iron tower
CN103427354A (en) * 2013-08-15 2013-12-04 国家电网公司 Early determination method for substation grounding grid

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008224405A (en) * 2007-03-13 2008-09-25 Tokyo Electric Power Co Inc:The Corrosion rate evaluating method
CN101315403A (en) * 2007-05-29 2008-12-03 华北电力科学研究院有限责任公司 Ground net corrosion detection method and system
CN103105355A (en) * 2011-11-14 2013-05-15 华北电力科学研究院有限责任公司 Method and device for detecting corrosion of grounding grid of electric transmission line iron tower
CN103427354A (en) * 2013-08-15 2013-12-04 国家电网公司 Early determination method for substation grounding grid

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
刘洋等: "基于电磁感应原理的变电站接地网腐蚀诊断方法", 《中国电机工程学报》 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105069202A (en) * 2015-07-22 2015-11-18 国网天津市电力公司 Intelligent laying design method of substation grounding grid
CN105069202B (en) * 2015-07-22 2018-06-12 国网天津市电力公司 A kind of Intelligent laying design method of grounding net of transformer substation
CN105675475B (en) * 2015-12-25 2018-10-30 西安科技大学 A kind of ground net corrosion speed grade prediction technique
CN105894096A (en) * 2016-04-22 2016-08-24 国家电网公司 Cloud-model-based transformer station grounding grid state evaluation method
CN105894096B (en) * 2016-04-22 2019-06-07 国家电网公司 A kind of grounding net of transformer substation state evaluating method based on cloud model
CN109580463A (en) * 2018-11-22 2019-04-05 国网天津市电力公司电力科学研究院 A method of measurement ground net corrosion degree
CN111048919A (en) * 2019-12-24 2020-04-21 嘉兴恒创电力设计研究院有限公司 Energy station grounding grid in high-soil-resistivity area and resistance reduction optimization method thereof
CN111257794A (en) * 2020-01-20 2020-06-09 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 Transformer substation grounding device thermal stability checking method based on conduction test

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