CN106777760A - A kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis - Google Patents

A kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis Download PDF

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Publication number
CN106777760A
CN106777760A CN201611264810.3A CN201611264810A CN106777760A CN 106777760 A CN106777760 A CN 106777760A CN 201611264810 A CN201611264810 A CN 201611264810A CN 106777760 A CN106777760 A CN 106777760A
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China
Prior art keywords
metallic conduit
electrical current
stray electrical
earthing pole
dtri
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CN201611264810.3A
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Chinese (zh)
Inventor
钱洲亥
沈晓明
祝郦伟
何为
杨帆
金东春
胡家元
周海飞
刘敏
陈建伟
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YINENG ELECTRIC TECHNOLOGY Co Ltd HANGZHOU
Chongqing University
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
Original Assignee
YINENG ELECTRIC TECHNOLOGY Co Ltd HANGZHOU
Chongqing University
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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Application filed by YINENG ELECTRIC TECHNOLOGY Co Ltd HANGZHOU, Chongqing University, State Grid Corp of China SGCC, Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd filed Critical YINENG ELECTRIC TECHNOLOGY Co Ltd HANGZHOU
Priority to CN201611264810.3A priority Critical patent/CN106777760A/en
Publication of CN106777760A publication Critical patent/CN106777760A/en
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/14—Pipes

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Prevention Of Electric Corrosion (AREA)

Abstract

The invention discloses a kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis.At present, direct transmission system earthing pole can cause metallic conduit stray electrical current nearby and cause metallic conduit to be etched electrochemically.The present invention first carries out simplifying treatment to metal target pipeline and DC transmission system earthing pole situation；Then build DC transmission system earthing pole caused by metallic conduit stray electrical current Mathematical Modeling；Mathematical Modeling is then based on, corresponding boundary condition is limited the region of metallic conduit and DC transmission system earthing pole and determined；Build the geometrical model of metal target pipeline；Finally using described Mathematical Modeling and geometrical model, it is simulated using numerical simulation software and is emulated, calculates the size of metallic conduit stray electrical current.The present invention can estimate out stray electrical current size of the DC transmission system earthing pole to neighbouring metallic conduit, so that for the anticorrosive measure of metallic conduit provides foundation.

Description

A kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis
Technical field
Cause the pre- of neighbouring metallic conduit stray electrical current the present invention relates to high pressure/extra-high voltage DC transmission system earthing pole Survey, specifically a kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis.
Background technology
With country's transferring electricity from the west to the east strategy implementation, China has built up a plurality of high pressure/extra high voltage direct current transmission line, at it Sending end and receiving end current conversion station are respectively equipped with earthing pole.Simultaneously as China's energy demand is fast-developing, oil-gas pipeline project is quick Propulsion, be present in same corridor while there is the multiple system such as direct current grounding pole and oil-gas pipeline.
When high pressure/extra-high voltage DC transmission system DC operating current (such as：Under monopolar ground circuit operation mode) or it is uneven When electric current leaks into the earth by direct current grounding pole, each point potential change in soil nearby will be caused, if buried metal pipeline is in In the soil media of different potentials, longitudinal current will be formed on pipeline, influence the normal operation of pipeline cathode protection system, and There is anodic attack reaction in the place for leaving metal in electric current, cause the electrochemical corrosion of metallic conduit.High pressure/extra-high voltage direct-current Main influence of the transmission system earthing pole on metallic conduit safe operation is corrosion.In addition, earthing pole is to pipeline affiliated facility Influence is mainly the interference to cathodic protection facility and the insulation damages to pipeline valve internal connection.
But because earthing pole and metallic conduit are all embedded in underground, cause people to the stray electrical current in underground metal pipes Corrosion condition be unable to Real Time Observation, so need a kind of method to predict the size of its stray electrical current, so as to preferably be gold Metal conduit carries out anticorrosion work, when for earthing pole and pipeline addressing, it is also possible to as one of reference frame.
The content of the invention
The present invention causes metallic conduit stray electrical current nearby and causes for the direct transmission system earthing pole of high pressure/extra-high voltage A kind of present situation that metallic conduit is etched electrochemically, there is provided metallic conduit stray electrical current Forecasting Methodology based on numerical analysis, its Stray electrical current size in the metallic conduit near direct current grounding pole can be accurately calculated, for metallic conduit provides anti- The foundation of corrosion measure, for design pipeline provides theoretical foundation with the position of earthing pole.
Therefore, the present invention is adopted the following technical scheme that：A kind of metallic conduit stray electrical current prediction based on numerical analysis Method, comprises the following steps：
Step one, carries out simplifying treatment to metal target pipeline and DC transmission system earthing pole situation, reduces follow-up meter Calculation amount；
Step 2, builds the Mathematical Modeling of metallic conduit stray electrical current caused by DC transmission system earthing pole, local electricity Field is in stable state, while pipeline cathode protection system Potential distribution is stable state, is described using electrostatic field equation；
Step 3, the Mathematical Modeling based on step 2, the region to metallic conduit and DC transmission system earthing pole is carried out Limit and determine corresponding boundary condition；
Step 4, builds the geometrical model of metal target pipeline, and the geometrical model includes three computational fields, is respectively grounded Pole, soil, metallic conduit；
Step 5, using described Mathematical Modeling and geometrical model, using numerical simulation software (in preferably ANSYS CFX modules) emulation is simulated, calculate the size of metallic conduit stray electrical current.
Further, simplifying in step one processes as follows：
1) buried depth of DC transmission system earthing pole is to metallic conduit current potential, longitudinal current and overflows the influence for dissipating electric current very It is small, ignore；
2) assume that infinite point soil boundary is natural potential, be insulating surfaces, corresponding target near the border of earthing pole The outer line resistance of metallic conduit is zero, metallic conduit any surface finish；
3) assume that the size of soil region relative duct size is infinitely great, homogeneous media and isotropism, soil conductivity in soil The polarization curve of rate and metallic conduit in soil media is unique.
Further, the electrostatic field equation in step 2 is as follows：
Because earthing pole and metallic conduit Potential distribution are electrostatic field, therefore only consider two before Maxwell equation, i.e.,
Wherein ρtRefer to the distribution of free charge in space, under static state, haveNow Electric Field Characteristics equation is：
So as to obtain electrostatic field potential fundamental differential：
Assuming that there is no distribution of charges inside domain, i.e., there is no the gain and loss of electric current in system, also in the absence of far point or Person's meeting point, so as to the governing equation for obtaining Mathematical Modeling is as follows,
In formula：ε is the electrical conductivity of place medium in metallic conduit, mA/m2；ρ is the resistance of place medium in metallic conduit Rate, Ω m；φ is potential, V.
Simplify pipeline for further, metallic conduit is all equivalent to cylindrical structure, correct its resistivity and ensure that its is equivalent Resistance afterwards is constant；Assuming that the inside radius of metallic conduit is r1, outer radius is r2, the thickness of tube wall is d, then metallic conduit list The resistance of bit length is
The resistance of equivalent metallic conduit unit length is
Simplified
In formula, ρ1、ρ2The resistivity of the front and rear place medium of metallic conduit, Ω m are represented respectively.This step is in order to more square Just calculating metallic conduit coating surface resistance and polarization resistance, are equivalent easy explanations.
Further, in step 3, in conditions setting, current conversion station as current boundary is set, and will be remote enough A earth distant place is set as equipotential boundary condition, and boundary condition is as follows：
Current conversion station boundary condition：
Ground surface boundary condition：
The impacted boundary condition of metallic conduit：
In formula, Rc(x, y, z) is metallic conduit coating surface resistance, Ω m2；χ represents dielectric susceptibility,Represent pipeline Interior current density, A/m2；RpIt is metallic conduit polarization resistance, Ω；ρsoil(s, y, z) is soil resistivity, Ω m.
The device have the advantages that：The present invention can accurately calculate the metal near direct current grounding pole Stray electrical current size in pipeline, the foundation of anticorrosive measure is provided for metallic conduit, is design pipeline and the position of earthing pole There is provided theoretical foundation.
Brief description of the drawings
The metallic conduit galvano-cautery schematic diagram that Fig. 1 causes for DC stray current；
Fig. 2 is ground potential liter simulation result figure in present invention pipe；
Fig. 3 is pipe internal leakage current density analog result figure of the present invention；
Fig. 4 is that stray electrical current forms schematic equivalent circuit；
Fig. 5 is stray electrical current experimental provision schematic diagram of the present invention.
Specific embodiment
A kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis, its step is as follows：
Step one, geometrical model foundation is carried out using ANSYS softwares to metallic conduit and earthing pole, due to actual field compared with It is complexity, carries out simplifying treatment for metal target pipeline and earthing pole situation.After model simplification, three computational fields are determined, point Wei not earthing pole, soil, metallic conduit.
Step 2, solves the Mathematical Modeling of stray electrical current caused by D. C. Electric transmission earthed pole.When earth electric field is in stable state, together When pipeline cathode protection system Potential distribution be stable state, described using electrostatic field equation.Electrostatic field equation is as follows：
Wherein ρtRefer to the distribution of free charge in space.
It is as follows so as to obtain electrostatic field potential fundamental differential：
Assuming that there is no distribution of charges inside domain, i.e., there is no the gain and loss of electric current in system, also in the absence of far point or Person's meeting point, so as to the governing equation for obtaining Mathematical Modeling is as follows,
In formula：ε is the electrical conductivity of place medium in pipeline, mA/m2；
ρ is the resistivity of place medium in pipeline, Ω m；
φ is potential, V.
Step 3, based on Mathematical Modeling, is limited the region of pipeline and earthing pole and is determined corresponding boundary condition. Current conversion station as current boundary is set, and is set as equipotential boundary condition in a earth distant place first enough.Specific boundary condition is as follows：
Current conversion station boundary condition：
Ground surface boundary condition：
The impacted boundary condition of metallic conduit：
In formula, Rc(x, y, z) is pipeline coatings surface resistance, Ω m2；RpIt is pipeline polarization resistance, Ω；ρsoil(s,y,z) It is soil resistivity, Ω m.
Step 4, using the Mathematical Modeling and geometrical model set up, uses the CFX modules in numerical simulation software ANSYS Simulation calculation is simulated, the size of metallic conduit stray electrical current is calculated.
1. pipeline is set away from earthing pole apart from 5km, earthing pole earth current 3000A, pipeline longitudinal electrical resistance 9.98 × 10-3 Ω/m, simulation obtains curent change, such as Fig. 2 in different pipeline coatings surface resistance down tubes.
2. the Ω .m of soil resistivity 100 are set, and pipeline is away from earthing pole apart from 5km, earthing pole earth current 3000A, pipeline Longitudinal electrical resistance 9.98 × 10-3Ω/m, simulation obtains the change of pipeline leakage current density, such as Fig. 3 under different pipeline coatings surface resistances.
The equivalent circuit that stray electrical current is formed is as shown in figure 4, experimental provision such as Fig. 5 institutes used by stray electrical current of the present invention Show.

Claims (6)

1. a kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis, comprises the following steps：
Step one, carries out simplifying treatment to metal target pipeline and DC transmission system earthing pole situation；
Step 2, builds the Mathematical Modeling of metallic conduit stray electrical current caused by DC transmission system earthing pole, at earth electric field In stable state, while pipeline cathode protection system Potential distribution is stable state, described using electrostatic field equation；
Step 3, the Mathematical Modeling based on step 2, the region to metallic conduit and DC transmission system earthing pole limits And determine corresponding boundary condition；
Step 4, build metal target pipeline geometrical model, the geometrical model include three computational fields, respectively earthing pole, Soil, metallic conduit；
Step 5, using described Mathematical Modeling and geometrical model, is simulated using numerical simulation software and emulated, and calculates metal The size of pipeline stray electrical current.
2. metallic conduit stray electrical current Forecasting Methodology according to claim 1, it is characterised in that at simplifying in step one Reason is as follows：
1) buried depth of DC transmission system earthing pole is to metallic conduit current potential, longitudinal current and the influence very little of the scattered electric current that overflows, suddenly Slightly disregard；
2) assume that infinite point soil boundary is natural potential, be insulating surfaces, corresponding metal target near the border of earthing pole The outer line resistance of pipeline is zero, metallic conduit any surface finish；
3) assume that the size of soil region relative duct size is infinitely great, homogeneous media and isotropism in soil, soil conductivity and Polarization curve of the metallic conduit in soil media is unique.
3. metallic conduit stray electrical current Forecasting Methodology according to claim 1, it is characterised in that the electrostatic field in step 2 Equation is as follows：
Because earthing pole and metallic conduit Potential distribution are electrostatic field, therefore only consider two before Maxwell equation, i.e.,
▿ · D = ρ t ▿ × E = ∂ B ∂ t
Wherein ρtRefer to the distribution of free charge in space, under static state, haveNow Electric Field Characteristics equation is：
▿ · D = ρ t ▿ × E = 0
So as to obtain electrostatic field potential fundamental differential：
▿ 2 φ = - ρ t ϵ
Assuming that there is no distribution of charges inside domain, i.e., there is no the gain and loss of electric current in system, in the absence of far point or remittance yet Point, so as to the governing equation for obtaining Mathematical Modeling is as follows,
▿ · ( - ϵ ▿ φ ) = ▿ · ( - 1 ρ ▿ φ ) = 0
In formula：ε is the electrical conductivity of place medium in metallic conduit, mA/m2；ρ is the resistivity of place medium in metallic conduit, Ω·m；φ is potential, V.
4. metallic conduit stray electrical current Forecasting Methodology according to claim 1, it is characterised in that by metallic conduit all etc. It is cylindrical structure to imitate, correct its resistivity ensure its it is equivalent after resistance it is constant；Assuming that the inside radius of metallic conduit is r1, outward Radius is r2, the thickness of tube wall is d, then the resistance of metallic conduit unit length is
R 1 = ρ 1 1 π ( r 2 2 - r 1 2 )
The resistance of equivalent metallic conduit unit length is
R 2 = ρ 2 1 S 2 = ρ 2 1 πr 2 2 ,
Simplified
ρ 1 = ρ 2 ( r 2 2 - r 1 2 ) r 2 2 ;
In formula, ρ1、ρ2The resistivity of the front and rear place medium of metallic conduit, Ω m are represented respectively.
5. metallic conduit stray electrical current Forecasting Methodology according to claim 3, it is characterised in that in step 3, in setting During boundary condition, current conversion station as current boundary is set, and a earth distant place remote enough is set as equipotential boundary condition, perimeter strip Part is as follows：
Current conversion station boundary condition：
∂ φ ∂ n = I 0
Ground surface boundary condition：
∂ φ ∂ n = 0
The impacted boundary condition of metallic conduit：
▿ φ = { R c ( x , y , z ) + R p χ [ R c ( x , y , z ) , ρ s o i l ( s , y , z ) ] } · j ( n ‾ )
In formula, Rc(x, y, z) is metallic conduit coating surface resistance, Ω m2；χ represents dielectric susceptibility,Represent electricity in pipeline Current density, A/m2；RpIt is metallic conduit polarization resistance, Ω；ρsoil(s, y, z) is soil resistivity, Ω m.
6. metallic conduit stray electrical current Forecasting Methodology according to claim 1, it is characterised in that in step 5, use number CFX modules in value simulation softward ANSYS are simulated emulation.
CN201611264810.3A 2016-12-30 2016-12-30 A kind of metallic conduit stray electrical current Forecasting Methodology based on numerical analysis Pending CN106777760A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110470723A (en) * 2019-03-18 2019-11-19 中国电力科学研究院有限公司 A kind of buried metal pipeline DC influence of protective layer breakage determines method
CN111750731A (en) * 2020-06-29 2020-10-09 中国南方电网有限责任公司超高压输电公司广州局 Corrosion-resistant treatment method and device for aluminum radiator for converter valve
CN111996534A (en) * 2019-05-08 2020-11-27 中国石油天然气股份有限公司 Pipe network corrosion condition acquisition method
CN112649356A (en) * 2020-11-29 2021-04-13 中国科学院金属研究所 Method for evaluating material selection of abradable seal coating system from corrosion protection perspective
CN113378436A (en) * 2021-06-10 2021-09-10 贵州电网有限责任公司 Subway stray current leakage and distribution characteristic simulation method based on ANSYS

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110470723A (en) * 2019-03-18 2019-11-19 中国电力科学研究院有限公司 A kind of buried metal pipeline DC influence of protective layer breakage determines method
CN110470723B (en) * 2019-03-18 2022-12-20 中国电力科学研究院有限公司 Buried metal pipeline direct current interference determination method for damage of protective layer
CN111996534A (en) * 2019-05-08 2020-11-27 中国石油天然气股份有限公司 Pipe network corrosion condition acquisition method
CN111750731A (en) * 2020-06-29 2020-10-09 中国南方电网有限责任公司超高压输电公司广州局 Corrosion-resistant treatment method and device for aluminum radiator for converter valve
CN112649356A (en) * 2020-11-29 2021-04-13 中国科学院金属研究所 Method for evaluating material selection of abradable seal coating system from corrosion protection perspective
CN113378436A (en) * 2021-06-10 2021-09-10 贵州电网有限责任公司 Subway stray current leakage and distribution characteristic simulation method based on ANSYS

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Application publication date: 20170531