CN112347643B - Nonlinear fitting method and system for contact resistance of GIS circuit breaker - Google Patents

Nonlinear fitting method and system for contact resistance of GIS circuit breaker Download PDF

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CN112347643B
CN112347643B CN202011228536.0A CN202011228536A CN112347643B CN 112347643 B CN112347643 B CN 112347643B CN 202011228536 A CN202011228536 A CN 202011228536A CN 112347643 B CN112347643 B CN 112347643B
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gis
contact resistance
contact
model
breaker
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陈邦发
陈道品
武利会
刘益军
胡志鹏
陈斯翔
何子兰
黄静
曾烨
谢志扬
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Foshan Power Supply Bureau of Guangdong Power Grid Corp
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Abstract

The invention provides a nonlinear fitting method of GIS breaker contact resistance, which comprises the following steps: s1: constructing a GIS breaker contact resistance and a GIS breaker shell model, and acquiring GIS breaker temperature data through simulation; s2: constructing a numerical calculation model of the contact resistance of the GIS bus joint; s3: and establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculated value according to the GIS breaker temperature data collected in the step S1. According to the invention, by simplifying a GIS breaker model and utilizing nonlinear fitting, the accurate contact resistance value is calculated, the system operation cost is reduced, and the operation reliability of the power transmission line is improved.

Description

Nonlinear fitting method and system for contact resistance of GIS circuit breaker
Technical Field
The invention relates to the field of GIS substations, in particular to a nonlinear fitting method and a nonlinear fitting system for contact resistance of a GIS breaker.
Background
With the rapid development of the electric power industry in China and the continuous increase of demand, a metal enclosed switch (GIS) is widely applied to an electric power systemIn (1). The GIS equipment has strict processing technology and advanced technology, and the insulating medium is SF6. The gas has good breaking capacity, slight contact burn, long maintenance period, low failure rate, low maintenance cost, small occupied area and the like. Due to the outstanding advantages of the GIS equipment, the GIS equipment is increasingly used in substations. When the contact of the GIS equipment is poor in contact, due to the fact that contact resistance is increased, overheating can occur when load current flows. The contact and the bus are overheated to cause insulation aging and even breakdown, thereby causing short circuit, forming major accidents and causing huge economic loss. According to incomplete statistics, GIS equipment adopted by numerous power generation companies and power companies in China has the phenomenon that accidents are caused by abnormal temperature changes caused by insulation aging or poor contact of parts such as an enclosed bus, an isolating switch, a cable head and the like to different degrees. Therefore, online temperature monitoring of contact resistance in GIS equipment is realized, heat fault hidden danger is found and eliminated in advance, and the method has very important significance for safe and reliable operation of the GIS.
Chinese patent publication No. CN102798757A, publication No. 11/28/2012, discloses a method and system for detecting contact resistance of a GIS busbar joint, which includes the steps of: determining the contact pressure of the plum-blossom contact fingers of the GIS bus joint and the conductor according to the material parameters of the GIS bus joint and the holding spring thereof; and determining the contact resistance of the GIS busbar joint according to the contact pressure. At present, the research on the aspect of nonlinear fitting in the calculation of the contact resistance of the GIS breaker is less.
In non-linear fitting, the training set and the test set have the same distribution, i.e., they are co-distributed. This is more advantageous for practical applications. In linear regression, the desired model function is f (x) ═ WX + b, and in the training process of the model, the model needs to be optimized by iteratively optimizing the loss function J (W, b) to train a better parameter W. In general, linear regression is usually expressed by a sum of squares error, for example:
Figure BDA0002764393120000011
the above two functions in fact involve two processes: 1. and (3) prediction process: it is true that the fixed parameters W, b give us a prediction by obtaining the model given the input x
Figure BDA0002764393120000021
Then f (x) here is indeed a function of x; 2. the optimization process comprises the following steps: what needs to be optimized is minimizeW, bJ (W, b), in which process training data is needed, no matter how many training data exist, x in the loss function can be determined when the training data is determined(i),y(i)That is, they are considered to be constants, then J is a function of W, b. That is to say the distribution of the training data here is in fact equivalent to the parameters of the loss function. First, the function J is not the same when the parameters are not the same. If the distribution of the training set is different from the distribution of the real data, even if the loss function is optimized to a minimum value on the training machine, the loss value on the real data may still be large, i.e. the error is large, and the prediction function cannot be performed. The loss function to be optimized on the training set may be J (W) ═ W-32。
The above explains why the data sets are chosen carefully from the point of view of the loss function, because different distributions of the data sets result in different optimized and real data loss functions, i.e. possibly resulting in the optimization direction itself being wrong. To some extent, the model structure is designed to be perfect, and a proper loss function is selected to be perfect, but the training number is prepared carefully, which is the most effective way and possibly the most possible way to greatly remind the accuracy of the model.
Disclosure of Invention
The invention aims to provide a nonlinear fitting method of a contact resistance of a GIS circuit breaker, which solves the problem of complex calculation in the prior art.
It is a further object of the present invention to provide a system for nonlinear fitting of contact resistance of a GIS circuit breaker.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a nonlinear fitting method for GIS breaker contact resistance comprises the following steps:
s1: constructing a GIS breaker contact resistance and a GIS breaker shell model, and acquiring GIS breaker temperature data through simulation;
s2: constructing a numerical calculation model of the contact resistance of the GIS bus joint;
s3: and establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculated value according to the GIS breaker temperature data collected in the step S1.
Preferably, the step S1 of constructing a contact resistance and a housing model of the GIS circuit breaker specifically includes:
in the simulation process, the insulating part with small volume and the gas are treated in a unified way;
neglecting the influence of internal components of the GIS breaker, including a piston, a guide sleeve, a bolt and a pull bolt, on a calculation result, and regarding all the components as fastening connection;
and establishing a model comprising a shell, internal gas, an insulating cylinder, a contact, a current-carrying conductor and an external air layer to obtain a GIS breaker simplified structure finite element model.
Preferably, the step S1 collects the temperature data of the GIS breaker, specifically:
and uniformly collecting GIS breaker temperature data along the isotherm.
Preferably, in step S2, a GIS busbar joint contact resistance numerical calculation model is constructed, specifically:
the two conductors that make electrical contact are referred to as contact elements. The surface of a finely machined conductor is in fact always uneven, and the mechanical contact only occurs on a series of raised spots in the apparent contact surface, called hills, the contact pressure between two contacting objects being equal to the sum of the contact forces on the individual hills.
Since the actual material is deformable, the contact elements are brought into contact under pressure, and the area of macroscopic overlap of the contact elements is referred to as the apparent contact area Aa. Mechanical contact occurs over a small portion of the contact surface, and the sum of these areas is referred to as the actual contact surface Ab. Due to the presence of the surface film, only a small number of spots in the actual contact surface actually achieve conductive contact, the sum of these areas is called the conductive surface Ac, and these spots are called conductive spots or "α spots". The current lines contract as they pass through the conductive spots, and the resistance resulting from this effect is referred to as the contraction resistance. The contact resistance is actually the sum of the resistance of the contraction caused by the contraction of the current through the conductive spot and the resistance of the surface film.
The calculation formula of the contact resistance R of the rough contact surface based on the Bahraini model is as follows:
Figure BDA0002764393120000031
where ρ is the resistivity of the contact material, as(r) is the radius of the hump in a discrete unit, for a GIS plum blossom contact, the mechanical contact hump radius as(r) is equal to the radius a, n of the conductive spots(r) the number of hillocks in a discrete unit, aLIs the upper limit of integration;
the average hillock radius and hillock number within a discrete cell are calculated as follows:
Figure BDA0002764393120000032
Figure BDA0002764393120000033
in the formula, σsM is the slope of the surface of the hillock,
Figure BDA0002764393120000034
and (b) is a rough surface contact clearance characteristic function, Y (r) is the equivalent spacing of the elastic rough surface and the smooth rigid spherical surface on the discrete units at the distance r from the central line of the rigid sphere, erfc () is a Gaussian error function complement function, and aa (r) is a macroscopic apparent contact area. .
Preferably, the upper limit of integration aLIs determined, in particularThe following were used:
in the Bahraini macro-contact model, assuming that microhardness is constant throughout the contact area and the peak slope is a function of roughness, the mathematical expression for the macro-contact model taking roughness into account shows:
P0＝P0(ρ,σs,E*,FK,Hmic)
where ρ represents a radius of curvature, σsDenotes the surface roughness, E*Denotes the equivalent modulus of elasticity, HmicRepresents microhardness;
the contact problem considering the roughness is expressed by a roughness parameter, a geometric parameter and a hardness parameter by using a dimensional analysis method according to a Buckingham pi criterion:
roughness parameter:
Figure BDA0002764393120000041
in the formula, aHRepresents the Hertz calculated contact radius;
geometric parameters:
Figure BDA0002764393120000042
hardness parameters:
Figure BDA0002764393120000043
e' is elastic modulus, and because the microhardness in the contact region is constant, the influence of the hardness parameter on the macroscopic contact mode can be ignored, and the corrected maximum pressure p0And a contact radius aLThe dimensions of (a) are as follows:
Figure BDA0002764393120000044
Figure BDA0002764393120000045
corrected Hertz contact radius
Figure BDA0002764393120000046
I.e. as the upper integral limit of the solution domain.
Preferably, the discrete units are specifically:
discretizing the calculation domain into N discrete units, wherein the radius scale of each discrete unit is aLN, contact pressure f of the hillocks in each discrete unitiThe distribution is approximately equal to the macroscopic elastic contact continuous contact pressure distribution p (r), and the equivalent radius of curvature and slope of the hillocks within the discrete units are the same.
Preferably, the initial geometric parameters u of the rigid sphere and the semi-plane are sampled0(1)＝-4.1σs，u0(2)＝-4.3σsThe macroscopic elastic deformation parameter ω is 0 as the initial parameter, and the sum F of the contact pressures p (r) in all discrete units is adoptedcolWith normal force F acting on the rigid sphereKRepeatedly and iteratively calculating the contact resistance of the GIS breaker according to the convergence criterion of the whole GIS breaker.
Preferably, the step S3 of establishing a nonlinear fitting model of the contact resistance of the GIS busbar joint specifically includes:
in numerical calculation of the nonlinear curve, the cubic design fitting nonlinear curve is an optimal method for dynamically estimating parameter values and repeatedly searching by using an orthogonal table and assuming that each parameter is in a large area range and taking the minimum sum of squared residuals as a target function.
Preferably, in step S3, the calculated value of the contact resistance of the GIS bus bar connector is calculated according to the GIS breaker temperature data collected in step S1, specifically:
and (4) inputting the surface temperature data collected in the step S1 and the GIS contact resistance data collected in the step S2 as training data sets into a GIS busbar joint contact resistance nonlinear fitting model for calculation, and outputting the calculated value of the contact resistance by the GIS busbar joint contact resistance nonlinear fitting model.
A system for nonlinear fitting of contact resistance of a GIS circuit breaker, comprising:
the first construction module is used for constructing a GIS breaker contact resistor and a GIS breaker shell model and acquiring GIS breaker temperature data through simulation;
the second construction module is used for constructing a GIS bus joint contact resistance numerical calculation model;
and the contact resistance calculation module is used for establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculation value according to the GIS circuit breaker temperature data collected by the first construction module.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the invention provides a nonlinear fitting method of a GIS breaker contact resistor, which can calculate the accurate contact resistor value by simplifying a GIS breaker model and utilizing nonlinear fitting, reduce the system operation cost and improve the operation reliability of a power transmission line.
Drawings
FIG. 1 is a schematic flow chart of the method of the present invention.
Fig. 2 is a schematic diagram of a circuit breaker.
FIG. 3 is a schematic diagram of data collected uniformly along an isotherm.
FIG. 4 is a schematic diagram of a discrete process of computing a domain.
Fig. 5 is a schematic diagram of a nonlinear fitting of the contact resistance of the circuit breaker.
Fig. 6 is a schematic diagram of the system module connection according to the present invention.
In the figure, 1 is a static flange, 2 is a shell, 3 is a conducting rod, 4 is a static contact, 5 is a piston rod, 6 is an insulating pull rod, 7 is a moving flange, 8 is a static supporting conductor, 9 is a moving contact, 10 is a pressure cylinder, 11 is a moving supporting conductor, 12 is an insulating cylinder, and 13 is a direct-acting sealing shell.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent;
for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;
it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Example 1
The embodiment provides a nonlinear fitting method for contact resistance of a GIS breaker, as shown in FIG. 1, comprising the following steps:
s1: constructing a GIS breaker contact resistance and a GIS breaker shell model, and acquiring GIS breaker temperature data through simulation;
s2: constructing a numerical calculation model of the contact resistance of the GIS bus joint;
s3: and establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculated value according to the GIS breaker temperature data collected in the step S1.
Constructing a GIS breaker contact resistance and a GIS breaker shell model in the step S1, which specifically comprises the following steps:
as shown in fig. 2, the circuit breaker is composed of a movable supporting conductor 11, a static supporting conductor 8, a conducting rod 3, a movable contact 9, a static contact 4, a shielding case, a puffer cylinder 10, an insulating cylinder 12, a static flange 1, a shell 2 and the like, wherein the conducting rod 3 and the shell 2 of the circuit breaker are both made of aluminum alloy materials, the insulating cylinder 12 is made of epoxy resin materials, and in order to ensure good insulating performance, the interior of the circuit breaker is filled with 0.4MPa of SF6 gas. The movable supporting conductor 11 and the static supporting conductor 8 are connected through a self-force contact to form a conductive path, the self-force contact is composed of 36 contact fingers, the contact fingers provide surface contact pressure through reaction force generated by self elastic deformation to realize connection of the movable contact and the static contact, so that contact resistance exists between the contact fingers and the movable contact, and under normal conditions, the contact resistance of the silver-plated GIS contact fingers is usually 5-10 mu omega.
When eddy current field simulation is carried out, the magnetic permeability of most non-magnetic conducting materials is almost the same as that of air, so that insulating parts with small volume and gas can be treated uniformly;
the requirements of simulation calculation of the eddy current field and the temperature field on the structural similarity of the model and the entity are not strict, so that the influence of internal components of the GIS breaker, including a piston, a guide sleeve, a bolt and a pull bolt, on a calculation result can be ignored, and all the components are regarded as fastened connection;
based on the two points, a model comprising a shell, internal gas, an insulating cylinder, a contact, a current-carrying conductor and an external air layer is established, and a GIS breaker simplified structure finite element model is obtained.
Collecting GIS breaker temperature data in step S1, specifically:
and uniformly collecting GIS breaker temperature data along an isotherm, as shown in figure 3.
In step S2, a GIS busbar joint contact resistance numerical calculation model is constructed, specifically:
the calculation formula of the contact resistance R of the rough contact surface based on the Bahraini model is as follows:
Figure BDA0002764393120000071
where ρ is the resistivity of the contact material, as(r) is the radius of the hump in a discrete unit, for a GIS plum blossom contact, the mechanical contact hump radius as(r) is equal to the radius a, n of the conductive spots(r) the number of hillocks in a discrete unit, aLIs the upper limit of integration;
the average hillock radius and hillock number within a discrete cell are calculated as follows:
Figure BDA0002764393120000072
Figure BDA0002764393120000073
in the formula, σsM is the slope of the surface of the hillock,
Figure BDA0002764393120000074
and (b) is a rough surface contact clearance characteristic function, Y (r) is the equivalent spacing of the elastic rough surface and the smooth rigid spherical surface on the discrete units at the distance r from the central line of the rigid sphere, erfc () is a Gaussian error function complement function, and aa (r) is a macroscopic apparent contact area.
Upper limit of integration aLThe determination is as follows:
the Hertz's calculated contact radius is a finite constant, while the radius of the area of elastic deformation is virtually infinite when the sphere is in contact with a flat surface, so that the upper limit of the integral of macroscopic elastic deformation in equation 1 is taken to be infinite. Both of these methods have their limitations and the Hertz's assumption of the resulting contact radius can be used to qualitatively determine the size of the elastic contact surface, but neglecting the fact that the actual contact surface is infinite. Equation 1 has no solution when infinite integration is taken, and cannot be applied to actual numerical calculation. Therefore, a Hertz contact radius correction is required.
The real contact surface is not smooth, so that the pressure distribution and the contact radius of the real contact deviate from the Hertz contact, and the influence of the surface roughness on the macroscopic mechanical contact model is mainly reflected in that the radius of the apparent contact area is larger, and the maximum contact pressure is smaller.
In the Bahraini macro-contact model, assuming that microhardness is constant throughout the contact area and the peak slope is a function of roughness, the mathematical expression for the macro-contact model taking roughness into account shows:
P0＝P0(ρ,σs,E*,FK,Hmic)
where ρ represents a radius of curvature, σsDenotes the surface roughness, E*Denotes the equivalent modulus of elasticity, HmicRepresents microhardness;
the contact problem considering the roughness is expressed by a roughness parameter, a geometric parameter and a hardness parameter by using a dimensional analysis method according to a Buckingham pi criterion:
roughness parameter:
Figure BDA0002764393120000081
in the formula, aHRepresents the Hertz calculated contact radius;
geometric parameters:
Figure BDA0002764393120000082
hardness parameters:
Figure BDA0002764393120000083
e' is elastic modulus, and because the microhardness in the contact region is constant, the influence of the hardness parameter on the macroscopic contact mode can be ignored, and the corrected maximum pressure p0And a contact radius aLThe dimensions of (a) are as follows:
Figure BDA0002764393120000084
Figure BDA0002764393120000085
corrected Hertz contact radius
Figure BDA0002764393120000086
I.e. as the upper integral limit of the solution domain.
The discrete units are specifically:
as shown in fig. 4, the computation domain is discretized into N discrete units, each discrete unit having a radius dimension aLN, contact pressure f of the hillocks in each discrete unitiThe distribution is approximately equal to the macroscopic elastic contact continuous contact pressure distribution p (r), and the equivalent radius of curvature and slope of the hillocks within the discrete units are the same.
Sampling initial geometric parameter u of rigid sphere and semi-plane0(1)＝-4.1σs，u0(2)＝-4.3σsThe macroscopic elastic deformation parameter ω is 0 as the initial parameter, and the sum F of the contact pressures p (r) in all discrete units is adoptedcolWith normal force F acting on the rigid sphereKRepeatedly and iteratively calculating the contact resistance of the GIS breaker according to the convergence criterion of the whole GIS breaker.
In step S3, a nonlinear fitting model of the contact resistance of the GIS busbar joint is established, specifically:
in numerical calculation of the nonlinear curve, the cubic design fitting nonlinear curve is an optimal method for dynamically estimating parameter values and repeatedly searching by using an orthogonal table and assuming that each parameter is in a large area range and taking the minimum sum of squared residuals as a target function.
In step S3, calculating a calculated value of contact resistance of the GIS bus bar connector according to the GIS breaker temperature data collected in step S1, specifically:
and (3) inputting the surface temperature data collected in the step S1 and the GIS contact resistance data collected in the step S2 as training data sets into a GIS busbar joint contact resistance nonlinear fitting model for calculation, wherein the GIS busbar joint contact resistance nonlinear fitting model outputs the calculated value of the contact resistance as shown in figure 5.
Example 2
A system for nonlinear fitting of contact resistance of a GIS breaker, as shown in fig. 6, comprising:
the first construction module is used for constructing a GIS breaker contact resistor and a GIS breaker shell model and acquiring GIS breaker temperature data through simulation;
the second construction module is used for constructing a GIS bus joint contact resistance numerical calculation model;
and the contact resistance calculation module is used for establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculation value according to the GIS circuit breaker temperature data collected by the first construction module.
The same or similar reference numerals correspond to the same or similar parts;
the terms describing positional relationships in the drawings are for illustrative purposes only and are not to be construed as limiting the patent;
it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (7)

1. A nonlinear fitting method for GIS breaker contact resistance is characterized by comprising the following steps:
s1: constructing a GIS breaker simplified structure finite element model, and acquiring GIS breaker temperature data through simulation;
s2: constructing a numerical calculation model of the contact resistance of the GIS bus joint;
s3: establishing a GIS bus connector contact resistance nonlinear fitting model and calculating a GIS bus connector contact resistance calculated value according to the GIS breaker temperature data collected in the step S1;
in step S2, a GIS busbar joint contact resistance numerical calculation model is constructed, specifically:
the calculation formula of the contact resistance R of the rough contact surface based on the Bahraini model is as follows:
Figure FDA0003327960210000011
where ρ is the resistivity of the contact material, as(r) is the radius of the hump in a discrete unit, for a GIS plum blossom contact, the radius of the mechanical contact bump as(r) is equal toRadius of the conductive spot a, ns(r) the number of hillocks in a discrete unit, aLIs the upper limit of integration;
the average hillock radius and hillock number within a discrete cell are calculated as follows:
Figure FDA0003327960210000012
Figure FDA0003327960210000013
in the formula, σsM is the slope of the surface of the hillock,
Figure FDA0003327960210000014
is a rough surface contact clearance characteristic function, Y (r) is the equivalent spacing between the elastic rough surface and the smooth rigid spherical surface on the discrete unit at the position r away from the central line of the rigid sphere, erfc () is a Gaussian error function complement function, and aa (r) is a macroscopic apparent contact area;
in step S3, a nonlinear fitting model of the contact resistance of the GIS busbar joint is established, specifically:
in numerical calculation of the nonlinear curve, the three-time design fitting nonlinear curve is an optimization method which dynamically estimates parameter values and repeatedly searches by using an orthogonal table and assuming that each parameter is in a large area range and taking the minimum sum of squared residuals as a target function, the optimization method has good fitting results, does not depend on a single initial value, does not judge the relative minimum error into the absolute minimum, does not need to calculate a partial derivative, is simple to calculate, and establishes a GIS bus joint contact resistance nonlinear fitting model based on the method;
in step S3, calculating a calculated value of contact resistance of the GIS bus bar connector according to the GIS breaker temperature data collected in step S1, specifically:
and (4) inputting the surface temperature data collected in the step S1 and the GIS contact resistance data collected in the step S2 as training data sets into a GIS busbar joint contact resistance nonlinear fitting model for calculation, and outputting the calculated value of the contact resistance by the GIS busbar joint contact resistance nonlinear fitting model.
2. The nonlinear fitting method for the contact resistance of the GIS breaker according to claim 1, wherein the step S1 is implemented by constructing a GIS breaker simplified structure finite element model, specifically:
in the simulation process, the insulating part with small volume and the gas are treated in a unified way;
neglecting the influence of internal components of the GIS breaker, including a piston, a guide sleeve, a bolt and a pull bolt, on a calculation result, and regarding all the components as fastening connection;
and establishing a model comprising a shell, internal gas, an insulating cylinder, a contact, a current-carrying conductor and an external air layer to obtain a GIS breaker simplified structure finite element model.
3. The method for nonlinear fitting of contact resistance of a GIS circuit breaker according to claim 2, wherein the step S1 collects GIS circuit breaker temperature data, specifically:
and uniformly collecting GIS breaker temperature data along the isotherm.
4. The method of claim 1, wherein the upper limit of integration a is determined by a non-linear fitting method of the contact resistance of the GIS breakerLThe determination is as follows:
in the Bahraini macro-contact model, assuming that microhardness is constant throughout the contact area and the peak slope is a function of roughness, the mathematical expression for the macro-contact model taking roughness into account shows:
P0＝P0(ρ1,σs,E*,FK,Hmic)
in the formula, ρ1Denotes the radius of curvature, σsDenotes the surface roughness, E*Denotes the equivalent modulus of elasticity, HmicRepresents microhardness;
the contact problem considering the roughness is expressed by a roughness parameter, a geometric parameter and a hardness parameter by using a dimensional analysis method according to a Buckingham pi criterion:
roughness parameter:
Figure FDA0003327960210000021
in the formula, aHRepresents the Hertz calculated contact radius;
geometric parameters:
Figure FDA0003327960210000031
hardness parameters:
Figure FDA0003327960210000032
e' is elastic modulus, and because the microhardness in the contact region is constant, the influence of the hardness parameter on the macroscopic contact mode can be ignored, and the corrected maximum pressure p0And a contact radius aLThe dimensions of (a) are as follows:
Figure FDA0003327960210000033
Figure FDA0003327960210000034
corrected Hertz contact radius
Figure FDA0003327960210000035
I.e. as the upper integral limit of the solution domain.
5. The nonlinear fitting method of the contact resistance of the GIS breaker according to claim 4, wherein the discrete units are specifically:
discretizing the calculation domain into N discrete units, wherein the radius scale of each discrete unit is aLN contact pressure of hillocks in each discrete unitfiThe distribution is approximately equal to the macroscopic elastic contact continuous contact pressure distribution p (r), and the equivalent radius of curvature and slope of the hillocks within the discrete units are the same.
6. The method of claim 5, wherein the initial geometric parameters u of the rigid sphere and the semi-plane are sampled0(1)＝-4.1σs，u0(2)＝-4.3σsThe macroscopic elastic deformation parameter ω is 0 as the initial parameter, and the sum F of the contact pressures p (r) in all discrete units is adoptedcolWith normal force F acting on the rigid sphereKRepeatedly and iteratively calculating the contact resistance of the GIS breaker according to the convergence criterion of the whole GIS breaker.
7. A GIS breaker contact resistance's nonlinear fitting system characterized by, includes:
the first construction module is used for constructing a GIS breaker simplified structure finite element model and acquiring GIS breaker temperature data through simulation;
the second construction module is used for constructing a GIS bus joint contact resistance numerical calculation model;
the contact resistance calculation module is used for establishing a GIS bus joint contact resistance nonlinear fitting model and calculating a GIS bus joint contact resistance calculation value according to the GIS circuit breaker temperature data collected by the first construction module;
the second construction module is used for constructing a GIS bus joint contact resistance numerical calculation model, and specifically comprises the following steps:
the calculation formula of the contact resistance R of the rough contact surface based on the Bahraini model is as follows:
Figure FDA0003327960210000041
where ρ is the resistivity of the contact material, as(r) is the radius of the hillock within the discrete cell, forGIS plum blossom connector, mechanical contact convex point radius as(r) is equal to the radius a, n of the conductive spots(r) the number of hillocks in a discrete unit, aLIs the upper limit of integration;
the average hillock radius and hillock number within a discrete cell are calculated as follows:
Figure FDA0003327960210000042
Figure FDA0003327960210000043
in the formula, σsM is the slope of the surface of the hillock,
Figure FDA0003327960210000044
is a rough surface contact clearance characteristic function, Y (r) is the equivalent spacing between the elastic rough surface and the smooth rigid spherical surface on the discrete unit at the position r away from the central line of the rigid sphere, erfc () is a Gaussian error function complement function, and aa (r) is a macroscopic apparent contact area;
the contact resistance calculation module establishes a GIS bus joint contact resistance nonlinear fitting model, and specifically comprises the following steps:
in numerical calculation of the nonlinear curve, the three-time design fitting nonlinear curve is an optimization method which dynamically estimates parameter values and repeatedly searches by using an orthogonal table and assuming that each parameter is in a large area range and taking the minimum sum of squared residuals as a target function, the optimization method has good fitting results, does not depend on a single initial value, does not judge the relative minimum error into the absolute minimum, does not need to calculate a partial derivative, is simple to calculate, and establishes a GIS bus joint contact resistance nonlinear fitting model based on the method;
contact resistance calculation module calculates GIS busbar joint contact resistance calculation value according to the GIS circuit breaker temperature data that first construction module was collected, specifically is:
and inputting the surface temperature data acquired by the first construction module and the GIS contact resistance data acquired by the second construction module into a GIS busbar joint contact resistance nonlinear fitting model as a training data set for calculation, and outputting the calculated value of the contact resistance by the GIS busbar joint contact resistance nonlinear fitting model.
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