CN109885847B - Wind-proof strength calculation and tower reinforcement method for power transmission line of bottom-protection power grid - Google Patents
Wind-proof strength calculation and tower reinforcement method for power transmission line of bottom-protection power grid Download PDFInfo
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- CN109885847B CN109885847B CN201810404367.8A CN201810404367A CN109885847B CN 109885847 B CN109885847 B CN 109885847B CN 201810404367 A CN201810404367 A CN 201810404367A CN 109885847 B CN109885847 B CN 109885847B
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Abstract
The invention discloses a novel windproof reinforcement design method for a bottom-protecting power grid transmission line, which comprises the following steps of: s1, calculating wind load of a transmission line iron tower, wherein the wind load comprises line wind load and tower body wind load; s2, establishing a three-dimensional model for all tower shapes, carrying out finite element stress analysis and calculation, and checking the strength of the existing tower; and S3, reinforcing the tower according to the wind load calculation result and the stress analysis result.
Description
Technical Field
The invention relates to the field of reinforcement of power grid towers, in particular to a wind-proof strength computer tower reinforcement method for a bottom-protection power grid transmission line.
Background
The Guangdong coastal region is located on the main paths of the North Pacific ocean and the south sea tropical cyclone landing China, is influenced by high altitude guiding airflow, and has the highest frequency of the tropical cyclone landing in the Guangdong, thus being the most serious tropical cyclone disaster region of the whole country. In recent years, coastal areas in Guangdong are continuously blown by a plurality of strong typhoons, including 'Wei Ma Xun', 'rainbow', and the like, and the super typhoons land in coastal areas in Guangdong province, so that large-area tower-falling accidents of overhead transmission lines in the coastal areas are caused.
According to the analysis report conclusion of the typhoon accidents of 'Wei Ma Xun' and 'rainbow' written by the southern power grid company organization, the lower standard of fortification is one of the main reasons for causing the line to generate a large-area wind disaster and tower inversion accident.
For wind resistance reinforcement of the power transmission line, the mode of adopting a new standard to perform "push-down reconstruction" is certainly the most direct mode, and the effect of instant effect can be achieved. However, in the actual situation, 220kV lines in Zhanjiang areas are more, the wiring of a power grid is relatively complex, if the power grid is modified according to the thought of a knife, not only is the investment cost consumed larger, but also a longer construction power failure period is required, and the difficulty of actual operation is very high.
Disclosure of Invention
The invention aims to solve one or more of the defects, and designs a wind-proof strength computer tower reinforcement method for a power transmission line of a bottom-protection power grid.
In order to achieve the aim of the invention, the technical scheme adopted is as follows:
a wind-proof strength calculation and tower reinforcement method for a bottom-protection power grid transmission line comprises the following steps:
s1: calculating wind load of the transmission line iron tower, wherein the wind load comprises line wind load and tower body wind load;
s2: establishing three-dimensional models for all tower shapes, carrying out finite element stress analysis and calculation, and checking the strength of the existing towers;
s3: and reinforcing the tower according to the wind load calculation result and the stress analysis result.
Preferably, the calculation formula of the stroke load in step S1 is as follows:
WX＝α·W0·μZ·μSC·βC·d·Lp·sin2θ；
W0＝V2/1600；
wherein WX is a horizontal wind load standard value perpendicular to the direction of the lead and the ground wire and kN; alpha is a wind pressure non-uniformity coefficient and is determined according to a design reference wind speed; the beta C is a wind load adjustment coefficient of a 500kV line lead and a ground wire, is only used for calculating wind loads of the lead and the ground wire acting on a tower, and the beta C of the lines of other voltage levels is 1.0; μZ is the wind pressure height variation coefficient; μsc is the body form factor of the wire or ground wire, and when the wire diameter is smaller than 17mm or ice is covered, μsc=1.2 should be taken; when the wire diameter is larger than or equal to 17mm, the mu SC is 1.1; d is the outer diameter of the wire or the ground wire or the calculated outer diameter during icing; the split conductor takes the sum of the outer diameters of all sub-conductors, m; lp is the horizontal span of the tower, m; θ is the angle between the wind direction and the direction of the wire or ground wire; w0 is a standard wind pressure standard value and kN/m2; v is the wind speed value of the reference altitude, m/s.
Preferably, the step S2 includes the steps of:
s2.1: performing system analysis, analyzing and calculating the under-constrained degrees of freedom of the legs, then supposing that support constraints are applied to the under-constrained degrees of freedom, and then finding out which rod pieces are redundant rods;
s2.2: performing static force analysis, restraining the under-restrained degree of freedom, performing tower displacement and internal force analysis according to line load, tower body sectional load, temperature load and support displacement load, and performing checking calculation according to the rod internal force calculation result and the combination specification;
s2.3: and (5) performing frequency analysis, and analyzing and calculating the frequency of the leg. Carrying out support constraint on the under-constrained points, and solving frequency, vibration mode participation coefficients and quality coefficients;
s2.4: analyzing wind vibration coefficients, and analyzing and calculating tower body wind vibration coefficients under the frequency of the legs;
s2.5: performing earthquake-resistant analysis, and analyzing the earthquake-resistant analysis under the frequency of the calculation legs;
s2.6: and outputting a static calculation model and a frequency analysis model for Abaqus calculation.
Preferably, the earthquake-resistant analysis in the step S2.5 includes taking a large value from the consideration of the earthquake three-direction ratio of 1:0.85:0.65 and 0.85:1:0.65; the vibration mode combination adopts a CQC method, and the three directions adopt an SRSS method; the seismic effect criterion employs a large combination of simultaneous vertical and horizontal calculations.
Preferably, the step S3 includes replacing the old wire with the windproof wire, and fixing the original main tower body material with the newly-added member by punching, splicing and clamping.
Preferably, the outer aluminum strand wires of the windproof lead adopt trapezoidal or Z-shaped wires, and the outer diameter of the new lead is reduced by about 30-40 percent.
Compared with the prior art, the invention has the beneficial effects that:
1) The mode of 'pushing down and rebuilding' is avoided, and a great amount of investment cost is saved;
2) The original line corridor and the tower are utilized for reinforcement and reconstruction, so that the power failure time is shortened, the civil coordination difficulty during construction is greatly reduced, and the progress of engineering is forcefully promoted;
3) The wind load of the wires is effectively reduced, the bearing strength of the built tower is improved, the line reaches the fortification standard of the bottom protection power grid, and the probability of high wind accidents of the line is greatly reduced.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the present patent;
the invention is further illustrated in the following figures and examples.
Example 1
Referring to fig. 1, the method for calculating wind-proof strength and reinforcing a tower of a power transmission line of a bottom-protecting power grid comprises the following steps:
s1: calculating wind load of the transmission line iron tower, wherein the wind load comprises line wind load and tower body wind load;
s2: establishing three-dimensional models for all tower shapes, carrying out finite element stress analysis and calculation, and checking the strength of the existing towers;
s3: and reinforcing the tower according to the wind load calculation result and the stress analysis result.
In this embodiment, the calculation formula of the wind load in step S1 is as follows:
WX＝α·W0·μZ·μSC·βC·d·Lp·sin2θ；
W0＝V2/1600；
wherein WX is a horizontal wind load standard value perpendicular to the direction of the lead and the ground wire and kN; alpha is a wind pressure non-uniformity coefficient and is determined according to a design reference wind speed; the beta C is a wind load adjustment coefficient of a 500kV line lead and a ground wire, is only used for calculating wind loads of the lead and the ground wire acting on a tower, and the beta C of the lines of other voltage levels is 1.0; μZ is the wind pressure height variation coefficient; μsc is the body form factor of the wire or ground wire, and when the wire diameter is smaller than 17mm or ice is covered, μsc=1.2 should be taken; when the wire diameter is larger than or equal to 17mm, the mu SC is 1.1; d is the outer diameter of the wire or the ground wire or the calculated outer diameter during icing; the split conductor takes the sum of the outer diameters of all sub-conductors, m; lp is the horizontal span of the tower, m; θ is the angle between the wind direction and the direction of the wire or ground wire; w0 is a standard wind pressure standard value and kN/m2; v is the wind speed value of the reference altitude, m/s.
In this embodiment, the step S2 includes the following steps:
s2.1: performing system analysis, analyzing and calculating the under-constrained degrees of freedom (usually expressed as plane nodes) of the legs, then assuming that support constraints are applied to the under-constrained degrees of freedom, and then finding out which rods are redundant rods (namely hyperstatic); the system analysis is a basis for assisting subsequent analysis, for example, unbalanced force is generated if load is applied to an under-constrained point during static force calculation, so that calculated displacement internal force is distorted, constraint application is adopted during frequency extraction during dynamic force calculation, so that vibration mode and frequency distortion are caused when the whole structure is changed, and wind vibration coefficient calculation and anti-seismic analysis are affected.
S2.2: performing static force analysis, restraining the under-restrained degree of freedom, performing tower displacement and internal force analysis according to line load, tower body sectional load, temperature load and support displacement load, and performing checking calculation according to the rod internal force calculation result and the combination specification; since the bending regulation of the diagonal steel member is not clear at present, only the unit axial force is adopted for checking calculation. The calculation uses a linear assumption, so that the calculation result is not very accurate for the large displacement of the support.
S2.3: and (5) performing frequency analysis, and analyzing and calculating the frequency of the leg. Carrying out support constraint on the under-constrained points, and solving frequency, vibration mode participation coefficients and quality coefficients; the program solving method is a subspace iteration method, the more the calculation frequency is, the lower the efficiency is, and the sensitivity to the underconstraint degree of freedom processing is relatively high, so that the adoption of a beam unit for the underconstraint point processing is suggested for improving the accuracy, and the reduction of the calculation efficiency is brought.
S2.4: analyzing wind vibration coefficients, and analyzing and calculating tower body wind vibration coefficients under the frequency of the legs; the wind vibration coefficient is given for the vibration mode, the wind vibration coefficients given by different vibration modes are different, the main vibration mode can be judged according to the effective mass coefficient in the appointed direction, and the effective mass coefficient is large. The vibration mode is two-order bending and torsion, and the wind vibration coefficient of which the local is smaller than 1 can appear. The wind vibration coefficient calculation method adopts a higher-precision algorithm considering the area and quality influence. The total coefficient of vibration mode wind vibration is equivalent to the base bending moment. The wind vibration coefficient calculation model suggests that a beam unit is adopted to eliminate translational under-constraint degrees of freedom.
S2.5: performing earthquake-resistant analysis, and analyzing the earthquake-resistant analysis under the frequency of the calculation legs;
s2.6: and outputting a static calculation model and a frequency analysis model for Abaqus calculation.
In this embodiment, the earthquake-proof analysis in step S2.5 includes taking a large value from the three-direction ratio of earthquake according to 1:0.85:0.65 and 0.85:1:0.65; the vibration mode combination adopts a CQC method, and the three directions adopt an SRSS method; the seismic effect criterion employs a large combination of simultaneous vertical and horizontal calculations.
In this embodiment, step S3 includes replacing the old wire with the windproof wire, and fixing the original main tower body material with the newly-added member by punching, splicing and clamping.
In the embodiment, the outer layer aluminum strand single wire of the windproof lead adopts a trapezoid or Z-shaped wire, and the outer diameter of the new lead is reduced by about 30-40%.
It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (3)
1. The wind-proof strength calculation and tower reinforcement method for the power transmission line of the bottom-protection power grid is characterized by comprising the following steps of:
s1: calculating wind load of the transmission line iron tower, wherein the wind load comprises line wind load and tower body wind load;
s2: establishing three-dimensional models for all tower shapes, carrying out finite element stress analysis and calculation, and checking the strength of the existing towers; the method comprises the following steps:
s2.1: performing system analysis, analyzing and calculating the under-constrained degrees of freedom of the legs, then supposing that support constraints are applied to the under-constrained degrees of freedom, and then finding out which rod pieces are redundant rods;
s2.2: performing static force analysis, restraining the under-restrained degree of freedom, performing tower displacement and internal force analysis according to line load, tower body sectional load, temperature load and support displacement load, and performing checking calculation according to the rod internal force calculation result and the combination specification;
s2.3: performing frequency analysis to analyze and calculate the frequency of the legs; carrying out support constraint on the under-constrained points, and solving frequency, vibration mode participation coefficients and quality coefficients;
s2.4: analyzing wind vibration coefficients, and analyzing and calculating tower body wind vibration coefficients under the frequency of the legs;
s2.5: performing earthquake-resistant analysis, and analyzing the earthquake-resistant analysis under the frequency of the calculation legs; comprising the following steps:
taking the seismic three-direction proportion as 1:0.85:0.65 and 0.85:1:0.65, taking a large value; the vibration mode combination adopts a CQC method, and the three directions adopt an SRSS method;
s2.6: outputting a static calculation model and a frequency analysis model for Abaqus calculation;
s3: reinforcing the tower according to wind load calculation results and stress analysis results, comprising:
the wind-proof wire is used for replacing the old wire, and the original main material of the tower body is fixed with the newly-added rod piece in a punching, splicing and clamping mode.
2. The method for calculating wind-proof strength and reinforcing a tower of a power transmission line of a bottom protection power grid according to claim 1, wherein the calculation formula of wind load in the step S1 is as follows:
WX＝α·W0·μZ·μSC·βC·d·Lp·sin2θ；
W0＝V2/1600；
wherein WX is a horizontal wind load standard value perpendicular to the direction of the lead and the ground wire and kN; alpha is a wind pressure non-uniformity coefficient and is determined according to a design reference wind speed; the beta C is a wind load adjustment coefficient of a 500kV line lead and a ground wire, is only used for calculating wind loads of the lead and the ground wire acting on a tower, and the beta C of the lines of other voltage levels is 1.0; μZ is the wind pressure height variation coefficient; μsc is the body form factor of the wire or ground wire, and when the wire diameter is smaller than 17mm or ice is covered, μsc=1.2 should be taken; when the wire diameter is larger than or equal to 17mm, the mu SC is 1.1; d is the outer diameter of the wire or the ground wire or the calculated outer diameter during icing; the split conductor takes the sum of the outer diameters of all sub-conductors, m; lp is the horizontal span of the tower, m; θ is the angle between the wind direction and the direction of the wire or ground wire; w0 is a standard wind pressure standard value and kN/m2; v2 is the wind speed value of the reference altitude, m/s.
3. The method for calculating the wind-proof strength and reinforcing a tower of a power transmission line of a bottom-protected power grid according to claim 1, wherein the outer layer aluminum strand wires of the wind-proof type lead are trapezoidal or Z-shaped wires, and the outer diameter of a new lead is reduced by 30-40%.
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| 复合材料输电杆塔结构受力分析;赵胜利等;《电网与清洁能源》;20180225;第34卷(第02期);正文第2-3节 * |
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