CN104167076A - Ice-coated electric transmission line weak link early warning method - Google Patents

Abstract

The invention discloses an ice-coated electric transmission line weak link early warning method. The ice-coated electric transmission line weak link early warning method comprises the following steps that firstly, weather forecast information, ice-coating information and electric transmission line information are determined; secondly, the real-time stress values of grades in a tension support section are solved based on an accurate model stress calculation model of an electric transmission line wire, and the unbalanced force received by a pole tower is worked out; thirdly, the numerical relationship between the real-time stress values and the limiting stress value is analyzed, wire early warning is carried out according to grades, the unbalanced force of the pole tower and the limiting unbalanced force are compared, and pole tower early warning is carried out according to grades. By means of the ice-coated electric transmission line weak link early warning method, the broken electric transmission line wire can be intelligently judged when an electric system is in an ice-coating period. Information is comprehensively collected, stress values of all the grades of the line are measured through a ruling span calculation model and the accurate stress calculation model, and therefore whether the line faces the line broken risk or not can be accurately judged, and the defects that a traditional judging method is not direct and is low in precision and long in consumed time can be avoided.

Description

A kind of icing transmission line of electricity weak link method for early warning

Technical field

The invention belongs to electric system icing disaster Prevention-Security, particularly a kind of icing transmission line of electricity weak link method for early warning.

Background technology

Because China is vast in territory, the variation of geographical environment complexity and climate type, extreme frequent natural calamity occurs, the typhoon disaster occurring as normal in the annual southeastern coastal areas, at the ice damage of the Yunnan-Guizhou Plateau and Sanxia area etc.Under these extreme weather conditions, transmission line of electricity load can surpass its design ability to bear, causes that marked change can occur power transmission line stress, thereby causes electric network fault.As in ice and snow disaster in 2008, due to long sleet, on transmission line of electricity, produced serious icing, cause the variation of the stress of conductor, cause the excessive transmission line of electricity wire breaking and tower falling accident that causes of the stress of conductor.Therefore, in electrical network design, operation and fault post analysis, often need to carry out Mechanics Calculation to the circuit under extreme weather conditions.

At present, be commonly used to judge that the method for icing transmission line wire in period broken string has two kinds: a kind of is to judge its stress value by the sag of wire; Another kind is to obtain ice thickness data by special ice covering thickness monitoring device, more rule of thumb judge wire roughly suffered stress whether in risk range.Above-mentioned these two kinds of common weak points of method are, indirectly obtain stress value, lack degree of accuracy; First method needs relevant staff to remove in-site measurement sag, not only labor intensive resource, and length consuming time; Second method relies on expertise, robotization not, and degree of accuracy is relatively low.

Summary of the invention

Technical matters solved by the invention is to provide a kind of icing transmission line of electricity weak link method for early warning.

The technical solution that realizes the object of the invention is: a kind of icing transmission line of electricity weak link method for early warning, comprises the steps:

Step 1, determine weather information, ice covering thickness information and overhead transmission line details, described weather information specifically comprises: real time temperature t, highest temperature t _max, lowest temperature t _min, temperature on average t _avtemperature on average t with icing generation _ice; Ice covering thickness information i.e. the ice covering thickness b of continuous each grade of shelves; Overhead transmission line details specifically comprise wire type, elasticity coefficient E, sectional area A, outer diameter D, linear mass q, each grade of span l that this wire type is corresponding _i0, each grade of discrepancy in elevation h _i0, each grade of height difference angle β _i0, the length lambda of suspension string on each base tangent tower _i, vertical load G _i, temperature t during stringing ₀, each grade of horizontal stress σ under stringing temperature ₀₀;

Step 2, according to known weather information, by ruling span method computation model, determine initial level stress, then by accurate Stress calculation model, determined the real-time stress value σ of each grade in anchor support section _i; Specifically comprise following several step:

Step 2-1, determine the ultimate stress σ of transmission line wire _lim; Formula used is:

${\mathrm{\σ}}_{\lim }=\frac{T_b\×0.4}{A}$

In formula, T _bfor the calculating pull-off force of wire, the sectional area that A is wire.

Step 2-2, definite height difference angle β that represents _rwith ruling span l _r; Formula used is respectively:

$\cos {\mathrm{\β}}_r=\frac{\underset{1}{\overset{n}{\mathrm{\Σ}}}(l_{i0}/\cos {\mathrm{\β}}_{i0})}{\underset{1}{\overset{n}{\mathrm{\Σ}}}(l_{i0}/{\cos }^2{\mathrm{\β}}_{i0})}$

In formula, β _rwait to ask, for representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

$l_r=\frac{1}{\cos {\mathrm{\β}}_r}\sqrt{\frac{\underset{1}{\overset{n}{\mathrm{\Σ}}}{l}_{i0}^3\cos {\mathrm{\β}}_{i0}}{\underset{1}{\overset{n}{\mathrm{\Σ}}}(l_{i0}/\cos {\mathrm{\β}}_{i0})}}$

In formula, l _rwaiting to ask, is ruling span, β _rfor representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

Step 2-3, by ruling span method computation model, utilize the temperature t while installing electric wiring ₀with the parameter of transmission line wire, calculate highest temperature t _max, lowest temperature t _min, temperature on average t _avstress value separately under three kinds of meteorological conditions, approaches horizontal stress design load σ most by stress value _ithe corresponding meteorological condition of computing mode as the initial meteorological condition of accurate Stress calculation model, and the final states meteorological condition of calculating in following step 2-5; Described ruling span method computation model is as follows:

${\mathrm{\σ}}_{02}-\frac{E{\mathrm{\γ}}_2^2{l}_r^2{\cos }^3{\mathrm{\β}}_r}{24{\mathrm{\σ}}_{02}^2}={\mathrm{\σ}}_{01}-\frac{E{\mathrm{\γ}}_1^2{l}_r^2{\cos }^3{\mathrm{\β}}_r}{24{\mathrm{\σ}}_{01}^2}-\mathrm{\αE}(t_2-t_1)\cos {\mathrm{\β}}_r$

In formula, numeral 1 represents initial meteorology, and numeral 2 represents end meteorology, the elasticity coefficient that E is transmission line wire, and the linear expansion coefficient that α is transmission line wire, t is temperature, σ ₀₁for initial state horizontal stress, σ ₀₂for final states horizontal stress, l _γfor ruling span, β _γfor representing height difference angle, γ is than carrying, γ=q*g/A, and wherein q is wire linear mass, g is acceleration of gravity, the sectional area that A is wire.

Step 2-4, again by ruling span method computation model, utilize the temperature t while installing electric wiring ₀, the temperature on average t that produces of icing _icewith the parameter of transmission line wire, determine that wire that different ice covering thickness are corresponding is always than carrying a γ _bstress value under condition, approaches limit σ most by stress value _limthe corresponding meteorological condition of computing mode as the initial meteorological condition in following step 2-5; Wire corresponding to described different ice covering thickness is always than carrying a γ _bcomputing formula is:

${\mathrm{\γ}}_b=\frac{9.81q+0.03b(b+D)}{A}$

In formula, the unit mass that q is wire, the external diameter that D is wire, b ice covering thickness, the sectional area that A is wire.

Step 2-5, utilize the final states meteorological condition as described in step 2-3 in calculation process, the initial meteorological condition as described in step 2-4, and establish ultimate stress σ _limfor initial stress values, use for the third time ruling span method computation model, try to achieve initial level stress value σ ₀, and the initial level stress using it as accurate Stress calculation model;

Step 2-6, according to all known real-time meteorological conditions, use accurate Stress calculation model to determine the real-time stress value σ of each grade in anchor support section _i; Described accurate Stress calculation model comprises following three relational models:

(1) span increment Delta l _iwith horizontal stress σ _ibetween relational model:

$\begin{array}{c}\mathrm{\Δ}{l}_i=\left\{\right[{\left(\frac{{\mathrm{\γ}}_0}{{\mathrm{\σ}}_0}\right)}^2-{\left(\frac{{\mathrm{\γ}}_i}{{\mathrm{\σ}}_i}\right)}^2]\frac{l_{i0}^2{\cos }^2{\mathrm{\β}}_{i0}}{24}+\left(\frac{{\mathrm{\σ}}_i-{\mathrm{\σ}}_0}{E\cos {\mathrm{\β}}_{i0}}\right)+\mathrm{\α}(t-t_0)-\frac{\mathrm{\Δ}{h}_i}{2l_{i0}}{\cos }^2{\mathrm{\β}}_{i0}\}\\ \×\frac{l_{i0}}{{\cos }^2{\mathrm{\β}}_{i0}(1+{\mathrm{\γ}}_i^2{l}_{i0}^2/8{{\mathrm{\σ}}_i}^2)}\end{array}$

σ in formula _i---to be evaluated, be the horizontal stress of i shelves, be specially i shelves and at temperature, be t, than carrying, be γ _iunder electric wire horizontal stress; I is the positive integer from 1 to n, and n is gear number;

σ ₀---initial level stress value;

L _i0---i shelves span;

γ ₀, γ _i---before wire icing than carry and wire icing after than carrying, γ ₀for q*g/A, γ _ifor q*g/A+0.027728 (b (b+D)/A), wherein q is wire linear mass, and g is acceleration of gravity, the sectional area that A is wire, and b is wire icing thickness, D is wire diameter;

Δ l _i---to be evaluated, the l of i shelves span _i0increment, be specially i shelves span than stringing situation suspension string in the increment of span while hanging down position;

Δ h _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, be specially discrepancy in elevation h between the suspension string deflection aft hook of i shelves two ends _i0variable quantity, the high left hitch point person h of right hitch point _i0and height difference angle β _i0for on the occasion of;

T, t ₀---temperature while being respectively real time temperature and stringing;

α---conductor temperature expansion coefficient;

E---wire elasticity coefficient;

(2) i shelves discrepancy in elevation increment Delta h _iwith i base tower hitch point skew δ _ibetween relational model:

$\mathrm{\Δ}{h}_i=\sqrt{{\mathrm{\λ}}^2-{\mathrm{\δ}}_{i-1}^2}-\sqrt{{\mathrm{\λ}}^2-{{\mathrm{\δ}}_i}^2}$

Δ h in formula _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, i is the positive integer from 1 to n, n is gear number;

δ _i, δ _i-1the horizontal range of hitch point skew on the-the i shelves two ends i-1 Ji Ta, wherein the δ of two ends anchor support is 0;

λ---the suspension insulator string length on each shaft tower, wherein on the anchor support of two ends, also supposition has λ, but δ is 0;

(3) i base tower hitch point skew δ _iand σ between horizontal stress _irelational model:

$\begin{array}{c}{\mathrm{\σ}}_{i+1}=\{(\frac{G_i}{2A}+\frac{{\mathrm{\γ}}_i{l}_{i0}}{2\cos {\mathrm{\β}}_{i0}}+\frac{{\mathrm{\γ}}_{(i+1)}{l}_{(i+1)0}}{2\cos {\mathrm{\β}}_{(i+1)0}}+\frac{{\mathrm{\σ}}_i{h}_{i0}}{l_{i0}})+\frac{{\mathrm{\σ}}_i}{{\mathrm{\δ}}_i}\sqrt{{{\mathrm{\λ}}_i}^2-{{\mathrm{\δ}}_i}^2}\}\\ \÷(\frac{1}{{\mathrm{\δ}}_i}\sqrt{{{\mathrm{\λ}}_i}^2-{{\mathrm{\δ}}_i}^2}+\frac{h_{(i+1)0}}{l_{(i+1)0}})\end{array}$

σ in formula _i---to be evaluated, be i shelves horizontal stress, be specially i shelves and at temperature, be t, than carrying, be γ _iunder electric wire horizontal stress; I is the positive integer from 1 to n, and n is gear number;

δ _i——δ _i＝δ _i-1+Δl _i；

The sectional area of A---wire;

γ _i---after wire icing, ratio carries, γ _ifor q*g/A+0.03 (b (b+D)/A), wherein q is wire linear mass, and g is acceleration of gravity, the sectional area that A is wire, and b is wire icing thickness, D is wire diameter;

δ _i---the horizontal range of hitch point skew on i shelves two end group towers, wherein the δ of two ends anchor support is 0;

G _i, λ---vertical load and the length of the suspension insulator on each shaft tower, wherein on the anchor support of two ends, also supposition has λ, but δ is 0;

L _i0---i shelves span;

H _i0, h _{(i+1) 0}---i shelves and the i+1 shelves discrepancy in elevation, be specially suspension string all in while hanging down position, on i base tangent tower electric wire hitch point to the discrepancy in elevation between adjacent tower i-1 and i+1 base hitch point, large size than small size tower height person h value itself be on the occasion of, otherwise be negative value, scene records;

β _i0---i shelves height difference angle.

Step 3, by the stress σ of each span inside conductor of determining in step 2 _i, determine suffered out-of-balance force Δ F on each shaft tower _i; The computation model of described shaft tower unbalanced tensile force is:

ΔF _i＝(σ _i+1-σ _i)A＝F _i+1-F _i (i＝1,2,…,n-1)

In formula: σ _i+1and σ _ibe respectively the horizontal stress of i+1 shelves and i shelves electric wire, i is the positive integer from 1 to n-1, and n is gear number;

A---be the sectional area of electric wire;

F _i+1and F _i---be the Horizontal Tension of i+1 and i shelves electric wire;

Δ F _i---the unbalanced tensile force bearing in i base straight line pole ice detachment is poor;

Step 4, by each span inside conductor stress σ _iwith its ultimate stress σ _limcompare, wire early warning is carried out in graduation; By out-of-balance force Δ F on each shaft tower _ican bear out-of-balance force Δ F with its design _scompare, the early warning of shaft tower out-of-balance force is carried out in graduation;

The concrete numerical relation of described wire early warning with corresponding advanced warning grade is:

Work as σ _i<50% σ _limtime, not early warning;

As 50% σ _lim≤ σ _i≤ 70% σ _limtime, the yellow early warning of output i shelves wire;

As 70% σ _lim< σ _i<85% σ _limtime, the orange early warning of output i shelves wire;

Work as σ _i>=85% σ _limtime, output i shelves wire red early warning.

The concrete numerical relation of described shaft tower out-of-balance force early warning with corresponding advanced warning grade is:

As Δ F _i≤ 0.6 Δ Fs, not early warning;

As 0.6 Δ Fs< Δ F _i<0.8 Δ Fs, the yellow early warning of output i base shaft tower;

As 0.8 Δ Fs≤Δ F _i≤ 0.95 Δ Fs, the orange early warning of output i base shaft tower;

As Δ F _i>0.95 Δ Fs, output i base shaft tower red early warning.

Compared with prior art, its remarkable advantage is in the present invention: 1) directly obtain circuit stress value, omit intermediate link, precision is higher and save the manpower and materials cost of in-site measurement sag; 2) use calculated with mathematical model circuit stress value, automaticity is higher.

Below in conjunction with accompanying drawing, the present invention is described in further detail.

Accompanying drawing explanation

Fig. 1 is icing transmission line of electricity weak link method for early warning process flow diagram of the present invention.

Embodiment

In conjunction with Fig. 1, a kind of icing transmission line of electricity weak link method for early warning of the present invention, comprises the steps:

Step 1, determine weather information, icing information, overhead transmission line details, weather information specifically comprises: real time temperature t, highest temperature t _max, lowest temperature t _min, temperature on average t _avtemperature on average t with icing generation _ice; Ice covering thickness information i.e. the ice covering thickness b of continuous each grade of shelves; Overhead transmission line details specifically comprise wire type, elasticity coefficient E, sectional area A, outer diameter D, linear mass q, each grade of span l that this wire type is corresponding _i0, each grade of discrepancy in elevation h _i0, each grade of height difference angle β _i0, the length lambda of suspension string on each base tangent tower _i, vertical load G _i, temperature t when temperature t during icing, stringing ₀, each grade of horizontal stress σ under stringing temperature ₀₀; The length lambda of suspension string on each base tangent tower wherein _iline inspection road design load obtains, vertical load G _iby suspension string model, tabled look-up.Real time temperature t is obtained by in-site measurement, temperature t during stringing ₀, each grade of horizontal stress σ under stringing temperature ₀₀by stringing design load, check in;

Step 2, according to known weather information, by ruling span method computation model, determine initial level stress, then by accurate Stress calculation model, determined the real-time stress value σ of each grade in anchor support section _i; Specifically comprise following several step:

Step 2-1, determine the ultimate stress σ of transmission line wire _lim; Formula used is:

${\mathrm{\&sigma;}}_{\lim }=\frac{T_b\&times;0.4}{A}$

In formula, T _bfor the calculating pull-off force of wire, the sectional area that A is wire.

Step 2-2, definite height difference angle β that represents _rwith ruling span l _r; Formula used is respectively:

$\cos {\mathrm{\&beta;}}_r=\frac{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/\cos {\mathrm{\&beta;}}_{i0})}{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/{\cos }^2{\mathrm{\&beta;}}_{i0})}$

In formula, β _rwait to ask, for representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

$l_r=\frac{1}{\cos {\mathrm{\&beta;}}_r}\sqrt{\frac{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}{l}_{i0}^3\cos {\mathrm{\&beta;}}_{i0}}{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/\cos {\mathrm{\&beta;}}_{i0})}}$

In formula, l _rwaiting to ask, is ruling span, β _rfor representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

Step 2-3, by ruling span method computation model, utilize the temperature t while installing electric wiring ₀with the parameter of transmission line wire, calculate highest temperature t _max, lowest temperature t _min, temperature on average t _avstress value separately under three kinds of meteorological conditions, approaches horizontal stress design load σ most by stress value _ithe corresponding meteorological condition of computing mode as the initial meteorological condition of accurate Stress calculation model, and the final states meteorological condition of calculating in following step 2-5; Described ruling span method computation model is as follows:

${\mathrm{\&sigma;}}_{02}-\frac{E{\mathrm{\&gamma;}}_2^2{l}_r^2{\cos }^3{\mathrm{\&beta;}}_r}{24{\mathrm{\&sigma;}}_{02}^2}={\mathrm{\&sigma;}}_{01}-\frac{E{\mathrm{\&gamma;}}_1^2{l}_r^2{\cos }^3{\mathrm{\&beta;}}_r}{24{\mathrm{\&sigma;}}_{01}^2}-\mathrm{\&alpha;E}(t_2-t_1)\cos {\mathrm{\&beta;}}_r$

In formula, numeral 1 represents initial meteorology, and numeral 2 represents end meteorology, the elasticity coefficient that E is transmission line wire, and the linear expansion coefficient that α is transmission line wire, t is temperature, σ ₀₁for initial state horizontal stress, σ ₀₂for final states horizontal stress, l _γfor ruling span, β _γfor representing height difference angle, γ is than carrying, γ=q*g/A, and wherein q is wire linear mass, g is acceleration of gravity, the sectional area that A is wire.

Step 2-4, again by ruling span method computation model, utilize the temperature t while installing electric wiring ₀, the temperature on average t that produces of icing _icewith the parameter of transmission line wire, calculate wire that different ice covering thickness are corresponding always than carrying a γ _bstress value under condition, approaches limit σ most by stress value _limthe corresponding meteorological condition of computing mode as the initial meteorological condition in following step 2-5; Wire corresponding to described different ice covering thickness is always than carrying a γ _bcomputing formula is:

${\mathrm{\&gamma;}}_b=\frac{9.81q+0.03b(b+D)}{A}$

In formula, the unit mass that q is wire, the external diameter that D is wire, b is ice covering thickness, the sectional area that A is wire.

Step 2-5, utilize the final states meteorological condition as described in step 2-3 in calculation process, the initial meteorological condition as described in step 2-4, and establish ultimate stress σ _limfor initial stress values, use for the third time ruling span method computation model, try to achieve initial level stress value σ ₀, and the initial level stress using it as accurate Stress calculation model;

Step 2-6, according to all known real-time meteorological conditions, horizontal stress σ while using accurate Stress calculation model to try to achieve in anchor support section i shelves icing _i; The real-time stress value of the accurate Stress calculation model solution of described utilization specifically comprises following several step:

(1) row are write the relational model between span variation and wire stress:

$\begin{array}{c}\mathrm{\&Delta;}{l}_i=\left\{\right[{\left(\frac{{\mathrm{\&gamma;}}_0}{{\mathrm{\&sigma;}}_0}\right)}^2-{\left(\frac{{\mathrm{\&gamma;}}_i}{{\mathrm{\&sigma;}}_i}\right)}^2]\frac{l_{i0}^2{\cos }^2{\mathrm{\&beta;}}_{i0}}{24}+\left(\frac{{\mathrm{\&sigma;}}_i-{\mathrm{\&sigma;}}_0}{E\cos {\mathrm{\&beta;}}_{i0}}\right)+\mathrm{\&alpha;}(t-t_0)-\frac{\mathrm{\&Delta;}{h}_i}{2l_{i0}}{\cos }^2{\mathrm{\&beta;}}_{i0}\}\\ \&times;\frac{l_{i0}}{{\cos }^2{\mathrm{\&beta;}}_{i0}(1+{\mathrm{\&gamma;}}_i^2{l}_{i0}^2/8{{\mathrm{\&sigma;}}_i}^2)}\end{array}$ σ in (formula 1) formula _i---to be evaluated, be i shelves horizontal stress, horizontal stress while being specially i shelves icing, is specially i shelves and at temperature, is t, than carrying, is γ _iunder electric wire horizontal stress, unit is: N/mm ²;

σ ₀---initial level stress value, unit is: N/mm ²;

L _i0---i shelves span, unit is: m;

γ ₀, γ _i---before wire icing than carry and wire icing after than carrying, unit is: N/ (mmm ²), γ ₀for q*g/A, γ _ifor q*g/A+0.03 (b (b+D)/A), wherein q is wire linear mass, and unit is: kg/m, and g is acceleration of gravity, the sectional area that A is wire, unit is: mm ², b is wire icing thickness, unit is: and mm, D is wire diameter, unit is: mm;

Δ l _i---to be evaluated, the l of i shelves span _i0increment, be specially i shelves span than stringing situation suspension string in the increment of span while hanging down position, Δ l when span shortens _ithis is as negative value, and unit is: m;

Δ h _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, be specially discrepancy in elevation h between the suspension string deflection aft hook of i shelves two ends _i0variable quantity, the high left hitch point person h of right hitch point _i0and height difference angle β _i0for on the occasion of, unit is: m;

T, t ₀---temperature while being respectively real time temperature and stringing, unit is: ℃;

E, α---wire elasticity coefficient, unit is N/mm ²; Conductor temperature expansion coefficient, unit is 1/ ℃;

(2) row are write the relational model between the variation of the i shelves discrepancy in elevation and the skew of i base tower hitch point:

$\mathrm{\&Delta;}{h}_i=(\mathrm{\&lambda;}-\sqrt{{\mathrm{\&lambda;}}^2-{{\mathrm{\&delta;}}_i}^2})-(\mathrm{\&lambda;}-\sqrt{{\mathrm{\&lambda;}}^2-{{\mathrm{\&delta;}}_{i-1}}^2})=\sqrt{{\mathrm{\&lambda;}}^2-{{\mathrm{\&delta;}}_{i-1}}^2}-\sqrt{{\mathrm{\&lambda;}}^2-{{\mathrm{\&delta;}}_i}^2}$ Δ h in (formula 2) formula _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, unit is: m;

δ _i, δ _i-1---the horizontal range of hitch point skew on i shelves two ends i and i-1 Ji Ta, wherein the δ of two ends anchor support is 0, unit is: m;

λ---the suspension insulator string length on each shaft tower, unit is: m;

(3) row are write the relational model between suspension string deflection and wire stress:

$\begin{array}{c}{\mathrm{\&sigma;}}_{i+1}=\{(\frac{G_i}{2A}+\frac{{\mathrm{\&gamma;}}_i{l}_{i0}}{2\cos {\mathrm{\&beta;}}_{i0}}+\frac{{\mathrm{\&gamma;}}_{(i+1)}{l}_{(i+1)0}}{2\cos {\mathrm{\&beta;}}_{(i+1)0}}+\frac{{\mathrm{\&sigma;}}_i{h}_{i0}}{l_{i0}})+\frac{{\mathrm{\&sigma;}}_i}{{\mathrm{\&delta;}}_i}\sqrt{{{\mathrm{\&lambda;}}_i}^2-{{\mathrm{\&delta;}}_i}^2}\}\\ \&divide;(\frac{1}{{\mathrm{\&delta;}}_i}\sqrt{{{\mathrm{\&lambda;}}_i}^2-{{\mathrm{\&delta;}}_i}^2}+\frac{h_{(i+1)0}}{l_{(i+1)0}})\end{array}$ δ in (formula 3) formula _i=δ _i-1+ Δ l _i(formula 4)

H _i0, h _{(i+1) 0}---i shelves and the i+1 shelves discrepancy in elevation, be specially suspension string all in while hanging down position, on i base tangent tower electric wire hitch point to the discrepancy in elevation between adjacent tower i-1 and i+1 base hitch point, large size than small size tower height person h value itself be on the occasion of, otherwise be negative value, unit is: m.

The above-mentioned 3n of a simultaneous equation, solves Δ l _i, Δ h _i, σ _i03n unknown number, obtains each grade of wire horizontal stress σ altogether _i.

Step 3, by the stress σ of each span inside conductor of determining in step 2 _i, determine suffered out-of-balance force Δ F on each shaft tower _i;

The computation model of described shaft tower unbalanced tensile force is:

ΔF _i＝(σ _i+1-σ _i)A＝F _i+1-F _i (i＝1,2,…,n-1)

In formula: σ _i+1and σ _ihorizontal stress while being respectively i+1 shelves and i shelves icing, i is the positive integer from 1 to n-1, n is gear number;

A---be the sectional area of wire;

F _i+1and F _i---be the Horizontal Tension of i+1 and i shelves electric wire;

Δ F _i---the unbalanced tensile force bearing in i base straight line pole ice detachment is poor;

Step 4, by each span inside conductor stress σ _iwith its ultimate stress σ _limcompare, wire early warning is carried out in graduation; By out-of-balance force Δ F on each shaft tower _ican bear out-of-balance force Δ F with its design _scompare, the early warning of shaft tower out-of-balance force is carried out in graduation;

The concrete numerical relation of described wire early warning with corresponding advanced warning grade is:

Work as σ _i<50% σ _limtime, not early warning;

As 50% σ _lim≤ σ _i≤ 70% σ _limtime, the yellow early warning of output i shelves wire;

As 70% σ _lim< σ _i<85% σ _limtime, the orange early warning of output i shelves wire;

Work as σ _i>=85% σ _limtime, output i shelves wire red early warning.

The concrete numerical relation of described shaft tower out-of-balance force early warning with corresponding advanced warning grade is:

As Δ F _i≤ 0.6 Δ Fs, not early warning;

As 0.6 Δ Fs< Δ F _i<0.8 Δ Fs, the yellow early warning of output i base shaft tower;

As 0.8 Δ Fs≤Δ F _i≤ 0.95 Δ Fs, the orange early warning of output i base shaft tower;

As Δ F _i>0.95 Δ Fs, output i base shaft tower red early warning.

Below in conjunction with embodiment, the present invention is done to further detailed description:

Embodiment 1

One icing scene, is comprised of continuous 6 grades of strain section.15 ℃ of real time temperature t=-5 ℃, 40 ℃ of the highest temperatures, the lowest temperature-20 ℃, temperature on average, temperature t during stringing ₀=10 ℃.Each grade of ice covering thickness value b _i=[10mm 15mm15mm 25mm 20mm 20mm].Transmission line wire model is LGJ-300/40, the elasticity coefficient E=73000N/mm that this wire is corresponding ², sectional area A=338.99mm ², outer diameter D=23.94mm, linear mass q=1.133kg/m, temperature expansion coefficient α=19.6/ ℃, corresponding ultimate tension be 92220N, each grade of span l _i0=[350m 400m 450m500m 500m 350m], each grade of discrepancy in elevation h _i0=[20m 20m 10m-10m-20m-20m], the length lambda of suspension string on each base tangent tower _i(m)=5.2m, vertical load G _i=2300N, initial level stress σ under stringing temperature ₀₀=51N/mm ².

Step 1, determine weather data, ice covering thickness and overhead transmission line details as mentioned above.

Step 2, by ruling span computation model, calculate the initial level stress of accurate stress model.

The ultimate stress σ of step 2-1, computing electric power line wire _lim=108.82N;

Step 2-2, calculating ruling span l _r=435.5888m with represent height difference angle cosine cos β _r=0.9991;

Step 2-3, by ruling span method computation model, utilize the temperature t while installing electric wiring ₀with the parameter of transmission line wire, calculate highest temperature t _max, lowest temperature t _min, temperature on average t _avnstress value separately under three kinds of meteorological conditions, approaches horizontal stress design load σ most by stress value ₀₀the corresponding meteorological condition of computing mode as the initial meteorological condition of accurate Stress calculation model, and the final states meteorological condition of calculating in following step 2-5;

Obtain the stress value 50.74N/mm under temperature on average ²approach most horizontal stress design load 51N/mm ², therefore, the initial meteorological condition using temperature on average meteorological condition as accurate Stress calculation model.

Step 2-4, again by ruling span method computation model, utilize the temperature t while installing electric wiring ₀, the temperature on average t that produces of icing _icewith the parameter of transmission line wire, calculate wire that different ice covering thickness are corresponding always than carrying a γ _bstress value under condition, approaches limit σ most by stress value _limthe corresponding meteorological condition of computing mode as the initial meteorological condition in following step 2-5;

Step 2-5, utilization final states meteorological condition, the initial meteorological condition as described in step 2-3, step 2-4 in calculation process, and establish ultimate stress σ _limfor initial stress values, use for the third time ruling span method computation model, try to achieve initial level stress value σ ₀=52.27N/mm ², and the initial level stress using it as accurate Stress calculation model;

Step 2-6, according to all known real-time meteorological conditions, by accurate Stress calculation model, tried to achieve the real-time stress value σ of each grade in anchor support section _i.

Step 3, use accurate Stress calculation model to calculate every grade of horizontal stress;

σ ₁＝121.14N/mm ²、σ ₂＝123.88N/mm ²、σ ₃＝130.20N/mm ²、σ ₄＝145.83N/mm ²、σ ₅＝143.79N/mm ²、σ ₆＝141.92N/mm ²；

Determine the suffered out-of-balance force of each shaft tower;

ΔF ₁＝925.9N、ΔF ₂＝2142.7N、ΔF ₃＝5298.1N、ΔF ₄＝688.5N、ΔF ₅＝634.3N。

The relation of the relation of step 4, more real-time stress value and horizontal limeit stress value and shaft tower out-of-balance force and limit out-of-balance force, the present embodiment horizontal limeit stress value σ _limfor 108.8N, each straight line pole design can be born out-of-balance force Δ Fs=7377.6N.

Each grade of horizontal stress σ in the present embodiment _i> σ _lim, export each grade of wire red early warning;

In the present embodiment, each shaft tower out-of-balance force is respectively: Δ F ₁=12.55%, Δ F ₂=29.04%, Δ F ₃=71.81%, Δ F ₄=9.33%, Δ F ₅=8.6%, wherein, the 3rd base straight line pole 0.6 Δ Fs< Δ F ₃<0.8 Δ Fs, the yellow early warning of output the 3rd base straight line pole, other not early warning of straight line pole.

Claims (4)

1. an icing transmission line of electricity weak link method for early warning, is characterized in that, comprises the following steps:

Step 1, determine weather information, ice covering thickness information and overhead transmission line details, described weather information specifically comprises: real time temperature t, highest temperature t _max, lowest temperature t _min, temperature on average t _avtemperature on average t with icing generation _ice; Ice covering thickness information i.e. the ice covering thickness b of continuous each grade of shelves; Overhead transmission line details specifically comprise wire type, elasticity coefficient E, sectional area A, outer diameter D, linear mass q, each grade of span l that this wire type is corresponding _i0, each grade of discrepancy in elevation h _i0, each grade of height difference angle β _i0, the length lambda of suspension string on each base tangent tower _i, vertical load G _i, temperature t during stringing ₀, initial level stress σ under stringing temperature ₀₀;

Step 2, according to known weather information, by ruling span method computation model, determine initial level stress, then by accurate Stress calculation model, determined the real-time stress value σ of each grade in anchor support section _i;

Step 3, by the stress σ of each span inside conductor of determining in step 2 _i, determine suffered unbalanced tensile force Δ F on each shaft tower _i;

Step 4, by each span inside conductor stress σ _iwith its ultimate stress σ _limcompare, wire early warning is carried out in graduation; Unbalanced tensile force on each shaft tower and its design can be born to unbalanced tensile force Δ F _scompare, the early warning of shaft tower out-of-balance force is carried out in graduation.

2. a kind of icing transmission line of electricity weak link method for early warning according to claim 1, it is characterized in that, described step 2 is according to known weather information, by ruling span method computation model, determine initial level stress, then by accurate Stress calculation model, determined the real-time stress value σ of each grade in anchor support section _i, specifically comprise the following steps:

Step 2-1, determine the ultimate stress σ of transmission line wire _lim; Formula used is:

${\mathrm{\&sigma;}}_{\lim }=\frac{T_b\&times;0.4}{A}$

In formula, T _bfor the calculating pull-off force of wire, the sectional area that A is wire;

Step 2-2, definite height difference angle β that represents _rwith ruling span l _r; Formula used is respectively:

$\cos {\mathrm{\&beta;}}_r=\frac{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/\cos {\mathrm{\&beta;}}_{i0})}{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/{\cos }^2{\mathrm{\&beta;}}_{i0})}$

In formula, β _rwait to ask, for representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

$l_r=\frac{1}{\cos {\mathrm{\&beta;}}_r}\sqrt{\frac{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}{l}_{i0}^3\cos {\mathrm{\&beta;}}_{i0}}{\underset{1}{\overset{n}{\mathrm{\&Sigma;}}}(l_{i0}/\cos {\mathrm{\&beta;}}_{i0})}}$

In formula, l _rwaiting to ask, is ruling span, β _rfor representing height difference angle, l _i0be i shelves span, β _i0be i shelves height difference angle, i is the positive integer from 1 to n, and n is gear number;

Step 2-3, by ruling span method computation model, utilize the temperature t while installing electric wiring ₀with the parameter of transmission line wire, determine highest temperature t _max, lowest temperature t _min, temperature on average t _avstress value separately under three kinds of meteorological conditions, approaches horizontal stress design load σ most by stress value ₀₀the corresponding meteorological condition of computing mode as the initial meteorological condition of accurate Stress calculation model, and the final states meteorological condition of calculating in following step 2-5; Described ruling span method computation model is as follows:

${\mathrm{\&sigma;}}_{02}-\frac{E{\mathrm{\&gamma;}}_2^2{l}_r^2{\cos }^3{\mathrm{\&beta;}}_r}{24{\mathrm{\&sigma;}}_{02}^2}={\mathrm{\&sigma;}}_{01}-\frac{E{\mathrm{\&gamma;}}_1^2{l}_r^2{\cos }^3{\mathrm{\&beta;}}_r}{24{\mathrm{\&sigma;}}_{01}^2}-\mathrm{\&alpha;E}(t_2-t_1)\cos {\mathrm{\&beta;}}_r$

In formula, numeral 1 represents initial meteorology, and numeral 2 represents end meteorology, and t is temperature, and α is conductor temperature expansion coefficient, the elasticity coefficient that E is transmission line wire, σ ₀₁for initial state horizontal stress, σ ₀₂for final states horizontal stress, l _γfor ruling span, β _γfor representing height difference angle, γ is than carrying, γ=q*g/A, and wherein q is wire linear mass, g is acceleration of gravity, the sectional area that A is wire;

Step 2-4, again by ruling span method computation model, utilize the temperature t while installing electric wiring ₀, the temperature on average t that produces of icing _icewith the parameter of transmission line wire, determine that wire that different ice covering thickness are corresponding is always than carrying a γ _bstress value under condition, approaches limit σ most by stress value _limthe corresponding meteorological condition of computing mode as the initial meteorological condition in following step 2-5; Wire corresponding to described different ice covering thickness is always than carrying a γ _bcomputing formula is:

${\mathrm{\&gamma;}}_b=\frac{9.81q+0.03b(b+D)}{A}$

In formula, the unit mass that q is wire, the external diameter that D is wire, b ice covering thickness, the sectional area that A is wire;

Step 2-5, utilize the final states meteorological condition described in step 2-3, the initial meteorological condition described in step 2-4, and establish ultimate stress σ _limfor initial stress values, use for the third time ruling span method computation model, try to achieve initial level stress value σ ₀, and the initial level stress using it as accurate Stress calculation model;

Step 2-6, according to all known real-time meteorological conditions, use accurate Stress calculation model to try to achieve the real-time stress value σ of each grade in anchor support section _i; Described accurate Stress calculation model comprises following three relational models:

(1) span increment Delta l _iwith horizontal stress σ _ibetween relational model:

$\begin{array}{c}\mathrm{\&Delta;}{l}_i=\left\{\right[{\left(\frac{{\mathrm{\&gamma;}}_0}{{\mathrm{\&sigma;}}_0}\right)}^2-{\left(\frac{{\mathrm{\&gamma;}}_i}{{\mathrm{\&sigma;}}_i}\right)}^2]\frac{l_{i0}^2{\cos }^2{\mathrm{\&beta;}}_{i0}}{24}+\left(\frac{{\mathrm{\&sigma;}}_i-{\mathrm{\&sigma;}}_0}{E\cos {\mathrm{\&beta;}}_{i0}}\right)+\mathrm{\&alpha;}(t-t_0)-\frac{\mathrm{\&Delta;}{h}_i}{2l_{i0}}{\cos }^2{\mathrm{\&beta;}}_{i0}\}\\ \&times;\frac{l_{i0}}{{\cos }^2{\mathrm{\&beta;}}_{i0}(1+{\mathrm{\&gamma;}}_i^2{l}_{i0}^2/8{{\mathrm{\&sigma;}}_i}^2)}\end{array}$

σ in formula _i---to be evaluated, be that i shelves are t at temperature, than carrying, are γ _iunder electric wire horizontal stress; I is the positive integer from 1 to n, and n is gear number;

σ ₀---initial level stress value;

L _i0---i shelves span;

γ ₀, γ _i---before wire icing than carry and wire icing after than carrying, γ ₀for q*g/A, γ _ifor q*g/A+0.027728 (b (b+D)/A), wherein q is wire linear mass, and g is acceleration of gravity, the sectional area that A is wire, and b is wire icing thickness, D is wire diameter;

Δ l _i---to be evaluated, the l of i shelves span _i0increment, be specially i shelves span than stringing situation suspension string in the increment of span while hanging down position;

Δ h _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, be specially discrepancy in elevation h between the suspension string deflection aft hook of i shelves two ends _i0variable quantity, the high left hitch point person h of right hitch point _i0and height difference angle β _i0for on the occasion of;

T, t ₀---temperature while being respectively real time temperature and stringing;

α---conductor temperature expansion coefficient;

E---wire elasticity coefficient;

(2) i shelves discrepancy in elevation increment Delta h _iwith i base tower hitch point skew δ _ibetween relational model:

$\mathrm{\&Delta;}{h}_i=\sqrt{{\mathrm{\&lambda;}}^2-{\mathrm{\&delta;}}_{i-1}^2}-\sqrt{{\mathrm{\&lambda;}}^2-{{\mathrm{\&delta;}}_i}^2}$

Δ h in formula _i---to be evaluated, i shelves discrepancy in elevation h _i0increment, i is the positive integer from 1 to n, n is gear number;

δ _i, δ _i-1the horizontal range of hitch point skew on the-the i shelves two ends i-1 Ji Ta, wherein the δ of two ends anchor support is 0;

λ---the suspension insulator string length on each shaft tower, wherein on the anchor support of two ends, also supposition has λ, but δ is 0;

(3) i base tower hitch point skew δ _iand σ between horizontal stress _irelational model:

$\begin{array}{c}{\mathrm{\&sigma;}}_{i+1}=\{(\frac{G_i}{2A}+\frac{{\mathrm{\&gamma;}}_i{l}_{i0}}{2\cos {\mathrm{\&beta;}}_{i0}}+\frac{{\mathrm{\&gamma;}}_{(i+1)}{l}_{(i+1)0}}{2\cos {\mathrm{\&beta;}}_{(i+1)0}}+\frac{{\mathrm{\&sigma;}}_i{h}_{i0}}{l_{i0}})+\frac{{\mathrm{\&sigma;}}_i}{{\mathrm{\&delta;}}_i}\sqrt{{{\mathrm{\&lambda;}}_i}^2-{{\mathrm{\&delta;}}_i}^2}\}\\ \&divide;(\frac{1}{{\mathrm{\&delta;}}_i}\sqrt{{{\mathrm{\&lambda;}}_i}^2-{{\mathrm{\&delta;}}_i}^2}+\frac{h_{(i+1)0}}{l_{(i+1)0}})\end{array}$

σ in formula _i---to be evaluated, be that i shelves are t at temperature, than carrying, are γ _iunder electric wire horizontal stress; I is the positive integer from 1 to n, and n is gear number;

δ _i——δ _i＝δ _i-1+Δl _i；

The sectional area of A---wire;

γ _i---after wire icing, ratio carries, γ _ifor q*g/A+0.03 (b (b+D)/A), wherein q is wire linear mass, and g is acceleration of gravity, the sectional area that A is wire, and b is wire icing thickness, D is wire diameter;

δ _i---the horizontal range of hitch point skew on i shelves two end group towers, wherein the δ of two ends anchor support is 0;

G _i, λ---vertical load and the length of the suspension insulator on each shaft tower, wherein on the anchor support of two ends, also supposition has λ, but δ is 0;

L _i0---i shelves span;

H _i0, h _{(i+1) 0}---i shelves and the i+1 shelves discrepancy in elevation, be specially suspension string all in while hanging down position, on i base tangent tower electric wire hitch point to the discrepancy in elevation between adjacent tower i-1 and i+1 base hitch point, large size than small size tower height person h value itself be on the occasion of, otherwise be negative value, scene records;

β _i0---i shelves height difference angle.

3. a kind of icing transmission line of electricity weak link method for early warning according to claim 1, is characterized in that the unbalanced tensile force of shaft tower described in step 3 Δ F _icomputation model be:

ΔF _i＝(σ _i+1-σ _i)A＝F _i+1-F _i (i＝1,2,…,n-1)

In formula: σ _i+1and σ _ibe respectively the horizontal stress of i+1 shelves and i shelves electric wire, i is that n is the number of shaft tower;

A---be the sectional area of wire;

F _i+1and F _i---be respectively the Horizontal Tension of i+1 shelves and i shelves electric wire;

Δ F _i---the unbalanced tensile force bearing in i base straight line pole ice detachment is poor.

4. a kind of icing transmission line of electricity weak link method for early warning according to claim 1, is characterized in that, the concrete numerical relation of the early warning of wire described in step 4 with corresponding advanced warning grade is:

The concrete numerical relation of described wire early warning with corresponding advanced warning grade is:

Work as σ _i<50% σ _limtime, not early warning;

As 50% σ _lim≤ σ _i≤ 70% σ _limtime, the yellow early warning of output i shelves wire;

As 70% σ _lim< σ _i<85% σ _limtime, the orange early warning of output i shelves wire;

Work as σ _i>=85% σ _limtime, output i shelves wire red early warning;

The concrete numerical relation of described shaft tower out-of-balance force early warning with corresponding advanced warning grade is:

As Δ F _i≤ 0.6 Δ Fs, not early warning;

As 0.6 Δ Fs< Δ F _i<0.8 Δ Fs, the yellow early warning of output i base shaft tower;

As 0.8 Δ Fs≤Δ F _i≤ 0.95 Δ Fs, the orange early warning of output i base shaft tower;

As Δ F _i>0.95 Δ Fs, output i base shaft tower red early warning.