Power transmission line equivalent icing thickness monitoring method

A transmission line and ice thickness technology, applied in measuring devices, instruments, etc., can solve the problems of large error in ice thickness, inability to accurately calculate the influence of horizontal wind load transmission lines, inability to accurately collect wind speed and direction, etc.

Inactive Publication Date: 2014-12-24
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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AI-Extracted Technical Summary

Problems solved by technology

[0003] At present, the typical ice thickness and ice monitoring methods are mostly based on the weighing method. The wind speed and direction sensors used are based on the two-dimensional horizontal plane to collect wind speed and direct...
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Abstract

The invention relates to a power transmission line equivalent icing thickness monitoring method. The method comprises the steps that according to axial tension, dip angles and other line status information of insulator chains and wind speed, wind directions, temperature, humidity and other weather information, information fusion is conducted through multisource sensors to qualitatively judge icing conditions first, wherein the influences of the temperature and stress on the lengths of wires are comprehensively considered; a vertical comprehensive load, a horizontal wind load and a vertical wind load of a line are calculated according to the stress of suspension points of the insulator chains; the self weight of the wires and an ice load of the line are solved according to the special situations that the virtual lowest point of the wires falls outside the span distance and the lowest point of the wires on a windage yaw plane deviates; a static equilibrium equation is established in the vertical direction of the windage yaw plane, and an equivalent icing thickness is solved in a loop iteration mode. Compared with the prior art, the method has the advantages that the calculation accuracy is high, and the convergence rate is high.

Application Domain

Measurement devices

Technology Topic

WindageSelf weight +10

Image

  • Power transmission line equivalent icing thickness monitoring method
  • Power transmission line equivalent icing thickness monitoring method
  • Power transmission line equivalent icing thickness monitoring method

Examples

  • Experimental program(1)

Example Embodiment

[0059] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.
[0060] like figure 1 As shown, the method for monitoring the equivalent icing thickness of a transmission line provided by the present invention includes the following steps:
[0061] Step S1: Receive the axial tensile force of the insulator string, the wind deflection angle of the transmission line conductor, the insulator string inclination angle, the atmospheric temperature, the atmospheric humidity, the horizontal transverse Wind speed, horizontal longitudinal wind speed and vertical wind speed.
[0062] In step S2, the vertical comprehensive load F of the transmission line is obtained according to the axial tension of the insulator string received in step S1, the wind deflection angle of the conductor of the transmission line and the inclination angle of the insulator string v , horizontal transverse wind load W h and transmission line vertical wind load W v.
[0063] like figure 2 As shown, for the analysis of the suspension point of the insulator string, η is the wind deflection angle of the insulator string, θ is the deflection angle of the insulator string, θ' is the deflection angle of the insulator string in the wind deflection plane, and θ" is the distance between the insulator string and the vertical direction. Included angle, F is the axial tension of the insulator string, F x , F h , F v are the component forces of F in the horizontal longitudinal, horizontal and vertical directions, respectively, ΔN x is the horizontal and longitudinal unbalanced tension difference, then:
[0064] F v = F 1 1 + tan 2 η + tan 2 θ
[0065] W h = tan · η · F · 1 cos η 1 + tan 2 η + tan 2 θ
[0066] W v = W h V v 2 V h 2
[0067] In the formula, F is the axial tension of the insulator string, η is the wind deflection angle of the transmission line conductor, θ is the insulator string inclination angle, V h is the horizontal wind speed, V v is the vertical wind speed.
[0068] Step S3, according to the atmospheric temperature, atmospheric humidity, horizontal transverse wind speed, horizontal longitudinal wind speed, vertical wind speed and the icing situation of the wire that was monitored in the previous step, it is judged whether the current wire may be covered with ice, if yes, then go to step S4, If not, go to step S11. To judge whether the current wire is likely to be covered with ice, the details are: if there is no ice covered in the previous monitoring, when the meteorological information satisfies that the temperature is lower than 0°C, the humidity is greater than 80%, and the horizontal transverse wind speed is greater than 1m/s, or the previous monitoring is covered with ice, Then it is judged that the current wire may be covered with ice.
[0069] Step S4, set the initial wire ice coating thickness b 0 is 0, the current wire specific load γ n Equal to the specific load of the wire itself γ 0 , the current wire length S n Equal to the length S when the wire is installed 0 , n=1;
[0070] Step S5, calculate the parameters in the vertical plane, and obtain the horizontal stress σ of the wire under the set conditions n.
[0071] Wire horizontal stress σ n The relationship between the length of the wire in the vertical plane span and the specific load of the wire is:
[0072] S = L cos β + γ 2 L 3 24 σ n 2 cos β
[0073] In the formula, S is the length of the conductor in the vertical plane span, L is the horizontal span (in the overhead line, the horizontal distance between the two suspension points in the plane parallel to the specific load of the conductor between the adjacent two towers), β is the height difference angle (the angle between the connecting line of the tower hanging points on both sides and the horizontal plane), and γ is the specific load of the wire.
[0074] Step S6, calculation of parameters in the wind deflection plane, such as image 3 As shown, obtain the wire length from the lowest point of the transmission line wire to the main tower.
[0075] In this embodiment, a large-sized tower and a small-sized tower are respectively provided on both sides of the main tower, that is, including insulator strings A, B, C, and the wire length S' from the lowest point of the wires on the side of the small and large towers to the main tower a , S' b The calculation formula is as follows:
[0076] S a ′ = L a ′ + L a ′ 3 γ ′ 2 6 σ 1 n ′ 2 cos 2 β 1 ′ = L a ′ + L a ′ 3 γ 2 6 σ 1 n 2 cos 2 β 1 · 1 cos 2 η [ 1 + ( tan β 1 sin η ) 2 ] 2
[0077] S b ′ = L b ′ + L b ′ 3 γ ′ 2 6 σ 2 n ′ 2 cos 2 β 2 ′ = L b ′ + L b ′ 3 γ 2 6 σ 2 n 2 cos 2 β 2 · 1 cos 2 η [ 1 + ( tan β 2 sin η ) 2 ] 2
[0078] In the formula, L' a , L' b are the horizontal spans from the lowest point of the conductor on the side of the small and large towers to the main tower in the wind deflection plane, respectively, η is the wind deflection angle of the transmission line conductor, β', γ', σ' are the height difference angles in the wind deflection plane , the vertical integrated specific load of the wire and the horizontal stress of the wire, the subscripts 1 and 2 represent the small tower and the large tower respectively.
[0079] Step S7, statics analysis in the wind deflection plane, and calculate the dead weight G of the wire borne by the main tower 0 and line ice load G ice , and obtain the equivalent ice load q per unit length ice.
[0080] Static analysis in the wind deflection plane, in the vertical direction of the wind deflection plane, the vertical upward insulator string pulling force is related to the vertically downward insulator string and the dead weight of the hardware, the dead weight of the wire, the line ice load and the line vertical wind load. Balance, write the balance equation and find the equivalent ice load q per unit length ice;
[0081] F cos θ ′ = G i cos η + G 0 cos η + W v cos η + G ice cos η
[0082] where: G i , G 0 , W v , G ice They are the dead weight of the insulator string and the fittings, the dead weight of the wire, the vertical wind load of the line and the ice load of the line, respectively.
[0083] Among them, the wire weight G 0 and line ice load G ice The calculation method is calculated according to the deviation characteristics of the lowest point of the wind deflection plane wire and the special case that the virtual lowest point of the wire falls outside the span, specifically:
[0084] a) When the height difference is large, the main tower is high and S' often occurs a Greater than the trumpet side gauge line length S 1 (or S’ b Greater than the large side gauge line length S 2 ), it means that the virtual lowest point of the wire is outside the span, that is, the actual lowest point of the wire is located at the suspension point of the low tower, and the pulling force of the wire on the suspension point of the low tower is the vector sum of the horizontal pulling force and the vertical upward pulling force, and the vertical upward The magnitude of the pulling force is equivalent to the vertical comprehensive load of the wire from the virtual lowest point of the wire to the suspension point of the low tower, so G 0 and G ice They are:
[0085] G 0 = γ 0 A ( S 1 + S b ′ ) p + γA ( S a ′ - S 1 ) p G ice = q ice ( S 1 + S b ′ ) p
[0086] or
[0087] G 0 = γ 0 A ( S a ′ + S 2 ) p + γA ( S b ′ - S 2 ) p G ice = q ice ( S a ′ + S 2 ) p
[0088] In the formula, S' a , S' b are the length of the conductor from the lowest point of the conductor on the side of the small and large towers to the main tower, S 1 , S 2 are the line lengths of the side spans of the small and large towers, respectively, and A is the cross-sectional area of ​​the split conductor, then γ 0 A is the weight per unit length of the split wire, p is the number of splits of the split wire, q ice Ice load per unit length of split conductor;
[0089] b) S' appears when the main tower is lower a less than 0 (or S' b When it is less than 0), it also indicates that the virtual lowest point of the wire is outside the span and the actual lowest point of the wire is located at the suspension point of the main tower. At this time, the pulling force of the wire on the suspension point of the main tower is the vector sum of the horizontal pulling force and the vertical upward pulling force, so G 0 and G ice They are:
[0090] G 0 = γ 0 AS b ′ p + γ AS a ′ p G ice = q ice S b ′ p
[0091] or
[0092] G 0 = γ 0 AS a ′ p + γ AS b ′ p G ice = q ice S a ′ p ;
[0093] c) The equivalent length of the wire for the dead weight and the ice weight of the main tower should be the length of the wire within the equivalent vertical span of the wind deflection plane. Therefore, in general, the dead weight of the wire G borne by the main tower 0 and the line ice load G on the main tower ice They are:
[0094] G 0 = γ 0 A ( S a ′ + S b ′ ) p G ice = q ice ( S a ′ + S b ′ ) p .
[0095] Step S8, according to the ice quality non-transformation algorithm, such as Figure 4 As shown, find the current equivalent ice thickness b n :
[0096] b n = 1 2 ( 4 q ice ρgπ + d 2 - d )
[0097] In the formula, ρ is the ice density, ρ is 0.9×10 -3 kg/(m mm 2 ), g is the gravitational acceleration constant, generally 9.80665N/kg, d is the diameter of the wire without ice.
[0098] Step S9, determine the equivalent ice thickness b n Whether to converge, that is, to judge the current equivalent ice thickness b n The equivalent ice thickness b calculated from the previous iteration n-1 The difference is less than the set threshold ε, if not, go to step S9, if yes, go to step S11.
[0099] Step S10, update the line parameters in the span, including the average stress of the conductor in the wind deflection plane, the length of the conductor in the span, and the vertical comprehensive specific load of the conductor in the span, n=n+1, go to step 5), and enter the next iteration calculate.
[0100] The specific update formula of the line parameters within the span is:
[0101] σ avn ′ = σ n ′ cos β ′ + γ ′ 2 L ′ 2 24 σ n ′ cos β ′ = σ n cos β + γ 2 L 2 24 σ n cos β cos 2 η
[0102] S n + 1 = S 0 [ 1 + σ avn ′ - σ av 0 E + α ( T - T 0 ) ]
[0103] γ n + 1 = γ 0 + q ice A
[0104] In the formula, σ' avn , S n+1 , γ n+1 are the average stress of the conductor in the wind deflection plane, the length of the conductor in the span, and the vertical comprehensive specific load of the conductor in the span, σ av0 is the average stress of the wire during installation, T is the current atmospheric temperature, T0 is the atmospheric temperature when the wire is installed, E is the elastic coefficient of the wire, and α is the linear expansion coefficient of the wire temperature.
[0105] In step S11, the exact value of the equivalent ice thickness is obtained, and the calculation ends.

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