CN104091031A - Method for determining maximum ice jumping height and maximum yawing distance of 20 mm heavy ice area transmission wire - Google Patents

Abstract

The invention discloses a method for determining the maximum ice jumping height and the maximum yawing distance of a 20 mm heavy ice area transmission wire. The maximum ice jumping height H of the wire is determined through the formula: H=24*(-omega2+2omega+gamma+eta)*delta, wherein delta is the difference of sagging before icing and sagging after icing, omega is the deicing rate, eta is the span length correction factor, the formula eta=(L-500)/100*0.06 is achieved, L is the span length, and gamma is the coefficient relevant to the type of the wire. The maximum yawing distance B of the wire is determined through the formula:B=(V/10)*2*(mul+tau), wherein V is the air speed generated while icing is conducted, l is the horizontal span length, mu is the coefficient relevant to the type of the wire, and tau is the coefficient relevant to the type of the wire and the type of an insulator string. According to the method for determining the maximum ice jumping height and the maximum yawing distance of the 20 mm heavy ice area transmission wire, the maximum ice jumping height and the maximum jawing distance of the transmission wire can be rapidly and accurately calculated, compared with an experiment value, errors are small, the requirement of engineering application can be met, and a foundation is laid for designing an iron tower head of the 20 mm heavy ice area transmission wire.

Description

Determine the method for 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance

Technical field

The present invention relates to heavy icing area transmission line of electricity field, relate in particular to a kind of method of definite 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance.

Background technology

The ice-melt of heavy icing area transmission line of electricity tends to cause the up-down vibration of wire while coming off, this phenomenon is called ice jumps, and during ice-shedding, lower layer line may jump to the upper layer line top not deicing, deice in process and may have wind speed simultaneously, therefore deice in process and also can produce teeter.At transmission line of electricity, deice in process, between each phase conductor, wire and spacing between ground wire may be less than alternate power frequency gap and power frequency gap mutually, thereby cause trip accident to occur, therefore, the frequency occurring in order to reduce trip accident as far as possible, heavy icing area transmission line of electricity is when the planning and design of steel tower tower head, ensure and between adjacent two layers line, have enough horizontal-shift distance and vertical separation, and horizontal-shift distance and vertical separation between adjacent two layers line and to deice maximum ice jump degree and the yaw distance of wire in process closely bound up.

Chinese scholars is mainly studied wire ice-shedding dynamic process by simulation test and two kinds of methods of numerical analysis.Because simulation test need to be set up mock-up and causes expense higher, and can not simulate actual condition completely, the test findings therefore obtaining also needs to be converted and just can be applied in actual Transmission Line Design and go by equivalent coefficient, and its degree of reliability reduces very much.Numerical analysis method has obtained along with the increasingly mature of numerical analysis software using widely, numerical analysis model all adopts the 3DOF leverage simplified model of ignoring wire bending resistance and torsional rigidity at present, and most impacts of not considering shaft tower constraint, its research conclusion majority has only provided part conclusion qualitatively, the Direct calculation formulas that does not provide wire maximum jump height and yaw distance in deicing process, engineering practicability is poor.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of method that can determine rapidly and accurately 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance.

The technical solution adopted for the present invention to solve the technical problems is:

Determine the method for 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance, wire maximum ice jump degree H is determined by following formula: H=24 (ω ²+ 2 ω+γ+η) δ, wherein,

Sag before and after δ-icing is poor; ω-deice rate; η-span correction factor, η=(L-500)/100 * 0.06, L-span; γ-coefficient relevant to wire type, when wire type is 500/45, the value of γ is-0.08, when wire type is 630/45, the value of γ is-0.17;

The maximum yaw of wire is determined by following formula apart from B: B=(V/10) ²* (μ l+ τ), wherein,

V-deice is wind speed simultaneously; L-horizontal span; μ-coefficient relevant to wire type, when wire type is 500/45, the value of μ is 0.0100, when wire type is 630/45, the value of μ is 0.0085; τ-coefficient relevant with insulator serial type to wire type, when wire type is 500/45, insulator serial type is while being I string, the value of τ is-1.9665, when wire type is 500/45, insulator serial type is while being V string, the value of τ is-1.5825, and when wire type is 630/45, insulator serial type is while being I string, the value of τ is-1.6620, when wire type is 630/45, insulator serial type is while being V string, the value of τ is-1.4115.

The invention has the beneficial effects as follows: the method that adopts definite 20mm heavy icing area transmission pressure maximum ice jump degree of the present invention and yaw distance, can calculate rapidly and accurately transmission pressure maximum ice jump degree and yaw distance, and compare with experiment value, error is little, can meet the needs of engineering application, for the steel tower tower head design of 20mm heavy icing area transmission line of electricity is laid a good foundation.

Embodiment

Below in conjunction with embodiment, the present invention is further described.

Determine the method for 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance, wire maximum ice jump degree H is determined by following formula: H=24 (ω ²+ 2 ω+γ+η) δ, wherein,

Sag before and after δ-icing is poor; ω-deice rate; η-span correction factor, η=(L-500)/100 * 0.06, L-span; γ-coefficient relevant to wire type, its value is in Table 1;

The value of table 1 γ

Wire type	γ
		500/45	-0.08
630/45	-0.17

The maximum yaw of wire is determined by following formula apart from B: B=(V/10) ²* (μ l+ τ); Wherein,

V-deice is wind speed simultaneously; L-horizontal span; μ-coefficient relevant to wire type, τ-coefficient relevant with insulator serial type to wire type, the value of μ and τ is in Table 2.

The value of table 2 μ and τ

Embodiment mono-:

Certain 20mm heavy icing area transmission line of electricity continuously interior certain grade of span of shelves is 454m, and horizontal span is 316m, and wire type is JL/G1A-500/45 steel-cored aluminium strand, and insulator pattern is V string, and deicing wind speed is simultaneously 15m/s.By mechanics general-purpose computations, can obtain icing 20mm front and back sag poor and be 1.19m, calculate while deicing rate 100%, wire maximum ice jump degree is:

H＝24(-ω ²+2ω+γ+η)δ＝24×(-1+2-0.08-0.0276)×1.19＝25.49m

When wire ice is jumped, maximum yaw distance is: B=(V/10) ²* (μ l+ τ)=1.5 ²* (0.01 * 316-1.5825)=3.55m

Table 3 is the maximum ice jump degree obtaining by simulation test value and the correlation data that adopts the definite maximum ice jump degree of method of the present invention;

Table 4 is correlation datas of the maximum yaw distance obtaining by simulation test value and the maximum yaw distance that adopts method of the present invention to determine;

Table 3

Table 4

As shown in Table 3, adopt the error of the definite maximum ice jump degree of method of the present invention in equal 10%, can meet engineering application requirements.

As shown in Table 4, adopt the error of the definite maximum yaw distance of method of the present invention in equal 10%, can meet engineering application requirements.

Ice jump degree increases with the increase of span, if when tower head planning and design, only consider that the dynamic security distance that increase shaft tower floor height meets in ice jump process not only can increase construction cost, the safety and reliability of steel tower also can further reduce along with the increase of floor height simultaneously; If allow lower layer conductor to jump to above the topping wire or ground wire not deicing, so for avoiding alternate flashover or phase ground flashover, must guarantee under ice-shedding current intelligence, between wire, meet and between the alternate gap of power frequency, lead wire and earth wire, meet power frequency gap mutually, therefore in the situation that not increasing shaft tower floor height, during tower planning design, must guarantee has enough horizontal-shift distances between different layers wire and between lead wire and earth wire.Maximum yaw distance in minimum level offset distance L >=power-frequency voltage gap width+composite conductor radius r+wire ice-shedding process between adjacent two layers line.

In the method for definite 20mm heavy icing area transmission pressure maximum ice jump degree of the present invention and yaw distance, the computing formula of wire maximum ice jump degree and yaw distance obtains in the following way:

A, determine the numerical model of each element of transmission line of electricity and various loads, utilize in finite element analysis software various unit to set up to comprise steel tower, lead wire and earth wire, insulator chain, conductor spacer, cover the many grades of tower line coupling models that become more meticulous that deice load, wind load; Described finite element analysis software refers to the software based on the establishment of finite element analysis algorithm, according to the scope of application of software, can be divided into professional finite element software and large-scale general finite element software, common common finite element software comprises LUSAS, Nastran, Ansys, Abaqus, LMS-Samtech, Algor, Femap/NX Nastran, Hypermesh, FEPG etc., preferably adopts Ansys software; Set up the many grades of tower line coupling model simulation ice-coating circuit dynamic response processes that deice under various conditions more exactly that become more meticulous;

B, the tower line coupling model that utilizes steps A to set up, obtain the static balancing state of lead wire and earth wire under various load case effects, contrasts the correctness of checking tower line coupling model with calculated value; Because statical equilibrium checking is basis and the prerequisite of carrying out dynamic simulation, and steel tower, insulator chain, conductor spacer and lead wire and earth wire link into an integrated entity, the sag that the variation of operating mode is finally all embodied in lead wire and earth wire changes, and therefore by checking lead wire and earth wire, the static balancing state under various load case effects just can be verified the correctness of whole tower line coupling model;

C, determine that tower line coupling model is correct after, the tower line coupling model that utilizes steps A to set up, simulate respectively the various operating mode lower wire ice-shedding dynamic processes that deice, obtain various deice under operating mode corresponding wire ice jump degree and yaw distances, then matching show that wire deices the computing formula of wire maximum ice jump degree and yaw distance in process.

Claims (1)

1. determine the method for 20mm heavy icing area transmission pressure maximum ice jump degree and yaw distance, it is characterized in that:

Wire maximum ice jump degree H is determined by following formula: H=24 (ω ²+ 2 ω+γ+η) δ, wherein,

Sag before and after δ-icing is poor; ω-deice rate; η-span correction factor, η=(L-500)/100 * 0.06, L-span; γ-coefficient relevant to wire type, when wire type is 500/45, the value of γ is-0.08, when wire type is 630/45, the value of γ is-0.17;

The maximum yaw of wire is determined by following formula apart from B: B=(V/10) ²* (μ l+ τ), wherein,

V-deice is wind speed simultaneously; L-horizontal span; μ-coefficient relevant to wire type, when wire type is 500/45, the value of μ is 0.0100, when wire type is 630/45, the value of μ is 0.0085; τ-coefficient relevant with insulator serial type to wire type, when wire type is 500/45, insulator serial type is while being I string, the value of τ is-1.9665, when wire type is 500/45, insulator serial type is while being V string, the value of τ is-1.5825, and when wire type is 630/45, insulator serial type is while being I string, the value of τ is-1.6620, when wire type is 630/45, insulator serial type is while being V string, the value of τ is-1.4115.