CN203351266U - Power transmission wire preventing ice and snow disasters - Google Patents

Abstract

The utility model provides a power transmission wire preventing ice and snow disasters. A conductor, a heat insulation layer and a support layer are successively arranged in the power transmission wire from inside to outside. The support layer comprises rubber, and the heat insulation layer and the heat insulation support layer are added around the surface of the conductor, so thermal losses of a power transmission line and thermal conduction and convective heat exchange process between the power transmission line and the surrounding environment of the power transmission line are changed, and a man-made "slow heating dam" which is capable of overflowing is made. Thus, temperature field distribution among the power transmission wire, the heat insulation layer and the support layer, between the power transmission wire and an air contact thin layer of surrounding environment, and between the power transmission wire and an air environment layer surrounding the power transmission line are changed, so a channel of ice disasters for power transmission lines caused by glaze, snow and the like is blocked, and an effect that the power transmission wire is protected from the ice and snow disasters is achieved.

Description

A kind of transmission pressure that prevents the ice and snow disaster

Technical field

The utility model belongs to the technical field of preventing and reducing natural disasters, and is specifically related to a kind of transmission pressure that prevents the ice and snow disaster.

Background technology

Sleet, strong wind disaster freezing and that usually follow is one of major casualty of facing of electrical network, this type of disaster often causes transmission line galloping simultaneously, thereby cause electric power line pole tower to fall tower, line tripping, the track bolt loose or dislocation, wire jumper comes off, disconnected strand of broken string, connecting gold utensil damages, the tower material is impaired, the serious damage situation such as icing flashover, its direct result is exactly easily to cause because of grid disconnection, electric grid large area power cut, the lonely network operation of partial electric grid, the secondary disasters such as electric power railway power failure, cause great difficulty to social economy and the people's livelihood, this type of disaster is in China, Russia, Canada, the U.S., Japan, Britain, Finland, Iceland etc. are often large tracts of land generation all, can say that the ice and snow disaster is the common issue with that world many countries faces.

The main method of the ice and snow of power industry reply at present disaster has:

1. external force is beaten method, is referred to as " ad hoc " method abroad, by the operator, is processed at the scene, and processing method is ever-changing.Though external force is beaten simple and easy to do, can only be a part of icing circuit deicing seldom, speed is slow, workload is large and uneconomical, so only there is no other more in emergency circumstances use of effective ways.

2. large current ice-melting method, comprise excess current de-icing, short circuit current ice-melt, direct current ice-melt etc., this class methods efficiency is higher, but the prior preparation of extras generally need to be arranged, cost is very high, consumes energy huge, and complicated operation, system safety is had to larger impact, and easily local overheating occurs and cause that grid equipment damages.Especially, be limited to system short circuit capacity, ice-melt power supply etc., to 500kV and above system, the short circuit ice-melt may realize hardly.

3. on-load ice-melting method, this technology is mainly to utilize twin bundled lines itself, increase thereby form loop generation current or change the distribution of power system operating mode adjustment electric network swim at double bundle conductor after boosting by autotransformer the line current that freezes, thereby conductor overheating is realized ice-melt.The ice-melt effect of this technology is better, no matter but be that line design, auxiliary facility construction or power system operating mode adjustment limitation are all larger, the scope of application is narrower.

4. passive deicing method, these class methods are that the devices such as resistance snow ring, counterweight are installed on wire, make ice and snow be difficult for coalescent on wire and self falling, although do not need substantially to drop into and operate cheap, but this method efficiency is low, be subject to natural conditions to restrict and be confined to the ice of certain type, therefore this method can not guarantee reliably.

5. the laser ice-melting method, generally have two kinds of situations, and the first is to utilize the high-energy ice-melt deicing of laser, and the second is that the pulse, the stress wave that utilize laser produce impact, thereby reaches the purpose of ice-melt.These class methods, high-power laser light source is difficult to obtain on the one hand, and power laser diode is also larger to the infringement of the objects such as pottery, metal on the other hand, seldom application in real work.

6. chemical deicing method, these class methods comprise methods such as hating ice coating, heat-absorbing paint, sprinkling deicing liquid, on anti-icing, the snow defence of aircraft, automobile, train, the pilot application have been arranged.But the deicing job area of transmission line is too large, consider on the impact of environment with to the corrosiveness of steel tower simultaneously, be difficult to apply in electric power system.

7. novel high-pressure aerial condutor (AERO-Z) method (Zhaotong County, Yunnan), this conductor cross-section is the Z-shaped arrangement of star, more solid, compact than twisted cable, and the surface that the AERO-Z wire is level and smooth can greatly reduce gathering of snow and frost.Because cost is very high, only depend on smooth surface to reduce ice and snow and gather, along with wire is aging, effect weakens, and promotes limited.

8. other also have robot Shovelling appts method, electromagnetic force deicing method, Electro-Impulse De-icing method etc., mostly also in the pilot study stage.

Above method is substantially all the removing method after the ice and snow formation of marine disasters, and often loss causes, no matter from the loss aspect or the counter-measure aspect, cost is all huger.In fact, ice and snow formation of marine disasters process " non-a day is cold ", the disaster accumulation is also not mutated, the disaster existence condition is very narrow, if set about from the prevention link, in ice and snow formation of marine disasters process " checking erroneous ideas at the outset ", so, ice and snow preventing effectiveness and pay a price and will make a world of difference.

The utility model content

In order to overcome above-mentioned the deficiencies in the prior art, the utility model provides a kind of transmission pressure that prevents the ice and snow disaster, by increase heat-insulation layer and insulation supporting layer around conductive surface, thereby change the hot conduction and convection heat exchanging process of transmission line losses heat and power transmission line surrounding environment, the people can be overflowed " Man Reba " for causing, thereby changes transmission pressure, heat-insulation layer and supporting layer, transmission pressure contact thin layer, transmission line surrounding air environment layer temperature field distribution with ambient air.Thereby the passage that blocking-up glaze, snow rime etc. cause the transmission line ice damage to form, play the effect that prevents transmission pressure ice and snow disaster.

To achieve these goals, the utility model is taked following scheme:

A kind of transmission pressure that prevents the ice and snow disaster is provided, and described transmission pressure from inside to outside sets gradually conductor, heat-insulation layer and supporting layer.

When ambient temperature is near 0 ℃, the heat-insulation layer surfaces externally and internally has 5 ℃ of left and right temperature differences, and when high temperature, wire heat balance meets the heat-insulation layer of national standard.

The following electrical network power transmission and distribution of 110kV wire, the heat-insulation layer closely formed around one deck softness, insulating polymer material around transmission pressure arranges the supporting layer rubber that one deck is corrosion-resistant, pliable and tough, insulate outside heat-insulation layer.

The transmission pressure of 110kV and above electrical network, for overcoming the impact on backing material of highfield dielectric loss, corona, partial discharge, be placed in heat-insulation layer in the middle of wire single line layer, and outer layer conductor doubles as supporting layer.

Adopt heat-insulation layer and supporting layer to unite two into one, adopt the situations such as heat insulation coating, thereby the ice damage of manufacturing identical function prevent transmission pressure.

Described transmission pressure is the power line for the transmission and distribution network of each electric pressure.

Compared with prior art, the beneficial effects of the utility model are: the transmission pressure that the utility model provides is by increasing heat-insulation layer and insulation supporting layer around conductive surface, thereby change the hot conduction and convection heat exchanging process of transmission line losses heat and power transmission line surrounding environment, the people can be overflowed " Man Reba " for causing, thereby changes transmission pressure, heat-insulation layer and supporting layer, transmission pressure contact thin layer, transmission line surrounding air environment layer temperature field distribution with ambient air.Thereby the passage that blocking-up glaze, snow rime etc. cause the transmission line ice damage to form, play the effect that prevents transmission pressure ice and snow disaster.

The accompanying drawing explanation

Fig. 1 is the structural section schematic diagram that prevents the transmission pressure of ice and snow disaster in the utility model embodiment;

Fig. 2 is that the transmission pressure that prevents the ice and snow disaster in the utility model embodiment is made the structural section schematic diagram that structure converts I;

Fig. 3 is that the transmission pressure that prevents the ice and snow disaster in the utility model embodiment is made the structural section schematic diagram that structure converts II; Wherein, the 1-conductor, the 2-heat-insulation layer, the 3-supporting layer, 4-is incubated supporting layer.

Embodiment

Below in conjunction with accompanying drawing, the utility model is described in further detail.

As Fig. 1, the utility model provides a kind of transmission pressure that prevents the ice and snow disaster, and transmission pressure from inside to outside sets gradually conductor, heat-insulation layer and supporting layer.According to different weather conditions and theoretical transmission pressure loss heat, adjust material and the thickness of heat-insulation layer and insulation supporting layer, thereby construct suitable " Man Reba ", thus blocking-up transmission pressure icing forming process.Because the interior heat of transmission pressure " Man Reba " slowly discharges (calorific potential) by surface, thereby make disappear or come off because melting at a small amount of icing of transmission pressure.

Utilize ice damage to be formed at 0 ℃ of above objective fact in next very narrow interval, disobey outer energy input, control or intervene, only utilize transmission pressure loss heat, by changing transmission pressure and ambient temperature field, translation transmission pressure and surperficial thermoisopleth thereof a little make progress, thereby stagger with environment sleet formation temperature, and make under the sleet condition (0 ℃ of left and right), do not freeze on the transmission pressure surface; When temperature further reduces, external environment condition has not possessed sleet formation condition (dry and cold or snowfall), on the transmission pressure surface, does not freeze.When ambient temperature is near 0 ℃, the heat-insulation layer surfaces externally and internally has 5 ℃ of left and right temperature differences, and when high temperature, wire heat balance meets the heat-insulation layer of national standard.

The following electrical network power transmission and distribution of 110kV wire, the heat-insulation layer closely formed around one deck softness, insulating polymer material around transmission pressure arranges the supporting layer rubber that one deck is corrosion-resistant, pliable and tough, insulate outside heat-insulation layer.

As Fig. 2, adopt heat-insulation layer and supporting layer to unite two into one, adopt the situations such as heat insulation coating, thereby the ice damage of manufacturing identical function prevent transmission pressure.

The transmission pressure of 110kV and above electrical network, for overcoming the impact on backing material of highfield dielectric loss, corona, partial discharge, be placed in heat-insulation layer in the middle of wire single line layer, and outer layer conductor doubles as supporting layer, as Fig. 3.

Described transmission pressure is the power line for the transmission and distribution network of each electric pressure.

Electric energy is in the transmitting procedure of described transmission pressure, and the line loss energy lost by transmission pressure is dispersed in atmospheric environment with heat exchange and thermal-radiating form; Described heat exchange comprises the heat by conduction exchange that the warm-up movement due to inner atom and free electron microcosmic particle causes, and between transmission pressure and surrounding air and the caused convective heat exchange of inside air generation relative displacement.

Temperature field (temperature field) is that in space, each point is in certain flashy Temperature Distribution, and the Temperature Distribution of object is the function of space coordinates and time,

t＝f(x,y,z,τ)

Wherein: t is temperature; X, y, z is space coordinates; τ is the time.

The face that synchronization uniform temp each point forms in temperature field is isothermal level.

The characteristics of isothermal level: 1. isothermal level can not intersect; 2. along the isothermal level empty calory, transmit.Along isothermal level by the empty calory transmission, and any direction that edge and isothermal level intersect, Yin Wendu changes the transmission of heat.Temperature be take along the vertical direction with isothermal level as maximum with the intensity of variation of distance.

The temperature of isothermal level x and xx Δ x is respectively t (x, τ) and t (x+ Δ x, τ), and the mean temperature rate of change between two isothermal levels is:

$\mathrm{\Δt}=\frac{t(x+\mathrm{\Δx},\mathrm{\τ})-t(x,\mathrm{\τ})}{\mathrm{\Δx}}$

Temperature gradient is:

$\mathrm{grad}t=\underset{\mathrm{\Δx}\→0}{\lim }\frac{t(x+\mathrm{\Δx},\mathrm{\τ})-t(x,\mathrm{\τ})}{\mathrm{\Δx}}=\frac{\∂t}{\∂x}$

Temperature gradient is vector, and its direction is perpendicular to isothermal level, and the direction increased with temperature is for just.

In temperature space, rate of heat transfer (heat flow) be the unit interval by the heat of heat transfer area, mean unit watt (W), joule/second (J/s) with Q.

In the heat by conduction exchange, according to the Fourier Heat Conduction law, conduction heat loss thermal power is followed following rule:

$\mathrm{dQ}=-\mathrm{\λdS}\frac{\mathrm{dt}}{\mathrm{dx}}---\left(1\right)$

Wherein, Q is rate of heat transfer, and S is heat-conducting area, and x is the temperature field location variable, and λ is conductive coefficient, and t is the temperature field temperature variable;

Described conductive coefficient λ is under the steady heat transfer condition, the material of unit thickness (1 meter), the heat that both side surface unit temperature poor (1 degree (K, ℃)) transmits by unit are (1 square metre) within the unit interval (1 second), its unit is watts/meter degree (w/m.k); And heat conduction is the physical parameter of λ exosyndrome material heat conductivility, and λ is larger, heat conductivility is better, and its value is relevant with composition, structure, density, temperature and the pressure of material.

Here, do not affect judgement and can obtain precise results by test, can think roughly in theory: wire heat conducting and radiating speed is directly proportional to transmission pressure mean coefficient of heat conductivity and temperature difference and heat-insulation layer is inversely proportional to.That is:

that is: $\mathrm{dx}=-\mathrm{\λds}\frac{\mathrm{dt}}{\mathrm{dQ}}.$

Due to the fluid transfer of heat that particle generation relative displacement causes in motion process, be called heat convection.Heat transfer process each other when fluid directly contacts with solid wall surface, the convection current produced while both comprising displacement of fluid, also comprise the conductive force between fluid molecule, is the common result of heat conduction and convection action.

In convective heat exchange, according to Newton's law of cooling, fluid heat transfer power Q is calculated by following formula:

Q＝αS(t ₁-t ₂) （2）

Wherein, t ₁and t ₂be respectively solid walls temperature and fluid temperature (F.T.), unit be degree centigrade (℃); S is heat-conducting area, and unit is a square metre (m ²), α is convection transfer rate, unit is watt/square metre degree centigrade (w/m ²℃); And α represents the size of heat convection ability, when its value equals between unit interval inner fluid and wall that temperature differs 1 ℃, the heat that per unit area transmits, shape and position with heat-transfer surface, the coefficient of heat conduction of fluid, thermal capacitance, density and the coefficient of viscosity, the laminar flow of fluid or turbulence state, and the motion state of fluid free movement or positive motion is relevant.

In described thermal radiation, the emittance Q of object is calculated by following formula:

$Q=\mathrm{\&epsiv;A\&sigma;}({\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="DEST\_PATH\_HDA0000404014140000011.png,DEST\_PATH\_HDA0000404014140000012.png"\; state="\{\{state\}\}">T</figure-callout>}}_1^4-{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="DEST\_PATH\_HDA0000404014140000011.png,DEST\_PATH\_HDA0000404014140000021.png"\; state="\{\{state\}\}">T</figure-callout>}}_2^4)---\left(3\right)$

Wherein, the emissivity that ε is object, the surface area that A is object, σ is this special fence-Boltzmann constant, its value is 5.67 * 10 ^-8watts/meter ²kelvin ⁴(w/m2K4), T ₁and T ₂be respectively object temperature and ambient temperature, temperature is kelvin degree.

By above analysis, can draw to draw a conclusion:

In the application scenarios of transmission pressure heat exchange, in factors, heat transmitted power Q and temperature difference Δ t are key and the target of problem.

Know that by above analysis ambient temperature, weather conditions, wind speed, wire table area etc. are limited to environment and concrete application is all uncontrollable factor, therefore, convective heat exchange, radiant heat exchange process can't manual controls, that is to say can not by the controlling changing transmission pressure of some variablees and on every side can amount temperature (temperature field) distribution.Thereby but the heat by conduction exchange process of transmission pressure is to be incubated and the material of support material changes average (equivalence) of transmission pressure by change

and be incubated and parcel mode of supporting layer, thickness etc. by change, thereby the conduction of velocity of regulation and control transmission pressure loss heating, make transmission pressure inside that higher interior energy be arranged, and and the transmission pressure top layer between have all the time " calorific potential " to exist, can be used as the inverse process (or feedback procedure) of transmission pressure icing, effectively stop and delay ice and snow condensing at transmission pressure.

Material and process condition, the conductive coefficient of power transmission line materials of aluminum wire processed is approximately 237w/m.k, the conductive coefficient of asbestos is approximately 0.15w/m.k, current, have a kind of coefficient of heat conduction of novel super glass wool can reach 0.008w/m.k, have lightweight, conductive coefficient is low, good springiness, nontoxic, pollution-free, high temperature resistant (can use at 600-1050 ℃ long-term), resistance to compression, tension, characteristics that flexural strength is high.Can manufacture satisfactory transmission pressure insulation and insulation supporting layer by test.

Below take LGJ500/35 as the example estimate analysis as follows:

The prerequisite explanation: because the steel core conductor resistance is greater than the aluminium wire, add kelvin effect, steel core interface size does not affect following analysis conclusion, therefore do not consider steel core section.

Calculating parameter is done following the selection:

Unit transmission pressure resistance (1 meter): the theoretical more complicated of calculating of transmission pressure resistance, comprise AC resistance and D.C. resistance, relate to temperature, twist into coefficient, aluminum steel radical, line diameter, eddy current, magnetic hysteresis, kelvin effect etc., here, theoretical resistance has directive significance, and actual resistance can obtain by testing accurately, does not lose points and analyses generality, transmission pressure resistance is by standard " aluminium and aluminium alloy draw the circle wire rod " (GB/T 3195-2008) regulation, and aluminum steel resistivity is got 0.028 Ω mm ²/ m, because conductor cross-section is S _cut=500mm ², the resistance of unit length (1 meter) wire is ohm (Ω).

Unit wire table area: ignore heat-insulation layer and insulation supporting layer thickness, unit wire table area

The wire maximum operation (service) temperature: according to " 110kV-750kV overhead transmission line design specification " (GB50545 – 2010), the wire maximum operation (service) temperature is got 70 ℃.

Ampacity: calculate ampacity (70 ℃ of maximum operation (service) temperatures) according to " 110kV-750kV overhead transmission line design specification " (GB50545 – 2010) regulation, the calculating ampacity of LGJ500/35 is approximately 670 amperes (A).

According to " 110kV-750kV overhead transmission line design specification " (GB50545 – 2010) regulation, other parameters are as follows: during high temperature, ambient temperature is 40 ℃, intensity of sunshine 1000(w/m ²).The conductive line surfaces radiation coefficient is 0.9, and the wire heat absorption coefficient is 0.9.

The computational scheme loss power is P thus _consumption=I ²r=670 ²* 0.000056 ≈ 25(W).

During low temperature (zero degree left and right), ignore thermal radiation, suppose the wire internal temperature and surface temperature is poor is controlled at 5 ℃, according to formula (6), suppose to select the super glass wool insulation material that the coefficient of heat conduction is 0.008w/m.k, can calculate heat-insulation layer thickness be dx=-0.008 * 79 * 10 ^-3* 5 ÷ (25)=0.13 * 10 ^-3rice=0.13 millimeter, that is to say, if on the transmission pressure surface or internal layer increase the heat-insulation layer of 0.13 millimeter, can make the inner and surface of wire maintain the temperature difference of about 5 ℃, also have " calorific potential " to exist.(the theoretical calculating in actual conditions and temperature field shows, if press the aluminum conductor conductive coefficient, because thermal capacitance is too little and the coefficient of heat conduction is too large, conductor temperature is also a little less than ambient temperature, do not possess " calorific potential "), thus stop or delay the generation of (according to weather condition and icing speed) ice damage.

During high temperature, press extreme case and consider, 70 ℃ of conductor temperatures, 40 ℃ of ambient temperatures, wire thermal radiation power P _consumption=0.9 * 79 * 10 ^-3* 5.67 * [(343/100) ⁴-(313/100) ⁴]=17.1(W); The hot conducted power P of wire _pass=4 * (70-40)=120(W); By 1/2 of wire glass, expose to sunlight, its power P _sun=0.5 * 79 * 10 ^-3* 1000=39.5(W); The line loss power P _consumption=I ²r=25(W).Obviously, P _pass+ P _spoke>P _sun+ P _consumption.The heat radiation power of wire is greater than the power of heat generation, that is to say, below 70 ℃, the lost power of the heat generation power and thermal of wire just can reach balance, and the wire maximum temperature can not break through 70 ℃.Transmission pressure through transformation can meet national standard when high temperature.

Further calculate and show: the loss thermal power of the steel reinforced aluminium conductor of current main specifications (1 meter length), in 20 watts (W) left and right, can meet requirement of the present invention.

According to concrete weather conditions, planning transmission line capability, determine transmission pressure inside and surperficial temperature difference (for example 5 ℃), and according to the Transmission Line Design standard, calculation and test thermal insulating, insulating supporting material, braiding, parcel mode etc., thereby reduce the comprehensive conductive coefficient of transmission pressure, adjust the thickness of insulation heat preservation layer, insulation support layer, make the heat by conduction exchange meet the target call that keeps temperature difference, and manufacture with this transmission pressure satisfied the demands.

Finally should be noted that: above embodiment is only in order to illustrate that the technical solution of the utility model is not intended to limit, although with reference to above-described embodiment, the utility model is had been described in detail, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement embodiment of the present utility model, and do not break away from any modification of the utility model spirit and scope or be equal to replacement, it all should be encompassed in the middle of claim scope of the present utility model.

Claims (4)

1. a transmission pressure that prevents the ice and snow disaster, it is characterized in that: described transmission pressure from inside to outside sets gradually conductor, heat-insulation layer and supporting layer.

2. the transmission pressure that prevents the ice and snow disaster according to claim 1, it is characterized in that: the following electrical network power transmission and distribution of 110kV wire, the heat-insulation layer closely formed around one deck softness, insulating polymer material around transmission pressure arranges the supporting layer rubber that one deck is corrosion-resistant, pliable and tough, insulate outside heat-insulation layer.

3. the transmission pressure that prevents the ice and snow disaster according to claim 1 is characterized in that: the transmission pressure of 110kV and above electrical network, heat-insulation layer is placed in the middle of wire single line layer, and outer layer conductor doubles as supporting layer.

4. the transmission pressure that prevents the ice and snow disaster according to claim 1, it is characterized in that: heat-insulation layer and supporting layer unite two into one, and adopt heat insulation coating.

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