CN109119931B - Power transmission line online anti-icing and de-icing heat quantity calculation method based on self-made thermal conductor - Google Patents
Power transmission line online anti-icing and de-icing heat quantity calculation method based on self-made thermal conductor Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
- H02G1/02—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines for overhead lines or cables
Abstract
A power transmission line online anti-icing and de-icing heat calculation method based on a self-made heat wire. And calculating the heat quantity of the online anti-icing working state and the ice-melting working state. In the anti-icing working state, calculating the heat required in the temperature rising stage and the heat preservation stage; the heating stage calculates the heat required by the lead when the lead is heated to 1 ℃, the heat required by the predicted icing within the next Ts minutes after the lead is dissolved and the heat of convection heat dissipation outside the lead, and the heat required by the predicted icing within the next Ts minutes after the lead is dissolved and the heat of convection heat dissipation outside the lead are calculated in the heat preservation stage. Respectively calculating the heat required in the temperature rising stage and the ice melting stage in the ice melting working state: and in the temperature rise stage, the heat required by the temperature rise of the lead, the heat required by the temperature rise of external ice to 0 ℃ and the heat flow of convection heat dissipation are calculated, in the ice melting stage, the heat required by ice melting is calculated, the ice melting heat required by ice coating in Tw minutes in the future is predicted, and the sum of the heat required by convection heat dissipation is resisted. The method accurately calculates the ice-melting power of the wire and guides the on-line ice-preventing and ice-melting working state of the power transmission line.
Description
(I) technical field
The invention relates to an online ice melting method for a power transmission line, in particular to an online ice-preventing and ice-melting heat calculation method for a power transmission line based on a self-made thermal conductor.
(II) background of the invention
With the development of social economy, the requirements for exposed power lines are higher and higher in the environment of increasing the application of power loads. In cold winter, the lines in many areas are frozen, and the lines are damaged. When the icing exceeds the bearing capacity of the line, serious accidents such as line breakage and the like can occur. Therefore, deicing of power transmission lines in winter is indispensable and very important. In the prior art, ice melting technology is continuously improving. The application number CN201610867150.1 'a self-melting ice conductor and melting ice device', and the application number CN201810370549.8 'self-made heat conductor and heating device embedded in insulating heat conduction material and implementation method thereof', disclose two different types of online melting ice methods for power transmission lines, and the melting ice effect is greatly improved compared with the prior art. However, the above two inventions do not further explain the power specifically required for online anti-icing and de-icing, and the de-icing power and the de-icing condition of the self-deicing wire cannot be accurately controlled. The invention discloses a power calculation method for ice prevention and melting, which provides a working state of a power supply for ice prevention and melting and can accurately control the ice melting working state of a power transmission line.
Disclosure of the invention
The invention aims to further improve the ice melting technology of the power transmission line on the basis of the application number CN201610867150.1 self-melting ice conductor and ice melting equipment and the application number CN201810370549.8 self-made heat conductor and heating equipment embedded with insulating heat conduction materials and an implementation method thereof.
In the inventions disclosed in application numbers CN201810370549.8 and CN201810370549.8, the transmission conductors thereof can perform the anti-icing and de-icing operations. When the power transmission conductor works, a sensor is installed, and an icing prediction technology is adopted. The sensor mounted on the power transmission line senses the temperature of the power transmission line and the current icing state of the power transmission line, and the power transmission line icing predicting technology predicts the future icing state of the power transmission line. And when the power transmission line is coated with ice, starting ice melting work of the power transmission line. And when the ice coating possibility of the power transmission line in the future is predicted, starting the anti-ice work of the power transmission line. The heat required in the anti-icing process needs to be calculated when the anti-icing work is started, and the heat required in the de-icing process needs to be calculated when the de-icing is started. In the two inventions, a heat calculation method for the anti-icing and de-icing process is not provided. The invention provides a method for calculating heat required by ice melting work of a power transmission line and ice preventing work of the power transmission line within a period of time. And through heat calculation, the heat required by the anti-icing and de-icing work of the power transmission line is accurately given, and the working state required by the anti-icing and de-icing of the power transmission line is guided.
The purpose of the invention is achieved by the following steps:
the on-line anti-icing and de-icing heat quantity calculation method for the power transmission line based on the self-made heat conducting wire comprises an inner conductor, an embedded material and an outer conductor, wherein the embedded material can be a self-heating material or a self-heating material, and can also be an insulating material. The self-made heat wire is provided with a sensor, the sensor senses the temperature of the power transmission line and the current icing state of the power transmission line when the power transmission line works, the future icing state of the power transmission line is predicted, the ice melting work is automatically carried out when the wire is iced, and the ice preventing work is carried out when the wire is not iced but the future icing is predicted.
The method is characterized in that: and respectively calculating the heat of the online anti-icing working state and the heat of the ice-melting working state according to the two conditions of the anti-icing working state and the ice-melting working state of the self-made heat conductor.
When the ice coating is predicted to be possible in the future, starting the heat calculation of the anti-icing working state, wherein the anti-icing working state is divided into two stages, namely a temperature rise stage and a heat preservation stage; when the temperature of the power transmission conductor is less than 1 ℃, the anti-icing working state is in a temperature rising stage, when the temperature of the power transmission conductor is more than 1 ℃, the anti-icing working state is in the temperature rising stage, and the working time of the anti-icing working temperature rising stage is Ts minutes.
When the self-made heat conductor sensor judges that ice is covered, starting heat calculation of an ice melting working state, wherein the ice melting working state is divided into a temperature rise stage and an ice melting stage; the temperature rise stage refers to the process from the start of ice melting to 0 ℃ of the self-made heat conductor, and the ice melting stage refers to the process of starting ice melting after the temperature of the conductor rises to 0 ℃; the time required by the temperature rise stage is Tu minutes, and the time required by the ice melting process is Tw minutes.
The self-heating wire with the length of 1 m is called a unit self-heating wire, and when heat is calculated, the required heat of the unit self-heating wire is firstly calculated, and then the total heat requirement of the power transmission line of the self-heating wire with any length is calculated according to the requirement.
In the two stages of the anti-icing working state, the required heat of the temperature rising stage and the heat preservation stage is respectively calculated:
the heat quantity required to be calculated in the temperature rising stage has three parts: the heat required by heating the lead to 1 ℃, the heat required by predicting ice coating in the future Ts minutes after the lead is melted and the heat of convection heat outside the lead are calculated, and the sum of the three parts is the heat required in the anti-ice working heating stage.
In the heat preservation stage of the anti-icing working state: when the temperature of the lead is raised to 1 ℃, the lead enters a heat preservation stage, and the anti-icing heat of the heat preservation stage comprises two parts: and predicting the heat required by icing and the heat flow of convection heat dissipation outside the wire within Ts minutes in the future of melting the wire.
In the two stages of the ice melting working state, the required heat of the temperature rising stage and the ice melting stage is respectively calculated:
in the temperature rise stage of the ice melting working state, the heat calculation comprises the heat required by the temperature rise of the lead, the heat required by the temperature rise of the external ice to 0 ℃ and the heat flow of convection heat dissipation, and the sum of the three parts is the heat required in the temperature rise stage of the ice melting working state. The temperature rise time was Tu minutes.
The heat required at the ice-melting stage in the ice-melting operating state is calculated as: and when the temperature of the wire is measured to be 0 ℃ by the sensor, calculating the heat quantity of the ice melting stage, wherein the time required by the ice melting process is calculated according to Tw minutes, the heat quantity of the ice melting stage comprises the heat quantity required by ice melting, the ice melting heat quantity required by ice coating in the Tw minutes in the future is predicted, and the sum of the heat quantity required by heat dissipation resistance by convection is predicted. The heat requirement of the transmission line of the homemade heat conducting wire with any length is that the actual length of the conducting wire in meters is multiplied by the heat required by the homemade heat conducting wire.
The heat quantity calculating step for calculating the heat quantity required by a unit self-made heat conducting wire in the temperature rising stage of the anti-icing work comprises the following steps:
1) calculating the heat required for the unit self-made heat wire to rise to 1 ℃:
before heating and temperature rising, the inner conductor, the embedded material and the outer conductor in the self-made heat conducting wire have the same temperature, and the temperature of the conducting wire before temperature rising is set as t1，t1<The heat required for the temperature of the lead to be raised to 1 ℃ is the heat Q required for the temperature of the inner conductor1tHeat quantity Q required for raising temperature of embedding material2tHeat Q required for temperature rise of external conductor3tSum Qup；Q1t、Q2t、Q3tThe calculation method is as shown in formula (3-1),
in the formula, r1Denotes the radius, r, of the inner conductor of the home-made wire2Denotes the radius, r, of the embedding material after it has wrapped around the inner conductor3Denotes the radius, r, of the entire wire after the outer conductor is wrapped around the embedding material1、r2、r3The unit of (a) is meter; the specific heat capacity of the inner conductor of the self-made lead is c1The specific heat capacity of the embedding material is c2The specific heat capacity of the outer conductor is c3The unit of specific heat capacity is Joule per kilogram centigrade degree; density of inner conductor is rho1Density of the embedding material is rho2Density of outer conductor is rho3(ii) a The density units are kilograms per cubic meter;
2) and (3) calculating the heat quantity required by predicting ice coating in the future Ts minutes after the unit self-made hot wire melts:
let the future Ts minute icing weight be g12And assuming that the temperature of the just-frozen ice coating layer is 0 ℃, the heat of fusion of ice is Lm,LmThe unit is joule per kilogram; the energy Q consumed to melt the icemAs shown in formula (3-2);
Qm＝g12·Lm(3-2)
3) and (3) calculating the convection heat dissipation outside the unit self-made heat conducting wire:
let the ambient temperature be tcThe surface heat transfer coefficient of air and the self-melting ice conductor is h, the unit of the surface heat transfer coefficient is watt per square meter, and the average heat flow phi of the convection heat transfer of the self-making ice conductor per unit of Ts minutessIs composed of
Фs＝πr3h(1-tc) (3-3)
4) In the temperature rising stage, the unit self-made heat conducting wire needs the total heat Q for anti-icing every Ts minutesallComprises the following steps:
Qall＝Qup+Qm+Фs×Ts×60 (3-4)
the heat calculation in the unit self-made heat conducting wire anti-icing work heat preservation stage is as follows:
when the temperature of the lead is raised to 1 ℃, the lead enters a heat preservation stage, and the anti-icing heat of the heat preservation stage comprises two parts: the melting of the conducting wire within Ts minutes in the futurePredicting the heat required by icing and the convection heat dissipation outside the wire, wherein the temperature of the wire is 1 ℃ in the heat preservation stage, and the heat Q required by self-making the hot wire per unit of Ts minutes in the heat preservation stageonComprises the following steps:
Qon＝g12·Lm+2πr3h(1-tc)×Ts×60 (3-5)
the method comprises the following steps of:
1) the heat required by the unit self-made heat conducting wire for raising the temperature to 1 DEG C
The heat required by the temperature rise of the lead at 1 ℃ is the heat Q required by the temperature rise of the inner conductor at 1 DEG C1aThe heat quantity Q required for heating the heating material to 1 DEG C2aThe heat Q required by the temperature rise of the outer conductor at 1 DEG C3aSum, Q1a、Q2a、Q3aThe calculation method is as in formula (3-6)
2) The heat required by the unit for self-made heat conducting wire to raise the temperature of ice to 1 DEG C
The predicted future Tu minute is set to be g in the weight of ice coated on each meter of lead22The current ice weight per meter measured by the sensor is gsThe specific heat capacity of ice is ciThe heat Q required for the ice to rise to 1 DEG CiaIs composed of
Qia＝(0.5g22+gs)·ci(3-7)
3) Unit self-made heat conducting wire convection heat radiation heat flow
According to formula (3-8a) by (0.5 g)22+gs) Calculating the thickness of the ice coating, and assuming the thickness of the ice coating to be b, according to a Newton cooling formula, determining the average heat flow phi of the unit self-made heat conductor convection heat transfersIs composed of
Φs＝π(r3+b)h(0-tc) (3-8b)
ρiDensity of iceIn kilograms per cubic meter;
4) total heat quantity needed by unit self-made heat conducting wire in temperature rising stage
Setting the temperature of the wire at the beginning of temperature rise to tcThe temperature rise time is Tu minutes, and the unit of the temperature rise stage is the required heat Q of the self-made heat conducting wireaComprises the following steps:
Qa＝-tc(Q1a+Q2a+Q3a+Qia)+Фs×Tu×60 (3-9)
the method comprises the following steps of calculating the heat required by a unit self-made hot wire in the ice melting stage in the ice melting working state:
1) the unit self-made heat wire melts the required heat:
the current ice weight per meter measured by the sensor is gmLet the predicted future Tw minutes be g ice coating weight per meter32，
Setting the heat required for melting ice as QawAnd then the heat required for ice melting is as follows:
Qaw＝(g32+gm)·Lm(3-10)
2) the unit self-made heat conducting wire resists the heat required by the convection heat dissipation:
according to formula (3-11a) by (g)32+gm) Calculating the thickness of the ice coating, and assuming that the thickness of the ice coating is c, calculating the heat flow phi of the convection heat transfer of the unit self-made heat conductorswIs composed of
Φsw＝2π(r3+c)h(0-tc) (3-11b)
3) Total heat quantity required by unit self-made heat conducting wire
Within Tw minutes, the total heat quantity Q required by unit self-made hot wire for melting iceasComprises the following steps:
Qas＝Qaw+Φsw×Tw×60 (3-12)
the heat requirement of the transmission line of the self-made heat conducting wire with any length is the length of the wire in meters multiplied by the heat required by the self-made heat conducting wire, and the specific calculation is as follows:
if the length of the power transmission line is LL meters, the total power calculation method of the power transmission line is as follows:
(1) heat quantity Q required in temperature rising stage of anti-icing operation every Ts minutesLall
QLall＝Qall×LL
(2) Heat quantity Q required in anti-icing working heat preservation stage every Ts minutesLon
QLon＝Qon×LL
(3) Heat Q required in the temperature rise stage of ice melting operation every Tu minutesLa
QLa＝Qa×LL
(4) Heat quantity required in the stage of melting ice in every Tw minute
QLas＝Qas×LL
The invention has the positive effects that:
two different types of self-ice-melting power transmission conductor design schemes are disclosed in the invention patent 'a self-ice-melting conductor and ice-melting equipment thereof' and the invention patent 'self-made thermal conductor and heating equipment embedded in insulating thermal conductive material and implementation method thereof'. However, the ice-freezing prevention heat amount calculation method is not described. The invention discloses an anti-icing and de-icing heat quantity calculation method based on a self-made heat wire. The heat required by the anti-icing and de-icing work of the power transmission line is accurately given through the anti-icing and de-icing heat calculation, the de-icing power of the self-deicing wire is accurately controlled, and the working state required by the anti-icing and de-icing of the power transmission line is guided, calculated and analyzed.
(IV) description of the drawings
The attached drawing is a sectional view of the self-made heat conducting wire structure of the invention.
In the figure, 1 is an inner conductor, 2 is an embedding material, and 3 is an outer conductor. The embedding material is a heating material or an insulating material. r is1Denotes the radius of the inner conductor, r2Denotes the radius, r, of the embedding material after it has wrapped around the inner conductor3Denotes the radius, r, of the entire wire after the outer conductor is wrapped around the embedding material1、r2、r3In meters.
(V) detailed description of the preferred embodiments
The present invention is further embodied on the basis of application numbers CN201810370549.8 and CN 201810370549.8. In the two inventions, the transmission conductors can perform online anti-icing and de-icing work. When the power transmission conductor works, a sensor is installed, and an icing prediction technology is adopted. The sensor installed on the power transmission line can sense the temperature of the power transmission line and the current icing state of the power transmission line, and has a power transmission line icing prediction technology to predict the future icing state of the power transmission line. And when the power transmission line is coated with ice, starting ice melting work of the power transmission line. And when the ice coating possibility of the power transmission line in the future is predicted, starting the anti-ice work of the power transmission line.
According to the two conditions of the anti-icing working state and the ice-melting working state of the self-made heat conducting wire, the heat of the on-line anti-icing working state and the heat of the ice-melting working state are calculated respectively.
The self-heating wire with the length of 1 m is called a unit self-heating wire, and when heat is calculated, the required heat of the unit self-heating wire is firstly calculated, and then the total heat requirement of the power transmission line of the self-heating wire with any length is calculated according to the requirement. When the ice coating is predicted to be possible in the future, starting the heat calculation of the anti-icing working state, wherein the anti-icing working state is divided into two stages, namely a temperature rise stage and a heat preservation stage; when the temperature of the power transmission conductor is less than 1 ℃, the anti-icing working state is in a temperature rising stage, when the temperature of the power transmission conductor is more than 1 ℃, the anti-icing working state is in the temperature rising stage, and the working time of the anti-icing working temperature rising stage is Ts minutes. The heat quantity calculation steps required to be calculated in the anti-icing working temperature rise stage of the unit self-made heat conducting wire are as follows:
1) calculating the heat required for the unit self-made heat wire to rise to 1 ℃:
before heating, the inner conductor, the embedded material and the outer conductor in the self-made heat conducting wire have the same temperature, and the real-time temperature of the conducting wire is t1，t1<The heat required for the temperature of the lead to be raised to 1 ℃ is the heat Q required for the temperature of the inner conductor1tHeat quantity Q required for raising temperature of embedding material2tHeat Q required for temperature rise of external conductor3tSum Qup；Q1t、Q2t、Q3tThe calculation method is as shown in formula (3-1),
in the formula, r1Denotes the radius, r, of the inner conductor of the home-made wire2Denotes the radius, r, of the embedding material after it has wrapped around the inner conductor3Denotes the radius, r, of the entire wire after the outer conductor is wrapped around the embedding material1、r2、r3The unit of (a) is meter; the specific heat capacity of the inner conductor of the self-made lead is c1The specific heat capacity of the embedding material is c2The specific heat capacity of the outer conductor is c3Density of the inner conductor is rho1Density of the embedding material is rho2Density of outer conductor is rho3；
2) And (3) calculating the heat quantity required by predicting ice coating in the future Ts minutes after the unit self-made hot wire melts:
let the ice coating weight of the unit self-made hot wire in the future Ts minute be g12And assuming that the temperature of the just-frozen ice coating layer is 0 ℃, the heat of fusion of ice is Lm,LmThe unit is joule per kilogram; the energy Q consumed to melt the icemAs shown in formula (3-2);
Qm＝g12·Lm(3-2)
3) and (3) calculating the convection heat dissipation outside the unit self-made heat conducting wire:
let the ambient temperature be tcThe surface heat transfer coefficient of air and the self-melting ice conductor is h, the unit of the surface heat transfer coefficient is watt per square meter, and the average heat flow phi of the convection heat transfer of the self-making ice conductor per unit of Ts minutessIs phis＝πr3h(1-tc)(3-3)
4) In the temperature rising stage, the unit self-made heat conducting wire needs the total heat Q for anti-icing every Ts minutesallComprises the following steps:
Qall＝Qup+Qm+Фs×Ts×60 (3-4)
the heat calculation of the unit self-made heat conducting wire in the anti-icing work heat preservation stage of the unit self-made heat conducting wire is as follows:
when the temperature of the wire is highWhen the temperature is raised to 1 ℃, the heat preservation stage is carried out, and the anti-icing heat quantity of the heat preservation stage comprises two parts: predicting the heat required by icing and the convection heat dissipation outside the lead within the Ts minute in the future of lead melting, wherein the temperature of the lead is 1 ℃ in the heat preservation stage, and the heat Q required by self-making the heat lead per unit of Ts minute in the heat preservation stageonComprises the following steps:
Qon＝g12·Lm+2πr3h(1-tc)×Ts×60 (3-5)
when the self-made heat conductor sensor judges that ice is covered, starting heat calculation of an ice melting working state, wherein the ice melting working state is divided into a temperature rise stage and an ice melting stage; the temperature rise stage is the process from the start of ice melting to 0 ℃ of the self-made heat conductor, and the ice melting stage is the process that the temperature of the conductor is raised to 0 ℃ and then the ice melting is started; the time required by the temperature rise stage is Tu minutes, and the time required by the ice melting process is Tw minutes.
In the two stages of the ice melting working state, the required heat of the temperature rising stage and the ice melting stage is respectively calculated:
in the temperature rise stage of the ice melting working state, the heat calculation comprises the heat required by the temperature rise of the conducting wire, the heat required by the temperature rise of external ice and the heat flow of convection heat dissipation, and the sum of the three parts is the heat required in the temperature rise stage of the ice melting working state.
The heat required at the ice-melting stage in the ice-melting operating state is calculated as: and when the temperature of the wire is measured to be 0 ℃ by the sensor, calculating the heat quantity of the ice melting stage, wherein the time required by the ice melting process is calculated according to Tw minutes, the heat quantity of the ice melting stage comprises the heat quantity required by ice melting, the ice melting heat quantity required by ice coating in the Tw minutes in the future is predicted, and the sum of the heat quantity required by heat dissipation resistance by convection is predicted. The heat required by the temperature rise stage in the ice melting working state is calculated by the following steps:
1) the heat required by the unit self-made heat conducting wire for raising the temperature to 1 DEG C
The heat required by the temperature rise of the lead at 1 ℃ is the heat Q required by the temperature rise of the inner conductor at 1 DEG C1aThe heat quantity Q required for heating the heating material to 1 DEG C2aThe heat Q required by the temperature rise of the outer conductor at 1 DEG C3aSum, Q1a、Q2a、Q3aThe calculation method is as in formula (3-6)
2) The heat required by the unit for self-made heat conducting wire to raise the temperature of ice to 1 DEG C
The predicted future Tu minute is set to be g in the weight of ice coated on each meter of lead22The current ice weight per meter measured by the sensor is gsThe specific heat capacity of ice is ciThe heat Q required for the ice to rise to 1 DEG CiaIs composed of
Qia＝(0.5g22+gs)·ci(3-7)
3) Unit self-made heat conducting wire convection heat radiation heat flow
According to formula (3-8a) by (0.5 g)22+gs) Calculating the thickness of the ice coating, and assuming the thickness of the ice coating to be b, according to a Newton cooling formula, determining the average heat flow phi of the unit self-made heat conductor convection heat transfersIs composed of
Φs＝π(r3+b)h(t1-tc) (3-8b)
ρiIs the density of ice in kilograms per cubic meter
4) The total heat required by the unit self-made heat conducting wire in the temperature rising stage
Setting the temperature of the wire at the beginning of temperature rise to tcTemperature rise time is Tu minutes, and heat quantity Q required in the temperature rise stageaComprises the following steps:
Qa＝-tc(Q1a+Q2a+Q3a+Qia)+Фs×Tu×60 (3-9)
the method comprises the following steps of calculating the heat required by a unit self-made hot wire in the ice melting stage in the ice melting working state:
1) the unit self-made heat wire melts the required heat:
the current ice weight per meter measured by the sensor is gmLet the predicted future Tw minutes be g ice coating weight per meter32Let the heat required for ice melting be QawThen melting iceThe heat quantity is:
Qaw＝(g32+gm)·Lm(3-10)
2) the unit self-made heat conducting wire resists the heat required by the convection heat dissipation:
according to formula (3-11a) by (g)32+gm) Calculating the thickness of the ice coating, and assuming that the thickness of the ice coating is c, calculating the heat flow phi of the convection heat transfer of the unit self-made heat conductorswIs composed of
Φsw＝2π(r3+c)h(t1-tc) (3-11b)
3) The total heat required by the unit self-made heat wire is as follows:
within Tw minutes, the total heat quantity Q required by unit self-made hot wire for melting iceasComprises the following steps:
Qas＝Qaw+Φsw×Tw×60 (3-12)
according to the method, when the heat quantity is calculated, the required heat quantity of the unit self-made hot wire is calculated, and then the total heat quantity requirement of the power transmission line of the self-made hot wire with any length is calculated according to the requirement.
If the length of the power transmission line is LL meters, the total power calculation method of the power transmission line is as follows:
(1) within Ts minutes, the heat quantity Q required in the temperature rising stage of the anti-icing workLall
QLall＝Qall×LL；
(2) Heat quantity Q required in anti-icing working heat preservation stage every Ts minutesLon
QLon＝Qon×LL；
(3) Within Tu minutes, the heat Q required in the temperature rising stage of the ice melting workLa
QLa＝Qa×LL；
(4) Within Tw minutes, the heat quantity Q required in the ice melting stage of the ice melting workLas
QLas＝Qas×LL。
Claims (4)
1. A self-made hot wire based on a method for calculating the on-line anti-icing and ice-melting heat of a power transmission line comprises an inner conductor, an embedded material and an outer conductor, wherein the self-made hot wire is provided with a sensor, the sensor senses the temperature of the power transmission line and the current icing state of the power transmission line when the power transmission line works, predicts the future icing state of the power transmission line, automatically implements ice-melting work when a wire is iced, and implements anti-icing work when the wire is not iced but predicts the future possible icing;
the method is characterized in that: calculating the heat of the online anti-icing working state and the heat of the ice-melting working state respectively according to the two conditions of the anti-icing working state and the ice-melting working state of the self-made heat conductor;
when the ice coating is predicted to be possible in the future, starting the heat calculation of the anti-icing working state, wherein the anti-icing working state is divided into two stages, namely a temperature rise stage and a heat preservation stage; when the temperature of the power transmission conductor is less than 1 ℃, the anti-icing working state is in a temperature rise stage, when the temperature of the power transmission conductor is more than or equal to 1 ℃, the anti-icing working state is in the temperature rise stage, and the working time of the anti-icing working temperature rise stage is Ts minutes;
when the self-made heat conductor sensor judges that ice is covered, starting heat calculation of an ice melting working state, wherein the ice melting working state is divided into a temperature rise stage and an ice melting stage; the temperature rise stage refers to the process from the start of ice melting of the self-made heat conductor to 0 ℃, and the ice melting stage refers to the process of starting ice melting after the temperature of the conductor is raised to 0 ℃; setting the time required by the temperature rise stage to be Tu minutes and the time required by the ice melting process to be Tw minutes;
the method comprises the following steps that 1 meter long self-made hot wire is called a unit self-made hot wire, and when heat is calculated, the required heat of the unit self-made hot wire is firstly calculated, and then the total heat requirement of the power transmission line of the self-made hot wire with any length is calculated according to the requirement;
in the two stages of the anti-icing working state, the required heat in the temperature rising stage and the heat preservation stage is respectively calculated as follows:
the heat quantity required to be calculated in the temperature rising stage has three parts: the heat required by heating the lead to 1 ℃, the heat required by predicting ice coating in the future Ts minutes of melting of the lead and the heat of convection heat outside the lead are the sum of the heat required in the anti-icing working heating stage;
in the heat preservation stage of the anti-icing working state: when the temperature of the lead is raised to 1 ℃, the lead enters a heat preservation stage, and the anti-icing heat of the heat preservation stage comprises two parts: predicting the heat required by icing and the heat flow of convection heat dissipation outside the lead within the Ts minutes of the future melting of the lead;
in the two stages of the ice melting working state, the required heat of the temperature rising stage and the ice melting stage is respectively calculated as follows:
in the temperature rise stage of the ice melting working state, heat calculation comprises heat required by the temperature rise of a lead, heat required by the temperature rise of external ice to 0 ℃ and convection heat dissipation heat flow, and the sum of the three parts is the heat required by the temperature rise stage of the ice melting working state;
the heat required at the ice-melting stage in the ice-melting operating state is calculated as: when the temperature of the wire is measured to be 0 ℃ by the sensor, calculating the heat quantity of the ice melting stage, wherein the time required by the ice melting process is calculated according to Tw minutes, the heat quantity of the ice melting stage comprises the heat quantity required by ice melting, and the sum of the ice melting heat quantity required by ice coating in the Tw minutes in the future and the heat quantity required by heat dissipation resistance by convection is predicted;
the heat requirement of the transmission line of the homemade heat conducting wire with any length is that the actual length of the conducting wire in meters is multiplied by the heat required by the homemade heat conducting wire.
2. The method for calculating the on-line anti-icing and de-icing heat quantity of the power transmission line based on the homemade thermal conductor of claim 1, wherein the method comprises the following steps: the heat quantity calculation steps required to be calculated in the anti-icing working temperature rise stage of the unit self-made heat conducting wire are as follows:
1) calculating the heat required for the unit self-made heat wire to rise to 1 ℃:
before heating and temperature rising, the inner conductor, the embedded material and the outer conductor in the self-made heat conducting wire have the same temperature, and the temperature of the conducting wire before temperature rising is set as t1，t1<Setting the heat required by the lead to heat up to 1 ℃ at 1 ℃: the heat quantity required for the temperature rise of the inner conductor is Q1tQ is the amount of heat required for raising the temperature of the embedding material2tThe temperature of the outer conductor needs to be raisedIs Q3tThe sum of the three heats is Qup；Q1t、Q2t、Q3tThe calculation method is as shown in formula (3-1),
in the formula, r1Denotes the radius, r, of the inner conductor of the home-made wire2Denotes the radius, r, of the embedding material after it has wrapped around the inner conductor3Denotes the radius, r, of the entire wire after the outer conductor is wrapped around the embedding material1、r2、r3The unit of (a) is meter; the specific heat capacity of the inner conductor of the self-made lead is c1The specific heat capacity of the embedding material is c2The specific heat capacity of the outer conductor is c3(ii) a The unit of specific heat capacity is Joule per kilogram centigrade degree; density of inner conductor is rho1Density of the embedding material is rho2Density of outer conductor is rho3(ii) a The density units are kilograms per cubic meter;
2) and (3) calculating the heat quantity required by predicting ice coating in the future Ts minutes after the unit self-made hot wire melts:
let the ice coating weight of the unit self-made hot wire in the future Ts minute be g12And assuming that the temperature of the just-frozen ice coating layer is 0 ℃, the heat of fusion of ice is Lm,LmThe unit is joule per kilogram; the energy Q consumed to melt the icemAs shown in formula (3-2);
Qm＝g12·Lm(3-2)
3) and (3) calculating the convection heat dissipation outside the unit self-made heat conducting wire:
let the ambient temperature be tcThe surface heat transfer coefficient of air and the self-melting ice conductor is h, the unit of the surface heat transfer coefficient is watt per square meter, and the average heat flow phi of the convection heat transfer of the self-making ice conductor per unit of Ts minutessIs phis＝πr3h(1-tc) (3-3)
4) In the temperature rising stage, the unit self-made heat conducting wire needs the total heat Q for anti-icing of the heat conducting wire every Ts minutesallComprises the following steps:
Qall＝Qup+Qm+Фs×Ts×60 (3-4)
the heat calculation in the unit self-made heat conducting wire anti-icing work heat preservation stage is as follows:
when the temperature of the lead is raised to 1 ℃, the lead enters a heat preservation stage, and the anti-icing heat of the heat preservation stage comprises two parts: predicting the heat required by icing and the convection heat dissipation outside the lead within the Ts minute in the future of lead melting, wherein the temperature of the lead is 1 ℃ in the heat preservation stage, and the heat Q required by self-making the heat lead per unit of Ts minute in the heat preservation stageonComprises the following steps:
Qon＝g12·Lm+2πr3h(1-tc)×Ts×60 (3-5)
3. the method for calculating the on-line anti-icing and de-icing heat quantity of the power transmission line based on the homemade thermal conductor of claim 1, wherein the method comprises the following steps: the method comprises the following steps of:
1) the heat required by the unit self-made heat conducting wire for raising the temperature to 1 DEG C
The heat required by the temperature rise of the lead at 1 ℃ is the heat Q required by the temperature rise of the inner conductor at 1 DEG C1aThe heat quantity Q required for heating the heating material to 1 DEG C2aThe heat Q required by the temperature rise of the outer conductor at 1 DEG C3aSum, Q1a、Q2a、Q3aThe calculation method is as in formula (3-6)
2) The heat required by the unit for self-made heat conducting wire to raise the temperature of ice to 1 DEG C
The predicted future Tu minute is set to be g in the weight of ice coated on each meter of lead22The current ice weight per meter measured by the sensor is gsThe specific heat capacity of ice is ciThe heat Q required for the ice to rise to 1 DEG CiaIs composed of
Qia＝(0.5g22+gs)·ci(3-7)
3) Unit self-made heat conducting wire convection heat radiation heat flow
According to formula (3-8a) by (0.5 g)22+gs) Calculating the thickness of the ice coating, and assuming the thickness of the ice coating to be b, according to a Newton cooling formula, determining the average heat flow phi of the unit self-made heat conductor convection heat transfersIs composed of
Φs＝π(r3+b) h(0-tc) (3-8b)
ρiIs the density of ice in kilograms per cubic meter;
4) total heat quantity needed by unit self-made heat conducting wire in temperature rising stage
Setting the temperature of the wire at the beginning of temperature rise to tcTemperature rise time is Tu minutes, and the unit of temperature rise is the heat Q required by self-making of a heat wire in the temperature rise stageaComprises the following steps:
Qa＝-tc(Q1a+Q2a+Q3a+Qia)+Фs×Tu×60 (3-9)
the method comprises the following steps of calculating the heat required by a unit self-made hot wire in the ice melting stage in the ice melting working state:
1) the unit self-made heat wire melts the required heat:
the current ice weight per meter measured by the sensor is gmLet the predicted future Tw minutes be g ice coating weight per meter32，
Setting the heat required for melting ice as QawAnd then the heat required for ice melting is as follows:
Qaw＝(g32+gm)·Lm(3-10)
2) the unit self-made heat conducting wire resists the heat required by the convection heat dissipation:
according to formula (3-11a) by (g)32+gm) Calculating the thickness of the ice coating, and assuming that the thickness of the ice coating is c, calculating the heat flow phi of the convection heat transfer of the unit self-made heat conductorswIs composed of
Φsw＝2π(r3+c) h(0-tc) (3-11b)
3) Total heat quantity required by unit self-made heat conducting wire
Within Tw minutes, the total heat quantity Q required by the unit for self-made hot wire ice melting stageasComprises the following steps:
Qas＝Qaw+Φsw×Tw×60 (3-12)
4. the method for calculating the on-line anti-icing and de-icing heat quantity of the power transmission line based on the homemade thermal conductor of claim 1, wherein the method comprises the following steps: the heat requirement of the transmission line of the self-made heat conducting wire with any length is the length of the wire in meters multiplied by the heat required by the self-made heat conducting wire, and the specific calculation is as follows:
if the length of the power transmission line is LL meters, the total power calculation method of the power transmission line is as follows:
(1) heat quantity Q required in temperature rising stage of anti-icing operation every Ts minutesLall
QLall＝Qall×LL；
(2) Heat quantity Q required in anti-icing working heat preservation stage every Ts minutesLon
QLon＝Qon×LL；
(3) Heat Q required in the temperature rise stage of ice melting operation every Tu minutesLa
QLa＝Qa×LL；
(4) The heat quantity Q required by the ice melting stage of the ice melting work every Tw minutesLas
QLas＝Qas×LL。
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