Power transmission line wire icing water drop capture rate calculation method, system, equipment and medium

Abstract

The invention discloses a power transmission line wire icing water drop capture rate calculation method, system and device and a medium, and belongs to the technical field of power system power transmission line icing prediction.The method comprises the steps that data are collected, and a stress model of water drops near a live wire under the multi-source mechanical effect is established; establishing a water drop motion equation according to the influence of force on water drop motion in combination with the stress model; setting a water drop initial position and initial speed boundary condition, and solving the water drop motion equation by adopting a numerical method to obtain a water drop motion track; and performing statistical analysis according to the motion trail of the water drops, and calculating the capture rate of the ice-coated surface of the wire to the water drops. According to the method, six kinds of acting force such as electric field polarization force, viscous force, gravity, buoyancy, wind power and corona wind power are comprehensively considered, a complete water drop stress model is established, the polarization phenomenon of water drops in a non-uniform electric field is deeply analyzed, the influence of the polarization force on the motion trail of the water drops is accurately calculated, and the calculation precision and stability are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system transmission line icing prediction, and particularly relates to a transmission line conductor icing water droplet capture rate calculation method, system, device and medium. BACKGROUND

[0002] Transmission line icing is one of the important natural disasters threatening the safe operation of power systems. In the process of icing formation, the motion trajectory and capture rate of water droplets in a complex electromagnetic environment are key factors determining the distribution and thickness of icing. The existing technology mainly has the following problems: incomplete physical model: existing methods usually ignore the influence of electric field on water droplet motion, only consider gravity and air resistance, and cannot accurately describe the behavior of water droplets near the charged conductor. Insufficient consideration of electric field effect: there is a strong electric field around the transmission conductor, and water droplets as dielectric will produce polarization phenomenon, and are subjected to significant polarization force in non-uniform electric field, and the existing technology lacks in-depth analysis. Missing of multi-field coupling: there are various complex factors such as external wind field and ion wind generated by corona discharge in the actual environment, and there is coupling between various physical fields, and the existing method is difficult to consider comprehensively. Low numerical solution accuracy: traditional methods use simplified analytical solution or low-precision numerical method, which cannot meet the engineering precision requirement.

[0003] Therefore, it is urgent to develop a high-precision water droplet capture rate calculation method which can comprehensively consider the electric field effect and multi-physical field coupling. SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, the technical problem solved by the present application is: how to solve the following problems existing in the prior art: incomplete physical model: existing methods usually ignore the influence of electric field on water droplet motion, only consider gravity and air resistance, and cannot accurately describe the behavior of water droplets near the charged conductor. Insufficient consideration of electric field effect: there is a strong electric field around the transmission conductor, and water droplets as dielectric will produce polarization phenomenon, and are subjected to significant polarization force in non-uniform electric field, and the existing technology lacks in-depth analysis. Missing of multi-field coupling: there are various complex factors such as external wind field and ion wind generated by corona discharge in the actual environment, and there is coupling between various physical fields, and the existing method is difficult to consider comprehensively. Low numerical solution accuracy: traditional methods use simplified analytical solution or low-precision numerical method, which cannot meet the engineering precision requirement.

[0006] To solve the above technical problems, the application provides the following technical scheme: a method for calculating the water droplet capture rate of conductor icing of a power transmission line, which comprises collecting data and establishing a force model of a water droplet under the action of multiple source mechanics near a live conductor; combining the force model to establish a water droplet motion equation according to the influence of force on water droplet motion; setting boundary conditions of the initial position and initial velocity of the water droplet, and solving the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory; and performing statistical analysis according to the water droplet motion trajectory to calculate the capture rate of the water droplet by the conductor icing surface.

[0007] As a preferred scheme of the method for calculating the water droplet capture rate of conductor icing of a power transmission line, the collecting data and establishing a force model of a water droplet under the action of multiple source mechanics near a live conductor comprises extracting various external forces affecting water droplet motion according to the electrical structure of the conductor and meteorological conditions; classifying and combing the direction characteristics and influence mechanisms of various external forces to clearly define the distribution characteristics of various external forces at different spatial positions; and combining the motion state of the water droplet near the power transmission conductor to express and integrate various external forces in a unified coordinate system to construct the force model under the action of multiple source mechanics.

[0008] As a preferred scheme of the method for calculating the water droplet capture rate of conductor icing of a power transmission line, the combining the force model to establish a water droplet motion equation according to the influence of force on water droplet motion comprises listing the expressions of forces affecting water droplet motion based on the force model; constructing a water droplet motion differential equation set according to Newton's second law; and substituting environmental factor parameters affecting water droplet motion into the equation set.

[0009] As a preferred scheme of the method for calculating the water droplet capture rate of conductor icing of a power transmission line, the setting boundary conditions of the initial position and initial velocity of the water droplet, and solving the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory comprises setting the initial position and velocity boundary conditions of the water droplet on a release plane; selecting a numerical integration method suitable for a nonlinear differential equation set to numerically solve the water droplet motion equation; obtaining the motion trajectory of the water droplet in a three-dimensional space and recording path information.

[0010] As a preferred scheme of the method for calculating the water droplet capture rate of conductor icing of a power transmission line, the constructing a force model under the action of multiple source mechanics comprises identifying typical external forces to which the water droplet is subjected during motion based on parameter information related to the conductor and the environment; considering the polarization effect of a non-uniform electric field, the viscous drag caused by air flow, and the combined action of gravity and buoyancy; introducing external wind force and corona wind force in the force model to form a complete force model containing six main external forces.

[0011] The preferred scheme forms a complete modeling system of six main external forces by simultaneously introducing electric field polarization, air viscous resistance, gravity, buoyancy, external wind force and corona wind force in the force model, so that the water droplet force environment can be consistent with the actual transmission line icing scene, thereby improving the physical authenticity and engineering applicability of the water droplet motion simulation result.

[0012] As a preferred scheme of the transmission line conductor icing water droplet capture rate calculation method, the numerical integration method suitable for the nonlinear differential equation set is selected, including using the fourth-order Runge-Kutta method to perform numerical integration on the water droplet motion differential equation set; an error estimation mechanism is introduced in the integration process to evaluate the local error of each calculation in real time; and the integration step is dynamically adjusted according to the error evaluation result to control the numerical error within a preset tolerance range.

[0013] The preferred scheme can significantly reduce invalid calculation while ensuring that the calculation accuracy meets the standard, and improve the numerical stability and overall calculation efficiency of the complex water droplet trajectory solving process.

[0014] As a preferred scheme of the transmission line conductor icing water droplet capture rate calculation method, the statistical analysis according to the water droplet motion trajectory is performed to calculate the capture rate of the conductor icing surface to the water droplet, including setting a water droplet release plane on the downwind side of the conductor, releasing water droplets at different heights and positions and recording the number; tracking the three-dimensional motion trajectory of each water droplet to determine whether it enters the area where the conductor icing surface is located and contact occurs; and counting the number of water droplets captured by the conductor icing area and comparing it with the total number of released water droplets to calculate the water droplet capture rate.

[0015] The preferred scheme realizes quantitative calculation of the capture rate of the conductor icing area by setting a release plane and tracking the trajectory of each water droplet, and combining collision determination to count the capture number, which can accurately reflect the capture difference under different height, wind speed and voltage conditions, and provide data support for icing risk prediction.

[0016] The application provides a transmission line conductor icing water droplet capture rate calculation system.

[0017] To solve the above technical problems, the present application provides the following technical solutions: a power transmission line conductor icing water droplet capture rate calculation system, comprising: a modeling module, an equation establishing module, a solving module and an output module; the modeling module is used to collect data, and establish a stress model of water droplets under the action of multiple source forces near a live conductor; the equation establishing module is used to establish a water droplet motion equation according to the influence of forces on water droplet motion in combination with the stress model; the solving module is used to set initial position and initial velocity boundary conditions of water droplets, and solve the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory; and the output module is used to statistically analyze the water droplet motion trajectory, and calculate the capture rate of the conductor icing surface to water droplets.

[0018] The present application provides a computer device, comprising a memory and a processor, the memory stores a computer program, characterized in that the processor implements the steps of the power transmission line conductor icing water droplet capture rate calculation method when executing the computer program.

[0019] The present application provides a computer readable storage medium, which stores a computer program, characterized in that the computer program is executed by a processor to implement the steps of the power transmission line conductor icing water droplet capture rate calculation method.

[0020] The present application has the following beneficial effects: The physical model of the present application is complete: for the first time, six kinds of forces, including electric field polarization force, viscous force, gravity, buoyancy, wind force and corona wind force, are comprehensively considered, and a complete water droplet stress model is established.

[0021] Accurate modeling of electric field effect: the polarization phenomenon of water droplets in a non-uniform electric field is analyzed in depth, and the influence of polarization force on the water droplet motion trajectory is accurately calculated.

[0022] Multi-physical field coupling: the coupling effects of electric field, flow field, gravity field and other multi-physical fields are comprehensively considered, which more accurately reflects the actual physical process.

[0023] High numerical solution accuracy: the fourth-order Runge-Kutta method and adaptive step control are used, which significantly improves the calculation accuracy and stability.

[0024] Strong engineering applicability: the method is applicable to power transmission line icing analysis under different voltage levels and different weather conditions. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows: obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 A flow chart of a method for calculating the water droplet capture rate of an iced conductor of a power transmission line according to an embodiment of the present application is shown in FIG. 1.

[0027] Figure 2 A flow chart of a method for calculating the water droplet capture rate of an iced conductor of a power transmission line according to an embodiment of the present application is shown in FIG. 1.

[0028] Figure 3 A schematic diagram of the force on a water droplet in an electric field according to an embodiment of the present application is shown in FIG. 2.

[0029] Figure 4 A flow chart of a method for calculating the water droplet capture rate of an iced conductor of a power transmission line according to an embodiment of the present application is shown in FIG. 1. DETAILED DESCRIPTION

[0030] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work should fall within the protection scope of the present application.

[0031] Embodiment 1, with reference to Figure 1 and Figure 2 According to an embodiment of the present application, the embodiment provides a method for calculating the water droplet capture rate of an iced conductor of a power transmission line, comprising:

[0032] S1, collecting data and establishing a force model of a water droplet under the action of multiple sources of force near a live conductor.

[0033] S2, establishing a water droplet motion equation according to the influence of force on water droplet motion in combination with the force model.

[0034] S3, setting initial position and initial velocity boundary conditions of the water droplet, and solving the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory.

[0035] S4, statistically analyzing the water droplet motion trajectory and calculating the capture rate of the water droplet by the iced surface of the conductor.

[0036] It should be noted that in the actual operation process of the power transmission line, the water droplet is affected by multiple external forces under the combined action of strong electric field and complex wind field, and the trajectory of the water droplet has significant uncertainty. Through the steps S1-S4, the force condition of the water droplet can be accurately characterized in a unified modeling framework, and the actual motion trajectory of the water droplet can be simulated by combining the numerical method, and finally the quantitative calculation of the water droplet capture rate in the icing area is realized, which provides a reliable basis for the icing risk prediction and prevention measures.

[0037] Embodiment 2, refer to Figure 3 and Figure 4 , one embodiment of the present application, based on the last embodiment provides a kind of power transmission line conductor icing water droplet capture rate calculation method, comprising:

[0038] In the embodiment of the application, the force model under the action of multiple source mechanics in step S1 is based on the conductor and environmental parameters, to establish six kinds of main force models of water droplet in non-uniform electric field polarization force, air viscous force, gravity and buoyancy, external wind force and corona wind force, to form the complete system of external force of water droplet near the power transmission conductor. By accurately modeling the above six kinds of external forces, the hydrodynamic behavior of water droplet under the running environment of power transmission conductor can be truly restored, which provides a physical basis for subsequent water droplet trajectory calculation and capture rate evaluation.

[0039] In an alternative embodiment, the force model under the action of multiple source mechanics can also be a simplified model considering only the water droplet in the electric field and air resistance, i.e. to construct two dominant forces of polarization force and viscous resistance, to be applicable to the power transmission line scene with lower voltage level and weaker wind field.

[0040] In another alternative embodiment, the force model under the action of multiple source mechanics can also be an equivalent force field model constructed based on statistical characteristics, i.e. without modeling each type of physical force separately, but by training the synthetic equivalent force field from historical data, and inputting the force field into the motion equation instead of multiple source terms.

[0041] The present application can comprehensively include the main physical forces in various typical power transmission scenarios such as electric field, airflow, gravity field, etc. in the modeling process, ensuring the completeness of the water droplet dynamic behavior simulation and the accuracy of the engineering application, and significantly improving the reliability of the capture rate evaluation.

[0042] Further, in step S1, data is collected to establish a force model of water droplet under the action of multiple source mechanics near the charged conductor, comprising the following steps A1-A3:

[0043] A1, according to the electrical structure of the conductor and the meteorological conditions, extract various external forces affecting the motion of water droplet.

[0044] A2, classify the direction characteristics and influence mechanism of various external forces, and clarify the distribution characteristics of various external forces in different spatial positions.

[0045] A3, combine the motion state of water droplets near the transmission conductor, express and integrate various external forces in a unified coordinate system, and construct a force model under the action of multiple source mechanics.

[0046] Specifically, in step A1, the conductor radius, conductor height, working voltage, environmental temperature, wind speed and liquid water content information are collected.

[0047] Specifically, in step A1, various external forces include polarization effect caused by non-uniform electric field, viscous drag caused by air flow, gravity, buoyancy, external wind force and corona wind force.

[0048] Further, in step A3, based on the analysis results, a force model under the action of multiple source mechanics is constructed, including steps A31-A33:

[0049] A31, based on the parameter information related to the conductor and the environment, identify the typical external force received by the water droplet during the motion process.

[0050] A32, consider the combined action of polarization effect caused by non-uniform electric field, viscous drag caused by air flow, gravity and buoyancy.

[0051] A33, introduce external wind force and corona wind force in the force model, and form a complete force description system containing six main external forces. As shown in Figure 3 .

[0052] Specifically, in step A32, the electric field polarization modeling when the water droplet enters the non-uniform electric field around the conductor, due to the relative dielectric constant of water being much larger than that of air, polarization phenomenon will occur inside the water droplet. The polarization force received by the polarized water droplet in the non-uniform electric field is:

[0053]

[0054] Wherein, the polarization rate a is calculated according to the geometric shape and dielectric properties of the water droplet:

[0055]

[0056] Wherein, ε o is the vacuum dielectric constant (8.854×10 -12 F / m), ε r is the relative dielectric constant of water (about 81), and r is the water droplet radius (m).

[0057] The direction of the polarization force on the polarized water droplet in the non-uniform electric field points to the direction where the electric field intensity increases, which is a key factor affecting the trajectory of the water droplet.

[0058] The air viscous resistance modeling considers the movement of the water droplet in the air, and adopts a modified Stokes resistance formula:

[0059]

[0060] wherein, N is the air viscous resistance (N), μ is the air dynamic viscosity (Pa·s), V is the velocity of the water droplet relative to the air (m / s), C a is the resistance correction coefficient (dimensionless)

[0061] The resistance correction coefficient C a The Reynolds number effect is considered:

[0062] C a = (24 / Re) (1+0.15Re ∧ 0.687)

[0063] The gravity and buoyancy modeling, gravity:

[0064]

[0065] Buoyancy:

[0066]

[0067] wherein, G is the gravity (N), ρ is the density of water (kg / m 3 ), g → is the gravity acceleration vector (m / s 2 ), F is the buoyancy (N), ρ is the air density (kg / m 3 ).

[0068] The external wind force modeling considers the effect of the environmental wind field on the water droplet, and the wind speed profile is described by a logarithmic law:

[0069]

[0070] wherein, u is the wind speed vector at height z (m / s), u * is the friction velocity (m / s), κ is the Karman constant (≈0.4), z is the height from the ground (m), z0 is the ground roughness (m), is the direction unit vector.

[0071] The corona wind force models the ion flow generated by the corona discharge around the high-voltage conductor to form a corona wind:

[0072]

[0073] wherein, is the corona wind force (N), β is the ion mobility (m 2 / (V·s)), ρ ion is the ion density (C / m 3 ), E → is the electric field strength vector (V / m), V arop is the water droplet volume (m 3 )

[0074] Further, in step S2, a water droplet motion equation is established according to the influence of forces on the water droplet motion in combination with the force model, including the following steps B1-B3:

[0075] B1. Expressions of forces affecting the water droplet motion are listed based on the force model.

[0076] B2. A water droplet motion differential equation set is constructed according to Newton's second law.

[0077] B3. Environmental factor parameters affecting the water droplet motion are substituted into the equation set.

[0078] In the embodiments of the present application, the water droplet motion differential equation set constructed according to Newton's second law in step B2 is based on the established force model under the action of multiple source forces, respectively taking the polarization force, viscous force, gravity, buoyancy, external wind force and corona wind force as input items, and substituting them into the expression of Newton's second law to form a water droplet acceleration calculation formula with velocity as an unknown quantity; in combination with the water droplet mass parameter, a complete water droplet acceleration-velocity-position three-dimensional coupled dynamic equation set is constructed to describe the change of the water droplet motion state under the action of forces. The equation set can comprehensively depict the dynamic behavior of the water droplet changing with time in three-dimensional space.

[0079] In an alternative embodiment, the water droplet motion differential equation set constructed according to Newton's second law can also consider only dominant force items such as gravity, viscous force and polarization force to construct a simplified dynamic model, and omit the buoyancy, wind force and corona wind force items according to empirical rules to simplify the equation structure and improve the solving efficiency, which is suitable for fast simulation scenarios.

[0080] In another alternative embodiment, the water droplet motion differential equation set constructed according to Newton's second law can also only calculate the linear change relationship of the current velocity and acceleration at each time step, without solving the complete equation system, but simulating the water droplet displacement change through piecewise iteration approximation, which is used for data-driven fast trajectory estimation.

[0081] The application can truly reflect the dynamic behavior of water droplets in a non-uniform electric field and a high wind speed environment by uniformly substituting a plurality of actually existing physical forces into a Newton second law framework to construct a differential equation set, and provide a clear structure and physically reasonable equation basis for high-precision numerical solution.

[0082] In the embodiments of the application, the environmental factor parameters affecting the water droplet motion in step B3 can be substituted into the equation set according to the current meteorological conditions and the operating state of the power transmission conductor, and representative parameters in the environment are selected as input items, including air density, air dynamic viscosity, wind speed profile, water droplet radius, conductor voltage, conductor radius and height from the ground, etc. The above parameters are substituted into the expression of each force term in the constructed water droplet motion differential equation set respectively, to realize the numerical representation of the polarization force, viscous drag, gravity, buoyancy, wind force and corona wind force, complete the quantitative processing of the motion model, and provide an input basis for subsequent numerical integration.

[0083] In an alternative embodiment, the environmental factor parameters affecting the water droplet motion substituted into the equation set can also be for standard working conditions or typical power transmission line scenes, and a preset static parameter group, such as fixed wind speed, temperature, voltage level and conductor size, etc. is directly input into the equation set, without real-time collection or dynamic updating, and is suitable for model evaluation in a stable environment.

[0084] In another alternative embodiment, the environmental factor parameters affecting the water droplet motion substituted into the equation set can also be dynamically read by linkage with an external monitoring system or weather data interface, and real-time parameters such as wind speed, voltage and temperature are periodically updated and substituted into the motion model, to realize online dynamic simulation of the water droplet behavior.

[0085] The application can effectively map key meteorological and line parameters into the differential equation set, so that the water droplet motion simulation process has high scene adaptability and data driving property, and the accuracy and practicality of the model under different working conditions are improved, to provide a solid data basis for the capture rate calculation.

[0086] Specifically, based on the Newton second law, a differential equation set of water droplet motion is established:

[0087] Dynamical equation:

[0088]

[0089] wherein m is the mass of the water droplet (kg), dv → / dt is the derivative of the velocity with respect to time, i.e. the acceleration (m / s 2 ), and t is the time (s).

[0090] Geometric equation:

[0091] dr →dt = v →

[0092] where dr → is the derivative of position with respect to time, i.e. velocity (m / s); r → is the position vector (m); v → is the velocity vector (m / s).

[0093] The system of equations fully describes the motion of the water droplet in three-dimensional space.

[0094] Electric field distribution calculation:

[0095] The mirror image method is used in the case of a single wire, and the electric field distribution around the wire is:

[0096] E r = V / [r ln (2h / r0)]

[0097] where E r is the radial electric field strength (V / m), V is the wire voltage (V), h is the wire height above ground (m), and r0 is the wire radius (m).

[0098] The superposition principle is used to calculate the composite electric field of multi-phase conductors in the case of multiple wires:

[0099]

[0100] The electric field gradient calculation calculates the electric field strength gradient in the cylindrical coordinate system:

[0101]

[0102] where, is the unit vector of the cylindrical coordinate system, is the partial derivative operator.

[0103] In the embodiments of the present application, the water droplet motion equation is solved by a numerical method in step S3 to obtain the water droplet motion trajectory, which can be based on the fourth-order Runge-Kutta method to solve the water droplet motion differential equation set established by the force model, and an error estimation mechanism is introduced during the integration process to evaluate the local error of each integration step in real time; the step size is dynamically adjusted according to the error estimation result to ensure that the error of the numerical solution is always controlled within the set tolerance range, thereby obtaining the continuous trajectory of the water droplet in three-dimensional space.

[0104] In an alternative embodiment, the water droplet motion equation is solved by a numerical method to obtain the water droplet motion trajectory, which can also be a fixed step explicit Euler method for numerical integration, and the trajectory changes at key time points are discretely sampled to estimate the motion path, which is used to quickly estimate the overall motion trend of the water droplet.

[0105] In another alternative embodiment, the water droplet motion equation is solved by a numerical method, and the water droplet motion trajectory can also be constructed based on existing scene simulation results to build an interpolation or fitting model, and the water droplet trajectory trend is quickly obtained by querying a table or a function mapping without real-time integral operation.

[0106] The present application can balance the calculation accuracy and efficiency when dealing with water droplet motion problems with strong nonlinear characteristics, ensure the numerical stability and convergence in the trajectory prediction process, and provide a reliable basis for subsequent capture judgment and risk assessment by using a high-order numerical integral method with an adaptive step size control mechanism.

[0107] Further, in step S3, the initial position and initial velocity boundary conditions of the water droplet are set, and the water droplet motion equation is solved by a numerical method to obtain the water droplet motion trajectory, including steps C1-C3:

[0108] C1, set the initial position and velocity boundary conditions of the water droplet on the release plane.

[0109] C2, select a numerical integral method suitable for nonlinear differential equation sets to numerically solve the water droplet motion equation. Figure 4 As shown.

[0110] C3, obtain the motion trajectory of the water droplet in three-dimensional space and record the path information.

[0111] Specifically, in step C2, a numerical integral method suitable for nonlinear differential equation sets is selected to numerically solve the water droplet motion equation, including steps C21-C23:

[0112] C21, the fourth-order Runge-Kutta method is used to numerically integrate and solve the water droplet motion differential equation set.

[0113] The high-precision integral algorithm uses the fourth-order Runge-Kutta method to solve the ordinary differential equation set, ensures numerical stability and calculation accuracy, and is suitable for solving strong nonlinear systems.

[0114] C22, an error estimation mechanism is introduced in the integral process to evaluate the local error of each calculation in real time.

[0115] C23, dynamically adjust the integral step size according to the error evaluation result to control the numerical error within the preset tolerance range.

[0116] The adaptive step size control realizes the adaptive step size control mechanism:

[0117] h (new) = h (old) (εtol / ε est ) ∧ (1 / 5)

[0118] wherein h (new) is the new time step (s), h (old) is the old time step (s), ε tol is the tolerance error, and ε est is the estimation error. The calculation efficiency is improved while ensuring the calculation accuracy.

[0119] Specifically, in step C3, the water droplet breaking judgment is based on the Weber number to determine whether the water droplet breaks:

[0120] We = p air v 2 d / σ

[0121] wherein We is the Weber number (dimensionless), d is the water droplet diameter (m), and σ is the surface tension (N / m).

[0122] We orit is the critical Weber number, and when We > We orit , the water droplet breaks, and the water droplet size distribution is updated.

[0123] The water droplet evaporation treatment considers the evaporation phenomenon of the water droplet during movement:

[0124] dm / dt = -4πrD v (ρ v,s -ρ v,∞ )

[0125] wherein dm / dt is the mass change rate (kg / s), D v is the water vapor diffusion coefficient (m 2 / s), p v,s is the water droplet surface water vapor density (kg / m 3 ), and p v,∞ is the far-field water vapor density (kg / m 3 ).

[0126] Further, in step S4, statistical analysis is performed according to the water droplet movement trajectory to calculate the capture rate of the conductor icing surface to the water droplet, including the following steps D1-D3:

[0127] D1, a water droplet release plane is arranged on the leeward side of the conductor, and water droplets are released at different heights and positions and numbered.

[0128] D2, the three-dimensional movement trajectory of each water droplet is tracked to determine whether it enters the area where the conductor icing surface is located and contacts.

[0129] D3, count the number of water droplets captured in the ice-coated area of the conductor, and compare it with the total number of released water droplets to calculate the water droplet capture rate.

[0130] Specifically, in step D2, trajectory tracking is performed on a large number of water droplets, and the motion history of each water droplet is recorded. Collision detection determines whether the water droplet collides with the ice-coated surface of the conductor:

[0131]

[0132] wherein, is the water droplet position vector (m), is the conductor position vector (m), r i c e is the ice radius (m).

[0133] Specifically, in step D3, the capture rate calculation counts the proportion of captured water droplets:

[0134] η=(N oapturea / N total )×100%

[0135] wherein, η is the capture rate (%), N oapturea is the number of captured water droplets, and N total is the total number of water droplets.

[0136] Example 3 is an embodiment of the present application, which provides a method for calculating the water droplet capture rate of the ice-coated conductor of a power transmission line. In order to verify the beneficial effects of the present application, scientific demonstration is carried out through experiments.

[0137] This embodiment takes a 220kV single conductor as an example to illustrate the implementation process of the method of the present application in detail.

[0138] Step 1, parameter setting.

[0139] Conductor radius r0=0.015m, conductor height h=20m, working voltage V=220 / √3kV, ambient temperature T=-2℃, wind speed v wind =5m / s, liquid water content LWC=0.5g / m 3 .

[0140] Step 2, initialization calculation.

[0141] Electric field distribution calculation: according to the image method, the electric field intensity distribution around the conductor is calculated. At different positions from the surface of the conductor, the electric field intensity decays according to the law of 1 / r.

[0142] Determination of physical property parameters: air density ρ air =1.293kg / m3, air viscosity μ=1.789×10 -5 Pa·s, water dielectric constant εr = 81.

[0143] Step three, force analysis process.

[0144] For any position of the water droplet, calculate each force according to the following steps:

[0145] Step1: Electric field strength calculation According to the current position of the water droplet (x, y, z), calculate the electric field strength E of the point → And the gradient

[0146] Step2: Polarization force calculation Water droplet polarization rate α, and then get the polarization force

[0147] Step3: Resistance calculation Based on the relative speed of the water droplet and the Reynolds number, calculate the air resistance

[0148] Step4: Other force calculation Gravitational force, buoyancy, wind force and corona wind force.

[0149] Step four, numerical solution process.

[0150] Initial condition setting: Set the release plane at 10 times the diameter of the wire upstream of the wire, and uniformly distribute N water droplets.

[0151] Time step solution:

[0152] Foreach timestep:

[0153] Foreach droplet:

[0154] 1.Calculate for cesat current position

[0155] 2.Update velocity using RK4 method

[0156] 3.Update position

[0157] 4.Checkcollisionwithwiresurface

[0158] 5.Update droplet properties(evaporation,breakup)

[0159] End For

[0160] Update time: t = t + dt

[0161] End For

[0162] Convergence check: The reliability of the numerical solution is ensured by mesh independence verification and time step sensitivity analysis.

[0163] Step five, result analysis.

[0164] Through statistical analysis, the water droplet capture rate η = 0.85 under this working condition is obtained, that is, 85% of the water droplets can be captured by the wire surface.

[0165] Embodiment 4 is an embodiment of the present application, which provides a power transmission line wire icing water droplet capture rate calculation system, comprising a modeling module, an equation establishing module, a solving module and an output module.

[0166] The modeling module is used to collect data and establish a force model of water droplets under the action of multiple source forces near a live wire.

[0167] The equation establishing module is used to establish a water droplet motion equation according to the influence of forces on water droplet motion in combination with the force model.

[0168] The solving module is used to set initial position and initial velocity boundary conditions of water droplets, and solve the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory.

[0169] The output module is used to perform statistical analysis according to the water droplet motion trajectory, and calculate the capture rate of water droplets on the wire icing surface.

[0170] The embodiment also provides an electronic device suitable for a power transmission line wire icing water droplet capture rate calculation method, comprising a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize a power transmission line wire icing water droplet capture rate calculation method as proposed in the above embodiment.

[0171] The embodiment also provides a storage medium having a computer program stored thereon, which is executed by a processor to realize a power transmission line wire icing water droplet capture rate calculation method as proposed in the above embodiment.

[0172] The storage medium proposed in the embodiment and the power transmission line wire icing water droplet capture rate calculation method proposed in the above embodiment belong to the same inventive concept, and the technical details not described in detail in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0173] From the above description of the embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software and necessary universal hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a floppy disk, a ROM, a RAM, a FLASH, a hard disk, or an optical disc, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of various embodiments of the present application.

[0174] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all of them should be covered in the scope of the claims of the present application.

Claims

1. A method for calculating the ice accretion droplet capture efficiency of a power line conductor, the method comprising: The application relates to a method for calculating the capture rate of water droplets on an icing surface of a power transmission line. ​ The method comprises the following steps: collecting data and establishing a force model of water droplets under the action of multiple sources of mechanics near a charged conductor; establishing a water droplet motion equation according to the influence of forces on water droplet motion in combination with the force model; setting boundary conditions of initial position and initial velocity of water droplets, solving the water droplet motion equation by using a numerical method, and obtaining a water droplet motion trajectory; 2. A method of calculating the water droplet trapping efficiency of an ice-covered conductor of a power transmission line according to claim 1, characterized in that: statistically analyzing the water droplet motion trajectory and calculating the capture rate of water droplets on the icing surface of the conductor. The method for collecting data and establishing a force model of water droplets under the action of multiple sources of mechanics near a charged conductor comprises the following steps: extracting various external forces influencing water droplet motion according to the electrical structure of the conductor and meteorological conditions; classifying and combing the direction characteristics and influencing mechanisms of various external forces, and clearly defining the distribution characteristics of various external forces at different spatial positions; 3. A method of calculating the ice accretion droplet collection efficiency of a power line conductor as defined in claim 2 wherein: expressing and integrating various external forces in a unified coordinate system in combination with the motion state of water droplets near the power transmission conductor, and constructing a force model under the action of multiple sources of mechanics. The method for establishing a water droplet motion equation according to the influence of forces on water droplet motion in combination with the force model comprises the following steps: listing the expressions of forces influencing water droplet motion based on the force model; constructing a water droplet motion differential equation set according to Newton's second law; 4. A method of calculating the ice accretion droplet collection efficiency of a power line conductor as defined in claim 3 wherein: substituting environmental factor parameters influencing water droplet motion into the equation set. The method for setting boundary conditions of initial position and initial velocity of water droplets, solving the water droplet motion equation by using a numerical method, and obtaining a water droplet motion trajectory comprises the following steps: setting boundary conditions of initial position and velocity of water droplets on a release plane; selecting a numerical integration method suitable for a nonlinear differential equation set to numerically solve the water droplet motion equation; 5. A method of calculating the ice accretion droplet collection efficiency of a power line conductor as defined in claim 4 wherein: obtaining a water droplet motion trajectory in a three-dimensional space and recording path information. The method for constructing a force model under the action of multiple sources of mechanics comprises the following steps: identifying typical external forces to which water droplets are subjected in a motion process based on parameter information related to the conductor and the environment; respectively considering the polarization effect of uneven electric fields, the viscous drag caused by air flow, the comprehensive action of gravity and buoyancy; 6. A method of calculating the ice accretion droplet collection efficiency of a power line conductor as defined in claim 5 wherein: introducing external wind force and corona wind force into the force model to form a complete force model containing six main external forces. The method for selecting a numerical integration method suitable for a nonlinear differential equation set comprises the following steps: adopting a fourth-order Runge-Kutta method to numerically integrate and solve the water droplet motion differential equation set; introducing an error estimation mechanism in the integration process to real-time evaluate the local error of each step of calculation; dynamically adjusting the integration step length according to the error evaluation result to control the numerical error within a preset tolerance range.

7. A method of calculating the ice accretion droplet collection efficiency of a power line conductor as defined in claim 6 wherein: The method for statistically analyzing a water droplet motion trajectory and calculating the capture rate of water droplets on the icing surface of a conductor comprises the following steps: setting a water droplet release plane on the leeward side of the conductor, releasing water droplets at different heights and positions and recording the numbers; tracking the three-dimensional motion trajectory of each water droplet, judging whether the water droplet enters the region where the icing surface of the conductor is located and whether contact occurs; counting the number of water droplets captured by the icing region of the conductor and comparing the number with the total number of released water droplets to calculate the water droplet capture rate.

8. A system for calculating the water droplet capture efficiency of an ice-coated conductor of a power transmission line, which applies the method for calculating the water droplet capture efficiency of an ice-coated conductor of a power transmission line according to any one of claims 1 to 7, characterized by The application further relates to a water droplet capture rate calculation device. The device comprises a modeling module, an equation establishing module, a solving module and an output module. The modeling module is used for collecting data and establishing a force model of water droplets under the action of multiple sources of mechanics near a charged conductor. The equation establishing module is configured to establish a water droplet motion equation according to the influence of force on the water droplet motion based on the force model; The solving module is configured to set initial position and initial velocity boundary conditions of the water droplet, and solve the water droplet motion equation by using a numerical method to obtain a water droplet motion trajectory; The output module is configured to perform statistical analysis according to the water droplet motion trajectory, and calculate a capture rate of the water droplet by the iced surface of the conductor. 9.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-8 when the computer program is executed by the processor. The processor executes the computer program to implement the steps of the method for calculating the water droplet capture rate of the iced conductor of the power transmission line according to any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the method for calculating the water droplet capture rate of the iced conductor of the power transmission line according to any one of claims 1 to 7.

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