Method for judging and analyzing vibration deicing effectiveness of current collection line unmanned aerial vehicle

Abstract

The invention discloses a current collection line unmanned aerial vehicle vibration deicing effectiveness judgment and analysis method, and the method comprises the steps: building an ice coating falling judgment criterion, analyzing the critical acceleration of a power transmission line under different impact vibrations, building an equivalent power transmission line ice coating falling model, and analyzing the overhead line deicing under the impact vibrations. According to the method, reference is provided for solving and analyzing overhead line impact vibration deicing and researching overhead transmission line vibration deicing.

Description

Technical Field

[0001] The present invention relates to a method for judging and analyzing the effectiveness of vibration de-icing of a collector line by an unmanned aerial vehicle, and belongs to the technical field of transmission line condition monitoring and diagnosis. Background Art

[0002] Icing on transmission lines is a common natural phenomenon. After severe ice and snow weather, serious icing on the lines may cause overload of the transmission lines. In severe cases, it may lead to wire breakage, damage to fittings, and even continuous tower collapse of the transmission lines, and even serious accidents such as continuous discharge and explosion of substation equipment. When the conductor is severely unevenly iced, the uneven icing of the conductors at both ends of the iron tower will generate serious unbalanced tension, causing varying degrees of damage to the iron tower, manifested as bending and collapse of the tower head, bending and deformation of the tower body, or serious damage to structural members such as the ground wire support and conductor cross arm, resulting in large-scale power supply interruption and endangering the stable and continuous operation of the power grid.

[0003] Therefore, to solve the problem of live ice removal on the line, a method for judging and analyzing the effectiveness of vibration de-icing of a collector line by an unmanned aerial vehicle is proposed. By applying an impact load to the conductor, vibration is generated to cause "induced de-icing", providing a basis for the de-icing plan. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for judging and analyzing the effectiveness of vibration de-icing of a collector line by an unmanned aerial vehicle. This method establishes a criterion for judging ice shedding, analyzes the critical acceleration of the transmission line under different impact vibrations, establishes an equivalent transmission line ice shedding model, and then analyzes the ice shedding of the overhead line under impact vibration to provide a plan for transmission line de-icing.

[0005] The technical solution adopted by the present invention is a method for judging and analyzing the effectiveness of vibration de-icing of a collector line by an unmanned aerial vehicle, including the following steps:

[0006] Step 1: Collect and process the parameters of the on-site transmission line, icing, and ice shedding parameters through an unmanned aerial vehicle and a monitoring system;

[0007] Step 2: Based on the preprocessing and analysis data, and based on the criterion for judging ice shedding, establish an equivalent transmission line ice shedding model;

[0008] Step 3: According to the equivalent transmission line ice shedding model, establish an impact load to simulate the vibration received by the line and conduct an analysis of ice shedding of the overhead line.

[0009] Among them, Step 1 is specifically implemented according to the following steps:

[0010] Step 1.1: Use an unmanned aerial vehicle to carry high-precision equipment to measure the sag, span, suspension height of the conductor, and the distance between towers, and extract the conductor diameter, insulator string length, etc. by combining image processing technology.

[0011] Step 1.2: Use a tensile sensor to monitor the change in wire tension, analyze the weight of the ice on the wire, and use a vibration sensor to capture the vibration frequency and amplitude of the wire to analyze the dynamic characteristics of ice shedding.

[0012] Step 1.3: Preprocess the data collected by the drone and the monitoring system.

[0013] Among them, Step 2 is specifically implemented according to the following steps:

[0014] Step 2.1: Considering the adhesion and cohesion of the ice, during the vibration of the wire under impact load, when the resultant force of the inertial force and gravity acting on the ice is greater than the adhesion and cohesion, the ice is considered to have shed at this time;

[0015] Step 2.2: The condition for ice shedding on the overhead line satisfies the following expression:

[0016] F inertia ±G≥F adhesive +F cohesive (1)

[0017] Among them, F inertia is the inertial force acting on the ice unit, G is the gravity of the ice, F adhesive is the bonding force, and F cohesive is the cohesion of the ice.

[0018] In formula (1), the “+” and “-” on the left side of the inequality respectively represent the upper and lower parts of the ice. After expressing each term in the formula with acceleration, we get:

[0019]

[0020] F adhesive =D cable Lτ adhesive (4)

[0021] F cohesive =(D - D cable )Lτ cohesive (5)

[0022] In formulas (2) - (5), ρ ice is the density of the ice, a is the lateral acceleration during the galloping of the wire, L is the length of the ice unit, D is the outer diameter of the ice, D cable is the outer diameter of the overhead transmission line, τ adhesive is the bonding strength between the ice and the overhead transmission wire, and τ cohesive is the cohesion inside the ice.

[0023] Substitute the above parameters into formula (1), move the terms and simplify to obtain the acceleration determination expression for ice shedding:

[0024]

[0025] Step 2.3: Determine the ice shedding condition. The ice shedding of the transmission line under impact load is only restricted by the acceleration a. When the actual acceleration a of the transmission line with ice satisfies a ≥ a (where a is the critical acceleration in the ice shedding determination criterion) after being subjected to the impact load, it is determined that the ice has shed, i.e.:

[0026] a 实 ≥ a 临 (7)

[0027] Among them, Step 3 is specifically implemented according to the following steps:

[0028] Step 3.1: In the ANSYS modeling environment, establish the coordinate system of the model. The z-axis is the vertical direction of the transmission conductor, the x-axis is set as the conductor direction, and the y-axis is set as the horizontal direction; use the K command to define the key points between the transmission conductors, representing each position on the transmission conductor, including the starting point and the ending point of the span; use the LSTR or L command to connect the defined key points to form the line representing the transmission conductor; according to the actual parameters of the transmission conductor, use the APDL module to assign material properties to the transmission conductor and perform mesh division on it to generate nodes and elements, facilitating subsequent finite element analysis of the transmission conductor;

[0029] Step 3.2: Analyze the actual parameters, comprehensively consider the influence of the self-weight and tension of the transmission conductor on the shape, and according to the catenary formula, determine the initial displacement form of the transmission conductor in the equilibrium state under its own weight. Through the direct iteration method of the nonlinear finite element method, apply the downward gravity load to calculate the initial configuration of the transmission conductor;

[0030] Step 3.3: Conduct ice coating simulation on the transmission conductor model. Equivalent the ice shape to annular ice coating. The method is as follows:

[0031]

[0032] In the formula: b is the equivalent ice coating thickness, D is the maximum value of the transverse dimension of the transmission conductor after ice coating, B is the maximum value of the longitudinal dimension of the transmission conductor after ice coating, and r is the radius of the transmission conductor;

[0033] According to the transmission conductor ice coating model, use equally spaced concentrated forces to calculate the force condition of each point on the transmission conductor before critical ice shedding:

[0034]

[0035] It can be known that the density of the ice coating is 900 kg / m 3, with a thickness of b covering the wire, an outer diameter of D for the wire, a length of L for the wire, and g being the acceleration due to gravity; the wire is divided into n units for calculation, each unit having a length of L / n, and the ice accretion mass per unit is m, kg / m;

[0036] Calculate the resultant force on the transmission wire under ice accretion and other external forces, and apply it to the transmission line using the applied load method;

[0037] Step 3.4: By the additional load method, apply a force to the transmission wire model according to different working conditions and then remove the applied force to simulate the impact load on the transmission wire, and calculate the acceleration a in the y - direction and the acceleration a in the z - direction of each unit of the ice - covered wire after being subjected to the impact load;

[0038] Step 3.5: By analyzing the magnitude relationship between the calculated acceleration a of the transmission wire and the critical acceleration a, when the ice - shedding condition is met, simulate de - icing by removing the ice - accretion load;

[0039] Step 3.6: Since the transmission line vibrates under the impact load and then "induces ice - shedding" is a continuous dynamic process, set the analysis time t = t+Δt, and repeat steps 3.4 and 3.5 until the total analysis step time is completed.

[0040] Step 3.7: Select the transient dynamics solver, that is, the "trans" command, to simulate the dynamic response of the overhead transmission wire during the ice - shedding process;

[0041] Step 3.8: The ice - shedding amount and the ice - shedding method are reflected by the removed ice - accretion load. Set the solution time step to 0.01 s to ensure that the dynamic process of ice - shedding can be captured, and set the total solution time to t + 50 s as needed to simulate the vibration de - icing process of the overhead transmission wire under complex conditions.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] 1. By pre - processing and analyzing data, based on the determination criterion of ice - shedding, the present invention establishes an equivalent transmission line ice - shedding model.

[0044] 2. According to the equivalent transmission line ice - shedding model, the present invention establishes an impact load simulation, conducts ice - shedding analysis of the overhead line, and provides a reference for the vibration de - icing scheme. Description of the Drawings

[0045] Figure 1 is a flow chart of a method for analyzing the vibration de - icing process based on the ice - shedding criterion of the present invention;

[0046] Figure 2 is a schematic diagram of the ice - shedding determination criterion model of the present invention;

[0047] Figure 3 This is a schematic diagram of the icing equivalent model of the present invention. Specific embodiments

[0048] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] As Figure 1 shown, this embodiment discloses a method for judging and analyzing the effectiveness of ice removal by vibration of a collector line unmanned aerial vehicle, including the following steps:

[0050] Step 1: Collect and process the parameters of the on-site transmission line, icing, and ice shedding through an unmanned aerial vehicle and a monitoring system;

[0051] Step 1.1: Use an unmanned aerial vehicle to carry high-precision equipment to measure the sag, span, suspension height of the conductor, and the distance between towers, and extract the conductor diameter, insulator string length, etc. by combining image processing technology.

[0052] Step 1.2: Use a tension sensor to monitor the change in conductor tension, analyze the weight of the ice on the conductor, and use a vibration sensor to capture the vibration frequency and amplitude of the conductor to analyze the dynamic characteristics of ice shedding.

[0053] Step 1.3: Preprocess the data collected by the unmanned aerial vehicle and the monitoring system.

[0054] Step 2: Based on the preprocessed and analyzed data, establish an equivalent transmission line ice shedding model based on the judgment criterion of ice shedding;

[0055] Step 2.1: Considering the adhesion force and cohesion force of the ice, during the vibration of the conductor under impact load, when the resultant force of the inertial force and gravity acting on the ice is greater than the adhesion force and cohesion force, the ice is considered to have shed at this time;

[0056] Step 2.2: The ice shedding condition of the overhead line satisfies the following formula, as Figure 2 shown:

[0057] F inertia ±G≥F adhesive +F cohesive (1)

[0058] Among them, F inertia is the inertial force acting on the ice unit, G is the gravity of the ice, F adhesive is the bonding force, and F cohesive is the cohesion force of the ice.

[0059] In formula (1), the "+" and "-" on the left side of the inequality respectively represent the upper and lower halves of the ice. After expressing each term in the formula with acceleration, we get:

[0060]

[0061] F adhesive = D cable Lτ adhesive (4)

[0062] F cohesive = (D - D cable )Lτ cohesive (5)

[0063] In formulas (2)-(5), ρ ice is the density of the ice coating, a is the lateral acceleration during conductor galloping, L is the length of the ice-coated unit, D is the outer diameter of the ice coating, D cable is the outer diameter of the overhead transmission line, τ adhesive is the bond strength between the ice coating and the overhead transmission conductor, τ cohesive is the cohesive force inside the ice coating.

[0064] Substitute the above parameters into formula (1), move the terms and simplify to obtain the acceleration determination expression for ice shedding:

[0065]

[0066] Step 2.3: Determine the ice-shedding condition. The de-icing of the transmission line under impact load is only restricted by the acceleration a. When the actual acceleration a of the ice coating on the transmission line after being subjected to the impact load is greater than or equal to the critical acceleration a in the ice-shedding determination criterion, it is determined that the ice has shed, that is:

[0067] a 实 ≥ a 临 (7)

[0068] Step 3: Based on the equivalent transmission line ice-shedding model, establish an impact load simulation and conduct an analysis of overhead line de-icing.

[0069] Step 3.1: In the ANSYS modeling environment, establish the coordinate system of the model. The z-axis is the vertical direction of the transmission conductor, the x-axis is set as the conductor direction, and the y-axis is set as the horizontal direction; use the K command to define the key points between the transmission conductors, representing each position on the transmission conductor, including the starting point and the ending point of the span; use the LSTR or L command to connect the defined key points to form a line representing the transmission conductor; according to the actual parameters of the transmission conductor, use the APDL module to assign material properties to the transmission conductor and perform mesh division on it to generate nodes and elements, facilitating subsequent finite element analysis of the transmission conductor;

[0070] Step 3.2: Analyze the actual parameters, comprehensively consider the influence of the self-weight and tension of the transmission line on its shape, and determine the initial displacement form of the transmission line when it reaches the equilibrium state under the action of self-weight according to the catenary formula. Then, through the direct iteration method of the nonlinear finite element method, apply a downward gravity load to calculate the initial configuration of the transmission line;

[0071] Step 3.3: Conduct ice coating simulation on the transmission line model, and equivalent the ice shape to annular ice coating as shown in Figure 3 follows:

[0072]

[0073] In the formula: b is the equivalent ice coating thickness, D is the maximum value of the transverse dimension of the transmission line after ice coating, B is the maximum value of the longitudinal dimension of the transmission line after ice coating, and r is the radius of the transmission line;

[0074] According to the transmission line ice coating model, use equally spaced concentrated forces to calculate the force on each point of the transmission line before critical ice shedding:

[0075]

[0076] It can be known that: the density of the ice coating is 900 kg / m 3 , the thickness covering the wire is b, the outer diameter of the wire is D, the length of the wire is L, and g is the acceleration due to gravity; divide the wire into n units for calculation, the length of each unit is L / n, and the ice coating mass on the unit is m, kg / m;

[0077] Calculate the resultant force on the transmission line under the action of ice coating and other external forces, and apply it to the transmission line using the load application method;

[0078] Step 3.4: Through the additional load method, apply a force to the transmission line model according to different working conditions and then remove the applied force to simulate the impact load received by the transmission line, and calculate the acceleration ay in the y direction and the acceleration az in the z direction of each unit of the ice-coated wire after receiving the impact load;

[0079] Step 3.5: Set the acceleration constraint, and by analyzing the magnitude relationship between the calculated acceleration a of the transmission line and the critical acceleration ac, when the ice shedding condition is met, simulate ice removal by removing the ice coating load;

[0080] Step 3.6: Since the transmission line vibrates under the impact load and then "induces ice shedding" is a continuous dynamic process, set the analysis time t = t + Δt, and repeat steps 3.4 and 3.5 until the total analysis step time is completed.

[0081] Step 3.7: Select the transient dynamics solver, i.e., the "trans" command, to simulate the dynamic response of the overhead transmission line during the ice shedding process;

[0082] Step 3.8: The amount of ice shedding and the ice shedding method are reflected by the removed ice load. Set the solution time step to 0.01 s to ensure that the dynamic process of ice shedding can be captured, and set the total solution time to t + 50 s as needed to simulate the vibration ice removal process of the overhead transmission line under complex conditions.

[0083] As described above, this is only the specific implementation manner of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for judging the effectiveness of vibration deicing of collector lines by drones, characterized in that: Follow the steps below to implement it: Step 1: Collect and process the transmission line parameters, icing and ice shedding parameters on site through drones and monitoring systems; Step 2: Based on the preprocessed and analyzed data and the ice shedding judgment criteria, an equivalent transmission line ice shedding model is established; Step 3: Based on the equivalent transmission line icing and shedding model, establish an impact load simulation and conduct an overhead line icing analysis.

2. The method for judging the effectiveness of vibration deicing of collector lines by drones according to claim 1 is characterized in that: The step 1 is specifically implemented according to the following steps: Step 1.1: Use drones equipped with high-precision equipment to measure the sag, span, suspension height and tower spacing of the conductors, and use image processing technology to extract the conductor diameter and insulator string length; Step 1.2: Use a tension sensor to monitor the change in conductor tension, analyze the weight of the conductor ice, use a vibration sensor to capture the vibration frequency and amplitude of the conductor, and analyze the dynamic characteristics of ice shedding; Step 1.3: Preprocess the data collected by the drone and monitoring system.

3. The method for judging the effectiveness of vibration deicing of collector lines by drones according to claim 1 is characterized in that: The step 2 is specifically implemented according to the following steps: Step 2.1: Considering the adhesion and cohesion of the ice, when the conductor is subjected to impact load and vibrates, when the combined force of the inertia force and gravity on the ice is greater than the adhesion and cohesion, the ice is considered to have fallen off; Step 2.2: The ice shedding condition of overhead lines satisfies the following expression: F inertia ±G≥F adhesive +F cohesive (1) Among them, F inertia is the inertial force on the ice-covered unit, G is the ice-covered gravity, and F adhesive is the bonding force, F cohesive for the cohesion of ice; In formula (1), the "+" and "-" on the left side of the inequality represent the upper and lower parts of the ice respectively, and the various terms in the formula are expressed in terms of acceleration to obtain: F adhesive =D cable Lτ adhesive (4) F cohesive =(D-D cable )Lτ cohesive (5) In formulas (2) to (5), ρ ice is the density of ice, a is the lateral acceleration of the conductor when it is dancing, L is the length of the ice unit, D is the outer diameter of the ice, and D cable is the outer diameter of the overhead transmission line, τ adhesive is the bonding strength between ice and overhead transmission lines, τ cohesive The internal cohesion of the ice cover; Substituting the above parameters into formula (1), moving the terms and simplifying them, we can get the acceleration determination expression of ice shedding: Step 2.3: Determine the ice shedding conditions. The ice shedding of the transmission line under impact load is only constrained by acceleration a. When the actual acceleration a of the ice on the transmission line after the impact load is greater than or equal to the critical acceleration a in the ice shedding judgment criterion, it is judged as ice shedding, that is: a 实 ≥a 临 (7)。 4. The method for judging the effectiveness of vibration deicing of collector lines by drones according to claim 1 is characterized in that: The step 3 is specifically implemented according to the following steps: Step 3.1: In the ANSYS modeling environment, establish the coordinate system of the model, with the z-axis being the vertical direction of the transmission line, the x-axis being the line direction, and the y-axis being the horizontal direction; use the K command to define the key points between the transmission lines, representing various positions on the transmission lines, including the starting point and end point of the span; Use LSTR or L command to connect the defined key points to form a line representing the transmission line; according to the actual parameters of the transmission line, use APDL module to assign material properties to the transmission line and mesh it to generate nodes and units to facilitate the subsequent finite element analysis of the transmission line; Step 3.2: Analyze the actual parameters, comprehensively consider the influence of the deadweight and tension of the transmission line on the shape, and determine the initial displacement shape of the transmission line to reach a balanced state under the action of its deadweight according to the catenary formula. Apply a downward gravity load through the direct iteration method of the nonlinear finite element method to calculate the initial configuration of the transmission line; Step 3.3: Simulate the ice covering model of the transmission line and make the ice shape equivalent to annular ice covering. The method is as follows: Where: b is the equivalent ice thickness, D is the maximum transverse dimension of the transmission line after ice coating, B is the maximum longitudinal dimension of the transmission line after ice coating, and r is the radius of the transmission line; According to the transmission line icing model, the force at each point of the transmission line before critical deicing is calculated using equally spaced concentrated forces: It can be seen that the density of ice is 900kg / m 3 , the thickness of the wire is b, the outer diameter of the wire is D, the length of the wire is L, and g is the acceleration of gravity; the wire is divided into n units for calculation, the length of each unit is L / n, and the mass of ice on the unit is m, kg / m; Calculate the resultant force on the transmission line under the action of ice and other external forces, and apply it to the transmission line using the load application method; Step 3.4: By using the additional load method, a force is applied to the transmission line model according to different working conditions and then the applied force is removed to simulate the impact load on the transmission line, and the acceleration a in the y direction and the acceleration a in the z direction of each unit of the ice-covered wire after the impact load is calculated; Step 3.5: Set acceleration constraints, analyze and calculate the relationship between the acceleration a of the transmission line and the critical acceleration a, and remove the ice load to simulate deicing when the ice shedding conditions are met; Step 3.6: Since the transmission line vibrates due to the impact load, "induced deicing" is a continuous dynamic process. Set the analysis time t = t + Δt, and repeat steps 3.4 and 3.5 until the total analysis time is completed; Step 3.7: Select the transient dynamics solver, i.e. the "trans" command, to simulate the dynamic response of the overhead transmission line during the ice shedding process; Step 3.8: The amount of deicing and the deicing method are reflected by the amount of ice load removed. The solution time step is set to 0.01s to ensure that the dynamic process of deicing can be captured. The total solution time is set to t+50s as needed to simulate the vibration deicing process of overhead transmission lines under complex conditions.

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