Power transmission line windage yaw prevention checking and evaluating method

Abstract

The invention relates to a windage yaw prevention check evaluation method for a power transmission line, and the method comprises the steps: building a line parameter model through collecting power transmission line information; performing windproof performance evaluation according to the constructed line parameter model; evaluating each element risk point according to the windproof performance evaluation, and calculating to obtain a corresponding risk value; and finally, making a corresponding treatment strategy according to the obtained risk value. According to the method, weak points which do not meet windage yaw checking can be obtained, the line is modified and upgraded in a targeted mode, and safe and stable operation of the power transmission line is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of power grid operation assessment, and in particular to a method for evaluating wind deflection prevention calibration of a power transmission line. Background Art

[0002] Sudden failures in important transmission channels pose a serious threat to the safe operation of large power grids, and active defense against strong convection is urgently needed. Important transmission channels are the main arteries of large regional power grids. If important transmission channels fail simultaneously or successively, the supply and demand balance of regional power grids may be affected, and even large-scale power restrictions or power outages may occur; at the same time, the voltage in some areas may drop sharply, which will also pose a major threat to system stability. Strong convective windy weather is irregular, with high wind speed and serious harm. In recent years, many transmission lines have been tripped, shut down, and even towers have collapsed and lines have been broken due to strong convective windy weather. Power grid safety is the foundation, the bottom line, and the lifeline. With global warming, extreme windy weather is frequent and frequent. It is urgent to carry out wind deflection verification and evaluation of transmission lines to improve the disaster prevention and mitigation capabilities of the power grid. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for checking and evaluating the wind deflection of a power transmission line, which can timely discover the shortcomings of the line's anti-icing and ice-melting capabilities, improve the line's anti-icing and ice-melting capabilities in a targeted manner, and ensure the safe and stable operation of the transmission line.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A method for evaluating the wind deflection of a transmission line comprises the following steps:

[0006] Step 1: Collect transmission line information and establish a line parameter model;

[0007] Step 2: Conduct wind protection performance evaluation based on the line parameter model constructed in step 1;

[0008] Step 3, assess the risk points of each factor according to the wind resistance performance assessment in step 2, and calculate the corresponding risk value;

[0009] Step 4: Develop corresponding governance strategies based on the risk value obtained in step 3.

[0010] Moreover, the transmission line information in step 1 includes detailed parameters of equipment such as ground wires, insulators, and towers.

[0011] Moreover, the specific implementation method of establishing the line parameter model in the step 1 is: after determining the pole tower model and height, take a point on the pole tower drawing, establish a coordinate system with the midpoint of the two tower feet on the drawing as the origin, the line connecting the two tower feet as the x-axis, and the centerline of the pole tower as the y-axis, and depict the node coordinates of the main material part of the pole tower according to the dimensions of each part of the pole tower marked on the drawing, fill in the provided pole tower modeling template in the prescribed order, and complete the two-dimensional modeling of the base pole tower.

[0012] Moreover, the wind resistance performance evaluation in step 2 includes calculation of wire curves, calculation of tower head clearance, and calculation of stresses of tower rods and bolts.

[0013] Moreover, the wire curve calculation reflects the stress conditions of the conductor, ground wire and hanging point when the line is covered with ice. The design safety factor of the conductor and ground wire at the lowest point of the sag should not be less than 2.5, and the design safety factor of the hanging point should not be less than 2.25. Maximum tension:

[0014]

[0015] Among them, Tmax is the maximum use tension of the conductor; Tp is the calculated breaking force of the conductor, N; Tps is the design breaking tension of the conductor, N; Kc is the design safety factor;

[0016] Calculate the stress at the lowest point of the wire and the wire hanging point:

[0017]

[0018] Wherein, σ is stress; S is the calculated total cross-sectional area of ​​the conductor. The line is qualified if the stress at the lowest point and the stress at the hanging point evaluated are less than the calculated stress.

[0019] Moreover, the calculation method of the tower head clearance is: verifying the electrical distance between the conductor and the tower body under different meteorological conditions, and using four meteorological conditions to perform wind deflection flashover verification of the insulator string:

[0020] (1) The power frequency voltage meteorological conditions are the same as the normal maximum design wind speed conditions;

[0021] (2) The meteorological conditions for operating overvoltage are the annual average temperature, no ice, and a wind speed of 50% of the maximum design wind speed, and not less than 15 m / s;

[0022] (3) When the meteorological conditions for lightning overvoltage are temperature +15℃, no ice, and maximum design wind speed less than 35m / s, the wind speed is generally 10m / s; when the maximum design wind speed is 35m / s or above and in areas with high wind speed during thunderstorms, 15m / s is generally used;

[0023] (4) Customized meteorological conditions, with a temperature of 21°C and a wind speed of 10 m / s;

[0024] By calculating the wind deviation angle, the gap between the live parts and the tower components can be deduced. In areas with an altitude not exceeding 1000m, the gap between the live parts and the tower components should not be less than the specified value under the corresponding wind deviation conditions.

[0025] Furthermore, the stress calculation of the tower rods and bolts is checked according to the reference wind speed, and the stress ratio distribution of the tower rods and bolts is calculated.

[0026] The advantages and positive effects of the present invention are:

[0027] The present invention collects transmission line information and establishes a line parameter model; conducts windproof performance evaluation based on the constructed line parameter model; evaluates the risk points of each factor based on the windproof performance evaluation, and calculates the corresponding risk value; and finally formulates a corresponding governance strategy based on the obtained risk value. The present invention can derive the weak points that do not meet the wind deviation verification, and carry out targeted transformation and upgrading of the line to ensure the safe and stable operation of the transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention takes a schematic diagram of key node coordinates according to the tower drawing;

[0029] Figure 2 The stress ratio distribution diagram of the iron tower rod of the present invention is

[0030] Figure 3 This is the bolt stress ratio distribution diagram of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the accompanying drawings.

[0032] A method for evaluating the wind deflection of a transmission line comprises the following steps:

[0033] Step 1: Collect transmission line information and establish a line parameter model. As shown in Tables 1, 2, and 3, the transmission line information includes detailed parameters of ground wires, insulators, towers, and other equipment.

[0034] Conductor and ground wire:

[0035] Table 1 Wire parameters

[0036] describe unit describe unit Lead wire model / Calculate quality kg / km Number of aluminum wires root Elastic modulus N / mm2 Aluminum wire diameter mm Temperature linear expansion coefficient 1 / ℃ Steel wire number root Twisted resistance constant / Steel wire diameter mm Number of aluminum wires in the first layer root Calculate total cross section mm2 Number of aluminum wires in the second layer root outer diameter mm Number of aluminum wires in the third layer root Aluminum to steel section ratio / The first layer of aluminum wire pitch ratio / DC resistance is not more than Ω / km The second layer aluminum wire pitch ratio / Calculate the breaking force N The third layer aluminum wire pitch ratio /

[0037] Table 2 Ground Wire Parameters

[0038] describe unit Ground wire model / Number of steel wires root Single wire diameter mm Strand diameter mm Calculate area mm2 Mass per unit length kg / km Rated breaking force N Elastic modulus N / mm2 Temperature linear expansion coefficient 1 / ℃ 20℃ DC resistance Ω / km

[0039] insulator:

[0040] Table 3 Insulator parameters

[0041] describe unit describe unit Manufacturer / Rated electromechanical (mechanical) breaking load kN model / quality kg Insulator Type / Disc diameter mm Insulator material / Number of umbrella skirts / Structure height mm Rated voltage / Creepage distance mm Arc distance mm

[0042] Tower:

[0043] (1) Determine the tower model, height and three-phase conductor sequence

[0044] During the verification and evaluation process, all parameters of the line should be restored as realistically as possible. The influence of different tower types, different tower heights and different phase sequences on the evaluation results of a line is completely different.

[0045] (2) Drawing point selection

[0046] like Figure 1 As shown in the figure, after the pole tower model and height are determined, points are taken on the pole tower drawing. A coordinate system is established with the midpoint of the two tower feet on the drawing as the origin, the line connecting the two tower feet as the x-axis, and the centerline of the pole tower as the y-axis. According to the dimensions of each part of the pole tower marked on the drawing, the node coordinates of the main material part of the pole tower are depicted (such as the position of the conductor, the position of the ground wire, and the connection points of each tower material. Generally, 49-55 points are required to fully depict a pole tower), and the pole tower modeling template provided is filled in according to the prescribed order to complete the two-dimensional modeling of a pole tower.

[0047] Step 2: Conduct wind protection performance evaluation based on the line parameter model constructed in step 1.

[0048] The wind resistance performance assessment includes calculation of wire curves, tower head clearance, and stress calculation of tower rods and bolts.

[0049] The wire curve calculation reflects the stress conditions of the conductor, ground wire and hanging point when the line is covered with ice. The design safety factor of the conductor and ground wire at the lowest point of the sag should not be less than 2.5, and the design safety factor of the hanging point should not be less than 2.25. The maximum tension is:

[0050]

[0051] Among them, Tmax is the maximum use tension of the conductor; Tp is the calculated breaking force of the conductor, N; Tps is the design breaking tension of the conductor, N; Kc is the design safety factor;

[0052] Calculate the stress at the lowest point of the wire and the wire hanging point:

[0053]

[0054] Wherein, σ is stress; S is the calculated total cross-sectional area of ​​the conductor. The line is qualified if the stress at the lowest point and the stress at the hanging point evaluated are less than the calculated stress.

[0055] The tower head clearance calculation verifies the electrical distance between the conductor and the tower body under different meteorological conditions. The following four meteorological conditions are used to verify the wind deflection flashover of the insulator string:

[0056] (1) The power frequency voltage meteorological conditions are the same as the normal maximum design wind speed conditions.

[0057] (2) The meteorological conditions for operating overvoltage are the annual average temperature, no ice, and a wind speed of 50% of the maximum design wind speed, and not less than 15m / s.

[0058] (3) When the meteorological conditions for lightning overvoltage are temperature of +15℃, no ice, and maximum design wind speed less than 35m / s, the wind speed is generally 10m / s. When the maximum design wind speed is 35m / s or above and in areas with higher wind speeds during thunderstorms, 15m / s is generally used.

[0059] (4) Customize the weather conditions, with a temperature of 21°C and a wind speed of 10 m / s.

[0060] By calculating the wind deviation angle, the gap between the live parts and the pole tower components (including guy wires, foot nails, etc.) can be deduced. In areas with an altitude not exceeding 1000m, the gap between the live parts and the pole tower components should not be less than the values ​​listed in Table 4 under the corresponding wind deviation conditions.

[0061] Table 4 Minimum clearance between live parts and tower components (m)

[0062]

[0063] The stress calculation of the tower rods and bolts is checked according to the reference wind speed, and the stress ratio distribution (the ratio of the actual stress value to the ultimate stress value of the component) of the tower rods and bolts is calculated.

[0064] like Figure 2 As shown in the figure, according to the distribution diagram of the tower rod stress ratio, if the rod stress ratio is greater than 1, the rod exceeds the limit. According to the actual use span and actual wind speed, the rod strength in the red position exceeds the limit. If the rod stress ratio is less than 1, the strength of the tower rods meets the requirements.

[0065] like Figure 3 As shown in the figure, according to the bolt stress ratio distribution diagram, if the stress ratio of all bolts in the tower is greater than 1, the bolts are out of limit; if it is less than 1, they are within the limit and meet the requirements.

[0066] Step 3: Evaluate the risk points of each factor based on the wind resistance performance evaluation in step 2 and calculate the corresponding risk value.

[0067] Step 4: Develop corresponding governance strategies based on the risk value obtained in step 3.

[0068] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the wind deflection of a transmission line, characterized by: The following steps are involved: Step 1: Collect transmission line information and establish a line parameter model; Step 2: Conduct wind protection performance evaluation based on the line parameter model constructed in step 1; Step 3, assess the risk points of each factor according to the wind resistance performance assessment in step 2, and calculate the corresponding risk value; Step 4: Develop corresponding governance strategies based on the risk value obtained in step 3.

2. A method for evaluating the wind deflection of a transmission line according to claim 1, characterized in that: The transmission line information in step 1 includes detailed parameters of equipment such as ground wires, insulators, and towers.

3. A method for evaluating the wind deflection of a transmission line according to claim 1, characterized in that: The specific implementation method of establishing the line parameter model in the step 1 is: after determining the pole tower model and height, take a point on the pole tower drawing, establish a coordinate system with the midpoint of the two tower feet on the drawing as the origin, the line connecting the two tower feet as the x-axis, and the centerline of the pole tower as the y-axis, and depict the node coordinates of the main material part of the pole tower according to the dimensions of each part of the pole tower marked on the drawing, fill in the provided pole tower modeling template in the prescribed order, and complete the two-dimensional modeling of the base pole tower.

4. A method for evaluating the wind deflection of a transmission line according to claim 1, characterized in that: The wind resistance performance evaluation in step 2 includes calculation of wire curves, calculation of tower head clearance, and calculation of stresses of tower rods and bolts.

5. A method for evaluating the wind deflection of a transmission line according to claim 4, characterized in that: The wire curve calculation reflects the stress conditions of the conductor, ground wire and hanging point when the line is covered with ice. The design safety factor of the conductor and ground wire at the lowest point of the sag should not be less than 2.5, and the design safety factor of the hanging point should not be less than 2.

25. Maximum tension: Among them, Tmax is the maximum use tension of the conductor; Tp is the calculated breaking force of the conductor, N; Tps is the design breaking tension of the conductor, N; Kc is the design safety factor; Calculate the stress at the lowest point of the wire and the wire hanging point: Wherein, σ is stress; S is the calculated total cross-sectional area of ​​the conductor. The line is qualified if the stress at the lowest point and the stress at the hanging point evaluated are less than the calculated stress.

6. A method for evaluating the wind deflection of a transmission line according to claim 4, characterized in that: The calculation method of the tower head clearance is: verify the electrical distance between the conductor and the tower body under different meteorological conditions, and use four meteorological conditions to perform wind deflection flashover verification of the insulator string: (1) The power frequency voltage meteorological conditions are the same as the normal maximum design wind speed conditions; (2) The meteorological conditions for operational overvoltage are the annual average temperature, no ice, and a wind speed of 50% of the maximum design wind speed and not less than 15 m / s; (3) When the meteorological conditions for lightning overvoltage are temperature +15℃, no ice, and maximum design wind speed less than 35m / s, the wind speed is generally 10m / s; When the maximum design wind speed is 35m / s or above and in areas with high wind speed during thunderstorms, 15m / s is generally used; (4) Customized meteorological conditions, with a temperature of 21°C and a wind speed of 10 m / s; By calculating the wind deviation angle, the gap between the live parts and the tower components can be deduced. In areas with an altitude not exceeding 1000m, the gap between the live parts and the tower components should not be less than the specified value under the corresponding wind deviation conditions.

7. A method for evaluating the wind deflection of a transmission line according to claim 4, characterized in that: The stress calculation of the tower rods and bolts is checked according to the reference wind speed, and the stress ratio distribution of the tower rods and bolts is calculated.

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