CN104182611A

CN104182611A - Weighing method based tangent tower wire icing thickness calculation method and system

Info

Publication number: CN104182611A
Application number: CN201410348869.5A
Authority: CN
Inventors: 张厚荣
Original assignee: Maintenance and Test Center of Extra High Voltage Power Transmission Co
Current assignee: Maintenance and Test Center of Extra High Voltage Power Transmission Co
Priority date: 2014-07-21
Filing date: 2014-07-21
Publication date: 2014-12-03

Abstract

The invention discloses a weighing method based tangent tower wire icing thickness calculation method and system. The method comprises steps as follows: firstly, the horizontal stress of a wire without covered ice is calculated, then, the preliminary calculation horizontal stress of the wire under the icing condition and the double calculation horizontal stress of the wire during icing are calculated sequentially, and finally, the equivalent icing thickness is obtained according to the double calculation icing specific load. The method and the system overcome the defect of a tangent tower wire icing thickness calculation model in engineering application, have the advantages of a few input monitoring parameters, low requirements for monitoring equipment, high calculation accuracy and the like and have a good effect during actual engineering application and good popularization and application prospect.

Description

Weighing method-based method and system for calculating icing thickness of tangent tower lead

Technical Field

The invention relates to the field of calculation of icing of a power transmission line, in particular to a method and a system for calculating the icing thickness of a wire of a linear tower based on a weighing method.

Background

The icing of the power transmission line is a great threat to the safe operation of the power grid, and serious icing can cause serious accidents such as tower collapse, line breakage and the like. In order to timely and effectively monitor and early warn the icing condition in the icing period, the southern power grid establishes an icing early warning system and provides great technical support for anti-icing workers to make anti-icing and ice-melting decisions.

The icing thickness calculation model is an important component of an icing early warning system. The basic data collected by the icing monitoring terminal can be converted into the on-site icing thickness through the icing thickness calculation model, and the icing condition of the power transmission line can be intuitively and accurately reflected. In the ice coating on-line monitoring technology, the weighing method principle is direct, and the technology application is relatively mature, so that an ice coating thickness calculation model based on the weighing method principle is mainly adopted in engineering practice.

At present, domestic tangent tower wire icing thickness calculation models are various in form, but generally stay on a theoretical level, the research on a targeted engineering model is still not deep enough, the accuracy of the calculation result of various tangent tower icing models cannot be guaranteed, and a unified model which can withstand engineering application inspection is lacked.

As shown in fig. 1, an ice coating monitoring terminal for an overhead transmission line is generally composed of a monitoring terminal, a communication network and a system master station (shown as a monitoring center master station). The ice coating monitoring terminal (namely the monitoring terminal) comprises a tension and angle sensor, a leakage current sensor, a meteorological sensor, an angle sensor, a camera and the like. The specific operation process is as follows: the sensor monitors field data, the field data are transmitted to a system main station through a GSM/GPRS network, and background software of the system main station calculates the icing thickness of the lead in real time according to an icing thickness calculation model. The ice coating on-line monitoring technology aims to solve the problems of low manual inspection efficiency, high cost for building an ice observation station, unobvious effect and the like.

At present, the icing thickness calculation method mainly comprises a fluid mechanics method, a weighing method, an inclination angle-tension method, an inclination angle-sag method, an image monitoring method, an analog lead method and the like, wherein the weighing method and the inclination angle method have simpler principles and lower equipment requirements, and are widely applied in domestic engineering practice. However, the inclination angle method has more technical difficulties due to the problems of insufficient precision of the angle sensor, high failure rate and the like, so the weighing method is the most suitable method for monitoring the icing thickness at present.

The weighing method is to monitor parameters such as suspension point load, environmental meteorological conditions, inclination angle and the like of the insulator string through the ice coating terminal, and convert the increment of the monitored load into equivalent ice coating thickness (ice density is 0.9 g/cm)³). Although different researchers adopt different static analysis methods, terminal monitoring parameters and data processing processes, the general ideas are similar.

In recent years, the calculation model of the icing thickness of the tangent tower proposed by the national scholars mainly comprises the following components:

an inversion calculation linear tower icing thickness calculation model is provided by Yanglin of southern China university, and the specific idea is as follows: the method comprises the steps of taking tension and an inclination angle of a suspension point of an insulator string as basic parameters, considering windage yaw factors, calculating mechanical parameters of a conductor to a windage yaw plane, calculating the length of an equivalent conductor through static stress balance in the vertical direction in the windage yaw plane, further calculating the equivalent ice coating thickness, continuously correcting the length of the equivalent conductor according to an artificial ice observation result, and improving the accuracy of a calculation result. This model, also known as an inverse computational model, is now a southern power grid unified deployment model.

The 'three-tower two-gear' tangent tower icing thickness calculation model is provided by the Xian gold source electricity, and the specific idea is as follows: considering that the suspension point of the monitoring tower is formed by vertical force, along-line force and vertical line wind load, the comprehensive load of the suspension point is reduced to the vertical load according to the monitoring amount of the tension sensor and the inclination angle sensor, the vertical load is divided by the length of the lead in the vertical span changed due to the change of the inclination angle to obtain the icing load of unit length, and finally the equivalent icing thickness is calculated.

The ice coating thickness calculation model idea of the overhead line ice coating on-line monitoring system of the power grid company in Huazhong is as follows: and according to the comprehensive load of the transmission conductor, the stress balance model is established by the self-weight load of the conductor, the icing load and the wind load, the self-weight load and the wind load of the conductor in the vertical span are subtracted from the comprehensive load to obtain the icing load, and the icing load is converted into the equivalent icing thickness.

Other weighing-method-based tangent tower wire icing models are similar to the three icing models in general thinking, namely the change of force in the vertical direction is solved, the icing load is solved, and finally the equivalent icing thickness is calculated. The straight line tower lead icing thickness calculation model has the following defects:

(1) a large number of tilt sensors are relied upon to monitor the data. The inclination angle sensor is easily influenced by external conditions and installation positions, the absolute error of measurement of the inclination angle sensor is generally 2-3 degrees (experimental data) and even larger, and if an ice coating model applied to engineering is adopted, the deviation of a calculation result is larger if the inclination angle sensor is used for monitoring data.

(2) The influence of the weight of the insulator string and the included angle is not fully considered in the calculation process. The insulator string of a 500kV transmission circuit generally weighs hundreds of kilograms, and the insulator string of an 800kV transmission circuit can weigh thousands of kilograms. In the calculation process, if the insulator string is neglected again or the stress analysis of the insulator string is incorrect, the final ice coating thickness calculation result is seriously influenced.

(3) And the requirement on input parameters of towers and lines is high. Most of domestic tangent tower wire icing thickness calculation models excessively depend on input tower and line design parameters, and the requirement on the accuracy of the design parameters is high. Meanwhile, almost all ice-coated models cannot self-check whether input data is erroneous.

(4) The effects of meteorological conditions cannot be fully considered. Meteorological conditions affecting the vertical span of a tangent tower include: air temperature, wind speed, ice coating thickness. In the calculation process of a general model, the relationship among air temperature, wind speed, icing thickness and monitoring tension cannot be comprehensively considered, so that the error of the icing thickness calculation result is large.

(5) The ability to adapt to the external environment is poor. Most of the calculation models of the icing thickness of the tangent tower can obtain better effect in the experimental environment, but if the calculation models are applied to actual work, the calculation result is greatly deviated from the actual situation because the actual calculation conditions are greatly different from the experimental calculation conditions. .

In view of this, there is a need for improvements and enhancements in the prior art.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a method and a system for calculating the icing thickness of a straight line tower lead based on a weighing method. The method aims to solve the problem that in the prior art, the error of a calculation result is large in engineering application.

The technical scheme of the invention is as follows:

a method for calculating the icing thickness of a wire of a tangent tower based on a weighing method sequentially comprises the following steps:

A. obtaining horizontal load P when the line tower lead is not coated with ice_HSaid horizontal load without ice coating P_HBy wind loading of the conductor P_dInsulator string wind load P_JLongitudinal tension P caused by angle of rotation_γForming; i.e. P_H＝P_d+P_J+P_γ；

B. According to the horizontal load P without ice coating_HAnd a first monitored tension value T₀Calculating the length S of the vertical span inner conductor without ice coating_V0And wire horizontal stress σ₀；

C. Obtaining a monitored air temperature t during icing₁And a second monitored tension value T₁(ii) a And combined with the monitored air temperature t without ice coating₀And wire horizontal stress σ₀Calculating the initial length S of the vertical span inner conductor during icing_V10Initial icing specific load g in icing₂₀；

D. Obtaining the statistical wind speed v during icing₁Calculating the horizontal load P during icing_H1(ii) a Initial calculation of specific ice coating g during combined ice coating₂₀Calculating the recomputed icing specific load g₂₁；

E. According to the recalculated specific icing load g₂₁The equivalent ice coating thickness b is obtained according to the following formula₁：

Wherein A is the calculated cross-sectional area of the wire, and d is the diameter of the wire.

The method for calculating the icing thickness of the wire of the linear tower based on the weighing method comprises the following steps of A, wherein the wind load P of the wire in the step A is_dThe following calculation is adopted:

wherein,

n is the number of split conductors; l₁、l₂Monitoring the large and small side span of the tower; beta is a₁、β₂Monitoring the height difference angle of the large and small sides of the tower; a is the calculated sectional area of the lead; s_hMonitoring the horizontal span of the tower; beta is a_cIs 500kV line powerThe wind load adjustment coefficient of the line is 1.0; g₄The horizontal wind specific load of the wire is obtained; gamma is the number of line corner degrees;the included angle between the wind speed and the trend of the conducting wire is generally 90 degrees; c is the wind load shape coefficient, and the value is 1.2; mu is the uneven coefficient of the wind pressure, and the value is 1.0; d is the calculated diameter of the wire; v. of₀Counting the wind speed when the ice coating is not generated;

the insulator string wind load P_JThe following calculation was used:

P_J＝W₀A_J；

wherein,W₀the standard value of the wind load of the insulator string is obtained; a. the_JCalculating the area of the insulator string bearing wind pressure; rho is the air density in strong wind; v. of₀Counting the wind speed when the ice coating is not generated;

longitudinal tension P caused by the angle of rotation_γThe following calculation was used:

wherein σ_16％Paying off horizontal stress for the wire in the design parameters, wherein the CUT is 16 percent; a is the calculated sectional area of the lead; gamma is the number of line turning angles.

The method for calculating the icing thickness of the wire of the linear tower based on the weighing method comprises the following specific steps:

b1 according to tension T monitored without ice coating₀And the calculated horizontal load P_HCalculating the vertical load

G_{V 0} = \sqrt{T_{0}^{2} - P_{H}^{2}};

B2, calculating the length S of the vertical span inner conductor without ice coating according to the following formula_V0：

B3, length of wire according to vertical span_V0Stress σ horizontal to the wire₀To solve the wire horizontal stress sigma₀：

Wherein h is₁、h₂The height difference between the tower hanging point of the monitoring tower and the hanging points of the large and small side towers is obtained; beta is a₁、β₂The height difference angle of the large and small sides of the monitoring pole tower is obtained; g_JThe weight of the insulator string and the connecting hardware thereof; g₁The dead weight of the wire is loaded; theta is an included angle of the insulator string; t is₀The tensile value was monitored without ice coating.

The method for calculating the icing thickness of the wire of the linear tower based on the weighing method comprises the following steps:

judging the horizontal stress sigma of the lead₀And C, if the input data is within the preset range, if so, performing the step C, otherwise, prompting that the input data is wrong, and prompting to input the data again.

The method for calculating the icing thickness of the wire of the tangent tower based on the weighing method is characterized in that the horizontal stress sigma of the wire is₀The preset range is as follows: 15 MPa-40 MPa.

c1, obtaining initial icing specific load g₂₀And comprehensive specific load g during ice coating₇₀And g is the comprehensive specific load without ice coating₆(ii) a The calculation formula is as follows:

g_{70} = \sqrt{{(g_{1} + g_{20})}^{2} + g_{4}^{2}};

g_{6} = \sqrt{g_{1}^{2} + g_{4}^{2}};

c2, according to the wire state equation:

initial calculation of horizontal stress sigma of lead in ice coating₁₀So that the initial length S of the vertical span inner conductor is calculated during ice coating_V10Comprises the following steps:

wherein, T₁Monitoring the tension value during ice coating; t is t₀Monitoring the air temperature when the ice coating is not generated; t is t₁Monitoring the air temperature during ice coating; l_rRepresents a span; beta is a_rIs representative of a height difference angle; alpha is the coefficient of thermal expansion of the wire; e is the elastic coefficient of the wire.

d1, specific icing load g according to initial calculation₂₀Calculating the initial equivalent icing thickness b₀。

Wherein d is the diameter of the wire;

d2, calculating the horizontal wind specific load g of the wire during ice coating₄₁Comprises the following steps:

wherein v is₁The statistical wind speed during icing;

d3, calculating the wind load of the wire to be P when the wire is covered with ice_d1Comprises the following steps:

d4, calculating the wind load P of the insulator string during ice coating_J1Comprises the following steps:

P_J1＝W₁BA_J；

wherein,W₁the standard value of the wind load of the insulator string during ice coating is obtained; and B is the insulator chain shape increasing coefficient in ice coating, and the value is 1.2.

D5, calculating the longitudinal tension P caused by the angle of rotation during ice coating_γ1Comprises the following steps:

d6, horizontal load P during ice coating_H1Comprises the following steps:

P_H1＝P_d1+P_J1+P_γ1；

d7 obtaining a composite icing specific load g₂₁Comprises the following steps:

and K is the ice coating coefficient of the insulator string.

A weighing method-based line tower wire icing thickness calculation system, wherein the system comprises:

a first calculating unit used for obtaining the horizontal load P when the line tower lead is not coated with ice_HSaid horizontal load without ice coating P_HBy wind loading of the conductor P_dInsulator string wind load P_JLongitudinal tension P caused by angle of rotation_γIs formed of, i.e. P_H＝P_d+P_J+P_γ；

A second calculating unit without ice coating for calculating the horizontal load P without ice coating_HAnd a first monitored tension value T₀Calculating the length S of the vertical span inner conductor without ice coating_V0And wire horizontal stress σ₀；

An initial calculation unit for obtaining the monitored air temperature t during icing₁And a second monitored tension value T₁(ii) a And combined with the monitored air temperature t without ice coating₀And wire horizontal stress σ₀Calculating the initial length S of the vertical span inner conductor during icing_V10And initial icing specific load g₂₀；

An icing time recalculation unit for acquiring the statistical wind speed v during icing₁Calculating the horizontal load P during icing_H1(ii) a Then combining the initial calculation of specific icing load g₂₀Calculating the recomputed icing specific load g₂₁；

An icing thickness calculating unit for calculating an icing specific load g according to the recalculation₂₁Obtaining the recalculated equivalent icing thickness b according to the following formula₁：

The system for calculating the icing thickness of the wire of the tangent tower based on the weighing method is characterized in that the second calculating unit further comprises:

The system for calculating the icing thickness of the wire of the tangent tower based on the weighing method is characterized in that the horizontal stress sigma of the wire is calculated₀The preset range is as follows: 15 MPa-40 MPa.

Has the advantages that:

the method and the system for calculating the icing thickness of the wire of the tangent tower based on the weighing method have the following advantages:

1. the monitoring quantity required to be input in the calculation process is only the hanging point tension, the air temperature and the air speed monitored by the ice coating terminal, the reliability of the monitoring quantity is high, and the monitoring quantity of an inclination angle sensor is avoided;

2. in the calculation process, the icing specific load during icing is accurately calculated through the two processes of initial calculation and recalculation, so that the accuracy of the calculation result is ensured.

3. The influence of meteorological conditions (including air temperature, wind speed and icing) is comprehensively considered in the calculation process;

4. the tower parameters required by the calculation process are basic parameters which can be directly measured, and secondary processing parameters such as vertical span, wire length and the like do not need to be input;

5. the calculation process has the function of automatically checking whether the input parameters of the foundation tower are wrong or not, and calculation results caused by wrong account data are avoided as much as possible;

6. the accuracy of the calculation result does not need to depend on repeated checking of the artificial ice observation result, and the accuracy of the calculation result can be ensured under the condition that the input parameters are correct.

The method makes up the defects of the calculation model of the ice coating thickness of the tangent tower wire in engineering application. The calculation model for the icing thickness of the guide wire of the tangent tower has the advantages of less input monitoring parameters, low requirement on monitoring equipment, high calculation accuracy, good effect in practical engineering application and good popularization and application prospect.

Drawings

Fig. 1 is a schematic diagram of an ice coating on-line monitoring technique in the prior art.

Fig. 2 is a flow chart of the method for calculating the icing thickness of the wire of the linear tower based on the weighing method.

Fig. 3 is a schematic diagram of geographical positions of a Guishan jiayi line ocean village section in an embodiment of the weighing-method-based method for calculating the icing thickness of the line tower conductor.

Fig. 4 is a plan view of a left section of a Guishan jiayi line ocean village section in an embodiment of the weighing-method-based method for calculating the icing thickness of the line tower lead.

Fig. 5a is a schematic diagram of a 16-day monitoring tension value change of a 103# tower of a Guishan mountain second line in an embodiment of the weighing-method-based method for calculating the icing thickness of the linear tower conductor.

Fig. 5b is a schematic diagram of a monitoring picture of a Guishan mountain second line 103# tower 13 in the embodiment of the weighing method-based method for calculating the icing thickness of the linear tower conductor.

Fig. 6 is a structural block diagram of a weighing-method-based linear tower wire icing thickness calculation system.

Fig. 7 is a schematic diagram of an engineering application flow of a tangent tower wire icing thickness calculation system in an embodiment of the invention.

Detailed Description

The invention provides a weighing method-based method and a weighing method-based system for calculating the icing thickness of a wire of a linear tower, and the invention is further described in detail below in order to make the purpose, the technical scheme and the effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

For convenience of understanding, the change rule of the insulator string of the line tangent tower of 110kV and above is required to be explained here.

According to the 7.4.5 regulations of GB 50233-2005110-500 kV overhead power line construction and acceptance regulations, the tangent tower insulator string is vertical to the ground plane, and the displacement between the direction of the line and the vertical position of the tangent tower insulator string does not exceed 5 degrees under individual conditions. Secondly, the standard defect knowledge base of the southern power grid equipment stipulates that the deviation angle of the suspension insulator string along the line direction exceeds 7.5-10 degrees, which is defined as a defect and needs to be eliminated. Thirdly, when ice is coated, if the ice is coated on the flat land section, the ice coating conditions of the leads on the two sides of the tangent tower are similar, and the ice coating basically cannot generate unbalanced tension; in case of a hilly area, under the condition of small ice coating (less than 20mm), the inclination angle of the insulator along the line direction cannot exceed 10 degrees due to unbalanced tension caused by the ice coating. Since cos10 °. apprxeq.0.985 is close to 1, the inclination of the insulator string in the line direction is not changed when the ice coating is not large, and the error is small.

Meanwhile, if a certain tangent tower has a larger inclination angle (more than or equal to 10 degrees) in the direction along the line under normal conditions due to design requirements, the inclination angle can be considered to be unchanged, and the tension T value of the monitored hanging point is multiplied by the cosine value of the corresponding inclination angle, so that the error caused by the inclination angle is reduced.

The calculation model of the icing thickness of the conductor of the tangent tower provided by the method and the system for calculating the icing thickness of the conductor of the tangent tower does not consider the change of the inclination angle of the insulator string along the line direction, and simultaneously does not consider the influence of unbalanced tension on two sides caused by icing because the tangent tower is generally positioned in a flat section. According to actual calculation and operation experience, the requirement of calculation precision is completely met. A linear tower wire icing thickness calculation model based on a weighing method is mainly divided into four parts: calculating the horizontal stress of the wire under the ice coating condition, calculating the initial horizontal stress of the wire under the ice coating condition, calculating the horizontal stress of the wire under the ice coating condition again, and calculating the equivalent ice coating thickness.

It should be understood that, since the force applied to the suspension point of the tangent tower is mainly the gravity of the wire in the vertical span, the calculation range of the calculation model of the ice thickness of the tangent tower of the present invention is within the range of the vertical span of the monitoring tower, as shown by 100 in fig. 8 (i.e., the black line segment area near the middle tangent tower in the figure).

Please refer to fig. 2, which is a flowchart of a method for calculating an icing thickness of a wire of a linear tower based on a weighing method according to the present invention. As shown, the method comprises the following steps in sequence:

s1, acquiring horizontal load P of the tangent tower lead without ice coating_HSaid horizontal load without ice coating P_HBy wind loading of the conductor P_dInsulator string wind load P_JLongitudinal tension P caused by angle of rotation_γForming; i.e. P_H＝P_d+P_J+P_γ；

S2, according to the horizontal load P when the ice coating is not generated_HAnd a first monitored tension value T₀Calculating the length S of the vertical span inner conductor without ice coating_V0And wire horizontal stress σ₀；

S3, obtaining the monitoring air temperature t during icing₁And a second monitored tension value T₁(ii) a And combined with the monitored air temperature t without ice coating₀And wire horizontal stress σ₀Calculating the initial length S of the vertical span inner conductor during icing_V10Initial icing specific load g in icing₂₀；

S4, obtaining the statistical wind speed v during icing₁Calculating the horizontal load during icingP_H1(ii) a Initial calculation of specific ice coating g during combined ice coating₂₀Calculating the recomputed icing specific load g₂₁；

S5, calculating the icing specific load g according to the recalculation₂₁The equivalent ice coating thickness b is obtained according to the following formula₁：

The following is a detailed description of the above steps, respectively:

step S1 is to obtain the horizontal load P when the tangent tower lead is not coated with ice_HSaid horizontal load without ice coating P_HBy wind loading of the conductor P_dInsulator string wind load P_JLongitudinal tension P caused by angle of rotation_γForming; i.e. P_H＝P_d+P_J+P_γ。

In particular, the combined load T of the suspension points of the pendulous string_ΣIs a horizontal load P_HAnd vertical load G_VVector synthesis of (2). For convenience of calculation, the models of the conductors on two sides of the tower are assumed to be the same, and the number of the split conductors is the same. Wherein, the wind load of the wire P_dThe following calculation is adopted:

wherein,

n is the number of split conductors; l₁、l₂Monitoring the large and small side span of the tower; beta is a₁、β₂Monitoring the height difference angle of the large and small sides of the tower; a is the calculated sectional area of the lead; s_hMonitoring the horizontal span of the tower; beta is a_cThe wind load adjustment coefficient of the 500kV line wire is 1.0; g₄The horizontal wind specific load of the wire is obtained; gamma is the number of line corner degrees;the included angle between the wind speed and the trend of the conducting wire is generally 90 degrees; c is the wind load shape coefficient, and the value is 1.2; mu is the uneven coefficient of the wind pressure, and the value is 1.0; d is the calculated diameter of the wire; v. of₀Counting the wind speed when the ice coating is not generated;

the insulator string wind load P_JThe following calculation was used:

P_J＝W₀A_J；

wherein σ_16％Paying off horizontal stress for the wire in the design parameters, wherein the CUT is 16 percent; a is the calculated sectional area of the lead; gamma is the number of line turning angles. Generally, the breaking stress (CUT) of the wire is about 200MPa, and the wire is generally paid out with 16% to 25% breaking stress in the paying out design.

The step S2 is based on the horizontal load P when there is no ice coating_HAnd a first monitored tension value T₀Calculating the length S of the vertical span inner conductor without ice coating_V0And wire horizontal stress σ₀. Specifically, the method comprises the following steps:

s21, calculating the vertical load

S22, calculating the length S of the vertical span inner conductor without ice coating according to the following formula_V0：

S23, according to the length S of the lead in the vertical span_V0Stress σ horizontal to the wire₀To solve the wire horizontal stress sigma₀：

It should be noted that the calculation formula of the length of the wire in the vertical span in the inclined parabolic type is not the above formula, because in the actual transmission line, the vertical span l_vSize and length S of vertical span inner conductor_VThe difference is less than 1%, and in order to avoid complex operation and not lose precision requirement, the projection length of the vertical span on the connecting line of the hanging points can be used as the length of the wire.

Wherein h is₁、h₂The height difference between the tower hanging point of the monitoring rod and the tower hanging points of the large and small side rods is obtained; beta is a₁、β₂Monitoring the height difference angle of the large and small sides of the tower; g_JThe weight of the insulator string and the connecting hardware thereof; g₁The dead weight of the wire is loaded; theta is an included angle of the insulator string; t is₀The pull value was monitored for the hanging point without ice coating.

Further, due to the need for sag control of power transmission lines, the paying-off stress is generally at the failure stress σ_maxAbout 16% of the total operating stress, resulting in an average annual operating stress of generally between 15MPa and 40 MPa. In the calculation process, if the horizontal stress sigma of the lead occurs₀If the input data exceeds the range, the input data is obviously wrong, and the input data needs to be checked again; if the wire has horizontal stress sigma₀And if the current time is in the normal range, continuing to press the step for calculation.

It should be noted that, in the calculation process, since the monitoring amount of the tilt sensor is not used, the included angle between the wind direction and the direction of the line cannot be determined, and the included angle is uniformly set to be 90 degrees in the calculation process. In order to reduce the error caused by meteorological conditions, the wind speed v without ice coating is selected₀Less than 5m/s, air temperature t₀Meteorological conditions below 5 ℃ and monitored tensile value T₀. The monitoring parameters in the ice coating-free state can be regarded as fixed parameters, and do not need to be changed after being selected.

The step S3 is to obtain the monitored air temperature t during icing₁And a second monitored tension value T₁(ii) a And combined with the monitored air temperature t without ice coating₀And wire horizontal stress σ₀Calculating the initial length S of the vertical span inner conductor during icing_V10Initial icing specific load g in icing₂₀。

When the transmission line is coated with ice, due to the influence of the ice coating and the low temperature, the horizontal stress of the transmission line conductor is increased, and the corresponding vertical span is slightly changed. In order to accurately calculate the thickness of the ice coated on the wire, the calculation model considers the change of the horizontal stress and the vertical span of the wire during ice coating, and calculates the more accurate ice coating specific load of the wire through two processes of initial calculation and secondary calculation.

In the initial calculation process, the length of the wire and the horizontal wind load in the vertical span of the wire are considered to be unchanged, and then the initial calculation icing specific load g of the wire is obtained during icing₂₀The calculation formula is as follows:

when icing, the comprehensive specific load g of the wire is calculated initially₇₀Comprises the following steps:

g_{70} = \sqrt{{(g_{1} + g_{20})}^{2} + g_{4}^{2}};

comprehensive specific load g of wire without ice coating₆Comprises the following steps:

g_{6} = \sqrt{g_{1}^{2} + g_{4}^{2}}

according to the wire state equation:

can solve the initial calculation of the horizontal stress sigma of the lead during ice coating₁₀So that the initial length S of the vertical span inner conductor is calculated during ice coating_V10Comprises the following steps:

Step S4 is to obtain the statistical wind speed v when icing₁Calculating the horizontal load P during icing_H1(ii) a Initial calculation of specific ice coating g during combined ice coating₂₀Calculating the recomputed icing specific load g₂₁. Specifically, the more accurate wire icing specific load g can be obtained in the initial calculation process₂₀Initial length S of vertical span wire during ice coating_V10. However, in the initial calculation process, the influence of wind load and insulator icing during icing is not considered. In order to more accurately determine the specific icing load of the wire during icing, the model further adopts a recalculation process.

According to the initial calculated wire icing specific load g₂₀The initial equivalent icing thickness b can be calculated₀。

Wherein d is the wire diameter.

Wire horizontal wind specific load g during icing₄₁Comprises the following steps:

wherein v is₁The wind speed is the statistical wind speed during ice coating.

When icing, the wind load of the wire is P_d1Comprises the following steps:

during icing, the wind load P of the insulator string_J1Comprises the following steps:

P_J1＝W₁BA_J；

wherein, W₁The standard value of the wind load of the insulator string is the standard value when the insulator string is coated with ice; and B is the insulator chain shape increasing coefficient in ice coating, and the value is 1.2.

Longitudinal tension P caused by angle of rotation during icing (also called icing)_γ1Comprises the following steps:

then the horizontal load P during icing_H1Comprises the following steps:

P_H1＝P_d1+P_J1+P_γ1；

recalculation icing specific load g₂₁The results were:

and K is the ice coating coefficient of the insulator string. According to the experience of anti-icing work and related technical data, the 500kV and 800kV lines can be valued according to the following table. (it is insulator chain icing coefficient K value table)

The step S5 is to calculate the icing specific load g according to the recalculation₂₁The equivalent ice coating thickness b is obtained according to the following formula₁：

In summary, the above method features include:

6. the accuracy of the calculation result does not need to depend on repeated checking of the artificial ice observation result, and the accuracy of the calculation result can be ensured under the condition of accurate input parameters.

Compared with the existing method, at present, the verification of the icing thickness calculation model by most researchers is only limited to the experimental environment. Specifically, a sensor is installed in an experimental environment, conductor icing is simulated, calculation is carried out according to the monitoring quantity of the sensor, and finally, the calculation result is compared with the measured ice thickness in the experimental environment for analysis. However, compared with the experimental environment, the field environment is much more complex, the sensor operation environment is severe, the line length is large, and the tightening degree is high, so that the verification accuracy in the experimental environment often meets the requirement, and the calculation result has a larger error in the actual engineering application.

Therefore, the strict application effect verification of the icing thickness calculation model needs to be related to engineering practice, and the accuracy of the model should be verified in a field environment. According to the invention, the application effects of field micro-terrain microclimate and comprehensive analysis models are obtained by monitoring data through the ultra-high voltage transmission company in the ice coating period of 2013-2014 and monitoring data through an ice coating early warning system. (please refer to fig. 7, which is a flow chart of the calculation system engineering application of the ice thickness of the tangent tower wire in the embodiment of the present invention)

Example one

The 500kV Guishan A-B line ocean village section governed by the ultra-high voltage transmission company is an icing key area, and the ice-coating key observation area is a tower-falling disconnection accident caused by ice coating. The study conducted analytical validation on the 12-month-16-day icing process in 2013 of this section. Fig. 3 is a schematic diagram of the geographic location of the Guishan mountain A-B line ocean village section.

Therefore, the middle part of the ocean rural area of the Guishan Jia Yinle is a basin, and hills are arranged on two sides of the basin. When a static front of south China passes through in winter, ice coating is light due to the windproof and heat-insulating effects of the basin, the ice coating thickness of hillsides on two sides is increased sharply, and the ice coating is thickest at a mountain top air opening.

According to the monitoring data of the ice coating early warning system at 12 months, 16 days and 18 days in 2013, the calculation result is shown in fig. 4 by applying the weighing-method-based method for calculating the ice coating thickness of the wire of the linear tower. Wherein, the dry-shaped tower represents a strain tower, and the calculation of the ice thickness is a calculation result by adopting another mature strain tower lead ice coating thickness calculation model; the cat-head tower represents a straight tower and is the result calculated for the study model.

Firstly, analyzing the left section of the ocean-rural area of the Guishan Jia Yinle. As can be seen from FIG. 4, the position of the Guishan jia line 110# tower is close to that of the second line 103# tower, the Guishan jia line 110# tower is located at the top end of a hillside on the left side of the basin, the tower types are different, the calculation results are respectively 7.26mm and 7.07mm, the calculation results are very close, and the accuracy of the calculation results of the linear tower ice thickness calculation model can be verified from the side. Meanwhile, at noon of 16 days, the organization personnel of the ultrahigh voltage company view ice on site, the ice viewing result of the 110# tension tower simulation lead of the A line is 5.5mm, the ice coating monitoring picture is shown in figure 5b, 12:30 minutes in the same noon of the day, the result of calculating the ice coating thickness of the 103# straight line tower lead of the B line by using the research model is 5.223mm, and as shown in figure 5a, the calculation result is very consistent with the ice viewing result.

In conclusion, the calculation result of the research model can be completely matched with the artificial ice observation result, the close tower calculation result, the micro-terrain influence result and the picture monitoring result, the influence of complex environmental factors on the site can be overcome, the ice coating thickness of the tangent tower wire can be accurately calculated, and the requirements of engineering application are met.

The invention also provides a weighing method-based linear tower wire icing thickness calculation system, as shown in fig. 6, the system comprises:

a first computing unit 100 for obtaining the horizontal load P of the tangent tower wire without ice coating_HSaid horizontal load without ice coating P_HBy wind loading of the conductor P_dInsulator string wind load P_JLongitudinal tension P caused by angle of rotation_γIs formed of, i.e. P_H＝P_d+P_J+P_γ；

A second calculation unit 200 for non-icing time for calculating a horizontal load P according to the non-icing time_HAnd a first monitored tension value T₀Calculating the length S of the vertical span inner conductor without ice coating_V0And wire horizontal stress σ₀；

An initial calculation unit 300 for obtaining a monitored air temperature t during icing₁And a second monitored tension value T₁(ii) a And combined with the monitored air temperature t without ice coating₀And wire horizontal stress σ₀Calculating the initial length S of the vertical span inner conductor during icing_V10And initial icing specific load g₂₀；

A recalculation unit 400 for icing time for obtaining the statistical wind speed v during icing time₁Calculating the horizontal load P during icing_H1(ii) a Then combining the initial calculation of specific icing load g₂₀Calculating the recomputed icing specific load g₂₁；

An icing thickness calculating unit 500 for calculating an icing specific load g according to the recalculation₂₁Obtaining the recalculated equivalent icing thickness b according to the following formula₁：

Further, in the system for calculating the thickness of the ice coating on the wire of the linear tower based on the weighing method, the second calculating unit further includes:

Further, in the weighing-method-based linear tower wire icing thickness calculation system, the wire horizontal stress sigma is₀The preset range is as follows: 15 MPa-40 MPa.

Because the specific implementation details of the module are described in detail in the calculation method of the ice coating thickness of the wire of the linear tower based on the weighing method, the details are not described here.

In summary, the invention provides a weighing method-based method and a system for calculating the icing thickness of a straight line tower lead, wherein the method comprises the following steps: firstly, calculating the horizontal stress of the wire when no icing is carried out, then sequentially obtaining the initial icing specific load of the wire under the icing condition and the re-calculated icing specific load of the wire, and finally obtaining the equivalent icing thickness according to the re-calculated icing specific load. The method makes up the defects of the calculation model of the ice coating thickness of the tangent tower wire in engineering application, has the advantages of less input monitoring parameters, low requirement on monitoring equipment, high calculation accuracy and the like, has good effect in practical engineering application, and has good popularization and application prospects.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A method for calculating the icing thickness of a wire of a tangent tower based on a weighing method is characterized by sequentially comprising the following steps of:

2. The method according to claim 1The method for calculating the icing thickness of the wire of the linear tower by using the weighing method is characterized in that the wind load P of the wire in the step A_dThe following calculation is adopted:

wherein,

n is the number of split conductors; l₁、l₂Monitoring the large and small side span of the tower; beta is a₁、β₂Monitoring the height difference angle of the large and small sides of the tower; a is the calculated sectional area of the lead; s_hMonitoring the horizontal span of the tower; beta is a_cThe wind load adjustment coefficient of the 500kV line wire is 1.0; g₄The horizontal wind specific load of the wire is obtained; gamma is the number of line corner degrees;taking an included angle of the wind speed and the trend of the wire, and taking the included angle at 90 degrees; c is the wind load shape coefficient, and the value is 1.2; mu is the uneven coefficient of the wind pressure, and the value is 1.0; d is the calculated diameter of the wire; v. of₀Counting the wind speed when the ice coating is not generated;

the insulator string wind load P_JThe following calculation was used:

P_J＝W₀A_J；

3. The weighing method-based method for calculating the icing thickness of the wire of the linear tower according to claim 1 or 2, wherein the step B specifically comprises the following steps:

G_{V 0} = \sqrt{T_{0}^{2} - P_{H}^{2}};

Wherein h is₁、h₂The height difference between the tower hanging point of the monitoring rod and the tower hanging points of the large and small side rods is obtained; beta is a₁、β₂Monitoring the height difference angle of the large and small sides of the tower; g_JThe weight of the insulator string and the connecting hardware thereof; g₁The dead weight of the wire is loaded; theta is an included angle of the insulator string; t is₀The tensile value was monitored without ice coating.

4. The weighing method-based tangent tower wire icing thickness calculating method according to claim 3, wherein the step B further comprises the following steps:

5. The weighing-method-based line tower wire icing thickness calculation method according to claim 4, wherein the wire horizontal stress sigma₀The preset range is as follows: 15 MPa-40 MPa.

6. The weighing method-based method for calculating the icing thickness of the wire of the linear tower according to claim 4 or 5, wherein the step C specifically comprises the following steps:

g_{70} = \sqrt{{(g_{1} + g_{20})}^{2} + g_{4}^{2}};

g_{6} = \sqrt{g_{1}^{2} + g_{4}^{2}};

c2, according to the wire state equation:

7. The weighing method-based method for calculating the icing thickness of the wire of the linear tower according to claim 6, wherein the step D specifically comprises the following steps:

Wherein d is the diameter of the wire;

wherein v is₁The statistical wind speed during icing;

P_J1＝W₁BA_J；

wherein，W₁The standard value of the wind load of the insulator string during ice coating is obtained; and B is the insulator chain shape increasing coefficient in ice coating, and the value is 1.2.

d6, horizontal load P during ice coating_H1Comprises the following steps:

P_H1＝P_d1+P_J1+P_γ1；

and K is the ice coating coefficient of the insulator string.

8. A weighing method-based line tower wire icing thickness calculation system is characterized by comprising the following steps:

9. The weighing-based tangent tower wire icing thickness calculation system of claim 8, wherein the non-icing second calculation unit further comprises:

10. The weighing-based line tower wire ice thickness calculation system of claim 9, wherein the wire horizontal stress σ is₀The preset range is as follows: 15 MPa-40 MPa.