An adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators

Abstract

This invention discloses an adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators. The invention acquires the conductor foundation parameters and designed ice thickness of the transmission line, calculates the equivalent ice thickness of the conductor based on tension monitoring data before and after icing, classifies the lines according to whether the designed ice thickness exceeds a preset value, and sets differentiated three-level alarm thresholds for conductor icing for each category. It combines the designed ice thickness of the conductor, the ratio of the equivalent ice thickness to the designed ice thickness, and implements hierarchical alarms for conductor icing. Furthermore, based on the equivalent ice thickness of the conductor, the equivalence calculation relationship between conductor icing and insulator icing, and acquiring and combining insulator structural type and environmental information, it calculates the equivalent ice thickness of the insulator. Based on the set insulator icing alarm thresholds, it outputs insulator icing alarm information and provides suggestions for insulator de-icing initiation. This invention does not require changes to existing monitoring device hardware, significantly improving alarm accuracy and timeliness.

Description

Technical Field

[0001] This invention belongs to the field of online monitoring and intelligent alarm technology for power system transmission lines. Specifically, it is an adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators based on conductor cross-section, conductor design ice thickness, and differences in different types of insulators. Background Technology

[0002] Icing on transmission lines is one of the major natural disasters threatening the safe operation of power grids. Currently, online icing monitoring devices are widely used in power grids. The typical approach is to monitor parameters such as conductor tension and tilt angle to infer the ice thickness and issue alarms based on preset thresholds, providing a basis for decisions on de-icing and de-icing.

[0003] However, existing icing monitoring devices typically use a uniform standard for alarm thresholds, failing to adequately consider the differences in ice thickness design and conductor type (especially conductor cross-section) across different lines. Actual operation shows that, under the same tensile force increase, the ice thickness varies significantly for conductors with different cross-sections. Using a fixed threshold may result in premature alarms for small-section conductors and delayed alarms for large-section conductors, affecting the accuracy of icing alarms and operational efficiency.

[0004] In addition, for lines with a designed ice thickness of 5mm, although the designed ice thickness is small, they often use large cross-section conductors (such as 800mm²). Under the same tensile force increase, the calculated ice thickness accounts for a much higher proportion of the designed ice thickness than other lines. If a uniform threshold is still used, it is easy to cause missed alarms or untimely alarms. Historically, faults such as ice break jumps have occurred because of this.

[0005] On the other hand, insulator icing flashover is the primary electrical cause of line tripping during ice storms. Due to the complex structure of insulators, their icing rate and risk of ice bridging are often higher than those of adjacent conductors, resulting in insulators being on the verge of flashover even when the conductors are still within the safe ice thickness. However, existing monitoring methods generally lack direct assessment and early warning of insulator icing conditions. Relying solely on conductor load criteria creates blind spots in electrical protection and is insufficient to meet the needs of on-site insulators for determining whether to initiate de-icing procedures.

[0006] Therefore, there is an urgent need for a monitoring and alarm method that can synchronously and adaptively assess the icing status of conductors and insulators, and can dynamically and accurately set alarm thresholds based on actual line parameters, insulator models, and environmental information, so as to improve the accuracy and applicability of icing monitoring. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the deficiencies of the existing technology and provide an adaptive graded alarm threshold setting method for icing monitoring of transmission lines and insulators. This method acquires the basic parameters of the transmission line conductors and the designed ice thickness of the conductors. Based on the tension monitoring data before and after icing, it uses an iterative correction method to calculate the equivalent ice thickness of the conductors to effectively compensate for the system error of the tension sensor. The method classifies the lines according to whether the designed ice thickness of the conductors exceeds a preset value and sets differentiated three-level alarm thresholds for conductor icing for each category. It combines the designed ice thickness of the conductors, the ratio of the equivalent ice thickness to the designed ice thickness, to achieve accurate graded alarms for conductor icing. Furthermore, based on the equivalent ice thickness of the conductors, the equivalence calculation relationship between conductor icing and insulator icing, and by acquiring and combining insulator structural type and environmental information, it calculates the equivalent ice thickness of the insulators. Based on the set insulator icing alarm thresholds, it outputs insulator icing alarm information to simultaneously achieve accurate graded alarms for conductors and insulators, and provides suggestions on whether to initiate insulator de-icing.

[0008] Therefore, the present invention adopts the following technical solution: an adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators, comprising the following steps: a) Obtain basic parameters of the transmission line, including the design ice thickness of the conductor; b) Obtain the conductor tension value before and after icing, and calculate the equivalent icing thickness of the conductor based on the conductor icing thickness conversion model; c) Calculate the ratio of the equivalent ice thickness to the design ice thickness of the conductor based on the design ice thickness of the conductor and the equivalent ice thickness of the conductor. d) Based on whether the designed ice thickness of the conductor is greater than the preset value, the conductor is divided into Class I and Class II lines, and a differentiated three-level alarm threshold for conductor icing is set for the two types of lines respectively. e) The ratio of the designed ice thickness of the conductor, the equivalent ice thickness of the conductor, and the designed ice thickness of the conductor are compared with the preset value and the differentiated conductor ice three-level alarm threshold, respectively, and the corresponding conductor ice alarm information is output. f) Obtain insulator structure type and environmental information, and calculate comprehensive environmental correction coefficient based on the environmental information; g) Calculate the equivalent ice thickness of the insulator based on the insulator structure type, comprehensive environmental correction factor, and equivalent ice thickness of the conductor; h) Set the three-level alarm threshold for insulator icing, compare the equivalent icing thickness of the insulator with the three-level alarm threshold for insulator icing, and output the corresponding insulator icing alarm information; i) Calculate the insulator flashover voltage under the current icing condition based on the insulator structure type, the equivalent ice thickness of the insulator, and the insulator flashover voltage calculation model; j) Obtain the highest operating voltage of the line, and then, in conjunction with the insulator flashover voltage, calculate the current flashover voltage safety margin; k) Set the insulator de-icing start safety margin threshold and compare it with the ice flashover voltage safety margin, and output the corresponding insulator de-icing start recommendation information.

[0009] This invention iteratively calculates the equivalent ice thickness of the conductor based on the actual parameters of the transmission line and the design ice thickness of the conductor. Considering the design ice thickness and the equivalent ice thickness, it adaptively sets the conductor icing alarm threshold in a graded manner. Taking into account the insulator type, environmental information, and the equivalent ice thickness of the conductor, it calculates the equivalent ice thickness of the insulator and compares it with the insulator icing alarm threshold to output insulator icing alarm information, thus achieving accurate graded alarms for transmission line and insulator icing. Based on the insulator flashover voltage calculation model, combined with the insulator equivalent ice thickness and insulator structure, it calculates the insulator flashover voltage under the current icing state, compares it with the actual operating voltage of the system, and provides corresponding insulator de-icing start suggestions.

[0010] This invention does not require changes to the existing monitoring device hardware, significantly improves the accuracy and timeliness of alarms, and provides an adaptive classification threshold setting basis for icing warnings of transmission lines with different models and ice thicknesses, and insulators with different models and structural types.

[0011] Furthermore, in step b), the calculation of the equivalent icing thickness of the conductor based on the conductor icing thickness conversion model is carried out as follows: b1) Preset the directional deflection parameters before and after icing, including the directional deflection angle along the line before icing, the directional deflection angle perpendicular to the line before icing, the directional deflection angle along the line after icing, and the directional deflection angle perpendicular to the line after icing. b2) Calculate the ice load on the conductor based on the preset directional deflection angle parameters before and after icing, as well as the conductor tension values ​​before and after icing. b3) Based on the aforementioned conductor icing load, the icing shape is treated as circular, and the equivalent icing thickness of the conductor is calculated according to the conductor icing thickness conversion model. b4) Determine the equivalent ice thickness of the conductor. If it meets the preset first judgment condition, the equivalent ice thickness of the conductor is the final equivalent ice thickness of the conductor. If it does not meet the first judgment condition, correct the directional deflection parameters before and after icing. Based on steps b2) and b3), the equivalent ice thickness of the conductor is recalculated and judged. If it meets the preset second judgment condition, the equivalent ice thickness of the conductor is the final equivalent ice thickness of the conductor. If it does not meet the second judgment condition, the directional deflection parameters before and after icing are corrected until the calculated equivalent ice thickness of the conductor meets the second judgment condition.

[0012] Furthermore, in step d), the specific settings for the differentiated conductor icing three-level alarm threshold include: d1) For Class I lines with an ice thickness of 5mm or less, the alarm thresholds for Level I, Level II, and Level III are 50%, 40%, and 20%, respectively. d2) For Class II lines with an ice thickness greater than 5mm, the alarm thresholds for Level I, Level II, and Level III are 70%, 50%, and 20%, respectively.

[0013] Furthermore, in step e), the formula for calculating the conductor icing alarm information is as follows: , in, level line This is the conductor icing alarm information. 0 represents no alarm for conductor icing, 1 represents a level 1 alarm for conductor icing, 2 represents a level 2 alarm for conductor icing, and 3 represents a level 3 alarm for conductor icing. This is the ratio of the equivalent ice thickness of the conductor to the designed ice thickness of the conductor. Ice thickness is designed for the conductor, in mm; else If the conditions for alarm levels one, two, and three are not met, then... level =0 outputs no alarm message.

[0014] Furthermore, in step f), the formula for calculating the comprehensive environmental correction factor is as follows: , in, This is a comprehensive environmental correction factor; Wind speed factor; Temperature factor; This refers to the liquid water content factor.

[0015] Furthermore, in step g), the formula for calculating the equivalent ice thickness of the insulator is as follows: , in, The equivalent ice thickness of the insulator is expressed in mm. This refers to the insulator structure type coefficient; This is a comprehensive environmental correction factor; It is a non-linear growth index; The equivalent icing thickness of the conductor is expressed in mm.

[0016] Furthermore, step h) specifically includes: h1) Set the three-level alarm threshold for insulator icing, with the first, second, and third level alarm thresholds corresponding to 15mm, 10mm, and 5mm, respectively; h2) Output insulator icing alarm information, the calculation formula of which is as follows: , in, level insulator This is the insulator icing alarm information. 0 represents no alarm for insulator icing, 1 represents a level 1 alarm for insulator icing, 2 represents a level 2 alarm for insulator icing, and 3 represents a level 3 alarm for insulator icing. The equivalent icing thickness of the insulator is expressed in mm.

[0017] Furthermore, in step i), the formula for calculating the insulator flashover voltage under the current icing condition is as follows: , in, The insulator flashover voltage is kV. The voltage is the 50% power frequency flashover voltage of the insulator string under clean and dry conditions, in kV. This is the icing attenuation coefficient; The equivalent ice thickness of the insulator is expressed in mm. Reference ice thickness for insulators; This is the insulator type correction factor.

[0018] Furthermore, in step j), the formula for calculating the ice flashover voltage safety margin is as follows: , in, k This is for the safety margin of ice flashover voltage; This refers to the insulator flashover voltage, measured in kV. This is the highest operating voltage of the line, expressed in kV.

[0019] Furthermore, in step k), the calculation formula for the insulator de-icing start-up suggestion information is as follows: , in, The insulator de-icing start suggestion information is: 0 means insulator de-icing is not started, and 1 means insulator de-icing is started. k This is for the safety margin of ice flashover voltage; The safety margin threshold for insulator de-icing startup.

[0020] Compared with existing technologies, the present invention has the following beneficial effects: Without changing the hardware of existing monitoring devices, the present invention establishes differentiated threshold setting rules for the fusion of conductor cross-section and conductor design ice thickness, and adopts an iterative correction algorithm based on ice thickness results. Combined with environmental information, it obtains the ice thickness of insulators, which significantly improves the accuracy of ice thickness calculation and alarm accuracy of conductors and insulators. Furthermore, it calculates the ice flashover voltage based on the equivalent ice thickness of insulators and provides suggestions on whether to initiate insulator de-icing. Thus, it realizes refined and adaptive early warning of ice risk for different transmission lines and insulators, and has significant engineering application value. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of an adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to the present invention; Figure 2 This is a flowchart illustrating the output of conductor icing alarm information in this invention. Figure 3 This is a flowchart illustrating the three-level alarm information for insulator icing in this invention. Figure 4 This is a flowchart illustrating the insulator de-icing start-up suggestion information output by the present invention; Figure 5 This is a flowchart illustrating the calculation process of the conductor icing thickness calculation model of the present invention. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] Example This embodiment describes an adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators, such as... Figure 1-5 As shown, the steps are as follows: a) Obtain the basic parameters of the transmission line, including conductor type, conductor diameter, conductor unit mass and conductor design ice thickness; b) Obtain conductor tension values ​​before and after icing, including conductor tension values ​​before icing. and conductor tension value after icing The equivalent ice thickness of the conductor is calculated based on the conductor ice thickness conversion model; c) Based on the wire design obtained in step a), the ice thickness and steps are as follows. b The equivalent ice thickness of the conductor is calculated, and the ratio of the equivalent ice thickness to the designed ice thickness of the conductor is calculated. ; d) Based on whether the designed ice thickness value of the conductor obtained in step a) is greater than the preset value (5mm in this embodiment), the conductor is divided into Class I and Class II lines, and a differentiated three-level alarm threshold for conductor icing is set for the two types of lines, where the third level alarm is the mildest and the first level alarm is the most severe. e) The ratio of the designed ice thickness of the conductor, the equivalent ice thickness of the conductor, to the designed ice thickness of the conductor. The alarms are compared with the preset value and the differentiated three-level alarm threshold for conductor icing, and the corresponding conductor icing alarm information is output. f) Obtain insulator structure type and environmental information, including wind speed, temperature, and liquid water content, and calculate a comprehensive environmental correction coefficient based on the environmental information. ; g) Based on the insulator structure type and comprehensive environmental correction factor Calculate the equivalent icing thickness of the insulator based on the equivalent icing thickness of the conductor. ; h) Set the three-level icing alarm threshold for insulators, and set the equivalent icing thickness of the insulators as the threshold. Compare with the aforementioned three-level alarm threshold for insulator icing, and output the corresponding insulator icing alarm information; i) Based on the insulator structure type and the equivalent ice thickness of the insulator And an insulator flashover voltage calculation model to calculate the insulator flashover voltage under the current icing condition. ; j) Obtain the highest operating voltage of the line Combined with the aforementioned insulator flashover voltage Calculate the current ice flashover voltage safety margin. k ; k) Set the safety margin threshold for insulator de-icing startup. K insulator and the aforementioned ice flash voltage safety margin k The comparison is performed, and the corresponding insulator de-icing start-up suggestion information is output.

[0025] Specifically, in step b), the calculation of the equivalent ice thickness of the conductor based on the conductor ice thickness conversion model is carried out as follows: b1) Preset the directional deflection parameters before and after icing. Specifically: directional deflection angle before icing along the track. =0°, vertical deflection angle of the line before icing =0°, deflection angle in the direction of the line after icing =20°, vertical deflection angle of the line after icing =20°; b2) Based on the preset directional deflection parameters before and after icing in b1), and the conductor tension value before icing... Wire tension value after icing Calculate the ice load on the conductor: , in, This refers to the ice load on the conductor, expressed in kg / m. The unit mass of the conductor is expressed in kg / m. This represents the conductor tension value before icing, in N. This is the conductor tension value after icing, in N; The angle of deviation along the track before icing, in degrees; The angle of deflection along the track after icing, in degrees. The angle of deviation of the vertical line direction before icing, in degrees; The angle of deviation of the line perpendicular to the direction of icing, in degrees; b3) Based on b2), the conductor icing load is obtained. Treating the icing shape as circular, the equivalent icing thickness of the conductor is calculated: , in, The equivalent ice thickness of the conductor is expressed in mm. This refers to the diameter of the conductor, in mm. This represents the ice load on the conductor, expressed in kg / m.

[0026] b4) The equivalent icing thickness of the conductor obtained in step b3) b To make a judgment, specifically: b4.1) When the equivalent ice thickness of the conductor calculated in step b3) b <5mm, calculation ends, step b3) calculate the equivalent icing thickness of the conductor. b This is the final equivalent ice thickness of the conductor; b4.2) When the equivalent ice thickness of the conductor calculated in step b3) b ≥5mm, return to step b1), correct the directional deflection parameters before and after icing, specifically, correct as follows: directional deflection angle along the track before icing. =0°, vertical deflection angle of the line before icing =0°, deflection angle in the direction of the line after icing =30°, vertical deflection angle of the track after icing =30°, repeat steps b2) and b3) to obtain the equivalent ice thickness of the conductor. b ; b4.3) The equivalent icing thickness of the conductor obtained in step b4.2). b To make a judgment, specifically: b4.3.1) When the equivalent ice thickness of the conductor calculated in step b4.2) b Meets 10mm ≥ b ≥5mm, calculation ends, step b4.2) calculate the equivalent icing thickness of the conductor. b This is the final equivalent ice thickness of the conductor; b4.3.2) When the equivalent ice thickness of the conductor calculated in step b4.2) b >10mm, return to step b1), correct the directional deflection parameters before and after icing, specifically, correct as follows: directional deflection angle along the track before icing. =0°, vertical deflection angle of the line before icing =0°, deflection angle in the direction of the line after icing =35°, vertical deflection angle of the track after icing =35°, repeat steps b2) and b3) to obtain the ice thickness. b The equivalent icing thickness of the conductor obtained at this time b This is the final equivalent icing thickness of the conductor.

[0027] Specifically, in step c), the ratio of the equivalent ice thickness of the conductor to the designed ice thickness of the conductor... The calculation formula is as follows: , in, This is the ratio of the equivalent ice thickness of the conductor to the designed ice thickness of the conductor. b The equivalent ice thickness of the conductor is expressed in mm. Ice thickness is designed for the conductor, in mm.

[0028] Specifically, in step d), the differentiated conductor icing level three alarm threshold is set as follows: d1) For Class I lines with an ice thickness of 5mm or less, the alarm thresholds for Level I, Level II, and Level III are 50%, 40%, and 20%, respectively. d2) For Class II lines with an ice thickness greater than 5mm, the alarm thresholds for Level I, Level II, and Level III are 70%, 50%, and 20%, respectively.

[0029] Specifically, in step e), the specific calculation formula for the conductor icing alarm information is as follows: , in, level line This is the conductor icing alarm information. 0 represents no alarm for conductor icing, 1 represents a level 1 alarm for conductor icing, 2 represents a level 2 alarm for conductor icing, and 3 represents a level 3 alarm for conductor icing. else If the conditions for alarm levels one, two, and three are not met, then... leve =0 outputs no alarm message.

[0030] Specifically, in step f), the comprehensive environmental correction coefficient The calculation process is as follows: f1) Obtain environmental information, specifically including wind speed, temperature, and liquid water content; f2) Comprehensive environmental correction factor The calculation formula is as follows: , in, This is a comprehensive environmental correction factor; The wind speed factor is used when the wind speed is less than 4 m / s. =1.0, when the wind speed is greater than or equal to 4 m / s =1.2; The temperature factor is used when the temperature is greater than or equal to -4℃. =1.0, when the temperature is below -4℃ =1.3; The liquid water content factor is defined as follows: when the liquid water content is less than or equal to 36 g / m³. =1.0, when the liquid water content is greater than 36 g / m³, =1.1.

[0031] Specifically, in step g), the equivalent icing thickness of the insulator... The calculation formula is as follows: , in, The equivalent ice thickness of the insulator is expressed in mm. This is the insulator structure type coefficient, with a value ranging from 1 to 2. Recommended for standard porcelain / glass insulators. =1.15, Recommended standard composite insulator =1.3; This is a comprehensive environmental correction factor; b The equivalent ice thickness of the conductor is expressed in mm. It is a non-linear growth index, with a value ranging from 1 to 2, and a value of 1.2 is generally recommended.

[0032] Specifically, the details of step h) are as follows: h1) Set the three-level icing alarm thresholds for insulators, with the alarm thresholds for the first, second, and third levels corresponding to 15mm, 10mm, and 5mm, respectively; h2) Output the corresponding insulator icing alarm information. The specific calculation formula is as follows: , in, level insulator This is the insulator icing alarm information. 0 represents no alarm for insulator icing, 1 represents a level 1 alarm for insulator icing, 2 represents a level 2 alarm for insulator icing, and 3 represents a level 3 alarm for insulator icing. The equivalent icing thickness of the insulator is expressed in mm.

[0033] Specifically, in step i), the insulator flashover voltage under the current icing condition. The calculation formula is as follows: , in, This refers to the insulator flashover voltage, measured in kV. This is the 50% power frequency flashover voltage of the insulator string under clean and dry conditions, in kV, and is generally determined based on the line voltage level and the number of insulator discs. This is the icing attenuation coefficient, with a value ranging from 0.15 to 0.30, and a value of 0.22 is generally recommended. The equivalent ice thickness of the insulator is expressed in mm. The reference ice thickness for insulators is 1 mm. The correction factor is 1.0 for standard porcelain / glass insulators and 0.8~0.9 for composite insulators.

[0034] Furthermore, the insulator structure includes the insulator type, number of discs, and dry flashover voltage of a single insulator disc, and the 50% power frequency flashover voltage of the insulator string under clean and dry conditions. The result is obtained by calculation using the following formula: , in, The voltage is the 50% power frequency flashover voltage of the insulator string under clean and dry conditions, in kV. N represents the flashover voltage of a single insulator, in kV; N is the number of insulator discs, in discs. This is the voltage distribution coefficient, with a value ranging from 0.90 to 0.95, and a value of 0.92 is generally recommended.

[0035] Specifically, in step j), the formula for calculating the ice flashover voltage safety margin is as follows: , in, k This is for the safety margin of ice flashover voltage; This refers to the insulator flashover voltage, measured in kV. This is the highest operating voltage of the line, expressed in kV.

[0036] Specifically, in step k), the calculation formula for the insulator de-icing start-up suggestion information is as follows: , in, The insulator de-icing start suggestion information is: 0 means insulator de-icing is not started, and 1 means insulator de-icing is started. k This is for the safety margin of ice flashover voltage; The recommended safety margin threshold for insulator de-icing startup is 1.2 to 1.5, with a general recommended value of 1.3.

[0037] Application examples The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators described in the above embodiments is applied as follows, with the steps as follows: a) Obtain the basic parameters of the transmission line, including conductor type: JL / LB20A-630 / 55, conductor diameter: 33.80mm, conductor unit mass: 2.630kg / m, and conductor design ice thickness. b 0:10mm; b) Obtain the conductor tension values ​​before and after icing, specifically including the conductor tension value before icing T0=25000N and the conductor tension value after icing T=46250N. The process for calculating the equivalent ice thickness of the conductor is as follows: b1) First, preset the direction deflection angle parameters before and after icing. =0°、 =0°、 =20° =20°, combined with the conductor tension value before icing T0=25000N and the conductor tension value after icing T=46250N, calculate the conductor icing load q. i for: , Further calculation of the equivalent icing thickness of the conductor b for: , The equivalent ice thickness of the conductor bIf the conditions are not met, discard the relevant option; and correct the directional deflection parameters before and after icing as follows: =0°、 =0°、 =30° =30°, recalculated conductor icing load q i for: , Update the calculation of equivalent icing thickness of the conductor. b for: At this time, 10mm ≥ b =8.51mm≥5mm, equivalent icing thickness of the conductor b The conditions are met. Therefore, the equivalent icing thickness of the output conductor is [not specified]. b =8.51mm.

[0038] c) Ice thickness based on conductor design b 0 = 10mm, equivalent icing thickness of the conductor b =8.51mm, calculate the ratio of the equivalent icing thickness of the conductor to the design icing thickness of the conductor. = b / b 0 = 8.51 mm / 10 mm = 85.10%; d) Design ice thickness values ​​for line conductors b If 0 = 10mm > 5mm, the line is classified as a Class II line, and its Level I, Level II, and Level III alarm thresholds correspond to tensile force increases of 70%, 50%, and 20%, respectively.

[0039] e) Ice thickness based on conductor design b 0 = 10mm, the ratio of the equivalent icing thickness of the conductor to the designed icing thickness of the conductor. =85.10%, which satisfies the requirement. conditions, that is ,so This means outputting a primary icing alarm message for the conductor.

[0040] f) Obtain the insulator structure type, insulator model LXY-100, number of discs 30, and single-disc dry flashover voltage 75kV; obtain environmental information, specifically including wind speed 3m / s, temperature -5℃, and liquid water content 40g / m³. Under these conditions, when the wind speed is less than 4m / s... =1.0, temperature less than -4℃ =1.3; when the liquid water content is greater than 36 g / m³ =1.1, calculate the comprehensive environmental correction factor. =1.0*1.3*1.1=1.43.

[0041] g) Obtain the insulator structure type LXY-100, which is a standard porcelain / glass insulator. =1.15, Comprehensive Environmental Correction Coefficient =1.43, equivalent icing thickness of the conductor b =8.51mm, As a non-linear growth exponent, a recommended value of 1.2 is used to calculate the equivalent icing thickness of the insulator. =1.15*1.43*8.51 1.2 ≈21.48mm.

[0042] h) Obtain the equivalent ice thickness of the insulator =21.48mm, which meets the requirements. The condition is that 21.48 mm ≥ 15 mm, therefore This means outputting a primary icing alarm message for the insulator.

[0043] i) Obtain the insulator structure type LXY-100, which is a standard porcelain / glass insulator with N=30 pieces, and the single-piece dry flashover voltage. =75kV, voltage distribution coefficient Take 0.92 as 50% of the power frequency flashover voltage of the insulator string under clean and dry conditions. =75*30*0.92=2070kV, icing attenuation coefficient Take 0.22 as the reference icing thickness for insulators. Take 1mm as the insulator type correction factor. Take 1.0 (standard porcelain insulator), insulator flashover voltage. =2070*(1-0.22*ln(21.48 / 1+1))*1.0≈652.51kV; j) Maximum operating voltage of the line =550kV, current ice flashover voltage safety margin k =652.51 / 550=1.186; k) Safety margin threshold for insulator de-icing startup K insulator Taking 1.3, the safety margin for ice flashover voltage is as follows: k =1.186<1.3= K insulator ,satisfy ,therefore The system outputs a suggestion to start insulator de-icing.

[0044] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A method for setting adaptive graded alarm thresholds for monitoring icing on transmission lines and insulators, characterized in that, Including the following steps: a) Obtain basic parameters of the transmission line, including the design ice thickness of the conductor; b) Obtain the conductor tension value before and after icing, and calculate the equivalent icing thickness of the conductor based on the conductor icing thickness conversion model; c) Calculate the ratio of the equivalent ice thickness to the design ice thickness of the conductor based on the design ice thickness of the conductor and the equivalent ice thickness of the conductor. d) Based on whether the designed ice thickness of the conductor is greater than the preset value, the conductor is divided into Class I and Class II lines, and a differentiated three-level alarm threshold for conductor icing is set for the two types of lines respectively. e) The ratio of the designed ice thickness of the conductor, the equivalent ice thickness of the conductor, and the designed ice thickness of the conductor are compared with the preset value and the differentiated conductor ice three-level alarm threshold, respectively, and the corresponding conductor ice alarm information is output. f) Obtain insulator structure type and environmental information, and calculate comprehensive environmental correction coefficient based on the environmental information; g) Calculate the equivalent ice thickness of the insulator based on the insulator structure type, comprehensive environmental correction factor, and equivalent ice thickness of the conductor; h) Set the three-level alarm threshold for insulator icing, compare the equivalent icing thickness of the insulator with the three-level alarm threshold for insulator icing, and output the corresponding insulator icing alarm information; i) Calculate the insulator flashover voltage under the current icing condition based on the insulator structure type, the equivalent ice thickness of the insulator, and the insulator flashover voltage calculation model; j) Obtain the highest operating voltage of the line, and then, in conjunction with the insulator flashover voltage, calculate the current flashover voltage safety margin; k) Set the insulator de-icing start safety margin threshold and compare it with the ice flashover voltage safety margin, and output the corresponding insulator de-icing start recommendation information.

2. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step b), the equivalent ice thickness of the conductor is calculated based on the conductor ice thickness conversion model. The specific calculation process is as follows: b1) Preset the directional deflection parameters before and after icing, including the directional deflection angle along the line before icing, the directional deflection angle perpendicular to the line before icing, the directional deflection angle along the line after icing, and the directional deflection angle perpendicular to the line after icing. b2) Calculate the ice load on the conductor based on the preset directional deflection angle parameters before and after icing, as well as the conductor tension values ​​before and after icing. b3) Based on the aforementioned conductor icing load, the icing shape is treated as circular, and the equivalent icing thickness of the conductor is calculated according to the conductor icing thickness conversion model. b4) Determine the equivalent ice thickness of the conductor. If it meets the preset first judgment condition, the equivalent ice thickness of the conductor is the final equivalent ice thickness of the conductor. If it does not meet the first judgment condition, correct the directional deflection parameters before and after icing. Based on steps b2) and b3), the equivalent ice thickness of the conductor is recalculated and judged. If it meets the preset second judgment condition, the equivalent ice thickness of the conductor is the final equivalent ice thickness of the conductor. If it does not meet the second judgment condition, the directional deflection parameters before and after icing are corrected until the calculated equivalent ice thickness of the conductor meets the second judgment condition.

3. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step d), the specific settings for the differentiated conductor icing level three alarm threshold include: d1) For Class I lines with an ice thickness of 5mm or less, the alarm thresholds for Level I, Level II, and Level III are 50%, 40%, and 20%, respectively. d2) For Class II lines with an ice thickness greater than 5mm, the alarm thresholds for Level I, Level II, and Level III are 70%, 50%, and 20%, respectively.

4. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 3, characterized in that, In step e), the formula for calculating the conductor icing alarm information is as follows: ， in, level line This is the conductor icing alarm information. 0 represents no alarm for conductor icing, 1 represents a level 1 alarm for conductor icing, 2 represents a level 2 alarm for conductor icing, and 3 represents a level 3 alarm for conductor icing. This is the ratio of the equivalent ice thickness of the conductor to the designed ice thickness of the conductor. Ice thickness is designed for the conductor, in mm; else If the conditions for alarm levels one, two, and three are not met, then... level =0 outputs no alarm message.

5. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step f), the formula for calculating the comprehensive environmental correction factor is as follows: ， in, This is a comprehensive environmental correction factor; Wind speed factor; Temperature factor; This refers to the liquid water content factor.

6. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step g), the formula for calculating the equivalent ice thickness of the insulator is as follows: ， in, The equivalent ice thickness of the insulator is expressed in mm. This refers to the insulator structure type coefficient; This is a comprehensive environmental correction factor; It is a non-linear growth index; The equivalent icing thickness of the conductor is expressed in mm.

7. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, Step h) specifically includes: h1) Set the three-level alarm threshold for insulator icing, with the first, second, and third level alarm thresholds corresponding to 15mm, 10mm, and 5mm, respectively; h2) Output insulator icing alarm information, the calculation formula of which is as follows: ， in, level insulator This is the insulator icing alarm information. 0 represents no alarm for insulator icing, 1 represents a level 1 alarm for insulator icing, 2 represents a level 2 alarm for insulator icing, and 3 represents a level 3 alarm for insulator icing. The equivalent icing thickness of the insulator is expressed in mm.

8. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step i), the formula for calculating the insulator flashover voltage under the current icing condition is as follows: ， in, The insulator flashover voltage is kV. The voltage is the 50% power frequency flashover voltage of the insulator string under clean and dry conditions, in kV. This is the icing attenuation coefficient; The equivalent ice thickness of the insulator is expressed in mm. Reference ice thickness for insulators; This is the insulator type correction factor.

9. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step j), the formula for calculating the safety margin of ice flashover voltage is as follows: ， in, k This is for the safety margin of ice flashover voltage; This refers to the insulator flashover voltage, measured in kV. This is the highest operating voltage of the line, expressed in kV.

10. The adaptive hierarchical alarm threshold setting method for icing monitoring of transmission lines and insulators according to claim 1, characterized in that, In step k), the calculation formula for the insulator de-icing start-up suggestion information is as follows: ， in, The insulator de-icing start suggestion information is: 0 means insulator de-icing is not started, and 1 means insulator de-icing is started. k This is for the safety margin of ice flashover voltage; The safety margin threshold for insulator de-icing startup.

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