Method and system for monitoring icing thickness of power transmission line

Abstract

The invention discloses a power transmission line icing thickness monitoring method and system, and belongs to the technical field of power transmission line on-line monitoring. The method comprises the following steps: respectively acquiring line natural vibration frequency, line temperature and line vibration characteristic data under an ice-free working condition and an ice-coated working condition, and constructing a relation formula of line tension and natural vibration frequency under the ice-free working condition and the ice-coated working condition; calculating the line pulling force under the ice-free working condition based on the relation between the line pulling force and the natural vibration frequency, and constructing a wire mechanical state equation; forming an equation set by a relation formula of the line tension and the natural vibration frequency under the icing working condition and a wire mechanical state equation, and substituting the equation set into the line natural vibration frequency and the line temperature under the icing working condition to solve the line tension, the comprehensive linear density and the icing linear density under the icing working condition; and substituting the linear densities into an equivalent icing thickness formula to obtain the equivalent icing thickness. According to the invention, the tension change generated by line vibration can be accurately measured and analyzed, and the icing state of the power transmission line can be monitored and evaluated in real time.

Description

Technical Field

[0001] The present invention relates to a method and system for monitoring the icing thickness of a transmission line, belonging to the technical field of on-line monitoring of transmission lines. Background Art

[0002] With the warming of the global climate and the frequent occurrence of extreme weather events, the problem of icing on transmission lines has become increasingly serious, posing a major threat to the safe operation of the power grid. Icing not only increases the weight of the conductor, changes its mechanical properties, but may also lead to serious accidents such as wire breakage, tower collapse, and insulator flashover, causing huge losses to the power system. Therefore, realizing real-time monitoring and accurate assessment of the icing state of transmission lines is of great significance for ensuring the safe operation of the power grid.

[0003] The methods for monitoring icing on transmission lines mainly include mechanical measurement methods, icing prediction methods, image processing methods, and simulated conductor methods, etc. However, these methods all have their own limitations. For example, although the mechanical measurement method is accurate in measurement, the stability and service life of the tension sensor in a low-temperature and high-humidity environment limit its wide application; the image processing method is extremely susceptible to weather conditions, and low visibility in fog and snow days results in unclear images, limiting the measurement accuracy; the icing prediction method relies on meteorological data and model prediction, and its accuracy still cannot meet the requirements of real-time monitoring. In view of the limitations of the existing technology, there is an urgent need for an on-line monitoring method for icing on transmission lines that is stable, accurate, and not restricted by the environment. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for monitoring the icing thickness of a transmission line, which can accurately measure and analyze the change in tension generated by the vibration of the line, and realize real-time monitoring and accurate assessment of the icing state of the transmission line.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0006] In a first aspect, the present invention provides a method for monitoring the icing thickness of a transmission line, including:

[0007] Obtaining the natural vibration frequency, line temperature, and line vibration characteristic data of the line under ice-free conditions and icing conditions respectively;

[0008] Constructing the relationship formula between the line tension and the natural vibration frequency under ice-free conditions and icing conditions respectively according to the natural vibration frequency, line temperature, and line vibration characteristic data of the line under ice-free conditions and icing conditions;

[0009] Importing the natural vibration frequency of the line under ice-free conditions into the relationship formula between the line tension and the natural vibration frequency under ice-free conditions to obtain the line tension under ice-free conditions, and constructing a conductor mechanical state equation according to the line tension under ice-free conditions;

[0010] Form a system of equations with the formula for the relationship between the line tension and the natural vibration frequency under icing conditions and the mechanical state equation of the conductor, and substitute the natural vibration frequency and the line temperature under icing conditions for solution to obtain the line tension, the comprehensive line density, and the ice-covered line density under icing conditions respectively;

[0011] Solve for the ice-covered line density based on the equivalent ice thickness formula to obtain the equivalent ice thickness.

[0012] Optionally, the line vibration characteristic data includes: the line density, the span of the transmission tower, the order of the natural vibration frequency, the equivalent line density during icing, the elastic modulus of the conductor, and the temperature expansion coefficient of the conductor.

[0013] Optionally, substituting the natural vibration frequency of the line under ice-free conditions into the formula for the relationship between the line tension and the natural vibration frequency under ice-free conditions, the formula for the line tension under ice-free conditions is obtained as:

[0014]

[0015]

[0016] Optionally, form a system of equations with the formula for the relationship between the line tension and the natural vibration frequency under icing conditions and the mechanical state equation of the conductor, and substitute the natural vibration frequency and the line temperature under icing conditions for solution. The expressions for the line tension, the comprehensive line density, and the ice-covered line density under icing conditions are obtained as:

[0017]

[0018]

[0019] Optionally, the calculation formula for the representative span of the continuous span where the line is located is:

[0020]

[0021]

[0022] Optionally, when the representative span of the continuous span where the line is located is greater than the set distance value, simplify the formula for the relationship between the line tension and the natural vibration frequency to remove the influence of the line bending stiffness on the line tension error, and obtain the simplified formula for the relationship between the line tension and the natural vibration frequency;

[0023] Based on the simplified formula for the relationship between the line tension and the natural vibration frequency and the mechanical state equation of the conductor, recalculate the natural vibration frequency of the line, the line temperature, and the line modal parameters during icing under icing conditions, and respectively obtain the line tension, the comprehensive line density, and the ice-covered line density under icing conditions after removing the error; the calculation formula is:

[0024]

[0025]

[0026] Optionally, the formula for the equivalent ice coating thickness is as follows:

[0027]

[0028]

[0029] Optionally, separately obtaining the natural vibration frequencies of the line under ice-free condition and ice-coated condition further includes:

[0030] Collecting the line vibration signals through a vibration pickup sensor;

[0031] Performing spectrum processing on the collected signals to obtain a spectrogram of the line vibration

[0032] Sampling the first three-order frequencies or the fundamental frequency according to the spectrogram to obtain the natural vibration frequencies of the line under ice-free condition and ice-coated condition that meet the requirements of measurement accuracy.

[0033] In a second aspect, the present invention provides a transmission line ice coating thickness monitoring system, including: a host, a vibration pickup sensor and a temperature sensor installed in the section of the transmission line to be monitored;

[0034] The host communicates with the vibration pickup sensor and the temperature sensor, and is used to separately obtain the natural vibration frequency and the line temperature of the line under ice-free condition and ice-coated condition, so as to execute the steps of the method in the first aspect.

[0035] Optionally, the installation position of the vibration pickup sensor is staggered from the low-order vibration mode nodes and is close to the position with a larger amplitude at the antinode;

[0036] The installation position of the temperature sensor is close to the node position.

[0037] Compared with the prior art, the beneficial effects achieved by the present invention:

[0038] The vibration-based measurement method is not affected by harsh environments such as low temperature and high humidity, and can work stably under various weather conditions; through vibration analysis, the mechanical properties of the line under ice-coated state can be more accurately reflected, thereby improving the measurement accuracy; this method is not limited by conditions such as the height difference between the suspension points of adjacent tower lines, and can truly reflect the ice coating situation of the transmission line.

[0039] A transmission line ice coating thickness monitoring method and system based on line vibration. It can not only be used to monitor the ice coating state of the transmission line in real time, improve the accuracy and stability of ice coating monitoring, improve the safe operation level of the power grid, but also provide a scientific basis for disaster prevention and reduction of the power system, and has wide popularization and application value. Description of the Drawings

[0040] Figure 1 is a schematic flow chart of a method and system for monitoring the icing thickness of a transmission line provided in this embodiment;

[0041] Figure 2 is a schematic structural diagram of the arrangement of sensors for measuring the line tension and equivalent icing thickness of a transmission line provided in this embodiment. Detailed Embodiments

[0042] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be used to limit the protection scope of the present invention.

[0043] Embodiment 1

[0044] This embodiment provides a method for monitoring the icing thickness of a transmission line, including:

[0045] Step 1: First, obtain the natural vibration frequency, line temperature, and line vibration characteristic data of the line under the ice-free condition.

[0046] Step 2: Respectively construct a relationship formula between the line tension and the natural vibration frequency under the ice-free condition according to the natural vibration frequency, line temperature, and line vibration characteristic data of the line under the ice-free condition.

[0047] Step 3: Substitute the natural vibration frequency of the line under the ice-free condition into the relationship formula between the line tension and the natural vibration frequency under the ice-free condition to obtain the line tension under the ice-free condition, and construct a conductor mechanical state equation according to the line tension under the ice-free condition.

[0048] Step 4: Then, obtain the natural vibration frequency, line temperature, and line vibration characteristic data of the line under the icing condition.

[0049] Step 6: Respectively construct a relationship formula between the line tension and the natural vibration frequency under the icing condition according to the natural vibration frequency, line temperature, and line vibration characteristic data of the line under the icing condition.

[0050] Step 7: Combine the relationship formula between the line tension and the natural vibration frequency under the icing condition and the conductor mechanical state equation into a system of equations, and substitute the natural vibration frequency and line temperature of the line under the icing condition for solution to respectively obtain the line tension, comprehensive line density, and icing line density under the icing condition.

[0051] Step 8: Solve the icing line density based on the equivalent icing thickness formula to obtain the equivalent icing thickness.

[0052] It should be noted that for a transmission line icing thickness monitoring method provided by an embodiment of the present invention, only a set of vibration sensors and temperature sensors need to be installed on the phase conductors (or ground wires) within the strain section, and the measurement and calculation of the line tension and equivalent icing thickness of the phase conductors (or ground wires) that can implement the above method can be achieved, and Figure 1 Before data collection in steps 1 and 5 shown, it is necessary to calculate and determine the installation positions of the vibration sensors and temperature sensors.

[0053] Optionally, the line vibration characteristic data includes: line linear density, span of transmission towers, order of natural vibration frequency, equivalent linear density of the line during icing, elastic modulus of the conductor, and temperature expansion coefficient of the conductor.

[0054] Optionally, by substituting the natural vibration frequency of the line under ice-free conditions into the relationship formula between the line tension and the natural vibration frequency under ice-free conditions, the formula for the line tension under ice-free conditions is obtained as:

[0055]

[0056]

[0057] Optionally, a system of equations is formed by combining the relationship formula between the line tension and the natural vibration frequency under icing conditions and the mechanical state equation of the conductor, and by substituting the natural vibration frequency of the line and the line temperature under icing conditions for solution, the expressions for the line tension, comprehensive linear density, and icing line density under icing conditions are respectively obtained as:

[0058]

[0059]

[0060] Optionally, the calculation formula for the representative span of the continuous span where the line is located is:

[0061]

[0062]

[0063] Optionally, when the representative span of the continuous span where the line is located is greater than the set distance value, the relationship formula between the line tension and the natural vibration frequency is simplified to remove the influence of the line bending stiffness on the line tension error, and the simplified relationship formula between the line tension and the natural vibration frequency is obtained;

[0064] Based on the simplified relationship formula between the line tension and the natural vibration frequency and the mechanical state equation of the conductor, the natural vibration frequency of the line, the line temperature, and the line modal parameters during icing under icing conditions are calculated again, and the line tension, comprehensive linear density, and icing line density under icing conditions after removing the error are respectively obtained; the calculation formulas are as follows:

[0065]

[0066]

[0067]

[0068] Optionally, the formula for the equivalent ice coating thickness is:

[0069]

[0070] Optionally, separately obtaining the natural vibration frequencies of the line under ice-free condition and ice-coated condition further includes:

[0071] Collecting the line vibration signals through a vibration pickup sensor;

[0072] Performing spectrum processing on the collected signals to obtain a spectrogram of the line vibration

[0073] Sampling the first three-order frequencies or the fundamental frequency according to the spectrogram to obtain the natural vibration frequencies of the line under ice-free condition and ice-coated condition required for measurement.

[0074] The spectrum processing in this embodiment includes: signal amplification, recording, and analyzing the Fourier transform of the acceleration-time relationship curve obtained from the test to obtain the spectrogram of the line vibration.

[0075] Embodiment 2

[0076] This embodiment provides a monitoring system for the ice coating thickness of a transmission line, including: a host, a vibration pickup sensor and a temperature sensor installed in the section of the transmission line to be monitored;

[0077] The host communicates with the vibration pickup sensor and the temperature sensor, and is used to separately obtain the natural vibration frequency and the line temperature of the line under ice-free condition and ice-coated condition, so as to execute the steps of the method described in Embodiment 1.

[0078] Optionally, as Figure 2 shown, the installation position of the vibration pickup sensor is staggered from the low-order vibration mode node and is close to the position with a larger amplitude at the antinode;

[0079] The installation position of the temperature sensor is close to the node position. In order to successfully collect the low-order mode signals, the selection of the installation position of the vibration pickup sensor on the line is at a position staggered from the low-order vibration mode node and as close as possible to the place with a larger amplitude at the antinode. The temperature sensor should be installed at the node position. The calculation formulas for the antinode and node positions are:

[0080]

[0081] Low-order vibration modes are vibration forms with low energy and low frequency in the vibration system. The amplitude at the node is zero, which means that the vibration signal is weakest at this position. Placing the vibration pickup sensor at a position staggered from the low-order vibration mode node can effectively capture the vibration signal; installing the vibration pickup sensor near the antinode with large amplitude can ensure that the sensor can receive a strong vibration signal, thereby improving the accuracy and sensitivity of the measurement. The temperature sensor should be installed at the node position, where the amplitude at the node is zero and the vibration energy is low, so the temperature change at this position is relatively small. The temperature sensor installed near the node can reduce the temperature measurement error caused by vibration, thereby more accurately reflecting the temperature state of the system. In addition, this embodiment can achieve the measurement and calculation of the line tension and equivalent ice thickness of the above-mentioned phase conductor (or ground wire) by installing a group of vibration pickup sensors and temperature sensors on the phase conductor or ground wire in the tension section. Therefore, the installation strategy of the present invention can ensure that the sensor can accurately and reliably measure the required physical quantities and provide accurate data support for the monitoring and analysis of the system.

[0082] In summary, the vibration-based measurement method of the present invention is not affected by harsh environments such as low temperature and high humidity, and can work stably under various weather conditions; through vibration analysis, it can more accurately reflect the mechanical properties of the line in an ice-covered state, thereby improving the measurement accuracy; this method is not limited by conditions such as the height difference of the suspension points of adjacent tower lines, and can truly reflect the ice coverage of the transmission line.

[0083] A transmission line ice thickness monitoring method and system based on line vibration can not only be used to monitor the ice status of transmission lines in real time, improve the accuracy and stability of ice monitoring, and improve the safe operation level of power grids, but also provide a scientific basis for disaster prevention and mitigation of power systems, and has wide promotion and application value.

[0084] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device generate means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0086] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0088] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the present invention and the claims. All of these fall within the protection scope of the present invention.

Claims

1. A method for monitoring ice thickness of a transmission line, characterized in that: include: Obtain the line natural frequency, line temperature and line vibration characteristic data under ice-free conditions and ice-covered conditions respectively; According to the line natural frequency, line temperature and line vibration characteristic data under ice-free and ice-covered conditions, the relationship formulas between line tension and natural frequency under ice-free and ice-covered conditions are constructed respectively; The relationship between the line tension and the natural frequency under ice-free conditions is introduced into the line natural frequency under ice-free conditions to obtain the line tension under ice-free conditions, and the conductor mechanical state equation is constructed based on the line tension under ice-free conditions; The relationship formula between the line tension and the natural frequency under icing conditions and the conductor mechanical state equation are combined into an equation group, and the line natural frequency and line temperature under icing conditions are substituted to solve the problem, and the line tension, comprehensive line density and ice line density under icing conditions are obtained respectively. The ice cover line density is solved based on the equivalent ice cover thickness formula to obtain the equivalent ice cover thickness.

2. The method for monitoring ice thickness of a power transmission line according to claim 1, characterized in that: The line vibration characteristic data include: line density, transmission tower spacing, natural frequency order, line equivalent density when covered with ice, conductor elastic modulus, and conductor temperature expansion coefficient.

3. The method for monitoring ice thickness of a power transmission line according to claim 1, characterized in that: The formula for the relationship between the line tension and the natural frequency under ice-free conditions is introduced into the line natural frequency under ice-free conditions, and the formula for the line tension under ice-free conditions is obtained as follows: In the formula, is the line tension under ice-free conditions, is the line density when there is no ice, is the spacing between adjacent transmission towers, is the order of the natural frequency, is the bending stiffness of the line, For ice-free conditions, line The natural frequency of the order.

4. The method for monitoring ice thickness of a power transmission line according to claim 3 is characterized in that: The relationship formula between the line tension and the natural frequency under icing conditions and the conductor mechanical state equation are combined into an equation group, and the line natural frequency and line temperature under icing conditions are substituted to solve them. The expressions of line tension, comprehensive line density and ice line density under icing conditions are obtained as follows: In the formula, The line tension when covered with ice, is the spacing between adjacent transmission towers, is the order of the natural frequency, is the bending stiffness of the line, is the comprehensive linear density under icing conditions, is the ice line density, is the elastic modulus of the conductor, is the temperature expansion coefficient of the conductor, The continuous gears where the lines are located represent the gear spacing. is the line temperature under ice-free conditions, is the line temperature under icing condition, For ice condition line The natural frequency of the order.

5. The method for monitoring ice thickness of a power transmission line according to claim 4, characterized in that: The formula for calculating the distance between the continuous gears represented by the lines is: In the formula, is the number of spans in the tension section, For the Gear spacing, It is the line spacing number.

6. The method for monitoring ice thickness of a power transmission line according to claim 4, characterized in that: It also includes simplifying the relationship formula between the line tension and the natural frequency when the continuous gear representative gear distance of the line is greater than the set distance value, removing the influence of the line bending stiffness on the line tension error, and obtaining a simplified relationship formula between the line tension and the natural frequency; Based on the simplified formula of the relationship between line tension and natural frequency and the conductor mechanical state equation, the line natural frequency, line temperature and line modal parameters under ice-covered conditions are calculated again, and the line tension, comprehensive line density and ice-covered line density under ice-covered conditions with errors removed are obtained respectively; the calculation formula is: In the formula, is the first-order natural frequency of the line under ice-free conditions, is the first-order natural frequency of the line under icing condition.

7. The method for monitoring ice thickness of a power transmission line according to claim 1, characterized in that: The equivalent ice thickness formula is: In the formula, is the equivalent ice thickness, is the ice line density, is the outer diameter of the line.

8. The method for monitoring ice thickness of a power transmission line according to claim 1, characterized in that: Obtaining the line natural frequency under ice-free conditions and ice-covered conditions also includes: The line vibration signal is collected by a vibration pickup sensor; Perform spectrum processing on the collected signal to obtain the spectrum diagram of line vibration; The first three frequencies or fundamental frequencies are sampled according to the spectrum diagram to obtain the line natural vibration frequencies under ice-free conditions and ice-covered conditions that meet the measurement accuracy requirements.

9. A transmission line ice thickness monitoring system, comprising: Host, vibration pickup sensor and temperature sensor installed in the section of the transmission line to be monitored; The host communicates with the vibration pickup sensor and the temperature sensor to obtain the line self-vibration frequency and line temperature under ice-free conditions and ice-covered conditions to execute the steps of the method according to claim 1.

10. The transmission line ice thickness monitoring system according to claim 9 is characterized in that: The installation position of the vibration pickup sensor is staggered from the low-order vibration mode nodes and close to the position where the antinode amplitude is large; The temperature sensor is installed close to the node.

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