Electromagnetic shielding design method for power transmission line

Abstract

The invention discloses an electromagnetic shielding design method for a power transmission line, and the method comprises the following steps: evaluating the electromagnetic environment of the power transmission line, and calculating the power frequency electric field intensity, the corona interference spectrum range and the transient overvoltage amplitude based on the voltage grade, the wire layout and the insulator installation position of the power transmission line; the maximum electromagnetic load capacity and the average electromagnetic load capacity which can be borne by the insulator detection equipment in normal work are calculated through the model; according to the electromagnetic environment of the power transmission line and the maximum electromagnetic load capable of being borne by the insulator detection equipment, the maximum electromagnetic attenuation and the average electromagnetic attenuation which need to be achieved are calculated; and designing electromagnetic shielding scheme groups of the insulator detection equipment in different electromagnetic environments according to the electromagnetic attenuation data, wherein different structures are designed and different materials are selected so as to ensure normal operation of the insulator detection equipment in different electromagnetic environments. According to the electromagnetic shielding design method, the insulator detection equipment can be effectively protected to work normally in the environment, the detection accuracy is improved, and the application range of the insulator detection equipment is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic protection, and particularly relates to a method for electromagnetic shielding design of a power transmission line. BACKGROUND

[0002] With the construction of high-voltage, extra-high-voltage power transmission lines, the problems of equipment caused by electromagnetic interference are significant. Generally speaking, the higher the voltage, the stronger the electric field; the greater the current, the stronger the magnetic field, so a very strong electromagnetic field is often generated on high-voltage or extra-high-voltage, ultra-high-voltage power transmission lines. In the prior art, in order to minimize the adverse effects of electromagnetic radiation on production and life, electromagnetic shielding needs to be considered when constructing high-voltage, extra-high-voltage power transmission lines. According to the safety specifications of power facilities and engineering practices, the extra-high-voltage power transmission line (usually refers to 110kV and above voltage grade) needs to be provided with shielding measures (such as protective barriers, warning signs, etc.) within a certain range, which mainly depends on the voltage level, line type (AC / DC) and the distance from the building or personnel activity area. If the line electromagnetic radiation causes complaints, it needs to be set as a sensitive point and be monitored specially, and electromagnetic shielding devices need to be added if necessary. For example, patent CN201210532956.7 proposes a kind of adjustable shielding net for improving the power frequency electromagnetic field around overhead power transmission line, which can improve the power frequency electromagnetic field around overhead power transmission line.

[0003] But in general prior art, the main consideration is the influence of electromagnetic environment under high voltage on the surrounding environment, production and life. For the detector or insulator detection device used for checking and repairing the performance of insulator, when the insulator is detected, the electromagnetic shielding of the adjustable shielding net for improving the surrounding power frequency electromagnetic field cannot play an electromagnetic shielding role on the insulator detector or electronic detection device due to too close distance. Since such detector or detection device is mainly composed of an electric field detection sensor antenna part and a PCB board for data acquisition and processing circuit part, under the environment of super and extra high voltage strong electromagnetic field, the power frequency electromagnetic field, harmonics and corona generated by conductors and fittings will cause strong electromagnetic interference to the detection device, especially when the detector or detection device is close to the transmission line and tower, the detector or detection device will be subjected to very strong electromagnetic interference. Such electromagnetic interference not only affects the normal working performance of the electronic equipment to some extent, but also may directly lead to damage of the detector and failure to work. The prior art such as patent application CN115453166A discloses an anti-interference method of insulator string detection robot, which realizes isolation of the interface of the circuit board from the external electromagnetic field by setting at least three layers of shielding structure control shell. The shielding structure of CN115453166A can solve the electromagnetic interference during detection of the detection robot to some extent. Since it is aimed at 800kV and above environment and is aimed at specific detection robot, it is greatly limited and universal applicability is not considered. Patent CN118898475B provides a distribution network maintenance strategy generation method based on heuristic algorithm, which optimizes the distribution network maintenance strategy to optimize the maintenance result by dividing the maintenance area and determining the best maintenance path. CN118898475B provides another maintenance method for optimizing maintenance result, which cannot fundamentally solve the problem of electromagnetic interference or failure to work of the insulator detector or insulator detection device during maintenance. SUMMARY

[0004] Therefore, the embodiment of the present application provides a design method of electromagnetic shielding of transmission line, which can effectively protect the insulator detection device to work normally in the environment, improve the detection accuracy and expand the application range of the insulator detection device.

[0005] The embodiment of the present application provides a design method of electromagnetic shielding of transmission line, which comprises the following steps:

[0006] The electromagnetic environment of the transmission line is evaluated, the power frequency electric field intensity, corona interference frequency spectrum range and transient overvoltage amplitude are calculated based on the voltage grade of the transmission line, the conductor layout and the installation position of the insulator;

[0007] The maximum electromagnetic load and the average electromagnetic load that the insulator detection device can withstand when working normally are calculated by model calculation;

[0008] According to the electromagnetic environment of the power transmission line and the maximum electromagnetic load that the insulator detection device can withstand, the maximum electromagnetic attenuation and the average electromagnetic attenuation required to be reached are calculated;

[0009] According to the electromagnetic attenuation data, the electromagnetic shielding scheme group of the insulator detection device in different electromagnetic environments is designed, including designing different structures and selecting different materials to ensure that the insulator detection device can normally work in different electromagnetic environments.

[0010] In the electromagnetic shielding design method of the present application, when evaluating the electromagnetic environment in which the insulator detection device is located, the present application considers the influence of electromagnetic such as corona interference frequency spectrum range and transient overvoltage amplitude, in addition to the power frequency electric field intensity considered in the prior art. The several electromagnetic loads that the insulator detection device can withstand under normal working conditions are calculated by model calculation, so that even when the insulator detection device is subjected to the combined action of transient overvoltage and corona interference, it can still work normally in this environment, thereby expanding the application range of the insulator detection device.

[0011] In addition, the electromagnetic shielding scheme group of the insulator detection device in different electromagnetic environments is designed according to the electromagnetic attenuation data to ensure that the insulator detection device can normally work in different electromagnetic environments, which can further ensure that the final insulator detection device will not be affected by electromagnetic interference. In the prior art, the selection of the insulator detection device is mainly based on whether it can accurately detect the performance of the insulator under normal conditions or on ordinary power transmission lines, and the influence of high electromagnetic environment on the performance of the insulator detection device is rarely considered, so it is often difficult to distinguish whether the abnormal detection result is caused by the performance of the insulator itself or by the influence of the insulator detection device, thereby leading to incorrect judgment. In order to reduce such errors or abnormal data, the commonly used method is to use different insulator detection devices for detection, and to remove abnormal detection results by comparing data and experience, which not only consumes time and effort but also greatly increases the detection cost. In addition, due to the inapplicability of the insulator detection device, some insulators in super-high electromagnetic environment cannot be detected in time. In the present application, the insulator detection device is redesigned to work normally in the electromagnetic environment in which it is located, so that the insulator detection device can work normally in the high electromagnetic environment, and then the insulator is detected. The accuracy of detection is improved, and the application range of the insulator detection device is expanded.

[0012] Further, the method further comprises the following steps: designing a shielding test experiment for the control group, and selecting the shielding design scheme group with the best cost performance and / or shielding performance according to the test experiment results and different electromagnetic environments.

[0013] In the present application, on the basis of normal working conditions, the shielding test experiment of the control group can be carried out, and the most cost-effective shielding design scheme group in different electromagnetic environments or the shielding design scheme group with the best shielding performance can be selected according to the experimental data as needed. The difference between selecting the most cost-effective shielding design scheme group and the shielding design scheme group with the best shielding performance is mainly realized by the selection of parameters during model calculation, the difference in the structure design of the insulator detection equipment, the selection of different materials and the design of material thickness.

[0014] Further, the designed insulator detection equipment realizes automatic switching of at least the following three working modes: average electromagnetic attenuation amount working mode, single-layer maximum electromagnetic attenuation amount working mode and transient high electromagnetic load safety working mode.

[0015] In the present application, the insulator detection equipment automatically switches among the three working modes according to the electromagnetic load amount detected by the sensor. According to the relevant regulations of our country on ultra-high voltage and extra-high voltage, ultra-high voltage generally refers to voltage levels of 330kV and above and 1000kV and below, and extra-high voltage refers to alternating current voltage levels of 1000kV and above and direct current voltage levels of ±800kV and above. The average electromagnetic attenuation amount working mode safety working mode is triggered according to the average electromagnetic load amount in the ultra-high voltage range according to the model calculation, and also belongs to the general normally open working mode of the insulator detection equipment. The single-layer maximum electromagnetic attenuation amount working mode is triggered according to the maximum electromagnetic load amount obtained by model calculation. The transient high electromagnetic load safety working mode is triggered by model calculation according to the weights of the average electromagnetic load amount and the maximum electromagnetic load amount.

[0016] Further, the insulator detection equipment designed according to the electromagnetic environment evaluation result adopts a layered shielding structure, which realizes automatic opening and closing according to the detected real-time electromagnetic load.

[0017] Further, the layered shielding structure of the insulator detection equipment includes an outer shielding layer and an inner shielding layer structure, the outer shielding layer realizes maximum electromagnetic attenuation amount, and the inner shielding layer realizes average electromagnetic attenuation amount.

[0018] Further, the outer shielding layer realizes maximum electromagnetic attenuation amount, which means that when the outer shielding layer is in a closed state, its shielding effectiveness is ≥80dB, and the outer shielding layer can shield 80% to 105% of the comprehensive maximum electromagnetic load amount under a 1000kV transmission line.

[0019] Further, the inner shielding layer realizes average electromagnetic attenuation amount, which means that when the inner shielding layer is in a closed state, its shielding effectiveness is ≥30dB, and the outer shielding layer can shield 95% of the average electromagnetic load amount under a 330kV to 1000kV transmission line.

[0020] Further, in the safety working mode of transient high electromagnetic load, the shielding effectiveness of the safety working mode is at least 1.3-1.6 times of the shielding effectiveness of the single-layer maximum electromagnetic attenuation working mode.

[0021] Further, the outer shielding layer is connected with a transient discharge mechanism or an electromagnetic elimination mechanism, when the transient high electromagnetic load is 1.1 times of the comprehensive maximum electromagnetic load of 1000kV transmission line, the transient discharge mechanism or the electromagnetic elimination mechanism is started, and a pre-warning report is sent to the PCB control board of the insulator detection device.

[0022] Further, after the transient discharge mechanism is triggered, a multi-stage surge discharge channel is started, and the peak current is greater than or equal to 20kA. After the electromagnetic elimination mechanism is triggered, the active cancellation coil array arranged in the inner side of the inner shielding layer generates at least 60%-80% of the reverse electromagnetic equivalent of the transient high electromagnetic load.

[0023] The present application mainly solves the following three main problems existing in the prior art:

[0024] 1) The influence of corona interference spectrum and transient overvoltage is not considered, resulting in that the detection accuracy of the insulator detection device is greatly affected when the corona interference and the transient overvoltage occur;

[0025] 2) The working mode of the traditional fixed shielding structure is single and the applicable range is relatively narrow;

[0026] 3) It cannot cope with transient overvoltage, and lacks dynamic protection mechanism when facing electromagnetic load overload, so that the insulator detection device cannot work normally or even be damaged under this condition.

[0027] Compared with the prior art, the present application has at least the following beneficial effects:

[0028] 1. The structure is simpler and the applicable range is wider. Compared with the traditional fixed multi-layer shielding (more than three layers), the inner-outer layered shielding structure composed of the inner shielding layer and the outer shielding layer of the present application is simpler. The layered shielding structure of the present application can dynamically adjust the opening and closing state of the inner shielding layer and the outer shielding layer according to the real-time electromagnetic load, and has a wider applicable range, which basically meets the electromagnetic shielding design requirements from extra-high voltage to ultra-high voltage transmission lines.

[0029] 2. Balance between reducing power consumption and ensuring protection performance. The balance between reducing power consumption and ensuring protection performance is realized by three working modes.

[0030] 3. Transient overvoltage active defense mechanism, further guaranteeing the service life and normal working state of the insulator detection device. When detecting ≥1.1 times the maximum design load (such as 220 kV / μs corresponding to a 1000 kV line), the transient discharge mechanism (20 kA discharge capacity) and the electromagnetic elimination mechanism (60% to 80% reverse offset) work cooperatively to minimize the risk of overvoltage damage. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0032] Figure 1 A flowchart of an electromagnetic shielding design method of a power transmission line provided for one preferred embodiment of the present application.

[0033] Figure 2 A shielding structure diagram of an electromagnetic shielding design method of a power transmission line provided for an embodiment of the present application.

[0034] Figure 3 A logic diagram between three working modes of an electromagnetic shielding design method of a power transmission line provided for one preferred embodiment of the present application.

[0035] Figure 4 A flowchart of a transient overvoltage active defense mechanism of an electromagnetic shielding design method of a power transmission line provided for one preferred embodiment of the present application. DETAILED DESCRIPTION

[0036] The embodiments of the present application will be described in detail below with reference to the drawings.

[0037] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] Reference Figure 1 The embodiments of the present application provide an electromagnetic shielding design method of a power transmission line, and provide an electromagnetic shielding design method of a power transmission line, including the following steps:

[0039] Assessing the electromagnetic environment of the power transmission line, calculating the power frequency electric field intensity, corona interference frequency spectrum range and transient overvoltage amplitude based on the voltage grade of the power transmission line, conductor layout and insulator installation position;

[0040] The maximum electromagnetic load and the average electromagnetic load that the insulator detection device can withstand in normal operation are calculated by the model;

[0041] The maximum electromagnetic attenuation and the average electromagnetic attenuation that need to be reached are calculated according to the electromagnetic environment of the transmission line and the maximum electromagnetic load that the insulator detection device can withstand;

[0042] The electromagnetic shielding scheme group of the insulator detection device in different electromagnetic environments is designed according to the electromagnetic attenuation data, including designing different structures and selecting different materials to ensure that the insulator detection device can operate normally in different electromagnetic environments.

[0043] In the electromagnetic shielding design method of the present application, the main problems existing in the prior art are solved, which are that the corona interference spectrum and the influence of transient overvoltage are not considered, resulting in that the detection accuracy of the insulator detection device is greatly affected when the corona interference and the transient overvoltage occur; the transient overvoltage cannot be coped with, further resulting in a narrow application range. In addition, it is very important that in the prior art, the selection of the insulator detection device mainly considers whether the performance of the insulator can be accurately detected on the conventional condition or on the ordinary transmission line, and basically the influence of the high electromagnetic environment on the performance of the insulator detection device is rarely considered, so it is often difficult to distinguish whether the detection result is abnormal due to the performance problem of the insulator itself or the problem of the insulator detection device affected, thereby causing the judgment result to be wrong. In some cases, the insulator detection device cannot adapt to the high electromagnetic environment, and some consider adding shielding to the insulator detection device to reduce the influence on detection, but more is to abandon the insulator detection device, and the original method of judging and estimating roughly by naked eye and experience is used. In the present application, the existing ideas are not limited, but the electromagnetic environment where the insulator detection device is located is detected again, the main influencing factors and parameters are designed again to ensure that the insulator detection device can work normally in the electromagnetic environment, and then the insulator is detected. Not only the detection accuracy is improved, but also the application range of the insulator detection device is expanded. Therefore, according to the electromagnetic shielding design method principle of the transmission line of the present application, through the above electromagnetic shielding design steps, no matter which specific structure and / or different materials are used to ensure that the insulator detection device can operate normally in different electromagnetic environments, they are all within the protection scope of the present application.

[0044] In one embodiment of the present application, in evaluating the electromagnetic environment in which the insulator detection device is located, compared with the prior art, the present application not only considers the power frequency electric field intensity, but also considers the electromagnetic load and influence such as the corona interference frequency spectrum range and transient overvoltage amplitude. The power frequency electric field intensity and influence factors are calculated through a model to obtain the maximum electromagnetic load, the minimum electromagnetic load and the average electromagnetic load that the insulator detection device can withstand under normal working conditions. Therefore, even when encountering the combined effects of transient overvoltage and corona interference, the insulator detection device can still work normally in this environment, thereby expanding the application range of the insulator detection device. Here, it is noted that the prior art generally determines whether the electromagnetic load exceeds the bearing capacity of the insulator detection device according to whether the insulator detection device can work normally, which can only be qualitatively confirmed and cannot be quantitatively calculated. In the present application, the model trained through different voltage test results can directly calculate the maximum electromagnetic load, the minimum electromagnetic load and the average electromagnetic load that the insulator detection device can withstand under normal working conditions according to the electromagnetic environment parameters and influence factors, so that qualitative judgment and quantitative confirmation can be made. In addition, the electromagnetic shielding scheme group of the insulator detection device in different electromagnetic environments is designed according to the electromagnetic attenuation data to ensure that the insulator detection device works normally in different electromagnetic environments, which can further ensure that the final insulator detection device will not be affected by electromagnetic interference.

[0045] In a preferred embodiment, as shown in Figure 1 The electromagnetic shielding design method of the present application further includes the following steps: designing a shielding test experiment for the control group, and selecting the shielding design scheme group with the best cost performance and / or shielding performance according to the test results and different electromagnetic environments.

[0046] In the present application, under the basic condition of ensuring normal working, the shielding design scheme group with the best cost performance in different electromagnetic environments or the shielding design scheme group with the best shielding performance can be selected according to the shielding test experiment of the control group and the experimental data as needed. For example, taking a 500kV AC transmission line as an example, a comprehensive electromagnetic shielding rate ≥90% can meet the normal working of the insulator detection device. If the comprehensive electromagnetic shielding rate is 90%, a thinner shielding material can be selected when the outer shielding layer uses the same material, which has a higher cost performance. If a thicker shielding material is selected, the comprehensive electromagnetic shielding rate can be further improved to achieve the optimal shielding rate. Therefore, the selection of the shielding design scheme group with the best cost performance or the shielding design scheme group with the best shielding performance can be mainly realized by parameter selection during model calculation, different structure designs of the insulator detection device, selection of different materials and design of material thickness, and the final shielding result is verified by test experimental data.

[0047] In a preferred embodiment, not only can the shielding test experiment of the control group be designed for the power transmission line of the same voltage (for example, 500 kV AC), but also for the power transmission line of different voltage levels (for example, 500 kV AC, 800 kV AC, 1000 kV AC). At least two groups of control groups with different structures and different materials are designed under each voltage level, so as to select the shielding design scheme group with the most cost-effective or the shielding design scheme group with the best shielding performance according to the results.

[0048] When the shielding test of the control group is designed above, the structures and materials selected are those that have been optimized under the normal working conditions of the insulator detection device through structure and material experiments.

[0049] In an embodiment, the electromagnetic shielding design method of the present application designs the insulator detection device to realize automatic switching of at least the following three working modes: average electromagnetic attenuation amount working mode, single-layer maximum electromagnetic attenuation amount working mode, and transient high electromagnetic load safety working mode.

[0050] In an embodiment, the electromagnetic shielding design method of the present application automatically switches the insulator detection device according to the electromagnetic load amount detected by the sensor. According to the relevant regulations of our country on ultra-high voltage and extra-high voltage, ultra-high voltage usually refers to voltage levels of 330 kV and above and 1000 kV and below, and extra-high voltage refers to AC voltage levels of 1000 kV and above and DC voltage levels of ±800 kV and above. In the present application, the insulator detection device is mainly applicable to 500 kV and above ultra-high voltage or extra-high voltage power transmission lines, so in the shielding test experiment, more attention is paid to 500 kV, ±800 kV, 1000 kV, 1100 kV, 1200 kV, and other ultra-high voltage and extra-high voltage power transmission lines. The average electromagnetic attenuation amount working mode and the safety working mode are designed according to the average electromagnetic load amount calculated by the model within the ultra-high voltage range, which also belongs to the general open working mode of the insulator detection device. The single-layer maximum electromagnetic attenuation amount working mode is triggered according to the maximum electromagnetic load amount calculated by the model. The safety working mode of transient high electromagnetic load is triggered by the average electromagnetic load amount and the maximum electromagnetic load amount according to the weight through the model calculation.

[0051] In an embodiment, in the electromagnetic shielding design method of the present application, the maximum electromagnetic load amount and the average electromagnetic load amount that the insulator detection device can withstand under normal working conditions are calculated by a model. Both a simple empirical model with a correction coefficient obtained through experimental detection and a complex neural network and deep learning calculation model can be used. However, regardless of which model is used, it needs to be verified through experimental testing.

[0052] In one embodiment, the electromagnetic shielding design method of the present invention adopts a layered shielding structure for the insulator detection device designed based on the electromagnetic environment assessment results. The layered shielding structure is automatically opened and closed according to the detected real-time electromagnetic load. Figure 2 As shown, in a preferred embodiment, the layered shielding structure includes an inner shielding layer and an outer shielding layer, wherein both the inner shielding layer and the outer shielding layer can be switched on and off by a rotating shaft. When the inner shielding layer is closed, the working state is the average electromagnetic attenuation working mode, and the outer shielding layer is in the open state. When the detected real-time electromagnetic load reaches the working threshold of the outer shielding layer, the detection sensor transmits a signal to the PCB board, controls the outer shielding layer to be closed, and starts the single-layer maximum electromagnetic attenuation working mode. Before the safe working mode is detected, after the outer shielding layer is closed, the inner shielding layer can be opened or set to closed, but generally the inner shielding layer is set to the closed state to deal with possible electromagnetic overload situations.

[0053] In a preferred embodiment, the electromagnetic shielding design method of the present invention can be used to design the most cost-effective shielding solutions for several common ultra-high voltage and UHV transmission lines, such as 500kV, ±800kV, 1000kV, 1100kV, and 1200kV. For example, insulator testing equipment designed for 500kV AC high-voltage transmission lines with a shielding performance of ≥90% can be constructed using inner and outer shielding layers, with the inner and outer shielding layers utilizing materials and structural combinations consistent with composite shielding requirements to achieve optimal cost-effectiveness.

[0054] In a preferred embodiment, the electromagnetic shielding design method of the present invention designs a set of shielding design solutions with optimal shielding performance. For example, an insulator testing device suitable for 800kV AC high-voltage transmission lines with a shielding performance of ≥95% is designed using inner and outer shielding layers, with the materials and structural design chosen to achieve optimal shielding performance.

[0055] In a preferred embodiment, the electromagnetic shielding design method of the present invention can be used to design universally applicable insulator testing equipment for ultra-high voltage or ultra-high voltage transmission lines within a certain voltage range. For example, an insulator testing device with optimal shielding performance can be designed for 500kV to 1000kV transmission lines. Another example is a device with the highest cost-effectiveness for 1000kV to 1400kV transmission lines.

[0056] In one embodiment, the insulator detection device designed for the ultra-high voltage or extra-high voltage transmission line in a certain voltage range has universal applicability. The triggering voltage / current conditions of the single-layer maximum electromagnetic attenuation mode and the safe working mode of transient high electromagnetic load are not higher than the triggering value corresponding to the lower voltage value, and the selected material and structure shielding design combination should not be lower than the triggering value corresponding to the next high voltage. For example, the insulator detection device designed for 500 kV-1000 kV transmission line, the triggering conditions of the single-layer maximum electromagnetic attenuation mode and the safe working mode of transient high electromagnetic load should not be higher than the lowest triggering value detected in this range, so as to maximize the sensitivity. The selected material and structure shielding design combination should not be lower than the triggering value corresponding to the next high voltage (for example, 900 kV), and within the highest safety value range of 1000 kV design, so as to ensure the safety of the insulator detection device.

[0057] In one preferred embodiment, as shown in Figure 3 When the sensor detects that the electromagnetic data load is greater than the set working threshold of the outer shielding layer (≥ the set maximum load V3), the safe working mode is started. If the sensor detects that the electromagnetic data load is less than the set working threshold of the outer shielding layer (< the set maximum load), it is further judged whether the set condition of the single-layer maximum electromagnetic attenuation mode (≥ the set working threshold in the single-layer attenuation mode V2, or the load fluctuation > 30%, one of the two conditions is met) is met, and the single-layer maximum electromagnetic attenuation mode is started. Otherwise, the average electromagnetic attenuation mode is maintained.

[0058] In one embodiment, the electromagnetic shielding design method of the present application, the layered shielding structure of the insulator detection device includes an outer shielding layer and an inner shielding layer structure, wherein the outer shielding layer realizes the maximum electromagnetic attenuation, and the inner shielding layer realizes the average electromagnetic attenuation. That is, when designing the outer shielding layer, whether it is material, thickness or structure design, it is designed according to the requirement that the maximum electromagnetic attenuation can be realized when the outer shielding layer is closed. It should be noted that when designing the outer shielding layer and the inner shielding layer, it needs to be considered whether it is designed for a specific ultra-high voltage transmission line (for example, it is designed for 750 kV circuit) or for ultra-high voltage transmission line in different voltage level range (for example, for 330 kV-1000 kV circuit), if the latter, it needs to be designed according to the electromagnetic shielding standard of higher transmission circuit.

[0059] In a preferred embodiment, the electromagnetic shielding design method of the present application, the outer shielding layer achieves the maximum electromagnetic attenuation amount refers to: when the outer shielding layer is in the closed state, its shielding effectiveness ≥ 80dB, the outer shielding layer can shield 80% ~ 105% of the maximum comprehensive electromagnetic load of 1000kV transmission line. That is, the insulator detection equipment designed according to the shielding standard of 1000kV transmission line can be safely used for transmission lines below 330kV ~ 1000kV, and for transmission lines exceeding 10% or more, it is necessary to judge whether it is applicable according to the proportion of influence factors and the highest safety parameters corresponding to the model.

[0060] In a preferred embodiment, the electromagnetic shielding design method of the present application, the inner shielding layer achieves the average electromagnetic attenuation amount refers to: when the inner shielding layer is in the closed state, its shielding effectiveness ≥ 30dB. The outer shielding layer can shield 95% of the average electromagnetic load of 330kV ~ 1000kV transmission line. The design of the inner shielding layer takes into account the requirements of sensitivity and safety.

[0061] In a preferred embodiment, the electromagnetic shielding design method of the present application, in the safety working mode of transient high electromagnetic load, the shielding effectiveness of the safety working mode is at least 1.3 ~ 1.6 times the shielding effectiveness of the single-layer maximum electromagnetic attenuation working mode. In the safety working mode, the inner shielding layer and the outer shielding layer are both in the closed state, so the shielding effectiveness of the safety working mode is at least 1.3 ~ 1.6 times the shielding effectiveness of the single-layer maximum electromagnetic attenuation working mode. In a preferred embodiment, the shielding effectiveness of the inner shielding layer is designed to be within the range of (30% ~ 60%) of the shielding effectiveness of the outer shielding layer.

[0062] In an embodiment, the electromagnetic shielding design method of the present application also sets up a transient overvoltage active defense mechanism. As shown in Figure 2 and Figure 4 When the transient high electromagnetic load ≥ 1.1 times the maximum comprehensive electromagnetic load of 1000kV transmission line, the transient discharge mechanism and the electromagnetic elimination mechanism are started, and a warning report is sent to the PCB control board of the insulator detection equipment.

[0063] In a preferred embodiment, the electromagnetic shielding design method of the present application, the transient discharge mechanism installed on the inner shielding layer is triggered to start a multi-stage surge discharge channel, and the peak current of the discharge ≥ 20kA. In a preferred embodiment, when the electromagnetic elimination mechanism is triggered, the active cancellation coil array inside the inner shielding layer generates at least 60% ~ 80% of the reverse electromagnetic equivalent of the transient high electromagnetic load. In a preferred embodiment, as shown in Figure 4The transient discharge mechanism and the electromagnetic elimination mechanism are provided simultaneously, and the transient overvoltage active defense mechanism is triggered, the transient discharge mechanism is started first, the electromagnetic elimination mechanism is started later, and finally a warning report is sent.

[0064] In summary, compared with the traditional fixed multi-layer shielding (three layers or more), the inner-outer layered shielding structure formed by the inner shielding layer and the outer shielding layer of the embodiment of the application is simpler. The layered shielding structure can dynamically adjust the opening and closing states of the inner shielding layer and the outer shielding layer according to real-time electromagnetic loads, has a wider application range, and basically meets the electromagnetic shielding design requirements of ultra-high voltage to extra-high voltage transmission lines. This scheme effectively overcomes the problems of single working mode and relatively narrow application range of the traditional fixed shielding structure and the inability to cope with transient overvoltage. At the same time, it has a dynamic protection mechanism, significantly enhances the application range of the insulator detection equipment, ensures that the insulator detection equipment can work normally in a wide high voltage range, and improves the detection accuracy. In addition, the transient overvoltage active defense mechanism further ensures the service life and normal working state of the insulator detection equipment.

[0065] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0066] In the embodiments of the application, the term "and / or" describes the association relationship of associated objects, which means that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the front and rear associated objects.

[0067] Each embodiment in the specification is described in a related manner, and the same and similar parts between each embodiment can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0068] Especially, for the apparatus embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant part can be seen from the part of the method embodiment.

[0069] For the convenience of description, the above apparatus is described in various units / modules respectively according to functions. Of course, in the implementation of the present application, the functions of each unit / module can be implemented in one or more software and / or hardware.

[0070] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing relevant hardware. The program can be stored in a computer readable storage medium, and when the program is executed, the program can include the processes of the above-mentioned embodiment methods. The storage medium can be a magnetic disc, an optical disc, a read-only memory (ROM) or a random access memory (RAM), etc.

[0071] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of electromagnetic shielding design of a power transmission line, characterized by, The method comprises the following steps: Assessing the electromagnetic environment of the power transmission line, calculating the power frequency electric field intensity, corona interference frequency spectrum range and transient overvoltage amplitude based on the voltage grade, conductor layout and insulator installation position of the power transmission line; Calculating the maximum electromagnetic load and average electromagnetic load that the insulator detection device can withstand under normal operation through model calculation; According to the electromagnetic environment of the power transmission line and the maximum electromagnetic load that the insulator detection device can withstand, calculating the maximum electromagnetic attenuation and average electromagnetic attenuation that need to be achieved; According to the electromagnetic attenuation data, designing electromagnetic shielding scheme groups of the insulator detection device in different electromagnetic environments, including designing different structures and selecting different materials to ensure that the insulator detection device can normally operate in different electromagnetic environments.

2. The method of claim 1, wherein, The method further comprises the following steps: Designing shielding test experiments for the control group, and selecting the shielding design scheme group with the best performance and / or cost performance according to the test results and different electromagnetic environments.

3. The method according to claim 1 or 2, characterized in that, The designed insulator detection device realizes automatic switching of at least the following three working modes: average electromagnetic attenuation working mode, single-layer maximum electromagnetic attenuation working mode and transient high electromagnetic load safety working mode.

4. The method of claim 3, wherein, The insulator detection device designed according to the electromagnetic environment assessment result adopts a layered shielding structure, which realizes automatic opening and closing according to the detected real-time electromagnetic load.

5. The method of claim 4, wherein, The layered shielding structure of the insulator detection device comprises an outer shielding layer and an inner shielding layer structure, the outer shielding layer realizes maximum electromagnetic attenuation, and the inner shielding layer realizes average electromagnetic attenuation.

6. The method of claim 5, wherein, The outer shielding layer realizes maximum electromagnetic attenuation, that is, when the outer shielding layer is in a closed state, its shielding effectiveness is ≥80 dB, and the outer shielding layer can shield 80% to 105% of the comprehensive maximum electromagnetic load under a 1000 kV power transmission line.

7. The method of claim 6, wherein, The inner shielding layer realizes average electromagnetic attenuation, that is, when the inner shielding layer is in a closed state, its shielding effectiveness is ≥30 dB, and the outer shielding layer can shield 95% of the average electromagnetic load under a 330 kV to 1000 kV power transmission line.

8. The method of claim 7, wherein, In the transient high electromagnetic load safety working mode, the shielding effectiveness of the safety working mode is at least 1.3 to 1.6 times that of the shielding effectiveness of the single-layer maximum electromagnetic attenuation working mode.

9. The method of claim 8, wherein, The outer shielding layer is connected with a transient discharge mechanism or an electromagnetic elimination mechanism, when the transient high electromagnetic load is ≥1.1 times the comprehensive maximum electromagnetic load under a 1000 kV power transmission line, the transient discharge mechanism or the electromagnetic elimination mechanism is started, and a warning report is sent to the PCB control board of the insulator detection device.

10. The method of claim 9, wherein, After the transient discharge mechanism is triggered, a multi-stage surge discharge channel is started, and the peak current of the discharge is ≥20 kA; after the electromagnetic elimination mechanism is triggered, an array of active cancellation coils arranged on the inner side of the inner shielding layer generates at least 60% to 80% of the reverse electromagnetic equivalent of the transient high electromagnetic load.

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