High-voltage long-gap current measurement shielding device

Abstract

The invention discloses a high-voltage long-gap current measurement shielding device, which adopts a double-layer shielding structure and comprises an inner shell and an outer shielding shell, the inner shell is internally covered with a wave-absorbing material, the inner shell is externally covered with a high-temperature insulating material, and the high-temperature insulating material is externally covered with the outer shielding shell. The external shielding device can be used for external shielding of a current measurement device in long-gap discharge, and measurement errors caused by the influence of stray capacitance during sampling measurement of equipment are reduced, so that the accuracy of long-gap discharge current measurement is improved, the electromagnetic shielding performance is optimized, and the safety of equipment operation is improved.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic protection, and in particular to a high-voltage long-gap current measurement shielding device. Background Art

[0002] Lightning strikes are the primary cause of tripping accidents on overhead transmission lines in my country. Air gaps are the primary form of external insulation in high-voltage transmission systems, and the proper selection of air gap structures is a key issue in the design of external insulation for high-voltage transmission systems. Air gaps exhibit a significant saturation effect as their length increases, posing a challenge to the insulation coordination design of ultra-high voltage transmission systems. Therefore, research on the discharge mechanism of long air gaps is crucial for optimizing the insulation design of transmission systems. However, current current measurement in air gaps still presents challenges such as large stray capacitance, excessively high cavity temperatures after discharge, and limited electromagnetic shielding effectiveness. Therefore, this patent proposes a current measurement shielding device for high-voltage, Class M air gaps, based on a Faraday cage-based current measurement device.

[0003] Measuring air gap discharge current is an important method for studying the discharge mechanism of long air gaps and is crucial for optimizing the insulation design of power transmission systems. However, current measurement of air gap current still faces challenges such as large stray capacitance, excessively high cavity temperature after discharge, and limited electromagnetic shielding effectiveness. This paper proposes a current measurement shielding device for ultra-high voltage, Class M air gaps. This device achieves accurate gap discharge current measurement while maintaining low internal stray capacitance. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a high-voltage long-gap current measurement shielding device, which reduces the measurement error caused by the influence of stray capacitance during equipment sampling and measurement, thereby improving the accuracy of long-gap discharge current measurement and is a high-voltage M-level air gap current measurement shielding hardware device.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A high-voltage long-gap current measurement shielding device adopts a double-layer shielding structure, including an inner shell and an outer shielding shell. The inner shell is covered with an absorbing material, the outer shell is covered with a high-temperature insulating material, and the outer shell is covered with the high-temperature insulating material.

[0007] Furthermore, the inner shell uses copper as the conductive material.

[0008] Furthermore, the outer shielding shell is made of light metal.

[0009] Furthermore, the outer shielding shell includes five layers of Ag metal covering films and is grounded.

[0010] Furthermore, the thickness of the five-layer Ag metal covering film is 1 mm.

[0011] Furthermore, the inner shell is provided with partition supports, and the partitions include three layers that are arranged at equal intervals.

[0012] Furthermore, the length of the partition is 1.73 times the radius of the inner shell to achieve an angle of 120° with the center of the inner shell.

[0013] Furthermore, the partitions are arranged at 1 / 5, 2 / 5 and 3 / 5 of the inner shell from top to bottom, and are arranged horizontally.

[0014] Furthermore, the width of each partition is 0.05 times the total length of the inner shell.

[0015] Furthermore, it also includes a sampling circuit chamber, which includes an electromagnetic shielding chamber and a squirrel cage resistor.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0017] The present invention can be used for the outer shielding of a current measuring device in a long-gap discharge, reducing the measurement error caused by the influence of stray capacitance during device sampling and measurement, thereby improving the accuracy of long-gap discharge current measurement, optimizing electromagnetic shielding performance, and improving the safety of device operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a three-dimensional solid diagram of the inner shell of the present invention;

[0019] Figure 2 is a three-dimensional solid diagram of the outer layer of the present invention;

[0020] Figure 3 is a schematic diagram of a sampling circuit chamber of the present invention;

[0021] Figure 4 It is a schematic diagram of the shielding device principle of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0023] Example

[0024] like Figure 1 and Figure 2 As shown, a high-voltage long-gap current measurement shielding device adopts a double-layer shielding structure, including an inner shell and an outer shielding shell. The inside of the inner shell is covered with absorbing material, the outside of the inner shell is covered with high-temperature insulating material, and the outer shielding shell is covered on the outside of the high-temperature insulating material.

[0025] Further explanation: Considering the poor electrical conductivity of iron tools and the tendency to generate heat under high-frequency working conditions, copper has better electrical conductivity and thermal conductivity than iron. Copper is used as the conductive material of the inner shell of the device to achieve faster diffusion of heat energy after passing through.

[0026] Further explanation: Since the current measuring device requires good electromagnetic shielding when measuring precision instruments, and the temperature will rise when high-voltage and high-frequency impact current passes through, the outside of the inner shell is covered with high-temperature insulating material, and the inside of the inner shell is covered with absorbing material to minimize the impact on the internal collection device of the equipment.

[0027] Further explanation: The outer shielding shell is made of light metal. Specifically, 5 layers of Ag metal covering film are evenly applied on the outside of the insulating material. Light metal is used as outer shielding on the outside of the high-temperature insulating material and grounding protection is performed. The covering thickness is 1mm.

[0028] The outer material is a lightweight insulating material coated with metallic silver, which reduces the weight of the device while achieving insulation. A door cabin is set on the side of the outer material to place the inner shell and equipment.

[0029] Further explanation: Considering that copper is a relatively soft material, a partition support is designed inside the copper device to ensure that it does not deform. The upper end of the device is thickened and designed with double-layer shielding, and a partition is designed in the middle to achieve the installation of collection equipment and inner shell support effect.

[0030] The size of the partition is flexibly set according to the size of the inner shell. Its length is 1.73 times the radius of the inner shell to achieve a 120° effect with the center of the inner shell. The width of a single partition is 0.05 times the total length of the inner shell to ensure sufficient area and space for placing equipment. At the same time, considering that the electromagnetic shock may be large when the lower end discharge circuit is running, the partition position is horizontally set at 1 / 5, 2 / 5 and 3 / 5 from top to bottom of the inner shell to leave space at the lower end for flexible adjustment of the end of the equipment.

[0031] This embodiment also includes a sampling circuit chamber, such as Figure 3 As shown, the chamber of the sampling circuit is located below the inner shell inside the outer shell. Its circuit structure includes an external electromagnetic shielding chamber and a squirrel cage resistor. The structure is cylindrical. The external electromagnetic shielding chamber is used to reduce the electromagnetic interference of the sampling circuit, and the internal squirrel cage resistor is used to pass the sampling current. There is only one squirrel cage resistor inside and no shell.

[0032] This embodiment designs a sampling circuit chamber, which is combined with electromagnetic shielding, equipment support, and probe sampling to achieve sample voltage collection and equipment shielding within the device.

[0033] The sampling circuit chamber uses metal copper to achieve electromagnetic shielding of the discharge chamber, and uses squirrel cage resistors inside to achieve accurate measurement of high-frequency voltage and current. Metal copper is used for connection through the squirrel cage resistors. The structure is as follows Figure 3 The double-layer structure of the inner network shown further reduces the distributed inductance in the case of high-frequency signal sampling, thereby improving the high-frequency characteristics of the sampling circuit chamber.

[0034] In the double-layer shielding, the inner layer material mainly passes the discharge current, and the outer metal is grounded for protection. Considering that the external current is small, the main external current generated is due to the capacitive displacement current. Considering that external grounding can improve safety and shielding effect and reduce charge dissipation, Ag with better electrical and thermal conductivity is used as the metal covering film.

[0035] The relationship between the electrical conductivity and the thermal effect is calculated according to the following formula:

[0036] P=I 2 (L / A·σ) (1)

[0037] Where P is the power loss, I is the current, L is the length of the conductor, A is the cross-sectional area of ​​the conductor, and σ is the conductivity.

[0038] The relationship between thermal conductivity and temperature rise is calculated according to the following formula:

[0039]

[0040] Where ρ is the density of the material, c p is the specific heat capacity of the material, T is the temperature, t is the time, and k is the thermal conductivity.

[0041] According to formula (1), the inner layer material mainly passes the discharge current, and its current path is compact (L is small), which further reduces the power loss P. Even if A is small, I 2 The L term is kept small, preventing runaway heat generation. For example, if the inner layer is made of a high-conductivity metal (such as copper or silver alloy), even if A is small, the increase in σ can offset the effect of the decrease in A, keeping the power loss P within a reasonable range (controllable heat generation).

[0042] According to formula (2), if the inner layer material has high thermal conductivity (such as metal material, k is large), the heat can be quickly conducted along the space ( Even if there is a certain amount of heat generation, the heat can be quickly diffused to the outer shielding layer (such as the external Ag cover film, which further enhances heat conduction), avoiding excessive local temperature rise.

[0043] The inner layer material offsets the increased power loss caused by the small A through high electrical conductivity (large σ) and short current path (small L), ensuring that heat generation is controllable. At the same time, high thermal conductivity (large k) and low heat capacity (ρ cp The characteristics of the cross-section (small) make the heat diffuse quickly. Even if the cross-sectional area is small, the temperature rise can still be maintained at an extremely low level, meeting the thermal stability requirements of the device.

[0044] This design not only uses the compact structure of the inner layer material to achieve space optimization, but also uses the electrical and thermal properties of the material (high σ, high k, low ρ cp ) ensures that energy loss and temperature rise are controllable, which is highly consistent with the physical laws of formulas (1) and (2), verifying the scientificity and rationality of the design.

[0045] like Figure 4 As shown, the current measuring device realizes a better electromagnetic shielding effect and better thermal conductivity of the current conducting part by realizing a double-layer outer coating grounding design. Figure 2 The outer three-dimensional solid diagram, the inner layer corresponds to Figure 1 The three-dimensional solid diagram of the inner shell of the present invention is shown in FIG. Figure 3 The sampling circuit chamber schematic diagram shown in the figure realizes electromagnetic shielding, and the double-layer squirrel cage design realizes the effect of low distributed inductance when measuring high-frequency signals, which improves the high-frequency characteristics. The parallel connection of metal strips realizes the large current sharing effect, realizes better electromagnetic shielding effect and more accurate long-gap discharge current measurement, and improves the safety of equipment operation.

[0046] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high voltage long gap current measurement shielding device, characterized in that: A double-layer shielding structure is adopted, including an inner shell and an outer shielding shell. The inner shell is covered with absorbing material, the outer shell is covered with high-temperature insulating material, and the outer shell is covered with the high-temperature insulating material.

2. The high-voltage long-gap current measurement shielding device according to claim 1, characterized in that: The inner shell adopts copper as the conductive material.

3. The high-voltage long-gap current measurement shielding device according to claim 1, characterized in that: The outer shielding shell is made of light metal.

4. The high-voltage long-gap current measurement shielding device according to claim 3, characterized in that: The outer shielding shell includes five layers of Ag metal covering films and is grounded.

5. The high-voltage long-gap current measurement shielding device according to claim 4, characterized in that: The thickness of the five-layer Ag metal covering film is 1 mm.

6. The high-voltage long-gap current measurement shielding device according to any one of claims 1 to 5, characterized in that: The inner shell is provided with partition support, and the partition comprises three layers which are arranged at equal intervals.

7. The high-voltage long-gap current measurement shielding device according to claim 6, characterized in that: The length of the baffle is 1.73 times the radius of the inner shell to achieve a 120° angle with the center of the inner shell.

8. The high-voltage long-gap current measurement shielding device according to claim 6, characterized in that: The partitions are arranged at 1 / 5, 2 / 5 and 3 / 5 from top to bottom of the inner shell and are arranged horizontally.

9. The high-voltage long-gap current measurement shielding device according to claim 8, characterized in that: The width of each partition is 0.05 times the total length of the inner shell.

10. The high-voltage long-gap current measurement shielding device according to claim 1, characterized in that: The device also includes a sampling circuit chamber, which includes an electromagnetic shielding chamber and a squirrel cage resistor.

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