GIS partial discharge monitoring crown type fractal dipole antenna

Abstract

The utility model relates to the technical field of partial discharge detection, and particularly discloses a GIS partial discharge monitoring crown type fractal dipole antenna, which is characterized by comprising a dielectric substrate, a feed connector and a dipole plate, the dipole plate comprises a plurality of first dipole plates and second dipole plates which are of cake structures; the first dipole plate and the second dipole plate are symmetrically arranged on the surface of the dielectric substrate; square grooves are formed in the center positions of the first dipole plate and the second dipole plate, circular dipole plates are embedded in the square grooves, and the structure that the square grooves are formed in the center positions of the dipole plates and the circular dipole plates are embedded can be circularly and repeatedly arranged; the utility model aims to combine the fractal technology to widen the working frequency band of the antenna and reduce the size of the antenna, and meanwhile, the antenna is high in gain and has good directional diagram bandwidth.

Description

Technical Field

[0001] The utility model relates to the technical field of partial discharge detection, and particularly relates to a crown-shaped fractal dipole antenna for GIS partial discharge monitoring. Background Technique

[0002] Defects inside or on the surface of the insulation of power equipment cause distortion of the original electric field, generating a local high-field-strength area. When the electric field strength in a local area is higher than the breakdown field strength, partial discharge will occur in this area while other areas still maintain insulation characteristics, that is, the partial discharge phenomenon occurs.

[0003] Partial discharge does not form a complete discharge channel and belongs to non-penetrating discharge. Usually, the influence of partial discharge on the overall electrical performance of the insulation can be ignored. However, if no measures are taken in time, long-term partial discharge will damage the insulation structure and cause insulation aging. The insulation failure area changes from small to large, expands from local to overall, and finally develops into through-breakdown or surface flashover, causing sudden insulation faults. Therefore, partial discharge is the inducement and sign of insulation deterioration of electrical equipment. Online monitoring of partial discharge phenomena in power equipment to detect early insulation defects inside it, so as to take measures to avoid the occurrence of sudden insulation faults, is of great significance for ensuring the safe and reliable operation of electrical equipment and even the entire power system.

[0004] At present, there are many methods for detecting partial discharge phenomena, including ultra-high frequency method, pulse current method, ultrasonic method, chemical monitoring method, and optical monitoring method. Among them, the ultra-high frequency method stands out among various monitoring methods with its high sensitivity and strong anti-interference ability.

[0005] The primary task of monitoring partial discharge using the ultra-high frequency method is to develop a suitable antenna sensor to receive the ultra-high frequency electromagnetic waves of partial discharge. Ultra-high frequency antenna sensors can be roughly divided into spiral antennas, loop antennas, Vivaldi antennas, microstrip monopole antennas, fractal antennas, three-dimensional structure antennas, and Bow-tie dipole antennas according to their shapes and principles.

[0006] Although many scholars have designed various ultra-high frequency antennas in the past, these antennas cannot meet the requirements simultaneously in terms of size, bandwidth, lower cut-off frequency, and gain. For example, narrowband or multi-band antennas such as loop antennas and microstrip monopole antennas meet the size requirements, but their detection frequency bands are limited, resulting in the loss of a large number of ultra-high frequency signals and the inability to obtain complete partial discharge signals. Planar spiral antennas, three-dimensional structure antennas, and Vivaldi antennas have relatively wide operating frequency band widths, but their sizes or volumes are too large, making them inconvenient to carry and install on-site. Fractal antennas have low gain and it is difficult to detect weak ultra-high frequency signals. Bow-tie dipole antennas are widely used due to their simple structure, wide frequency band, and good time-domain radiation characteristics. However, the impedance matching of the antenna arms of traditional triangular structure antennas is difficult, which severely limits the bandwidth and time-domain characteristics of Bow-tie dipole antennas. Therefore, it is necessary to design an ultra-high frequency antenna sensor with small size, wide bandwidth, low lower cut-off frequency, and high gain. Summary of the Utility Model

[0007] Aiming at the deficiencies of the prior art, the technical problem solved by the present utility model is a crown-shaped fractal dipole antenna for GIS partial discharge monitoring. By combining fractal technology, the working frequency band of the antenna is broadened and the size is reduced. At the same time, the antenna has a high gain and good pattern bandwidth.

[0008] To solve the above problems, the technical solution adopted by the present utility model is: a crown-shaped fractal dipole antenna for GIS partial discharge monitoring, characterized in that it includes a dielectric substrate, a feed joint, and a dipole plate; the dipole plate includes a plurality of first dipole plates and second dipole plates in the shape of round cakes; the first dipole plate and the second dipole plate are symmetrically arranged on the surface of the dielectric substrate; square grooves are provided at the central positions of the first dipole plate and the second dipole plate, and circular dipole plates are embedded in the square grooves, and the structure of setting square grooves at the central positions of the dipole plates and embedding circular dipole plates can be cyclically repeated.

[0009] The beneficial effects produced by this solution are: the fractal structure and symmetric design can enhance the antenna's ability to receive partial discharge signals, improve the monitoring sensitivity, and help to more accurately detect weak discharge signals. By optimizing the shape and nested structure of the dipole plate, the working frequency band of the antenna is effectively broadened, enabling it to adapt to a wider range of partial discharge frequencies; the symmetric structure and special slot design help to improve the directivity of the antenna, enabling the antenna to more accurately locate the position of partial discharge, reducing the physical size of the antenna without reducing performance, facilitating installation and layout in the limited space inside GIS equipment, and the optimized structure helps to reduce the influence of external interference signals and improve the anti-interference ability of the antenna in a complex electromagnetic environment, thereby more accurately obtaining partial discharge signals.

[0010] Furthermore, the dimensions of the first dipole plate and the second dipole plate are Re=80mm, Sf=2mm, Wf=1mm, and the input port impedance value is also 50Ω. The specific dimensions can optimize the resonant frequency of the antenna. The antenna has a good response in a specific frequency band, better adapts to the frequency range required for GIS partial discharge monitoring, improves the accuracy and reliability of monitoring, can radiate energy more effectively, and enhances the signal transmission and receiving capabilities of the antenna. The input port impedance is set to 50Ω, which can achieve good impedance matching with most transmission lines and systems, reduce signal reflection and energy loss, and improve the quality and efficiency of signal transmission.

[0011] Furthermore, the dielectric substrate is 162×80×1.6mm in size, the dielectric substrate material has a relative dielectric constant of 4.4, and the dielectric loss tangent is 0.030, which is FR4-epoxy (epoxy resin), so that the antenna's radiation unit and feeding structure can be reasonably arranged, thereby optimizing the antenna's radiation characteristics and impedance matching, ensuring that the antenna has good performance within the working frequency band, and the FR4-epoxy material with a relative dielectric constant of 4.4 helps to achieve the miniaturization design of the antenna. On the premise of meeting the antenna performance requirements, the size of the antenna can be reduced, making it easier to integrate and install in specific equipment. The dielectric loss tangent is 0.030, which is relatively small, and can effectively reduce the transmission loss of the signal in the dielectric substrate, improve the antenna's radiation efficiency and gain, and enhance the antenna's signal receiving and transmitting capabilities.

[0012] Furthermore, the diagonal length of the square slot is smaller than the diameter of the first dipole plate or the second dipole plate, which can ensure the effective radiation area of ​​the dipole plate, so that the antenna can radiate and receive electromagnetic waves more effectively, improve the gain and radiation efficiency of the antenna, enhance the signal strength and transmission distance, and help maintain the uniform distribution of current on the dipole plate, thereby optimizing the impedance matching of the antenna, reducing reflection loss, and improving the energy transmission efficiency, so that the antenna has more stable and good performance within the working frequency band, and at the same time, the radiation in a specific direction is stronger, which improves the positioning and detection accuracy of the target signal, and is particularly suitable for partial discharge monitoring applications with high requirements for directionality.

[0013] Furthermore, the side length of the square groove is less than or equal to the diameter of the nested inner dipole plate, ensuring that the nested inner dipole plate is accurately and firmly positioned in the square groove, avoiding shaking or displacement during use, thereby ensuring the stability and consistency of the antenna performance. Size matching helps to achieve a more uniform and reasonable current flow, improve the radiation efficiency and gain of the antenna, and enhance the signal transmission and reception capabilities of the antenna. Without affecting the performance, the overall size of the antenna is reduced, which is beneficial to the installation and layout of the antenna in a limited space, and is particularly suitable for application scenarios with high space requirements.

[0014] Furthermore, the square groove is arranged in a square structure, which helps to achieve uniform distribution of the electric and magnetic fields, thereby improving the radiation efficiency and gain of the antenna, making the radiation characteristics of the antenna more consistent in all directions, enhancing the stability and reliability of the antenna. The square shape is simpler and more intuitive when calculating and simulating its impact on the antenna performance, facilitating the optimization design; in the manufacturing process, it is also easier to achieve precise machining, reducing the production difficulty and cost.

[0015] Furthermore, the feeding joint is tangent to the first dipole plate and the second dipole plate. This tangential positional relationship enables the fed current to propagate more uniformly along the dipole plates, reducing the concentration and mutation of the current, thereby improving the radiation efficiency and gain of the antenna, enhancing the signal transmitting and receiving capabilities of the antenna. An appropriate tangential position can better match the input impedance of the antenna with the characteristic impedance of the transmission line, reducing the reflection loss, improving the energy transmission efficiency, and ensuring that the signal can be transmitted more effectively. The uniform current distribution makes the radiation of the antenna more consistent in different directions, reducing the radiation of side lobes and back lobes, improving the directivity and directionality of the antenna, and facilitating the more accurate reception and transmission of signals in a specific direction.

[0016] Furthermore, the first dipole plate and the second dipole plate are fixedly connected to the dielectric substrate by screws. For the adjustment, replacement, or repair of the dipole plates, screw fixation allows for convenient operation, reducing the operation difficulty and cost; screw fixation is conducive to controlling the fixation force, which can avoid damaging the dielectric substrate or the dipole plates due to excessive fixation, while ensuring sufficient connection strength and good electrical contact.

[0017] Furthermore, a circular dipole plate is arranged in the square groove, and the circular dipole plate is adhesively fixed to the square groove with glue, avoiding local stress concentration, reducing potential damage to the antenna structure, and helping to maintain the stability of the antenna performance. The glue can fill the tiny gaps between the dipole plate and the square groove, enhancing the connection tightness and preventing adverse effects of external environmental factors on the antenna performance.

[0018] Furthermore, radiation rings are arranged around the square groove, which can enhance the radiation performance of the antenna. The radiation rings can increase the current path, thereby improving the radiation efficiency, enhancing the transmitting and receiving capabilities of the antenna, making the signal transmission more stable and powerful, enabling the antenna to maintain good performance within a wider frequency range, adapting to different communication requirements and environmental changes, optimizing the radiation pattern of the antenna, reducing the radiation of side lobes and back lobes, improving the directivity of the main lobe, enhancing the directional transmission ability of the signal. Setting the radiation rings can also improve the impedance matching performance of the antenna, reducing reflection and loss, enabling more energy to be effectively radiated, and improving the overall efficiency of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural view of the present utility model;

[0020] Figure 2 is a schematic structural view of a traditional Bow-tie dipole antenna;

[0021] Figure 3 is a schematic structural view of a circular dipole antenna;

[0022] Figure 4 is a comparison chart of the standing wave ratio of the dipole antenna

[0023] Figure 5 is a schematic structural view of a crown-shaped fractal dipole antenna;

[0024] Figure 6 is a comparison chart of the standing wave ratio of the non-fractal and fractal dipole antennas;

[0025] Figure 7 is a comparison chart of the peak gain of the non-fractal and fractal dipole antennas;

[0026] Figure 8 is a curve of the standing wave ratio of the crown-shaped first-order fractal dipole antenna changing with frequency. Specific embodiments

[0027] The reference numerals in the accompanying drawings of the specification include: dielectric substrate 1, first dipole plate 2, radiation ring 3, feed joint 4, second dipole plate 5, circular dipole plate 6, square groove 7, dipole plate 8.

[0028] Example 1 is basically as shown in the appendix Figure 1 shown: A crown-shaped fractal dipole antenna for GIS partial discharge monitoring includes a dielectric substrate, a feed joint, and a dipole plate. The provided dipole plate includes two first dipole plates and second dipole plates in the shape of round cakes, and the sizes of the first dipole plate and the second dipole plate are Re = 80 mm, Sf = 2 mm, Wf = 1 mm, and the input port impedance value is 50 Ω. The first dipole plate and the second dipole plate are symmetrically arranged on the surface of the dielectric substrate; and the first dipole plate and the second dipole plate are fixedly arranged on the dielectric substrate by screws. Square grooves are provided at the center positions of the first dipole plate and the second dipole plate. The diagonal length of the square groove is less than the diameter of the first dipole plate or the second dipole plate where it is located. At the same time, the side length of the square groove is less than the diameter of the nested inner dipole plate. Radiation rings are arranged around the square groove. The square groove is arranged in a square structure. A circular dipole plate is embedded in the square groove. The circular dipole plate and the square groove are adhesively bonded. And the circular dipole plate embedded in the square groove can be repeatedly arranged at the center position of the dipole plate. At the same time, the feed joint is tangent to the first dipole plate and the second dipole plate, and the feed joint is tangent to the first dipole plate and the second dipole plate.

[0029] In use, as Figure 3 shown, a circular structure oscillator is used to replace the triangular antenna arm in the traditional Bow-tie dipole antenna to solve the problem of difficult impedance matching of the traditional Bow-tie dipole antenna.

[0030] HFSS is used to establish simulation models of two dipole antennas respectively. The size of the dielectric substrate is taken as 162×80×1.6 mm, and the relative permittivity of the dielectric substrate material is 4.4, and the tangent value of the dielectric loss angle is 0.030 for FR4-epoxy (epoxy resin).

[0031] The arm length of the Bow-tie dipole antenna determines the lower cut-off frequency. The longer the arm length, the lower the operating frequency; the characteristic impedance of the Bow-tie dipole antenna is only related to the flare angle. Increasing the flare angle can make the antenna easily match with a 50Ω coaxial cable. According to this, the size of the traditional Bow-tie dipole antenna is designed as La = 80 mm, Sf = 2 mm, Wf = 1 mm, Af = 53°, and the input port impedance is set to 50Ω.

[0032] Keeping the same dielectric substrate size, to achieve ultra-wideband characteristics, a circular structure oscillator is used to replace the triangular antenna arm in the Bow-tie dipole antenna to reduce the ringing effect. The size of the new circular dipole antenna is designed as Re = 80 mm, Sf = 2 mm, Wf = 1 mm. The input port impedance value is also 50Ω.

[0033] Figure 4 Fig. is the comparison diagram of the standing wave ratios of the traditional Bow-tie dipole antenna and the circular dipole antenna. Compared with the traditional Bow-tie dipole antenna, the curve of the standing wave ratio of the circular dipole antenna fluctuates less with the change of frequency. The frequency bands of the traditional Bow-tie dipole antenna with VSWR < 3 are 0.5~0.68 GHz and 1.94~2.27 GHz, and the frequency band of the circular dipole antenna with VSWR < 3 is 0.62~3 GHz. Therefore, the circular dipole antenna has a wider frequency band.

[0034] Fractal antennas have self-similarity and space-filling properties. Self-similarity enables fractal antennas to have multi-frequency or wide-band characteristics; space-filling properties enable the antenna to increase the effective electrical length within a limited space to achieve miniaturization, as Figure 5 shown.

[0035] A square groove inscribed in the first dipole plate and the second dipole plate is hollowed out, which is the 0th-order fractal antenna; on the basis of the 0th-order fractal antenna, an inscribed circular dipole plate is made in the hollowed-out inscribed square, and at the same time a new square groove inscribed in the new circular dipole plate is hollowed out, which is the 1st-order fractal antenna. In this way, 2nd-order fractal antennas, 3rd-order fractal antennas, etc. can be generated by successive iteration.

[0036] In theory, a fractal antenna can be infinitely large, but an increase in the fractal antenna order will lead to an increase in the complexity of the antenna and the processing difficulty.

[0037] As Figure 6 shown, compared with the non-fractal dipole antenna, the standing wave ratio (SWR) curve of the 0th-order fractal antenna deteriorates with frequency. The frequency bands with VSWR < 3 are 0.581 - 0.834 GHz, 1.515 - 1.864 GHz, and 2.128 - 2.338 GHz. However, compared with the non-fractal dipole antenna, the SWR curves of the 1st-order, 2nd-order, and 3rd-order fractal antennas do not change much. The lower cut-off frequencies are 0.598 GHz, 0.603 GHz, and 0.613 GHz respectively. That is, except for the 0th-order fractal antenna, in the same space, the fractal technology can effectively increase the electrical length of the antenna, thereby reducing the lower cut-off frequency of the antenna to achieve the purpose of antenna miniaturization. However, the higher the fractal order, the smaller the decrease in the lower cut-off frequency of the antenna.

[0038] As Figure 7 shown, compared with the non-fractal dipole antenna, the average peak gain of the 0th-order fractal antenna is 4.7509 dB, while the average peak gains of the 1st-order, 2nd-order, and 3rd-order fractal antennas are 3.9239 dB, 3.6804 dB, and 3.2569 dB respectively. That is, the fractal technology can effectively increase the average peak gain of the antenna, but the higher the fractal order, the more the average peak gain of the antenna shows a decreasing trend. However, too high a fractal order will cause the average peak gain of the antenna to be less than that of the non-fractal dipole antenna, that is, less than 3.4457 dB.

[0039] In summary, to balance the lower cut-off frequency and the average peak gain of the antenna, the fractal order of the circular dipole antenna is determined to be 1st order. Figure 7 is the SWR curve of this dipole antenna with respect to frequency. The frequency band with voltage standing wave ratio < 3 is 0.598 - 6.93 GHz, and the relative bandwidth reaches 168.22%.

[0040] Figure 8 are the gain patterns of the crown-shaped 1st-order fractal dipole antenna at 0.6375 GHz, 0.9750 GHz, 1.9875 GHz, and 3.0000 GHz. It can be seen from the figure that in the low-frequency range, the E-plane shows an "8" shape and the H-plane shows a regular circle, enabling omnidirectional radiation. As the frequency increases, the radiation performance of the antenna decreases. This may be because as the frequency increases, higher-order electromagnetic waves are excited, leading to the distortion of the pattern.

[0041] In summary, the present application proposes a novel crown-shaped first-order fractal dipole antenna for partial discharge detection. The size of the antenna is 162×80×1.6 mm, which is relatively small. The frequency band with a voltage standing wave ratio < 3 is 0.598 - 6.93 GHz, and the relative bandwidth reaches 168.22%. The average peak gain within the range of 0.3 - 3 GHz is 3.9239 dB, and the antenna gain is relatively high. It has a good pattern bandwidth.

[0042] The above has described the embodiments of the present utility model in detail in conjunction with the accompanying drawings, but the present utility model is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present utility model, various changes, modifications, substitutions, and deformations made to these embodiments still fall within the protection scope of the present utility model.

Claims

1. A crown-shaped fractal dipole antenna for GIS partial discharge monitoring, characterized in that: The invention comprises a dielectric substrate, a feeding connector and a dipole plate; the dipole plate comprises a first dipole plate and a second dipole plate of a plurality of pancake structures; the first dipole plate and the second dipole plate are symmetrically arranged on the surface of the dielectric substrate; a square groove is arranged at the center of the first dipole plate and the second dipole plate, and the circular dipole plate is embedded in the square groove, and the structure of arranging the square groove at the center of the dipole plate and embedding the circular dipole plate can be cyclically repeated.

2. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The dimensions of the first dipole plate and the second dipole plate are Re=80 mm, Sf=2 mm, and Wf=1 mm; the input port impedance value is also 50Ω.

3. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1 is characterized by: The dielectric substrate has a size of 162×80×1.6 mm, and the dielectric substrate material is FR4-epoxy (epoxy resin) with a relative dielectric constant of 4.4 and a dielectric loss tangent value of 0.

030.

4. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The diagonal length of the square slot is smaller than the diameter of the first dipole plate or the second dipole plate.

5. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The side length of the square groove is less than or equal to the diameter of the nested inner dipole plate.

6. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The square groove is arranged in a square structure.

7. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The feeding connector is arranged tangentially to the first dipole plate and the second dipole plate.

8. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The first dipole plate and the second dipole plate are fixedly connected to the dielectric substrate by screws.

9. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: A circular dipole plate is arranged in the square groove, and the circular dipole plate is fixed to the square groove by glue.

10. The GIS partial discharge monitoring crown-shaped fractal dipole antenna according to claim 1, characterized in that: The square groove is surrounded by radiation rings.

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