An ultra-large capacity, low-inductance, high-voltage film capacitor for ultra-high voltage transmission

Abstract

The present invention relates to the technical field of film capacitors, and specifically relates to an ultra-large capacity, low-inductance, high-voltage film capacitor applied to ultra-high voltage power transmission. The film capacitor can simultaneously meet the performance requirements of low inductance, low heat generation, small size, light weight, and long life, thereby improving the safety and reliability of the film capacitor. The film capacitor comprises a capacitor core, a potting material, an extraction electrode, and a shell. The capacitor core is formed by vapor deposition, slitting, winding, heat setting, and metal layer spraying of a metalized film. The metalized film is formed by a mixture of high-crystalline polypropylene and PPS resin. The surface roughness of the metalized film is 0.05-0.10 μm. A semi-T-shaped safety film is added during the vapor deposition process of the metalized film. The metalized film comprises a PP base film and a gradient metal coating. During winding, the metal coating thickness of the upper metalized film gradually becomes thinner from both sides to the middle, while the metal coating thickness of the lower metalized film gradually becomes thicker from both sides to the middle. The capacitor core is a flat core.

Description

Technical Field

[0001] The present invention relates to the technical field of film capacitors, and in particular to an ultra-large capacity, low inductance, high-voltage film capacitor used for ultra-high voltage power transmission. Background Art

[0002] my country's uneven east-west energy distribution is hindering the rapid and sustainable development of the national economy. Ultra-high voltage transmission is an effective technological solution for accommodating renewable energy, transmitting electricity over long distances and over large areas, and addressing the shortage of transmission corridors. It is a major national project contributing to national rejuvenation. In 2020, it was included among the seven key industries for new infrastructure development, helping my country achieve its "dual carbon" goals of carbon peak and carbon neutrality.

[0003] Ultra-high voltage (UHV) transmission requires a large number of organic film capacitors, which play a vital role in supporting the DC voltage in UHVDC transmission systems. They are core components that ensure the quality of DC transmission and the normal and stable operation of converter valves. During long-term online service, capacitors used on the HVDC side face operating conditions characterized by complex electric fields superimposed by high voltage DC, harmonics, and transient overvoltages, as well as elevated internal capacitor temperatures. Any problems can cause significant losses and impacts. Currently, DC-link capacitors used in large-scale flexible DC transmission projects at home and abroad are monopolized by foreign manufacturers, with long lead times and high product prices. This poses a risk of supply disruptions in the current complex international situation, making them a prominent shortcoming in my country's UHV project construction. Therefore, my country urgently needs to conduct research on high-end capacitor technology for UHV transmission, overcome bottleneck technologies in this field, break the monopoly of imported products, and achieve independent control and domestic substitution of key technologies.

[0004] In the field of ultra-high voltage transmission, the concept of flexible direct current (HVDC) technology was first proposed by McGill University in Canada in 1990. Since the early 21st century, my country has experienced over a decade of development in HVDC technology, achieving significant progress in both equipment and engineering. Specifically, my country has achieved significant breakthroughs in the development of key HVDC equipment, including high-power power electronics, converter valves, HVDC circuit breakers, high-voltage converter transformers, and DC cables, achieving "Made in China" status. However, domestically produced large-capacity DC capacitors for HVDC are still in the technical research phase and require market validation.

[0005] Currently, the high-end global market for organic film capacitors remains monopolized by foreign manufacturers, and core technologies remain in the hands of these companies. As the world's largest film capacitor production base and consumer market, Chinese film capacitor manufacturers only hold a commanding share of the low-end, low-value-added market, and have yet to gain recognition in high-end sectors, including flexible capacitors.

[0006] With the rapid development of power electronics technology in my country in recent years, domestic manufacturers have been able to compete with foreign manufacturers in a variety of fields, such as renewable energy generation (photovoltaic and wind power), electric vehicles, variable frequency energy conservation, and inverter welding machines, and have captured a share of the highly competitive film capacitor market. However, due to the complex operating conditions faced by capacitors used on the UHVDC side, including high voltage DC, harmonics, and transient overvoltage superposition, as well as the elevated internal temperature of the capacitors, coupled with the rigid requirement for high reliability (over 40 years of grid operation) for power transmission, domestic DC capacitors have yet to gain market recognition in the UHV transmission sector.

[0007] Because transmission projects operate continuously, film capacitors are required to have a failure rate of ≤30 FIT over 40 years of continuous use. Therefore, safety must be ensured when installing such a large number of capacitors in the valve hall. Flexible DC capacitors feature high voltage, large capacity, and high current, and are also required to have low losses, low inductance, and low heat generation. Furthermore, to reduce the floor space of the valve hall and the load-bearing capacity of valve tower components, the capacitors are also expected to be as small and light as possible. More critically, while meeting these requirements, an extremely low failure rate is also required over an expected lifespan of up to 40 years. This can only be achieved when the capacitor's design, process, equipment, and materials approach ideal values. Summary of the Invention

[0008] In order to solve the problem that existing film capacitors have poor safety and reliability and cannot simultaneously meet the requirements of low inductance, low heat generation, small size, light weight and long life, the present invention provides an ultra-large capacity, low inductance and high-voltage film capacitor for ultra-high voltage power transmission, which can simultaneously meet the performance requirements of low inductance, low heat generation, small size, light weight and long life, thereby improving the safety and reliability of film capacitors.

[0009] The technical solution is as follows: an ultra-large capacity, low-inductance, high-voltage film capacitor for ultra-high voltage transmission, comprising a capacitor core, a potting material, an extraction electrode, and a casing. The capacitor core is formed by vapor deposition, slitting, winding, heat setting, and metal layer spraying of a metalized film. The metalized film is characterized in that it is made of a mixture of high-crystalline polypropylene and PPS resin, has a surface roughness of 0.05-0.10 μm, and a semi-T-shaped safety film is added during the vapor deposition process of the metalized film. The metalized film comprises a PP base film and a gradient metal coating.

[0010] During winding, the metal coating thickness of the upper metallized film gradually becomes thinner from both sides to the middle, and the metal coating thickness of the lower metallized film gradually becomes thicker from both sides to the middle;

[0011] The capacitor core is a flat core. During heat setting, a heat setting tool is used to apply fixed pressure to the capacitor core and the core is placed in an oven for staged heating. The temperature control process is as follows: room temperature is heated to 60°C and held for 3 hours, it takes 10 minutes to heat up to 65°C and hold for 29 minutes, it takes 10 minutes to heat up to 70°C and hold for 29 minutes, it takes 10 minutes to heat up to 75°C and hold for 29 minutes, it takes 10 minutes to heat up to 80°C and hold for 29 minutes, it takes 10 minutes to heat up to 85°C and hold for 29 minutes, it takes 10 minutes to heat up to 90°C and hold for 29 minutes, it takes 10 minutes to heat up to 95°C and hold for 29 minutes, it takes 10 minutes to heat up to 98°C and hold for 59 minutes. It takes 10 minutes to heat up to 99°C and hold for 29 minutes, it takes 10 minutes to heat up to 100°C and hold for 29 minutes, it takes 10 minutes to heat up to 101°C and hold for 29 minutes, it takes 10 minutes to heat up to 102°C and hold for 29 minutes, it takes 10 minutes to heat up to 103°C and hold for 29 minutes, it takes 10 minutes to heat up to 104°C and hold for 29 minutes, it takes 10 minutes to heat up to 105°C and hold for 29 minutes, it takes 10 minutes to heat up to 106°C and hold for 29 minutes, it takes 10 minutes to heat up to 107°C and hold for 29 minutes, it takes 10 minutes to heat up to 108°C and hold for 29 minutes, it takes 10 minutes to heat up to 109°C and hold for 29 minutes, it takes 10 minutes to heat up to 110°C and hold for 4.3 hours; after the heat setting is completed, it is taken out of the oven and cooled to room temperature, and the capacitor core is taken out of the heat setting tooling;

[0012] The lead-out electrode includes an upper electrode plate and a lower electrode plate arranged in a stacked manner. The capacitor cores are arranged in groups in vertical columns. Each group of capacitor cores is connected to the upper electrode plate and the lower electrode plate respectively through a braided copper belt. The upper electrode plate and the lower electrode plate are respectively provided with electrode heads.

[0013] It is further characterized in that the heat setting tooling includes a lower support plate and an upper pressing plate, the lower support plate and the upper pressing plate are connected by bolts, a top plate and a matching nut are provided on the top of the bolts, a spring is sleeved on the bolts between the top plate and the upper pressing plate, an intermediate pressing plate is provided between the lower support plate and the upper pressing plate, and the capacitor core is pressed between the intermediate pressing plate and the lower support plate, between adjacent intermediate pressing plates, and between the intermediate pressing plate and the upper pressing plate;

[0014] A through hole is provided on the upper electrode plate, and an electrode head fixed on the lower electrode plate passes through the through hole;

[0015] The potting material is made of polyurethane A and B materials, which are mixed after degassing. The potting material is poured into the shell under vacuum conditions and cured under positive pressure conditions.

[0016] After adopting the present invention, high-crystalline polypropylene and PPS resin improve the crystallization of the metallized film, the surface roughness can enhance the self-healing property and thus improve the withstand voltage field strength, and the addition of a semi-T-shaped safety film can modify the film and improve the withstand voltage level of the film. The gradient metal coating on the metallized film can also take into account both current carrying capacity and self-healing property. During the heat setting process, the matching tooling and unique heat curing temperature control are used to ensure that the capacitor core has a stable shape and good withstand voltage consistency. The lead-out electrodes adopt a laminated busbar structure, and the capacitor cores are grouped and individually led out to the laminated busbar through braided copper strips, thereby reducing the inductance, so that the capacitor can simultaneously meet the performance requirements of low inductance, low heat generation, small size, light weight, and long life, thereby improving the safety and reliability of the film capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a comparison table of the properties of the film of the present invention and conventional films;

[0018] Figure 2 This is a comparison table of the pressure resistance of the film of the present invention and conventional films;

[0019] Figure 3 This is a schematic diagram of a semi-T-shaped safety film;

[0020] Figure 4 Schematic diagram of the upper and lower layers of metallized film during winding;

[0021] Figure 5 The stress distribution of two capacitor cores with different structures;

[0022] Figure 6 It is a three-dimensional schematic diagram of the heat setting tooling;

[0023] Figure 7 This is the main view of the heat setting tooling;

[0024] Figure 8 This is a schematic diagram of the connection between the capacitor core and the lead electrode;

[0025] Figure 9 It is the flow chart of potting;

[0026] Figure 10 This is a "bathtub curve" diagram of component failure. DETAILED DESCRIPTION

[0027] A super-large capacity, low-inductance, high-voltage film capacitor used for ultra-high voltage transmission, comprising a capacitor core, a potting material, lead electrodes, and a shell. The capacitor core is formed by evaporating, slitting, winding, heat setting, and spraying a metal layer on a metalized film.

[0028] The most important material for film capacitors is metallized film. Since the capacitance per unit volume is inversely proportional to the square of the film thickness, the most effective means of miniaturization is to reduce the film thickness. However, the film withstand voltage is directly proportional to the thickness. Modification can be performed using the following methods:

[0029] (1) Metallized film is made of a mixture of high crystalline polypropylene and PPS resin, which is further crystallized to improve performance. Figure 1 As shown;

[0030] (2) The roughness of the metallized film surface is 0.05-010um, which improves the self-healing property and thus increases the withstand voltage field strength. The performance improvement is as follows: Figure 2 As shown;

[0031] (3) Through the design of film inner string structure, a semi-T-shaped safety film is added during the metallized film evaporation process. The structure is as follows Figure 3 As shown, an isolation "fuse" is added to improve the film's withstand voltage while effectively reducing the capacitor's ESR and ESL, making the film resistant to breakdown and avoiding failure.

[0032] In addition to considering the film's voltage resistance and safety, the design of metallized film still needs to focus on the capacitor's overcurrent capability. Under normal circumstances where the volume size is certain, voltage and current are in a repulsive state: a simple high-square-resistance film has excellent self-healing ability and high voltage resistance, but the higher the square resistance, the thinner the metal coating, the weaker the current-carrying capacity, and the higher the heat generation, making the capacitor more prone to early failure. The metallized film includes a PP base film and a gradient metal coating. The present invention proposes to adopt a gradient metal coating design, which can not only withstand higher field strengths, but also overcome the shortcomings of conventional high-square-resistance films, taking into account both current-carrying capacity and self-healing properties. It is characterized by high square resistance and gradual changes. This gradient design can improve the voltage resistance of the polymer film, while its current-carrying capacity is better than that of conventional high-square-resistance films. From a process perspective, the thinner the metal coating, the greater the contact resistance between the gold-sprayed end portion of the capacitor's small component and the edge. Under the action of the closing surge current, the contact resistance heats up and causes losses, which will reduce the capacitor's capacity. According to the current distribution law, the change in square resistance can compensate for the problem caused by the current change, thereby making the current more uniform. This gradient high square resistance film can also appropriately reduce the thickness of the insulating layer. Gradient high square resistance film is also superior to low square resistance film. Because low square resistance film, although low square resistance, relatively thick metal coating, and enhanced current carrying capacity, but more difficult to self-heal. When the metal film self-heals, it generates a lot of energy, making it difficult to control the self-healing, resulting in continuous burns of multi-layer dielectrics. More seriously, the gas vaporized by the continuous self-healing metal layer may cause the capacitor to bulge, ultimately leading to capacitor failure.

[0033] When winding, the metal coating thickness of the upper metallized film gradually becomes thinner from both sides to the middle, and the metal coating thickness of the lower metallized film gradually becomes thicker from both sides to the middle, such as Figure 4 shown.

[0034] Improvements in the winding steps: (a) The traditional design concept of the metallized film winding process is changed, and the electro-cleaning process is no longer used to avoid the adverse hazards caused by electro-cleaning; (b) The inner sealing process is also cancelled, and a breakthrough method of inserting an inner lining film (no coating) is adopted to solve the insulation isolation problem of the inner film bipolar plates. At the same time, it can serve as an inner layer support to avoid the problem of film burns and wrinkles, making the inner circle of the core ideal; (c) The outer core also adopts the form of inserting an outer coating film to solve the insulation isolation problem of the thin film bipolar plates, and at the same time the wrapping protection effect is better and more stable; (d) The inserted inner lining and outer coating films are thicker and have no coating, which solves the problem that ultra-thin films are easily burned and wrinkled; (e) The inner lining film is used as the inner layer support and the outer coating film is used for wrapping protection. The ultra-thin metallized film is only realized as the functional part of the capacitor, and the overall design of the capacitor is more stable and reliable.

[0035] The capacitor core is a flat core, and the stress distribution of the flat core is not as uniform as that of the round core. Figure 5 As shown in the figure, during the heat setting process, the film is prone to shape inconsistency due to thermal shrinkage. At the same time, the uneven stress distribution of the film will also cause poor consistency in the product's withstand voltage. During heat setting, a heat setting tool is used to apply a fixed pressure to the capacitor core and place it in an oven for staged heating. The heat setting tool is as follows: Figure 6 and Figure 7 As shown, the heat setting tooling includes a lower support plate 1 and an upper pressing plate 2, which are connected by bolts 3, a top plate 4 and a matching nut 5 are provided on the top of the bolt 3, a spring 6 is provided on the bolt 3 between the top plate 4 and the upper pressing plate 2, an intermediate pressing plate 7 is provided between the lower support plate 1 and the upper pressing plate 2, and the capacitor core 8 is pressed between the intermediate pressing plate 7 and the lower support plate 1, between adjacent intermediate pressing plates 7, and between the intermediate pressing plate 7 and the upper pressing plate 2; multiple capacitor cores 8 can be fixed in a heat setting tooling to prevent shape rebound during film shrinkage.

[0036] Temperature control process: room temperature to 60℃ and hold for 3h, take 10min to heat up to 65℃ and hold for 29 minutes, take 10min to heat up to 70℃ and hold for 29min, take 10min to heat up to 75℃ and hold for 29 minutes, take 10min to heat up to 80℃ and hold for 29 minutes, take 10min to heat up to 85℃ and hold for 29 minutes, take 10min to heat up to 90℃ and hold for 29 minutes, take 10min to heat up to 95℃ and hold for 29 minutes, take 10min to heat up to 98℃ and hold for 59 minutes, take 10min to heat up to 99℃ and hold for 29 minutes, take 10min to heat up to 99℃ and hold for 29 minutes. min to 100℃ and hold for 29 minutes, 10 min to 101℃ and hold for 29 minutes, 10 min to 102℃ and hold for 29 minutes, 10 min to 103℃ and hold for 29 minutes, 10 min to 104℃ and hold for 29 minutes, 10 min to 105℃ and hold for 29 minutes, 10 min to 106℃ and hold for 29 minutes, 10 min to 107℃ and hold for 29 minutes, 10 min to 108℃ and hold for 29 minutes, 10 min to 109℃ and hold for 29 minutes, 10 min to 110℃ and hold for 4.3 hours; after heat setting is completed, take out from the oven and slowly cool to room temperature, and then take out the capacitor core from the heat setting tooling.

[0037] The DC capacitor and the parasitic inductance on the line form a spike reverse voltage when the IGBT is turned off, which in turn threatens the safety of the IGBT. The spike voltage increases with the increase of the parasitic inductance of the loop and the change of the IGBT turn-off current. The IGBT turn-off current change rate of the flexible DC converter reaches 3-6 kA / μs, so the flexible DC capacitor usually requires a parasitic inductance of less than 45nH to ensure the safe operation of the IGBT. The capacitor used in the flexible DC system has a large capacity and a very large volume. The number of its core components is as many as hundreds. It is very difficult to reduce its overall inductance. In order to achieve the performance requirements of low inductance, the present invention adopts the following optimization scheme in structural design, such as Figure 8 As shown:

[0038] (1) The lead-out electrode adopts a laminated busbar design to minimize ESL by eliminating the current magnetic field. The lead-out electrode includes an upper electrode plate and a lower electrode plate arranged in a laminated manner. The upper electrode plate and the lower electrode plate are respectively provided with electrode heads. A through hole is provided on the upper electrode plate, and the electrode head fixed on the lower electrode plate passes through the through hole.

[0039] (2) The capacitor cores are arranged in groups in vertical rows and are individually connected to the laminated busbars to reduce the impact of uneven current distribution at high frequencies;

[0040] (3) Use multiple strands of braided copper tape for connection to minimize the uneven heating of the capacitor caused by the skin effect of current under high frequency conditions. At the same time, ensure that the copper tape is in complete contact with the capacitor core at the soldering point to avoid concentrated heating of the capacitor core.

[0041] The potting process uses proprietary casting technology, such as Figure 9 As shown, the capacitor is first vacuum-dried, followed by polyurethane degassing. Material A and material B are then mixed using a mechanical metering, mixing, and potting machine. Casting is completed under vacuum, with positive pressure applied during the curing process. This critical potting and encapsulation process improves the product's internal structure's resistance to thermal shock, vibration, and impact, as well as the strength of solder joints. This ensures product quality, reduces polyurethane waste, and improves the efficiency and yield of the entire casting process, ultimately ensuring the capacitor's reliability and safety during use. This also minimizes internal porosity in the potting material after curing, reducing partial discharge.

[0042] Optimizing component pulse current aging technology: According to IEC61071 and GB / T 17702, power electronic capacitors must account for pulse current surges caused by switching or system conversions. Life test requirements are shown in the table below. To ensure product reliability, capacitors must undergo pulse current surge testing. However, due to the large capacity of the entire capacitor, the surge current is also high (reaching hundreds of kA). If a single component failure causes the entire unit to fail, the resulting loss is significant and poses a risk to testing safety.

[0043] The present invention adopts a method of sophisticated selection of dv / dt pulse current during the core testing stage, so that the product can ensure its pulse current capability from the component. The flexible capacitor is composed of multiple capacitor elements, and the typical design scheme is to use dozens to hundreds of elements in series and parallel. When any component that makes up the capacitor fails, the entire capacitor will fail. This means that the capacitor elements must achieve a lower failure rate in order to ensure that the failure rate of the capacitor is below 30FIT. Under such high performance, small size and high reliability requirements, in addition to selecting high-quality materials, high-performance processing equipment, and stable process guarantees, it is also necessary to have complete and effective inspection means and testing methods to screen out high-quality and reliable components for the assembly and production of capacitors.

[0044] Subjecting the capacitor to a large pulse current shock not only tests the performance of the thin film coating, but also can identify any internal poor connection defects that may occur during the manufacturing process, such as poor gold spraying or poor welding, which increases the contact resistance.

[0045] The technology of selecting the failure of finished products before aging is based on the statistical analysis of electronic component failures. The failure distribution of products will follow the "bathtub curve", such as Figure 10As shown, a large portion of failures occur in the early stages of product use. The failure probability of most products falls into three stages: initial failure, occasional failure (useful life), and wear-out failure. However, if all three stages of the bathtub curve for product failure rate were to manifest during customer use, this would be undesirable for designers and manufacturers and would be the root cause of customer dissatisfaction and complaints. Therefore, the goal of reliability engineering is to alter the trend of this bathtub curve and the stages of failure occurrence. All reliability engineering methods involve various technical designs, analyses, and tests centered around modifying the bathtub curve.

[0046] This invention utilizes reliability engineering to modify the three stages of the bathtub curve. While different reliability methods are typically employed at each stage of the product lifecycle, this proposal focuses on pre-shipment burn-in screening tests. By leveraging years of quality data and extensive testing in film capacitor production, we have designed an optimal environmental stress screening test. This ensures that products have passed the "initial failure period" during factory burn-in, ensuring stable operation within the "occasional failure period" upon delivery.

[0047] Before shipment, this invention subjects all products to a 100% burn-in test. The burn-in conditions employed are: 12-24 hours at maximum operating temperature and rated operating voltage. This prevents premature failure screening and ensures product reliability. Components that undergo premature failure screening are expected to have an order of magnitude lower failure rate than those that do not undergo burn-in.

[0048] The present invention provides key technologies for ultra-large capacity, low inductance, high-voltage thin-film capacitors for ultra-high voltage transmission. It focuses on improving the performance of key capacitor materials, optimizing the design of key structures, and improving and upgrading key processes. At the same time, it adopts new inspection technologies to ensure product stability and obtain capacitor products that meet market demand.

Claims

1. A super-large capacity, low-inductance, high-voltage film capacitor for ultra-high voltage transmission, comprising a capacitor core, a potting material, an extraction electrode, and a shell. The capacitor core is formed by evaporating, slitting, winding, heat setting, and spraying a metal layer on a metalized film. The invention is characterized in that: The metallized film is made of a mixture of high-crystalline polypropylene and PPS resin. The surface roughness of the metallized film is 0.05-0.10um. A semi-T-shaped safety film is added during the evaporation process of the metallized film. The metallized film includes a PP base film and a gradient metal coating. During winding, the metal coating thickness of the upper metallized film gradually becomes thinner from both sides to the middle, and the metal coating thickness of the lower metallized film gradually becomes thicker from both sides to the middle; The capacitor core is a flat core. During heat setting, a heat setting tool is used to apply fixed pressure to the capacitor core and the core is placed in an oven for staged heating. The temperature control process is as follows: room temperature is heated to 60°C and held for 3 hours, it takes 10 minutes to heat up to 65°C and hold for 29 minutes, it takes 10 minutes to heat up to 70°C and hold for 29 minutes, it takes 10 minutes to heat up to 75°C and hold for 29 minutes, it takes 10 minutes to heat up to 80°C and hold for 29 minutes, it takes 10 minutes to heat up to 85°C and hold for 29 minutes, it takes 10 minutes to heat up to 90°C and hold for 29 minutes, it takes 10 minutes to heat up to 95°C and hold for 29 minutes, it takes 10 minutes to heat up to 98°C and hold for 59 minutes. It takes 10 minutes to heat up to 99°C and hold for 29 minutes, it takes 10 minutes to heat up to 100°C and hold for 29 minutes, it takes 10 minutes to heat up to 101°C and hold for 29 minutes, it takes 10 minutes to heat up to 102°C and hold for 29 minutes, it takes 10 minutes to heat up to 103°C and hold for 29 minutes, it takes 10 minutes to heat up to 104°C and hold for 29 minutes, it takes 10 minutes to heat up to 105°C and hold for 29 minutes, it takes 10 minutes to heat up to 106°C and hold for 29 minutes, it takes 10 minutes to heat up to 107°C and hold for 29 minutes, it takes 10 minutes to heat up to 108°C and hold for 29 minutes, it takes 10 minutes to heat up to 109°C and hold for 29 minutes, it takes 10 minutes to heat up to 110°C and hold for 4.3 hours; after the heat setting is completed, it is taken out of the oven and cooled to room temperature, and the capacitor core is taken out of the heat setting tooling; The lead-out electrode includes an upper electrode plate and a lower electrode plate arranged in a stacked manner. The capacitor cores are arranged in groups in vertical columns. Each group of capacitor cores is connected to the upper electrode plate and the lower electrode plate respectively through a braided copper belt. The upper electrode plate and the lower electrode plate are respectively provided with electrode heads.

2. The ultra-large capacity, low inductance, high voltage film capacitor for ultra-high voltage power transmission according to claim 1, characterized in that: The heat setting tooling includes a lower support plate and an upper pressing plate, which are connected by bolts. A top plate and a matching nut are provided on the top of the bolts. A spring is provided on the bolts between the top plate and the upper pressing plate. An intermediate pressing plate is provided between the lower support plate and the upper pressing plate. The capacitor core is pressed between the intermediate pressing plate and the lower support plate, between adjacent intermediate pressing plates, and between the intermediate pressing plate and the upper pressing plate.

3. The ultra-large capacity, low inductance, high voltage film capacitor for ultra-high voltage power transmission according to claim 1, characterized in that: A through hole is provided on the upper electrode plate, and an electrode head fixed on the lower electrode plate passes through the through hole.

4. The ultra-large capacity, low inductance, high voltage film capacitor for ultra-high voltage power transmission according to claim 1, characterized in that: The potting material is made of polyurethane A and B materials, which are mixed after degassing. The potting material is poured into the shell under vacuum conditions and cured under positive pressure conditions.

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