China’s First 220kV/240MVA Vegetable Oil Transformer: R&D, Advantages & Dual Carbon Contribution
With the continuous development of power transformer insulation technology, vegetable oil transformer products using green, environmentally friendly, and high-flash-point vegetable oil as insulation medium are gradually replacing mineral oil transformers. These vegetable oil-based transformers minimize carbon emissions to the greatest extent and effectively extend the service life of power transformers, which is of great significance for helping achieve the "dual carbon" goals.
Recently, led by a certain power supply bureau, the first domestic 220kV/240MVA vegetable oil transformer with the highest voltage level and largest capacity in China, developed by a Chinese vegetable oil transformer manufacturer, has successfully passed type tests. This further consolidates the leading domestic position of Chinese vegetable oil transformer manufacturers in the field of vegetable oil transformers and marks a new level in China's vegetable oil transformer design and manufacturing technology.
Traditional mineral insulating oil has been used for over a hundred years, but it has shortcomings such as low flash point, slow degradation rate, easy environmental pollution, and weak overload capacity. Compared with traditional mineral oil transformers, vegetable oil transformers have advantages including extremely low fire risk, strong overload capacity, and low whole-life cycle cost. Additionally, as vegetable oil is a renewable resource extracted from plant seeds, it can effectively reduce carbon emissions compared with mineral oil. Moreover, vegetable oil transformers have a wider application range than existing mineral oil transformers, and are particularly suitable for areas with high requirements for fire safety and environmental protection such as densely populated areas and environmental protection zones.
Adhering to the new development concept, focusing on the market frontier, and based on scientific research and innovation, the Chinese vegetable oil transformer manufacturer has been engaged in the R&D and manufacturing of vegetable oil transformers since 2007. In 2017, it undertook the green manufacturing project "Green Key Technology and Process System Integration of Environmentally Friendly Transformers and Environmentally Friendly Gas-Insulated Metal-Enclosed Switchgear" commissioned by the Ministry of Industry and Information Technology. Relying on this project, it developed 10kV, 35kV, and 110kV vegetable oil transformer products, forming a relatively complete product series. These products have been successively applied in Shandong, Henan, Guangdong, Hubei, Shaanxi and other places, and have been operating well so far, winning high praise from customers.
In September 2019, the Chinese vegetable oil transformer manufacturer successfully won the bid for the scientific research project "Optimization and Engineering Application of Insulation and Heat Dissipation Structures for Large-Scale Vegetable Oil Power Transformers - Trial Production of 220kV Vegetable Oil Transformers and Simulation Tests of Typical Insulation Structures" of a power supply bureau under China Southern Power Grid. Led by the power supply bureau, this project aimed to develop the 240MVA/220kV vegetable oil transformer with the highest voltage level and largest capacity in China.
The Chinese vegetable oil transformer manufacturer attaches great importance to the R&D of the 220kV insulating oil transformer. The deputy general manager of the company personally takes charge of the overall technical control and product implementation of the project. "We have given full play to our technical advantages and organized elite R&D and design teams to tackle key problems together. Especially during the technical breakthrough phase, we organized relevant technical personnel to implement technical details one by one and check product and process specifications item by item," said the relevant person in charge.
The R&D team is led by a doctoral graduate who returned from Japan. "Working with many vegetable oil manufacturers, we started with basic research on domestic vegetable oil, successively tested and verified the withstand field strength of the domestic vegetable oil-paper insulation system under power frequency, lightning impulse, and switching overvoltage, and guided the insulation optimization design of the 240MVA/220kV product based on test data. We conducted compatibility tests on transformer materials, testing the compatibility of each type of material in the transformer with domestic vegetable insulating oil to ensure the long-term stable operation of the product. We also carried out process tests for domestic vegetable insulating oil transformers, forming a complete set of process plans from crude oil incoming inspection to product delivery," said the team leader.
The design and development team is led by senior design experts and the deputy chief engineer of the company's research institute. "We organized technical experts to verify the design plan from aspects such as magnetic field calculation, fluid simulation, insulation assessment, and short-circuit force withstand capacity. Fully considering the particularity of vegetable oil, we selected and applied components such as bushings only after test verification to ensure the long-term reliability of the product," explained the design team leader. The design team closely integrated the results of basic research with the plan, fully applying the research achievements in the electrical scheme and structural layout of the transformer, and achieving the product goals of lightweight, economy, and high reliability while ensuring safety margin.
Due to the particularity of the product, technical backbones provided itemized guidance to workshop production personnel during the production process. In the process steps related to insulating oil, technical backbones participated throughout, conducting layer-by-layer control and item-by-item implementation to ensure product reliability and quality.
After nearly two years of scientific research, the company has finally overcome key technical difficulties such as insulation design and verification, temperature rise optimization and verification, and partial discharge control for large-scale vegetable oil transformers, and completely solved critical technologies including design and verification methods and manufacturing processes for large-scale vegetable oil transformers. The first domestic 220kV vegetable oil transformer with independent intellectual property rights has successfully been developed.
In the field of vegetable insulating oil transformers, the Chinese vegetable oil transformer manufacturer leads the domestic industry in both R&D and production levels and market share, driving the overall improvement of the greenization level of China's transformer industry. In September 2020, the company's "green process for vegetable insulating oil transformers" was awarded the title of "New Leading Technology Product for Promoting High-Quality Energy Development".
The Chinese vegetable oil transformer manufacturer will keep a close eye on the goals of building an "origin" of original technologies and a "chain leader" of modern industrial chains, adhere to serving national strategies, leading industry development, and driving innovation through science and technology. It will stay true to its original aspiration and mission, fulfill the responsibilities of a central enterprise, and make persistent efforts to strive to become a world-class smart electrical system solution provider, contribute to the realization of the "dual carbon" goals and the construction of a new power system, and lay a solid foundation for the successful start of the 14th Five-Year Plan.
