Ⅰ. Introduction
As a high-efficiency and environmentally friendly renewable energy solution, wind power has maintained rapid development across the globe. Compared with onshore wind power, offshore wind energy features sufficient and stable wind resources, low environmental impact, and support for large-capacity unit installation, making it the core development direction of the global new energy industry. In offshore wind farm power generation systems, traditional oil-immersed transformers are no longer applicable due to extreme operating environments with high humidity and high salt density. Instead, the dry type distribution transformer has become the standard configuration for offshore wind turbine nacelle installation, effectively saving equipment occupation space and solving the protection difficulties of low-position installation.
The transformer installed inside the offshore wind turbine is close to the generator set, which can directly boost the 690V voltage generated by the wind turbine to 35kV through the converter. This structure greatly reduces the usage of low-voltage cables and effectively controls the overall construction cost of wind farms. The 300 kva dry type transformer is widely used in small and medium-sized offshore wind supporting power distribution systems, with stable performance and strong environmental adaptability, meeting the basic power transmission and transformation needs of distributed wind power units.
JINSHANMEN TECHNOLOGY CO., LTD is a professional manufacturer of power transmission and distribution equipment. The company mainly produces oil immersed power transformers, dry-type power transformers, oil immersed three-dimensional coiled power transformers, dry-type three-dimensional coiled power transformers, mining explosion-proof dry-type transformers, mining explosion-proof mobile substations, amorphous alloy power transformers, on load capacity regulating power transformers, locomotive dry-type transformers, as well as prefabricated substations, modular substations, wind energy box type substations, high and low voltage switchgear and other transmission and distribution equipment. With in-depth research on offshore wind power equipment scenarios, we customize high-reliability dry type distribution transformer products for marine environments to solve the pain points of corrosion, vibration and heat dissipation of offshore wind transformers.
Ⅱ. Special Technical Requirements for Offshore Wind Dry Type Transformers
Different from conventional onshore transformers, dry type transformers serving offshore wind farms face harsh working conditions such as high salt fog, high humidity and continuous vibration, which put forward higher standards for product performance, size and reliability. Taking the mainstream 3MW offshore wind turbine supporting transformer as an example, the core technical parameters are standardized and refined to adapt to marine scenarios.
The typical technical specifications include: rated capacity 3300kVA, high voltage 35kV, low voltage 0.69kV, vector group Dyn11, short-circuit impedance 8%, Class F insulation system with a 100K maximum temperature rise, standard insulation level LI 170 AC 70/AC 3, no-load loss not exceeding 6700W, load loss limited to 25800W at 75℃, forced air cooling (AF), maximum acoustic power noise of 78dB(A), Climate Class C2, Environmental Class E2, and Fire Behaviour Class F1, weight and overall dimension limits. Whether it is a large-capacity wind power special transformer or a matching 300 kva dry type transformer, all products need to strictly comply with marine environmental protection and safety grades to ensure long-term stable operation.
Ⅲ. Core Specialized Design Solutions for Offshore Wind Dry Type Transformers
1. Body Electromagnetic and Structural Design
Limited by the narrow installation space and load-bearing capacity of wind turbine nacelles, offshore wind dry type transformers require compact size and light weight on the premise of guaranteed electrical performance. The iron core adopts cold-rolled grain-oriented electrical steel with 45-degree full miter and five-step lap structure, which effectively reduces no-load loss and noise.
The high-voltage coil adopts a segmented cylindrical structure and is processed by vacuum casting process to ensure uniform insulation and strong pressure resistance. The low-voltage coil adopts foil winding structure with axial air passages, and the end is sealed and cured by pre-impregnated insulating resin to improve overall structural rigidity. In the electromagnetic calculation stage, we repeatedly compare copper and aluminum winding schemes to balance size and weight, meeting the installation and operation requirements of offshore wind dry type distribution transformer equipment.
2. Anti-Corrosion Design for Marine Salt Fog Environment
High humidity and salt fog are the main factors leading to transformer failure in offshore environments. The permeable salt-containing air will corrode metal structural parts, and form a conductive film on the insulation surface, triggering surface pollution flashover and even inducing wind turbine fire risks.
To solve this problem, the transformer is equipped with a closed shell with a protection level higher than IP44, adopting an internal independent circulating cooling system isolated from the external environment. This design avoids external salt fog and humid air from entering the equipment, greatly reducing the anti-corrosion pressure of the transformer body. The shell adopts professional anti-corrosion spraying technology, fully meeting the C4 high-corrosion resistance grade in accordance with ISO 12994 industrial coating standards, which adapts to long-term marine atmospheric corrosion.
3. Vibration Resistance Design for Wind Turbine Operation
Offshore wind turbines are in a continuous vibration state during operation, and the vibration impact will be more intense during yawing and braking processes. Long-term alternating vibration will easily cause fastener loosening and structural deformation of the transformer, affecting operational safety.
We adopt multiple anti-vibration optimization measures: the integral pouring structure makes the coil form an integral rigid body with excellent anti-vibration performance; increase the number of transformer bottom feet and fixing bolts to strengthen bottom fixation; install long bolts on the upper clamp to connect with the shell bracket, integrating the transformer body and the shell into a whole. In addition, all fasteners are equipped with anti-loosening devices to prevent parts from falling off and ensure stable operation of 300 kva dry type transformer and other power distribution equipment.
4. Optimized Ventilation and Heat Dissipation Design
The heat dissipation of offshore wind dry type transformers is a systematic project, which is affected by ventilation volume, heat exchange efficiency and external circulating water system. We configure axial fans, dedicated air duct systems and high-efficiency heat exchangers on the shell, and install diversion plates on the transformer body.
During operation, the axial flow fan extracts hot air inside the shell for centralized heat exchange, and the external water circulation system takes away heat efficiently. The cooled air flows through the main air duct and the internal air passage of the low-voltage coil under the guidance of the diversion plate, realizing uniform and efficient cooling of the coil. Combined with computer simulation analysis, a reasonable temperature rise margin is reserved in the design stage, and the scheme is iteratively optimized according to actual test data in mass production to adapt to continuous high-load operation.
5. Maintainability Optimization Design
Offshore wind farms are located in remote sea areas, with high maintenance difficulty and expensive operation and maintenance costs. Therefore, the design must focus on later maintenance convenience. The transformer shell adopts a spliced detachable structure, which is convenient for disassembly and replacement of core components such as high-voltage coils.
For the core heat dissipation components, the axial flow fans are designed in a one-active one-standby configuration with a service life of up to 40,000 operating hours, which effectively avoids equipment shutdown and power generation loss caused by fan failure, ensures the continuous operation rate of wind farm equipment, and reduces long-term operation and maintenance costs.
Ⅳ. Conclusion
Different from conventional indoor and outdoor transformers, offshore wind dry type transformers need targeted optimized design in terms of anti-corrosion, vibration resistance, heat dissipation and maintainability to adapt to high humidity, salt fog and strong vibration marine working conditions. Scientific structural design and process upgrading can effectively solve the failure pain points of offshore wind power distribution equipment and improve the service life and operational stability of transformers.
With the booming development of global offshore wind power, the market demand for high-reliability offshore dedicated dry type transformers continues to grow. Adhering to strict production standards, JINSHANMEN TECHNOLOGY CO., LTD provides customized and high-performance dry type distribution transformer and 300 kva dry type transformer solutions for offshore wind farms, helping global new energy projects achieve safe, stable and efficient operation.