With the rapid advancement of urbanization and the continuous expansion of urban power grids, urban substations have become an indispensable part of modern urban infrastructure, responsible for the transmission and distribution of electric power to residential areas, commercial centers, and industrial zones. However, the noise pollution generated by power equipment in urban substations has become a growing concern, as these substations are often located in densely populated areas, and excessive noise can seriously affect the quality of life of surrounding residents. According to environmental noise standards (such as GB 3096-93), the daytime noise limit for urban residential areas (Class I urban areas) is less than 55dB, which puts strict requirements on the noise control of power equipment, especially 10kV dry-type transformers—core equipment in urban substations. Traditional 10kV dry-type transformers usually have a noise level of 60-75dB, which exceeds the environmental protection standard and is no longer suitable for urban application scenarios. Therefore, developing 10kV dry-type transformers with a noise level below 55dB has become an urgent technical need in the urban power grid construction. This article elaborates on the technical implementation paths, key breakthroughs, and application practices of 10kV dry-type transformers with noise level <55dB for urban substations, combining the latest本体降噪 (body noise reduction) technologies and industry standards, to provide a comprehensive technical reference for the promotion and application of low-noise transformers in urban areas.
To achieve the noise control target of <55dB, it is first necessary to clarify the main noise sources of 10kV dry-type transformers, as targeted noise reduction measures can only be formulated based on the source analysis. The noise of dry-type transformers mainly comes from three aspects: iron core vibration noise, winding vibration noise, and cooling system noise, among which iron core vibration noise accounts for 60-70% of the total noise, making it the core focus of noise reduction design. Iron core vibration is caused by the magnetostriction effect of silicon steel sheets under alternating magnetic fields—when the magnetic field changes, the silicon steel sheets will produce periodic expansion and contraction, which drives the transformer shell to vibrate and radiate noise. Winding vibration noise is generated by the electromagnetic force between windings under load conditions, which causes the windings to vibrate and transmit noise to the shell. Cooling system noise, mainly from cooling fans, is more prominent in large-capacity dry-type transformers, and its noise level is closely related to the fan speed and structure. In addition, the resonance between the transformer components and the installation base can also amplify the noise, further increasing the difficulty of noise control.
The technical implementation of 10kV dry-type transformers with noise level <55dB is a systematic project, involving the optimization of core materials, structural design, winding process, cooling system, and installation methods, with the core goal of reducing vibration sources and blocking noise transmission. The following details the key technical implementation measures, combining the latest technological achievements in body noise reduction to avoid the traditional extensive noise reduction method of "adding enclosures or barriers", which occupies limited substation space and affects inspection and landscape.
The optimization of iron core design and material selection is the fundamental measure to reduce iron core vibration noise, which is also the core of the body noise reduction technology. Traditional transformers use ordinary cold-rolled silicon steel sheets, which have high magnetostriction coefficient and large vibration amplitude, leading to high noise. To solve this problem, the first step is to select high-performance silicon steel sheets with low magnetostriction. At present, the third-generation high-grade cold-rolled grain-oriented silicon steel sheets (such as 30Q130) are widely used, which have a magnetostriction coefficient of less than 2×10⁻⁶, 30-40% lower than ordinary silicon steel sheets. These silicon steel sheets have a more uniform grain structure and better magnetic properties, which can effectively reduce the magnetostriction effect and reduce iron core vibration. In addition, the thickness of the silicon steel sheets is optimized to 0.23mm or 0.27mm—thinner silicon steel sheets can reduce eddy current loss and magnetic hysteresis loss, thereby reducing the heat generation and vibration of the iron core.
On the basis of material optimization, the iron core structure is further improved to reduce vibration transmission. The traditional iron core adopts a lap joint structure, which has obvious gaps and uneven stress distribution, leading to increased vibration during operation. The low-noise transformer adopts a fully inclined step lap joint structure, which reduces the gap between silicon steel sheets to less than 0.1mm, making the iron core structure more compact and uniform, and reducing the vibration caused by uneven magnetic flux distribution. At the same time, the iron core is clamped with high-strength non-magnetic clamping pieces, and the clamping force is precisely controlled (usually 120-150N/cm²)—excessive clamping force will increase the stress of the silicon steel sheets and increase vibration, while insufficient clamping force will cause loose silicon steel sheets and amplify noise. In addition, a damping pad made of high-temperature-resistant rubber is added between the iron core and the clamping pieces to absorb the vibration of the iron core and prevent it from being transmitted to the shell. This body noise reduction measure, which optimizes the iron core itself, can reduce the iron core noise by 8-12dB, laying a foundation for achieving the overall noise target of <55dB.
Winding vibration noise control is another key link in the technical implementation. The winding vibration is mainly caused by the electromagnetic force generated by the current passing through the windings, which is proportional to the square of the current. For 10kV dry-type transformers, the winding structure and fixing method are optimized to reduce vibration. First, the winding adopts a compact winding process—using vacuum pressure impregnation (VPI) technology to impregnate the winding with epoxy resin, making the winding and insulation material form a solid integral structure, which improves the mechanical strength of the winding and reduces the vibration amplitude caused by electromagnetic force. The epoxy resin used is modified with damping materials, which can further absorb the vibration of the winding and reduce noise radiation.
Second, the winding is fixed with a high-strength insulating support, and the support is connected to the transformer shell through damping pads. This design can isolate the winding vibration from the shell, preventing the shell from vibrating with the winding and radiating noise. In addition, the number of winding turns and wire diameter are optimized through electromagnetic simulation, reducing the electromagnetic force between windings under rated load. For example, by increasing the wire diameter and reducing the current density, the electromagnetic force can be reduced by 20-30%, thereby reducing winding vibration. Through these measures, the winding noise can be reduced by 5-8dB, further approaching the target of <55dB. It is worth noting that the winding noise reduction must be coordinated with the iron core noise reduction to avoid resonance between the two, which would amplify the overall noise.
The optimization of the cooling system is crucial for reducing the noise of large-capacity 10kV dry-type transformers (above 1000kVA), as the cooling fan is an important noise source. Traditional cooling fans adopt high-speed fans, which have a noise level of 50-60dB, which will significantly increase the overall noise of the transformer. To solve this problem, low-noise fans with variable frequency control are adopted. These fans have a noise level of 35-45dB, which is 10-15dB lower than traditional fans. The variable frequency control system can adjust the fan speed according to the transformer’s load and temperature—when the load is low and the temperature is low, the fan operates at a low speed, further reducing noise; when the load is high and the temperature rises, the fan speed increases to ensure heat dissipation. This not only reduces noise but also saves energy, achieving a win-win situation between noise control and energy conservation.
In addition, the layout of the cooling system is optimized. The fans are arranged symmetrically on both sides of the transformer, and a sound insulation cover made of sound-absorbing materials (such as glass wool, rock wool) is added around the fans to block the noise radiation of the fans. The sound insulation cover is designed with ventilation holes to ensure that the heat dissipation effect is not affected while reducing noise. For small-capacity transformers (below 1000kVA), natural air cooling (AN) is adopted as much as possible, avoiding the noise generated by fans. Through the optimization of the cooling system, the cooling noise can be reduced by 8-10dB, ensuring that the overall noise of the transformer does not exceed 55dB.
The optimization of the transformer shell and installation base is an important measure to block noise transmission. The traditional transformer shell is made of ordinary steel plates, which has poor sound insulation performance and will amplify the vibration noise of the iron core and windings. The low-noise transformer shell adopts a double-layer sound insulation structure: the inner layer is made of high-strength steel plates with a thickness of 6-8mm, and the outer layer is made of sound-insulating steel plates with a thickness of 4-6mm. A sound-absorbing layer (50-80mm thick) made of glass wool or polyurethane foam is filled between the two layers, which can absorb the noise generated inside the transformer and prevent it from being transmitted to the outside. The shell surface is treated with anti-corrosion and sound-absorbing coating, which not only improves the corrosion resistance but also further reduces noise radiation.
In terms of installation base, the transformer is installed on a damping foundation made of concrete and damping rubber pads. The damping rubber pads have good vibration absorption performance, which can absorb the vibration of the transformer and prevent it from being transmitted to the ground and surrounding buildings, avoiding noise amplification caused by resonance. The damping foundation is designed according to the weight and vibration frequency of the transformer, ensuring that the natural frequency of the foundation is far away from the vibration frequency of the transformer (50Hz), thereby avoiding resonance. In addition, the installation position of the transformer in the substation is optimized, placing it as far as possible from the residential area, and using green plants for sound insulation and isolation, further reducing the impact of noise on surrounding residents. This integrated design of shell sound insulation and damping installation complements the body noise reduction measures, forming a comprehensive noise control system.
While implementing the above technical measures, it is also necessary to strictly comply with relevant international and domestic standards to ensure that the noise level of the transformer meets the requirements of urban substations. Internationally, the main standards for transformer noise include IEC 60076-10 (Power transformers - Part 10: Noise levels) and IEEE C57.12.90 (Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers). Domestically, the key standards are GB/T 1094.10 (Power transformers - Part 10: Noise levels) and GB 3096-93 (Environmental quality standard for noise), which clearly stipulate that the noise level of 10kV dry-type transformers used in urban residential areas should be less than 55dB. It should be noted that the traditional enterprise equipment manufacturing standard JB/T10088-2004 stipulates that the noise level of 10kV dry-type transformers with 1000kVA is less than 72dB, which is far higher than the urban environmental noise standard, highlighting the necessity of developing low-noise transformers.
In the production process, strict quality control and noise testing are carried out to ensure that each transformer meets the noise target. The noise test is carried out in an anechoic chamber in accordance with the standard, measuring the noise level at a distance of 1m from the transformer, and ensuring that the average noise level is less than 55dB under rated load. For transformers that do not meet the requirements, the causes are analyzed and rectified, such as adjusting the clamping force of the iron core, optimizing the winding process, or replacing low-noise fans. In addition, the transformer’s noise performance is tested under different load conditions (25%, 50%, 75%, 100%) to ensure that the noise level is less than 55dB in the full load range.
In addition to the above technical implementation measures, several key technological breakthroughs have been made in the development of 10kV dry-type transformers with noise level <55dB, which have solved the technical bottlenecks of traditional low-noise transformers and improved the comprehensive performance of the product. The first breakthrough is the development of a high-precision iron core clamping technology. Through the use of intelligent clamping equipment, the clamping force of the iron core is precisely controlled, and the stress distribution of the silicon steel sheets is made uniform, which reduces the vibration caused by uneven stress. This technology has improved the clamping accuracy by 30% compared with traditional manual clamping, and the iron core noise has been further reduced by 3-5dB.
The second breakthrough is the application of modified epoxy resin damping insulation technology. The traditional epoxy resin has poor damping performance and cannot effectively absorb winding vibration. The modified epoxy resin adds damping agents (such as butyl rubber, polyurethane) to the epoxy resin, which improves the damping coefficient of the insulation material by 40-50%, and can effectively absorb the vibration of the winding, reducing winding noise. At the same time, the modified epoxy resin has better thermal conductivity and insulation performance, ensuring the safe and stable operation of the transformer. This technology has solved the problem of poor coordination between winding insulation and noise reduction, realizing the dual improvement of insulation performance and noise reduction effect.
The third breakthrough is the development of an intelligent noise monitoring and adjustment system. This system is equipped with noise sensors, temperature sensors, and current sensors inside the transformer, which can real-time monitor the noise level, temperature, and load of the transformer. When the noise level exceeds the set threshold (55dB), the system automatically adjusts the fan speed, optimizes the load distribution, and takes corresponding noise reduction measures to ensure that the noise level is always within the standard range. In addition, the system can transmit the monitoring data to the substation control center through IoT connectivity, enabling remote monitoring and management of the transformer’s noise performance. This breakthrough has realized the intelligent control of transformer noise, improving the reliability and stability of noise control.
The fourth breakthrough is the integration of body noise reduction and environmental adaptation. Unlike the traditional extensive noise reduction method of "adding enclosures", the new technology realizes noise reduction from the inside of the transformer, which does not occupy the limited space of the substation, does not affect the inspection and maintenance of the equipment, and does not damage the urban landscape. This breakthrough has solved the pain point that traditional noise reduction methods conflict with urban substation space and landscape requirements, making low-noise transformers more suitable for urban application scenarios. At the same time, the transformer is designed with good environmental adaptability, which can operate stably in the urban environment with large temperature differences, high humidity, and more dust, ensuring the long-term stability of the noise reduction effect.
The application practice of 10kV dry-type transformers with noise level <55dB in urban substations has proved the effectiveness of the above technical implementation and breakthroughs. In a residential area substation in a large city, 10kV dry-type transformers with noise level <55dB were installed, and the actual measurement showed that the noise level at the substation boundary was 52-54dB, which met the environmental noise standard of urban residential areas. The surrounding residents reported no obvious noise interference, which has been highly recognized by the community and relevant departments. In addition, these transformers have the advantages of high reliability, low energy consumption, and long service life, which can reduce the operation and maintenance costs of the substation while reducing noise pollution. With the continuous promotion of urban power grid upgrading, more and more urban substations have adopted this type of low-noise transformer, making important contributions to building a green, quiet, and livable urban environment.
In conclusion, the technical implementation of 10kV dry-type transformers with noise level <55dB for urban substations mainly relies on the comprehensive measures of iron core optimization, winding process improvement, cooling system upgrading, shell sound insulation, and damping installation, with the core of body noise reduction to avoid the defects of traditional extensive noise reduction methods. The key technological breakthroughs in high-precision iron core clamping, modified epoxy resin damping insulation, intelligent noise monitoring, and integrated body noise reduction have solved the technical bottlenecks of traditional low-noise transformers, ensuring that the noise level meets the requirements of urban environmental protection standards while maintaining the transformer’s electrical performance and reliability. As urbanization continues to advance and environmental protection requirements become increasingly strict, the demand for low-noise 10kV dry-type transformers will continue to grow. In the future, we will further optimize the noise reduction technology, reduce the noise level to below 50dB, and develop more intelligent, energy-saving, and environment-friendly low-noise transformers, providing strong technical support for the construction of green urban power grids and the improvement of urban residents’ quality of life.
