Transformer Cooling Stage Control for In-Operation Drying
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Solution Overview
Problem
Existing methods for drying transformers during operation are inefficient, requiring long downtimes and affecting insulation monitoring, and existing drying processes can remove beneficial components along with moisture, leading to potential damage and reduced durability.
Innovation Solution
A method for drying transformers during operation by deactivating the upper cooling stage and activating the stage below it, using temperature increases to enhance moisture diffusion and absorption in insulating materials, without additional heating, achieving rapid and efficient drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transformer is moved into a drying oven for vapor-phase drying, then the moisture content is reduced, but the transformer experiences downtime and cannot operate
Solution Approach 1:
The transformer uses its own operational heat to drive the drying process. By controlling the cooling system to operate at reduced capacity, the transformer generates sufficient heat internally to evaporate moisture from the insulation materials, eliminating the need for external drying ovens and downtime.
Solution Approach 2:
The cooling system's operational parameters are modified during drying. The cooling stages are controlled to operate at reduced capacity rather than full capacity, allowing the transformer to maintain operational status while generating the necessary heat for moisture evaporation through controlled thermal conditions.
2Reliability
If filter cartridges are used to continuously absorb moisture from transformer oil during operation, then drying occurs during operation, but the process time is extremely long (exceeding one year)
Solution Approach 1:
The cooling system's thermal parameters are optimized to generate sufficient heat for rapid moisture evaporation. By controlling the cooling stages to operate at reduced capacity, the transformer achieves drying temperatures that accelerate moisture removal from both oil and solid insulation materials, reducing the process from over a year to a much shorter duration.
Solution Approach 2:
The cooling system operates in controlled cycles, alternating between normal cooling mode and drying mode. During drying mode, the cooling capacity is reduced to allow heat accumulation for moisture evaporation, while maintaining operational status. This periodic control accelerates the drying process compared to continuous low-level absorption methods.
3Reliability
If extraction methods under vacuum are used to remove moisture from insulating liquid, then moisture is removed, but other dissolved components such as fault gases are also removed, preventing insulation monitoring
Solution Approach 1:
The drying process selectively targets moisture removal through controlled thermal conditions. By operating the cooling system at reduced capacity, the temperature and pressure conditions are optimized to preferentially evaporate and remove water vapor while maintaining the dissolved state of other components like fault gases in the insulating oil, preserving their detectability for insulation monitoring.
Solution Approach 2:
The thermal and pressure parameters of the transformer operation are controlled within specific ranges during drying. The cooling system operates at reduced capacity to maintain temperatures below the boiling point of oil-dissolved gases while sufficient to evaporate moisture, creating selective separation conditions that remove water while preserving fault gases for monitoring purposes.
4Productivity
If the upper cooling stage is deactivated and the stage below it is activated, then the transformer temperature increases to enhance moisture diffusion, but this may cause hotspot formation
Solution Approach 1:
The cooling system applies differentiated cooling at different locations and stages. By deactivating the upper cooling stage while keeping the lower stage active, the system creates a controlled temperature gradient that promotes moisture diffusion from cooler to warmer regions while preventing excessive localized heating through the remaining active cooling stage.
Solution Approach 2:
The cooling system dynamically adjusts its operational configuration during the drying process. The transition between different cooling stage configurations allows the system to adapt thermal conditions in real-time, optimizing moisture evaporation rates while preventing hotspot formation through continuous adjustment of cooling capacity distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for rapid drying of transformers during operation, minimizing hotspot formation and reducing aging, while maintaining insulation integrity and avoiding downtime, thus extending service life and preventing damage.
Implementation Method 1
filter cartridges are used so as to continuously absorb or extract, respectively, moisture from the transformer oil
Implementation Method 2
not only the dissolved moisture but also other dissolved components such as, for example, fault gases are removed from the insulating liquid
Data Source
AI summary
A method for drying a transformer which has a multistage cooling system, in particular a power transformer or a choke, has at least one transformer winding and at least one insulator for electrical insulation. Individual cooling stages of the cooling system are respectively associated with a loading state range of the transformer and are activated when the respective loading state range of the transformer is reached. The loading state range is a function which depends at least on a temperature of the transformer. The drying method is carried out during the operation of the transformer. An upper cooling stage, which lies above the lowest cooling stage, is or remains deactivated and the cooling stage which is situated directly below the upper cooling stage is or remains activated while the transformer is in the loading state range which is associated with the upper cooling stage.