Periodic Reporting for period 2 - BIOTRAFO (Raising knowledge and developing technology for the design and deployment of high-performance power transformers immersed in biodegradable fluids“BIOTRAFO”)
Reporting period: 2022-01-01 to 2023-09-30
Transformers are basic components of the power systems providing electricity worldwide. Their effectiveness and lifespan depend on their insulation and cooling system. The insulation system of a transformer consists of both solid and liquid components. Cellulosic papers and pressboards are used as solid insulation, while transformer oils have the role of liquid insulation and cooling medium.
Most of these devices currently use mineral oil, derived from petroleum, for cooling and insulation. Hydrocarbon based paraffinic or naphthenic insulation oils manufactured from crude are used as liquid insulation medium due to their good insulation and cooling performance. Though, they possess two important drawbacks: 1) their low flash point, which could result in catastrophic failures due to the temperatures usually reached by transformers, and 2) low biodegradability representing a risk to the environment in case of a spill.
This situation has led to the development of alternative transformer oils such as: silicones, synthetic and natural esters. Under the point of view of environmental sustainability, the use of dielectric fluids based on esters (natural and synthetic), significantly improves the degree of biodegradability compared to conventional dielectric fluids. Such liquids are also characterized by good properties from the point of view of fire safety (higher flash and fire points that their mineral counterparts). Additionally, if we analyze them based on energy security perspective, these alternative liquids represent an adequate solution since they are not from fossil resources, such as mineral oils, and they can reduce European foreign dependence.
Most of the large energy distribution companies in Europe have or are starting to use transformers with biodegradable oils. Furthermore, some Transmission System Operators such as National Grid (UK), Terna (Italy) and REE (Spain) promote this kind of technology. Nevertheless, there is still a lack of knowledge about the mid and long-term consequences of the use of these alternative fluids, regarding the evolution of their and other transformer components’ properties under work conditions.
Thus, BIOTRAFO proposed the creation of an international and inter-sectorial network to develop knowledge and methodologies to address the design and deployment of high-performance, compact power transformers immersed in biodegradable fluids. It combines knowledge from two main scientific areas: experts in the thermal design of transformers and experts in the design of insulation systems for high voltage applications. Both groups worked together to analyze the limitations that could arise from the use of biodegradable oils in the cooling and insulation of power transformers, and generated interesting results.
Most of these devices currently use mineral oil, derived from petroleum, for cooling and insulation. Hydrocarbon based paraffinic or naphthenic insulation oils manufactured from crude are used as liquid insulation medium due to their good insulation and cooling performance. Though, they possess two important drawbacks: 1) their low flash point, which could result in catastrophic failures due to the temperatures usually reached by transformers, and 2) low biodegradability representing a risk to the environment in case of a spill.
This situation has led to the development of alternative transformer oils such as: silicones, synthetic and natural esters. Under the point of view of environmental sustainability, the use of dielectric fluids based on esters (natural and synthetic), significantly improves the degree of biodegradability compared to conventional dielectric fluids. Such liquids are also characterized by good properties from the point of view of fire safety (higher flash and fire points that their mineral counterparts). Additionally, if we analyze them based on energy security perspective, these alternative liquids represent an adequate solution since they are not from fossil resources, such as mineral oils, and they can reduce European foreign dependence.
Most of the large energy distribution companies in Europe have or are starting to use transformers with biodegradable oils. Furthermore, some Transmission System Operators such as National Grid (UK), Terna (Italy) and REE (Spain) promote this kind of technology. Nevertheless, there is still a lack of knowledge about the mid and long-term consequences of the use of these alternative fluids, regarding the evolution of their and other transformer components’ properties under work conditions.
Thus, BIOTRAFO proposed the creation of an international and inter-sectorial network to develop knowledge and methodologies to address the design and deployment of high-performance, compact power transformers immersed in biodegradable fluids. It combines knowledge from two main scientific areas: experts in the thermal design of transformers and experts in the design of insulation systems for high voltage applications. Both groups worked together to analyze the limitations that could arise from the use of biodegradable oils in the cooling and insulation of power transformers, and generated interesting results.
The first work package focused on the fluid-thermal modeling of transformers cooled with biodegradable oils. A total of 56.36 secondments were performed. Various modeling strategies were implemented to analyze the mass flows and temperature distributions in the transformer windings immersed in more viscous biodegradable fluids. This research has resulted in the publication of:
• 6 open-access (OA) articles in journals;
• 1 non-open-access paper published in the Journal of Energy Resources Technology, Transactions of the ASME;
• 19 contributions to conferences such as ICDL 19, ENIEF 2019, ICD 2020, CPOTE 2020, and ICDL 2022.
The characterization of aging processes in the dielectric system of transformers using biodegradable fluids was the main objective of the second work package of the project. Modeling aging, responding to partial discharge tests, and studying moisture dynamics were the main tasks carried out. This work was supported by the completion of 57.03 secondments. Thus:
• 15 conference papers have been presented at ICDL 19, ARWtr2019, ISEIM 2020, ICD2020, EEEIC 2020, CMD 2022, ICDL 2022, EuroDoble 2022, ICD 2022, ICDL 2023, and EEEIC 2023;
• 7 articles have been published in open-access journals.
Regarding the third work package, various activities have been undertaken concerning the actual operation of transformers immersed in biodegradable fluids: tests on a 100MVA transformer emulation platform cooled with biodegradable fluid, assessment of the environmental impact of dielectric fluids, implementation of fire safety measures associated with biodegradable liquids, and analysis of the performance of transformers using esters during real network operation. These studies were conducted through stays totaling 35.39 months at other institutions within the consortium. The results obtained were disseminated through:
• 5 conference papers presented at Cigre Paris Session 2022, ARWtr 2022, CMD 2022, SET 2022, and EEEIC 2023;
• 6 articles published in open-access journals.
The dissemination activities of the fourth work package were, 19 OA and 1 non-OA articles have been published, 39 papers have been presented in conferences, 34 papers were joint actions between partners, 32 working group sessions and 3 workshops were held. The project has a webpage and three profiles in social media (Twitter, ResearchGate and LinkedIn), and participated in events focused on outreach as “Week of Science”, “Pint of Science” or “European Researchers’ Night”.
The results regarding the fifth work package were also relevant. More than 100 events were reported, including seminars, visits to factories and meetings with stakeholders. Three training courses about project topics were designed and made available for partner’s staff.
Finally, the sixth work package focused on the project management, following the objectives as initially planned. Whether in person or virtually, numerous meetings have been held since the launch meeting in Brussels: steering committees, technical meetings of working groups to verify progress and analyze difficulties, or meetings related to each secondment to solve technical issues, supplies or travel. All scheduled deliverables were delivered including a high level of detail of the proposed activities.
• 6 open-access (OA) articles in journals;
• 1 non-open-access paper published in the Journal of Energy Resources Technology, Transactions of the ASME;
• 19 contributions to conferences such as ICDL 19, ENIEF 2019, ICD 2020, CPOTE 2020, and ICDL 2022.
The characterization of aging processes in the dielectric system of transformers using biodegradable fluids was the main objective of the second work package of the project. Modeling aging, responding to partial discharge tests, and studying moisture dynamics were the main tasks carried out. This work was supported by the completion of 57.03 secondments. Thus:
• 15 conference papers have been presented at ICDL 19, ARWtr2019, ISEIM 2020, ICD2020, EEEIC 2020, CMD 2022, ICDL 2022, EuroDoble 2022, ICD 2022, ICDL 2023, and EEEIC 2023;
• 7 articles have been published in open-access journals.
Regarding the third work package, various activities have been undertaken concerning the actual operation of transformers immersed in biodegradable fluids: tests on a 100MVA transformer emulation platform cooled with biodegradable fluid, assessment of the environmental impact of dielectric fluids, implementation of fire safety measures associated with biodegradable liquids, and analysis of the performance of transformers using esters during real network operation. These studies were conducted through stays totaling 35.39 months at other institutions within the consortium. The results obtained were disseminated through:
• 5 conference papers presented at Cigre Paris Session 2022, ARWtr 2022, CMD 2022, SET 2022, and EEEIC 2023;
• 6 articles published in open-access journals.
The dissemination activities of the fourth work package were, 19 OA and 1 non-OA articles have been published, 39 papers have been presented in conferences, 34 papers were joint actions between partners, 32 working group sessions and 3 workshops were held. The project has a webpage and three profiles in social media (Twitter, ResearchGate and LinkedIn), and participated in events focused on outreach as “Week of Science”, “Pint of Science” or “European Researchers’ Night”.
The results regarding the fifth work package were also relevant. More than 100 events were reported, including seminars, visits to factories and meetings with stakeholders. Three training courses about project topics were designed and made available for partner’s staff.
Finally, the sixth work package focused on the project management, following the objectives as initially planned. Whether in person or virtually, numerous meetings have been held since the launch meeting in Brussels: steering committees, technical meetings of working groups to verify progress and analyze difficulties, or meetings related to each secondment to solve technical issues, supplies or travel. All scheduled deliverables were delivered including a high level of detail of the proposed activities.
We can highlight the following potential impacts:
• A significant part of the results will give information on the optimal geometries of windings cooled by biodegradable oils. The most likely products in this case would be large transformers specifically designed for these fluids.
• It is expected to develop software tools to assist in the thermal design of transformers. The most likely product in this case would be a commercial software to automate these studies, usable also as simulator of a variety of working conditions, as predictive monitoring of equipment.
• It is likely that exploitable results will be obtained on aging studies of biodegradable liquids and cellulosic solids. In this case, it would contribute to the design of large transformers whose dynamics of aging would be known.
• The knowledge generated throughout the project could become different consulting services to third parties.
Most probable lines of exploitation of obtained knowledge and results may consist in:
• Production, sale and installation of power transformers optimized for vegetal cooling fluids.
• Monitorization and maintenance of power transformers optimized for vegetal cooling fluids.
• Sale of here created design and simulation software, and associated formation and support services.
• Transformer design engineering services.
• Testing services for new materials from transformer components suppliers.
• A significant part of the results will give information on the optimal geometries of windings cooled by biodegradable oils. The most likely products in this case would be large transformers specifically designed for these fluids.
• It is expected to develop software tools to assist in the thermal design of transformers. The most likely product in this case would be a commercial software to automate these studies, usable also as simulator of a variety of working conditions, as predictive monitoring of equipment.
• It is likely that exploitable results will be obtained on aging studies of biodegradable liquids and cellulosic solids. In this case, it would contribute to the design of large transformers whose dynamics of aging would be known.
• The knowledge generated throughout the project could become different consulting services to third parties.
Most probable lines of exploitation of obtained knowledge and results may consist in:
• Production, sale and installation of power transformers optimized for vegetal cooling fluids.
• Monitorization and maintenance of power transformers optimized for vegetal cooling fluids.
• Sale of here created design and simulation software, and associated formation and support services.
• Transformer design engineering services.
• Testing services for new materials from transformer components suppliers.