BIOTRAFO · Raising knowledge and developing technology for the design and deployment of high-performance power transformers immersed in biodegradable fluids “BIOTRAFO”

Raising knowledge and developing technology for the design and deployment of high-performance power transformers immersed in biodegradable fluids“BIOTRAFO”

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.

Data: CORDIS, © European Union