Energy saving is a major societal issue that concerns a large field of technical applications, in particular electric power generation. The basic statement motivating the ANASTASIA project is that today the energy conversion efficiency of generators is restricted by (i) thermal as well as (ii) electrical strength limitations due, in particular, to the electrical insulation itself. The key feature of the generator field is that it deals with very long lifetime systems (40 years!). Consequently, it involves very traditional insulating materials and well established tape structures whose electrical properties and concepts are in fact far behind the current insulating material state of the art. As a result, high voltage insulating tapes are rather thick, poor thermal conductors and require energy consuming cooling systems.
Today, high voltage insulating tape technology presents a very significant scope for progress that must be absolutely exploited to increase the generator conversion efficiency.
This is why the ANASTASIA project intends to introduce into the generator industry advanced insulating tapes based on nanostructured material scenarios to address the energy saving concern.
Even for a small efficiency increase (+0.2%) the expected benefit represents very substantial energy saving. At the European scale, a +0.2% gain in generator conversion efficiency could save the equivalent of one nuclear power plant of 1000 MW (1.5 billion €) or nearly 10 fossil fuel power plants and the related reduction in CO2 emission.
The main characteristic of the conventional insulating tape used today (fig 2) is the strong heterogeneity of its structure since there is a glass fibre carrier tape co-laminated with a mica paper (dielectric barrier) and impregnated by polymer resin. This multilayer tape structure multiplies the number of interfaces (glass-polymer, mica-polymer and mica-glass) and is conceptually in contradiction with the targeted electrical and thermal properties. Indeed, each interface behaves as an additional thermal barrier and/or a potential source of high voltage partial discharges. In practice, to overcome these drawbacks a large quantity of mica is required (typically, 1 mm mica paper thick) to provide an efficient partial discharge protection thanks to the “brick wall” effect. This results in the tape exhibiting very poor mechanical stability and a high sensitivity to environmental factors, notably water. To offer new perspectives of insulating tape improvement, a technological breakthrough is necessary.
The ANASTASIA tape concept needs to develop a new process chain leading to a drastic improvement of tape structure homogeneity. To facilitate this homogenisation higher performance materials are required, which will be obtained by the incorporation (or in-situ synthesis) of inorganic nanofillers. This will lead to:
- A robust and more homogeneous process flow with a better productivity (+50%).
- A radical change in the filler to polymer interface providing a multifunctional insulating tape with enhanced electrical, thermal and mechanical performances