Out with the Old and in with the New

Study Committee A2 branches into new transformer applications.

 

Don’t worry, traditional transformers – aren’t going anywhere. They are just transforming… and so is Study Committee A2.

 

As we start to see a lot of new applications for transformers due to the worldwide energy transition process.

It starts with the massive expansion of photovoltaic and wind energy plants, thus today an additional installed energy capacity of around 2.500 GW worldwide has been reached. Therefore, additional new transformers have been installed in a range of 1 million pieces worldwide. Most of them acting as generator step up transformers (GSUs).

These transformers differ from conventional GSU transformers because they have significantly lower power ratings (typically <10 MVA in contrast to >100 MVA) and significantly lower operating voltages (medium voltage area). Therefore, these transformers are designated as Lower Voltage Generator Step-Up Transformers (LV-GSUs) as they are more like distribution transformers. Moreover, usually these LV-GSUs are in comparison to conventional GSUs highly stressed by fluctuating loads and in addition by harmonics, because they are often fed by inverter-systems instead of generator sets. Therefore, the design and the insulating system of these LV-GSUs differ significantly compared to the conventional ones. In comparison to large GSUs the small units can be designed as dry type transformer insulated by epoxy resin. In case of liquid insulated systems, alternative liquids like natural or synthetic esters in combination with thermally upgraded or even aramid paper are often used, which is unusual for conventional GSUs. Of course, the cost-price of the LV-GSUs is much lower compared to conventional ones, but the importance is similar, because a failure led to a power interruption and in case of off-shore systems the installation/repair/exchange is extremely costly.

In the last decade several failures on such LV-GSUs have been reported, leading to the assumption that they are less reliable than the conventional large GSUs. Therefore CIGRE has started the working group WG A2.68 with the goal to better estimate the failure rate, the reliability and failure root causes of these LV-GSUs. Based on such a study, it would be possible to determine failure rates of such transformers and therefore also to compare the reliability of different insulating systems. This will allow to recommend certain design parameters or improved testing for future applications and might trigger additional working groups if specific failure root causes can be identified more often than other ones.

This is important because today only approx. 10% of the transformers needed for the energy transition are installed, thus millions of transformers for such and similar applications are required in the future. For example, charging stations for E-mobility as well as Battery Energy Storage System require also special transformers with high fluctuating loads. Furthermore, many transformers will also be used in the future in the field of fuel cell energy supply, which may also have certain similarities to the LV-GSUs.

 

The trend to lower voltage applications can also be seen in the increasing use of “electronic transformers”. These transformers should be called Power Electronic Inverters (PEI) or Power Electronic Converters (PEC), because the term “transformer” is already taken and clearly defined in various standards. Furthermore, these applications become more and more important, so that these components should also have its own name.

 

As a result of the energy transition, many conventional GSUs were taken out of service as a result of the phase-out of coal or nuclear power, but instead thousands of new LV-GSUs are installed, thus there are many new challenges in the transformer sector that require innovative solutions and new technologies. This can only be solved with the help of increasing engineering capacity, whereby experienced and young professionals must exchange ideas in committees such as CIGRE. The CIGRE Study Committee for Transformers (SC A2) therefore calls on young professionals to connect with CIGRE to jointly realize the electrical energy system of the future.

 

We envision that we will always need transformers and that we will keep adapting for new applications in the future.