Welkomstwoord door dagvoorzitter

Mischa Vermeer (DNV)

Design criteria for VFD transformers (*)

Different design approaches required for various converter topologies.

Renato Rebeschini (TMC Transformers SpA) & introduction (Leendert Klaassen) TMC (Transformers SpA)

Modern converters provide new challenges to the transformer manufacturers and a quick overview of the design process is here presented. The presentation contains several examples of FEM (finite element method) analysis in relation to different converter topologies. The impact of the current harmonics and stray magnetic fluxes in the design is analyzed with deep view in the transformer details. Some hints on thermal aspects, efficiency, different type of windings and technical solutions are included.

A magnifying view of the dielectric condition of high-voltage bushings and transformers (*)

Diego Robalino (Megger)

A good and clear analysis of dielectric dissipation factor (DDF) is important. The DDF test (power factor or tan delta) is a powerful tool within the transformer condition assessment Toolbox. The power industry faces an ever increasing complexity of the power grid, load variability and a continuous aging of the existing infrastructure. Therefore, technical and financial questions rise every day. Is a good DDF value (say <0.5%) really a good value? What is the level of confidence with operation- and asset managers that a good DDF value means the safe, reliable and efficient operation of transformers? The answer is found the solution where measurement of DDF is done at 1 Hz. This provides a greater level of confidence, allows prioritization of field maintenance activities and determines if an insulation system requires advanced tools for condition assessment. A magnifying tool to better understand the dielectric condition of these critical assets.

Sound Level Requirements: Challenges Facing Transformer Technologies under New Standards (*)

Ali Al-Abadi (Hitachi Energy)

With the increase of the energy demand while constantly growing of the sustainability value and environmentally friendly requirement, the necessity of reliable sound specifications is becoming more persistent. Sound emission pollution by power transformers has been an issue since last few decades due to the increase of transformers’ rated power and the extension of power stations within residential areas. A Cigre working group “Power Transformer audible sound requirements” was established by Study Committee A2 in 2015 to conduct investigations and to generalize recent achievements on average load and no-load sound levels of liquid-filled power transformers with target to provide guidelines for the industry on the sound specification. The new study offers more reliable models to specify sound levels for both load and noload and finally aims to fulfill the operator’s legislations to align with the increasing awareness on improving the existing (limited) information on sound levels specification in the existing standards. The main purpose of this presentation is to highlight the new achievement in the standards and the associated challenged and due requirement and preparations that need to be considered by different transformer’s technologies.

Acoustic localization of PD on energized substation assets such as transformers (*)

Stefan Voeten (Royal Smit) & Nikita Lebedev (Optics11)

Acoustic localization of PD on energized substation assets such as transformers. The energy transition is gaining momentum, and this is noticeable in the heavier loading of the power grid. Monitoring of grid assets, such as transformers, is a first line of defense to maintaining a reliable grid and to mitigate potential failure of such assets. Partial discharges in transformers and reactors are an indicator of a potential upcoming failure. A new system has been devised that allows for acoustic detection and localization of partial discharges on assets that are in service. The system and a showcase are presented. 

Alternative fluids for transformers – Natural Esters (*)

Roberto Fernández (Cargill Power Systems)

Dielectric liquids - in combination with solids - have been used for insulation in power apparatus for over a century. Applications range goes from large power transformers with large liquid filled open volumes to power capacitors with micrometer liquid layers. In this presentation we will focus on the comparison of the different properties of mineral oil as benchmark against natural ester as well as their effects on transformer design and their evolution with time.

Metingen van transienten door middel van capacitieve sensoren en resultaten

Sven de Clippelaar (DNV)

DNV heeft onlangs een nieuwe meettechniek aan zijn arsenaal van diagnostische metingen toegevoegd. Namelijk het meten van transienten door middel van capacitieve sensoren met de zogenoemde D-I methode. Deze meettechniek is ooit door de TU Eindhoven ontwikkeld en nu volledig overgenomen door DNV. Met de D-I methode kunnen signalen tot 25 MHz worden gemeten zonder dat er fysiek contact wordt gemaakt met onder spanningstaande delen. Tijdens de presentatie zullen de volgende vragen worden beantwoord. Waarom is het meten van transienten spanningen belangrijk? Wat zijn de voorbeelden van deze meettechniek ten opzichte van andere technieken zoals een R of RC-divider? Hoe werkt de D-I meettechniek? Als laatste zal er een meetcampagne worden getoond, zodat duidelijk wordt hoe zo'n meting er in de praktijk aan toe gaat

Stresses in tank of power transformers due to overpressure caused by arc energy (*)

Andrija Trčak (Končar D&ST)

The demand for power transformer tanks with increased rupture resistance is becoming increasingly apparent, driven by the need to withstand sudden pressure increase resulting from electrical arc occurrences. The importance of such a technical requirement cannot be overstated. Failure to meet this standard can lead to catastrophic consequences, including the release of a substantial volume of mineral oil into the environment, air pollution from fires, damage to nearby substation equipment, and, in exceedingly rare instances, loss of human life. Rupture resistance tank design provides transformation of arc energy into plastic deformation of the tank. Without such design, additional devices had to be installed around the transformer units to prepare for unexpected fault events, creating the need for a larger installation area and higher cost. Therefore, it is reasonable to believe that global demand for rupture resistance transformers will continue to grow with the implementation of ESG policies and the increasing interest in safety and environmental responsibility among the public.

Afsluiting door de dagvoorzitter

Aansluitend een informele borrel.