Journal of Energy - Energija

New transformer procurement concepts in times of high uncertainty and market instability

Jose Quintana, Wilson Smith, Mateja Cepin — Mon, 25 Mar 2024 00:00:00 +0100

New and proactive strategies are required in utilities and other transformer purchasers to ensure delivery of transformer capital investment plans in the current times of market saturation and various supply chain issues. Close collaboration with suppliers and adaptative and flexible engineering and commercial initiatives need to be implemented from as early stage in the project lifecycle as definition of requirements and tendering. This paper presents the strategy adopted by SP Energy Networks, and one of their main suppliers of power transformers, Kolektor Etra, in this regard.

Hybrid Analytical-FEM Approach for Power Transformer Transient Analysis

Bruno Jurišić, Zvonimir Jurković, Tomislav Župan, Mladen Marković — Mon, 25 Mar 2024 00:00:00 +0100

The paper describes a high-frequency model for transient calculation in transformer windings with segmentation on a turn level. The windings are represented by lumped RLC parameters given by the analytical approach, whereas the model is solved in the time domain. The accuracy of the analytical calculation is improved with correction factors obtained with a set of numerical calculations. The presented model is verified by measurements on the example of power transformer disc winding.

Measurement uncertainty in on-line bushing monitoring

Wiesław Gil, Wiktor Masłowski — Mon, 25 Mar 2024 00:00:00 +0100

The high voltage bushing on-line monitoring has been performed for many years to prevent unexpected rapid power network failures. Network unbalance correction, based on separate voltage phase measurement or phasor technique, effectively improves the measurements of bushing dielectric dissipation factor tgδ and capacitance factor C₁. The newly implemented monitoring units reveal that the uncertainty of station voltage measuring transformers manifest the greatest influence on the overall uncertainty budget, regardless of the measurement method.

Improving the Reliability of Online Bushing Monitoring

Vedran Jerbic, Samir Keitoue, Jurica Puskaric, Ivan Tomic — Mon, 25 Mar 2024 00:00:00 +0100

This paper discusses the common issue of bushing failures in power transformers and presents methods for preventing such failures through online monitoring. The paper presents a method based on the comparison of bushing leakage currents from different transformers connected to the same busbars to overcome problems with unreliable measurement results due to grid voltage imbalance or frequent transformer outages.

Is Nuclear Fusion Losing the Race with Global Warming?

Nikola Dragić, Vladimir Knapp — Mon, 25 Mar 2024 00:00:00 +0100

According to plans for development of fusion energy, the first stage is construction of device tokamak ITER [1] with main task of establishing burning gas plasma with required stability and duration. This stage should be accomplished by 2035, starting in 2005. The next stage should be the construction of complex DEMO [2] with the task of producing all the equipment for energy production and finally producing large amounts of carbon free energy. We do not want to make predictions on the outcome of fusion program, wishing the final success to the thousands of scientists and engineers who are contributing to this heroic effort. However, there are reasons to think (Seife [18], Stork[7]) that the time is too short. Starting with a planned date of end of work with ITER by 2035, we estimate that one needs to add 25 years for development of DEMO. By 2060 it would be too late to initiate actions to stop global warming. In the present situation we propose the intervention use of nuclear fission energy. New nuclear fission energy of PWR type could be available not later than 2034, some 25 years before expected fusion energy device could start. Our proposal could be of dramatic importance depending on the evolution of global warming.