Research Profiles

Monitoring the condition of power transformers plays a decisive role in the reliability of power systems operations. Oil and paper represent the main insulation system within a power transformer. Dissolved gas in oil analysis (DGA) using gas chromatography has been proven to be very effective over the years in detecting faults in transformers. DGA can detect levels of various gases that are formed through decomposition of oil and paper insulation. It is believed that deterioration of paper is a key indicator of damage of transformer insulation, which is measured by observing the degree of polymerization (DP) of paper.  However, it is impractical to collect paper samples from an operating transformer to make such measurements. Hence, the degree of polymerization is only indirectly determined by measuring degradation products from the paper. These include gases, as well as furan compounds in the transformer oil (mainly 2-furaldehyde; 2-FAL) which are analysed using the oil chromatography technique. For conventional insulating paper (Manila Kraft) and mineral oils (i.e. Shell Diala, Nynax etc) this method provides an excellent indication of the loss of the paper’s tensile strength. However, recently developed thermally upgraded insulating paper retains cellulosic bonding more than conventional Manila-Kraft papers. These upgraded papers release very little furanic compounds until the solid insulation undergoes significant deterioration. Some studies conducted by European utilities suggest that methanol (MeOH) could be used as a diagnostic indicator for early detection of paper degradation in place of the furans. However, the correlation between MeOH concentration in oil and the level of paper degradation has not been investigated yet. Moreover, there is no simple, cost effective and online technique to detect MeOH in oil as the current technique through headspace measurement using gas chromatography and mass selector in electron impact mode is very complex, time consuming and expensive. This research is aimed at developing a novel reliable cost effective technique to assess the oil-paper insulation condition in power transformers equipped with either normal or upgraded solid insulation.

Due to the huge renewable energy penetration, including photovoltaic systems and wind turbines, the old power system is getting restructured and re-architected aiming to make a carbon-neutral society. However, the intermittency and stochastic nature of renewable sources trigger many typical problems of power system, including voltage and frequency stabilities which may even lead to a wide-scale blackout if an adequate preventive measure is not considered. The renewable power sources that are replacing conventional synchronous generators make a significant loss of system inertia as they are fully or partially decoupled from power network. The only feasible solution is to play with the spinning reserve in case of an under-frequency scenario or take advantage of the energy storage system to absorb renewable power fluctuations and also participate in a demand management program.