Research
Transformers are an important part of the electrical distribution network and have to work in a range of environments. We research the best ways to design transformers as well as developing the most efficient maintenance strategies for them.
In 2005 we formed a Transformer Research Consortium that brings experts together to further our research. As a consortium, we have successfully completed three phases of research and are now working on our fourth. This phase aims to tackle industry-wide transformer issues such as: condition assessment, asset management, thermal modelling, and discharge and breakdown mechanisms.
Design and fundamental
Alternative insulation materials
Esters are obtained from natural sources as well as manufactured synthetically by reacting alcohols with acids. Both natural and synthetic esters are highly biodegradable and have a much higher flash point (above 300 °C) than mineral oil. Different aspects of esters including, impregnation of Cellulose Materials; partial discharges and Breakdown under AC; streamer propagation and breakdown under lighting impulses; creepage discharges; dissolved gas analysis; and thermal ageing performances are studied.
Thermal modelling
Hot-spot temperature prediction for different winding geometries and winding models are calculated through computational fluid dynamic (CFD) simulation techniques
Effect of different oil types and cooling techniques are studied. Results from the simulations are verified through experiments with winding models and particle image velocimetry systems.
Magnetic modelling
Ferro resonance is modelled Using EMTP-ATP, and SLIM. Saturation characteristics of steel lamination & core is measured to develop a transformer model to represent the effect of core saturation under GIC and Ferro resonance scenarios.
Discharge and breakdown mechanisms
Understanding failure mechanism is critical in cost effective transformer design. Failure mechanisms are different in solid and liquid insulation. Solids undergo much slower breakdown than the liquid. Streamer initiation, propagation and breakdown stages are studied for different insulation material using different electrode geometries.
Condition assessment
Novel ageing markers
Condition monitoring of transformer can be conducted through both chemical and electrical methods. Chemical methods include conventional parameters such as acidity, moisture, dissolved gases, furanic compounds as well as novel ageing markers such as methanol and ethanol. It is important to understand the generation mechanism of these chemical markers, their stability and partitioning between oil and paper in order to improve the reliability of the predictions through chemical analysis.
Dissolved gas analysis
Electrical and thermal faults in transformers can led to the formation of different gases. Most common gas types formed in liquid include hydrogen, C1 and C2 hydrocarbons. Faults involved with paper insulation can led to the formation of CO and CO2. Concentration as well as their relative percentages is used to detect incipient faults. Conventionally these gases were measured in laboratories. However, now a days more and more online DGA analysers are used due to the time criticality of these measurement.
Partial discharge analysis
Partial discharges are the first indication of a possible future insulation failure. Therefore, it is important to measure partial discharges in transformers. Electrical measurement as well as ultrahigh frequency (UHF) measurements are used to detect partial discharges in transformers. Laboratory studies incorporating high-speed cameras and conventional PD measurements can be used to understand partial discharge behaviour in different oil types under different electrode configurations which can be used to interpret PD measurement from transformers.
Frequency response analysis
Frequency Response Analysis (FRA) is a non-destructive measurement technique thatcan be used to understand changes in winding structure. Development of FRA fingerprints can be used for diagnostic purposes.
Asset management
Transformers are one of the most expensive assets in the power network and hence they should be manged in a safe and cost effective manner. Oil test databases from the utilities consist of large amount of data that can be used to build asset management through various data analysing techniques. In addition, the failure data obtained from transformers are used for reliability studies of various transformer families
End-of-life analysis and life extension
Post-mortem analysis is one of the important aspects of the life cycle of transformer. This analysis can be done on both failed and retired transformers. The analysis allows access to solid insulation and hence to understand the ageing and failure mechanisms of paper insulation. Furthermore, post-mortem analysis helps to bridge the gap between “lab ageing” and “in-service ageing”.
Facilities
See what facilities are available to our research group members.
Our researchers
See who makes up our research group.
Contact Us
+44 (0) 161 306 6000
