- Date:
- 2012-2016
- Themes:
- High Voltage Engineering, Condition monitoring
- Funding:
- TechImp SPA
This project aims to study and model partial discharge (PD) in a cavity, and induced physical-chemical effects. Among which effects degradation, damage rate, and eventually a life model are the main interests of this project. Different from other PD studies and modelling, this project focuses on detailed physical and chemical phenomenon after each discharge event. Major considerations include the energy spectrum of electron streams impinging into the cavity surface, physical-chemical effects brought on by this process such as polymeric bond breaking, local accumulation of matter, and changes of conductivity. Based on above information, it is hypothesised that damage growth rate can be derived, and a global failure time estimated. During the project, simulation and laboratory studies are carried out simultaneously, aiming at producing comparable and comprehensive result. Simulation studies are based on Matlab and COMSOL modelling, and for laboratory work, insulating materials (XLPE, LDPE, and epoxy) are comprehensively assessed over the life time of the project.
Primary investigators
- Prof. Paul Lewin
- Prof. Alun Vaughen
- Dr. James Pilgrim
Partner
- TechImp SPA
Associated research group
- Electronics and Computer Science
- Date:
- 2012-2016
- Themes:
- High Voltage Engineering, Space and surface charge
With growing interests in renewable energy, high voltage dc transmission has become a hot topic worldwide. Charge accumulation under high voltage dc is a major issue as its presence distorts the electric field, leading to premature failure. In the present project, we aim to chemically treat polymeric insulation and change charge transport characteristics of the material via fluorination process. Various samples will be electrically characterised and tested, so an optimal processing condition can be achieved to meet practical requirements as dc insulating material. Modelling and simulation of electric field distribution with new developed insulating material have been planned to help design an insulation spacer in high voltage dc GIS systems.
Primary investigators
- am306r
- George Chen
Associated research group
- Electrical Power Engineering
- Themes:
- High Voltage Engineering, Space and surface charge, Liquid dielectrics
- Funding:
- National Grid plc
High voltage DC power transmission technology has attracted considerable attention and will play an important role in the UK future transmission system. This project investigates the performance of the oil-paper insulation system used in HVDC transformers under a variety of electric stress conditions. It attempts to determine the effects of oil resistivity and other insulation conditions parameters on the capability of the insulation to withstand the electric stresses seen within HVDC transformers particularly during polarity reversal or other changes in stress. The pulsed electro acoustic (PEA) technique is used to measure the charge accumulation in oil-paper insulation system under different stresses and oil conditions, especially the polarity reversal. Oil conductivity will play an important role in the polarity reversal test of HVDC transformers, therefore, it is important to understand the characteristics of oil under dc conditions. The project intends to measure oil conductivity over a range of electric fields and temperatures. In addition, oil conductivity provides an important diagnostic measure for the insulation of a transformer.
Primary investigator
- Professor George Chen
Secondary investigators
- Miao Hao
- Yuan Zhou
Associated research groups
- Electrical Power Engineering
- Electronics and Electrical Engineering
- Date:
- 2011-
- Themes:
- Space and surface charge, Liquid dielectrics
- Funding:
- Chinese Scholarship Council
This project is concerned with modeling conduction process in liquid dielectrics, specifically where transformer oil is subjected to high electric stress. The physical processes including the generation, recombination and motion of free charge carriers are modeled so that the development of streamers and their respective discharge characteristics in transformer oil can be simulated using a FEA software package. The advantage of this FEA software is its ability to accurately model dynamic, thermal and electrical processes simultaneously. Future work involves validation experiments that will be undertaken at the Tony Davies High Voltage Laboratory. This project is undertaken with collaboration with the State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University.
Primary investigators
- cj8g11
- Paul Lewin
Associated research group
- Electronics and Electrical Engineering
- Date:
- 2012-
- Theme:
- High Voltage Engineering
- Funding:
- Mars Space Ltd
The aim of the research is to study the factors affecting the lifetime of pulsed plasma thruster (PPT) for nano and pico satellites applications and to optimize their performance whilst keeping lifetime long enough to fulfil their mission requirements. The baseline thruster to be used in the campaign will be the PPTCUP propulsion subsystem already developed at the University of Southampton to provide drag compensation for Cubesats. The test campaign is mainly focus on the performance testing and on the lifetime. The performance testing needs to verify the thruster performance in terms of impulse bit, thrust, specific impulse; a thrust balance able to measure the impulse bit delivered by the PPT will also be developed. The lifetime has the aim to verify the PPT lifetime and its total impulse capability. The test will consist in firing the thruster until all the propellant has been used or until the required total impulse has been reached. The results obtained from the whole test campaign will be used to develop a model able to predict the influence of the thruster geometric design parameters over performances in terms of thrust, specific impulse and ablated mass per shot. The tests will also be used to understand what the main life limiting mechanism of PPTCUP is and how its lifetime can be extended.
Primary investigators
- Steve Gabriel
- Michele Coletti
Associated research group
- Electronics and Electrical Engineering
- Date:
- 2009-2012
- Themes:
- High Voltage Engineering, Condition monitoring, Liquid dielectrics, Solid dielectrics
- Funding:
- Ministry of Higher Education, Malaysia and Universiti Teknikal Malaysia Melaka (Chines Scholarship Council), _other
The aim of the research is to investigate and analyse the full discharge events occurring on the oil-pressboard interface that leads to the flow of leakage current. The leakage current is relatively small and insufficient to trip the protection system of a large transformer. The repetition of this kind of discharges could further degrade the barrier board surface. Experimental work to study the characteristics of this leakage current is required to provide understanding and useful information for condition monitoring programs as well as assist manufacturers in improving their design of inter-phase barrier board arrangements. The research is also developing models that are verified against the experimental data.
Primary investigators
- hz3g09
- Paul Lewin
Secondary investigator
- cj8g11
Associated research group
- Electronics and Computer Science
- Date:
- 2010-2014
- Theme:
- Nanomaterials and Dielectrics
- Funding:
- National Grid plc
Transformer oil, or insulating oil, is usually a highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties. Its functions are to insulate, suppress corona and arcing, and to serve as a coolant. As the oil is in a direct contact with electrodes and paper insulation and experiences high temperatures, certain additives have to be included to stabilise its properties. On the other hand, key information about transformer insulation system can be extracted from the oil. It has been claimed that transformer oil contains about 70% of diagnostic information. However, due to lack of understanding and limited research, traditional oil test program utilizes only some of diagnostic parameters.
DC conductivity measurements have provided an important diagnostic measure for many solid insulation systems such as power cables. However, it receives little attention as far as transformers are concerned. The UK government has introduced initiatives and proposals to ensure more of our energy comes from renewable energy. Offshore wind farms play a key role in the UK energy policy and the number of wind farms in the UK will be steadily increasing. The energy transfer from the offshore wind farms to the NGC transmission systems is likely to be based on dc links. A high voltage dc converter transformer is an essential part of the dc link. The behaviour of insulation system in a high voltage dc converter transformer needs to be investigated as the insulation experiences a dc voltage component in addition to ac voltage. In the light of increasing interest in high voltage dc converter transformers, the study of oil conductivity becomes an ever urgent issue for oil producers, transformer manufacturers and power transmission and distribution utilities. Initial literature survey indicates that the conductivity of a liquid dielectric may span several orders in magnitude depending on the status of the liquid and its value is very sensitive to the dc field applied, temperature, moisture, contamination. Oil is particularly responsible for functional serviceability of the dielectric system in transformers. On the one hand, condition of oil can be a decisive factor, which determines the life span of the transformer. On the other hand, it also contains abundant diagnostic information which can be potentially used for transformer life management.
Primary investigators
- George Chen
- asv
Secondary investigator
- mh2e10
Associated research group
- Electronics and Computer Science
- Date:
- 2010-2014
Transformer oil, or insulating oil, is usually a highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties. Its functions are to insulate, suppress corona and arcing, and to serve as a coolant. As the oil is in a direct contact with electrodes and paper insulation and experiences high temperatures, certain additives have to be included to stabilise its properties. On the other hand, key information about transformer insulation system can be extracted from the oil. It has been claimed that transformer oil contains about 70% of diagnostic information. However, due to lack of understanding and limited research, traditional oil test program utilizes only some of diagnostic parameters.
DC conductivity measurements have provided an important diagnostic measure for many solid insulation systems such as power cables. However, it receives little attention as far as transformers are concerned. The UK government has introduced initiatives and proposals to ensure more of our energy comes from renewable energy. Offshore wind farms play a key role in the UK energy policy and the number of wind farms in the UK will be steadily increasing. The energy transfer from the offshore wind farms to the NGC transmission systems is likely to be based on dc links. A high voltage dc converter transformer is an essential part of the dc link. The behaviour of insulation system in a high voltage dc converter transformer needs to be investigated as the insulation experiences a dc voltage component in addition to ac voltage. In the light of increasing interest in high voltage dc converter transformers, the study of oil conductivity becomes an ever urgent issue for oil producers, transformer manufacturers and power transmission and distribution utilities. Initial literature survey indicates that the conductivity of a liquid dielectric may span several orders in magnitude depending on the status of the liquid and its value is very sensitive to the dc field applied, temperature, moisture, contamination. Oil is particularly responsible for functional serviceability of the dielectric system in transformers. On the one hand, condition of oil can be a decisive factor, which determines the life span of the transformer. On the other hand, it also contains abundant diagnostic information which can be potentially used for transformer life management.
Primary investigators
- George Chen
- asv
Secondary investigator
- mh2e10
Associated research group
- Electrical Power Engineering
- Date:
- 2010-2013
- Themes:
- Nanomaterials and Dielectrics, Solid dielectrics, High Voltage Engineering
- Funding:
- Ministry of Higher Education, Malaysia and Universiti Teknologi Malaysia
Although nanocomposites have been exploited for many years in connection with their enhanced mechanical properties, the potential of these materials for use in electrical systems has only recently begun to be considered. Nevertheless, nanodielectrics are now attracting worldwide interest as a result of the attractive combinations of properties that these materials can exhibit. A consequence of introducing a nanofiller into a polymer appears to be the incorporation of a multitude of shallow traps that are associated with the polymer/nanofiller interface, which serve to assist in charge transport. Or, more importantly, serve to prevent the build up of potentially damaging space charge ââ¬â an issue that will be of increasing technological importance as our reliance on DC links to renewable generation and interconnection of asynchronous generation islands grows. This project will examine the effect of nanostructuration on charge transport dynamics in polymer-based nanocomposites and will extend existing studies of this material class.
Primary investigators
- kyl1g10
- asv
- George Chen
Associated research group
- Electronics and Computer Science
- Date:
- 2010-2014
- Themes:
- High Voltage Engineering, Modelling and Simulation, Condition monitoring, Solid dielectrics
- Funding:
- Self funded - no external funds requested
This project is concerned with experimental and simulation studies into the degradation processes that occur when voids in solid dielectric materials experience high applied electric fields. A method has been developed for manufacturing 2mm thick samples of silicone resin that contain a single void of around 1mm diameter. Five samples are simultaneously electrically stressed under an applied ac sinusoidal voltage of 12kV for 6 hours and the voltage is then increased to 15kV until a sample fails. During the stressing period, PD data is regularly acquired. The remaining 4 samples are then inspected for signs of degradation. Degraded samples that have not suffered catastrophic failure and contain pits or evidence of electrical trees are sectioned using an ultra-microtome equipped with a CR-21 cryo-system set at -110ãâ¬âC in order to provide a surface containing open segments of pits or trees. The experiment is repeatable and the obtained degraded samples and the degradation areas of microtomed samples have been analysed using Raman spectroscopy to identify the chemical content of the degraded areas at the void /silicone rubber interface. In addition, models have been developed to simulate the observed PD behavior. These models will be adapted to include the degradation processes observed in the experiments.
Primary investigators
- Paul Lewin
- tb6g10
Associated research group
- Electronics and Computer Science