Doctor of Philosophy (University of The Witwatersrand, Johannesburg)
BSc (Eng) WITS 1990
PhD (Eng) WITS 2002
- University of the Witwatersrand Johannesburg, South Africa
- Professional Assistant
- Junior Research Officer
- Eskom Enterprises TSI now Eskom Holdings, Resources and Strategies C,R&D group.
- Senior Engineer (PPP)
- Chief Consultant (SS2)
- Nu-Lec Industries now Schneider Electric Australia, Power division recloser solutions.
- Medium Voltage Technology Specialist
2010 to present
- Queensland University of Technology
- Senior Research Fellow
- Senior Lecturer
- EGB241 : Electromagnetics and Machines
- EGB341 : Energy Supply and Delivery
- SEB701 : Work Integrated Learning
- EGH454 : Power Systems Management with Renewable & Storage Resources
- ENB454 : Power Systems Management
- ENB453 : Power Equipment and Utilisation
- ENB245 Introduction to Design and Professional Practice
- Academic coordinator of the Postgraduate Electricity Supply Training Course (PESTC).
- Modeling of the V-I characteristics of high temperature superconductors in the presence of high magnetic fields.
- Measurement of real-time winding movement in large power transformers using dynamic vector network analyses.
- On-line dielectric response measurements on large power transformers.
- Design and construction of SMALA (Switch Mode Assisted Linear Amplifier) voltage sources for use in dielectric testing.
- The use of restrikes in vacuum switchgear as a diagnostic tool.
- Performance of SF6 insulated co-axial gaps under disconnector generated Very fast Transience’s.
- Breakdown of co-axial gaps insulated with SF6/N2 mixtures under power frequency voltages.
- 10kV shielded impulse voltage generator used for high voltage divider calibration and response certification.
- Use of an SF6 GIS voltage transformer for the synthetic generation of Very Fast Transience’s in GIS.
- Design and construction of a 100kA 4/10μs lightning current impulse generator.
- Design, construction and calibration of a capacitive voltage divider for the measurement of Very Fast Transience’s in GIS.
- Design, construction and calibration of numerous voltage dividers up to 1MV peak including resistive, capacitive and mixed dividers.
- Ultra-High Frequency (UHF) Partial Discharged (PD) detection method in Gas Insulated Switchgear (GIS) under Lightning Impulse (LI) Voltage excitation.
- Detection of corona activity in SF6 and air using an image intensifier and a photo multiplier.
- Application of the UHF PD detection method to power transformers for the detection of defects and tap changer arcing.
- Modelling of the electromagnetic field on the earth’s surface due to geomagnetic storms.
- Supervised 2 successful PhD candidates:
- Shui-Cheong Kam (2012) Assessing of Circuit Breaker Restrike using Computer Simulation and Wavelet Analysis.
- Xu Yang (2015) Enhancements to Dielectric Response Measurements of Oil-paper Insulation for Online and Offline Applications.
- Supervised numerous (70+) final year projects.
- Design of outdoor pole mount Recloser and Load Break switches up to and including 38kV:
- Dielectric design.
- Short circuit forces.
- Termination design.
- Switching medium.
- Thermal design.
- Molding of Epoxy components.
- External insulation design and testing for polluted conditions.
- Pressure rise determination in power equipment due to internal arc events.
- Thermal compensation of imbedded capacitive voltage sensors for improved temperature range accuracy.
- Current transformer design.
- Failure investigation and reporting:
- Dielectric and switching failures in Gas Insulated Switchgear up to and including 765kV.
- Dielectric and switching failures in Reclosers and Load Break switches up to 38kV.
- High Voltage Engineering and the associated testing of high voltage equipment:
- Properties of insulating dielectrics:
- Comparative study of the performance of Cycloaliphatic epoxy and Hydrophobic epoxy for outdoor equipment using an in-house constructed salt fog chamber.
- Comparative study of filling compounds for “wet” terminations.
- Study into the performance of silicone over molding of epoxy for outdoor equipment.
- Environmental effects of SF6.
- Development of strategies and best practice for utility’s using SF6.
- Handling, recycling and disposal of SF6 and associated by-products.
- Test voltage/current generation and measurement:
- Determination of the core material of current transformers from standard IEC performance measurements as a quality control tool.
- Diagnostics of power equipment:
- Diagnostics of GIS using gas analyses.
- Leak detection in SF6 filled equipment using infrared background scattering absorption imaging.
- Detection of fires under high voltage power lines using corona induced noise.
- Detection of faults in power cables using frequency domain reflectometry techniques.
- Partial discharge detection and interpretation.
- Detection of partial discharge activity in power equipment using low cost microwave C and Ku band low noise block down-converters.
- Partial discharge testing in a production environment as a quality control tool.
- Electric and magnetic field modelling as well as coupled multi-physics modelling:
- Glass cap and pin insulator strings under polluted conditions.
- Dielectric design of epoxy Reclosers with vacuum interrupters.
- A capacitance change of CVT’s embedded in epoxy bushings due to thermal heating.
- Electric field stresses on silicone rubber terminations for pole mount switchgear.
- Modelling of electric and magnetic fields associated with High Voltage transmission lines.
- Written numerous programs in Matlab to calculate the electric and magnetic fields along transmission lines.
- High voltage laboratory design and specification.
- Electrical safety during high voltage and high current testing.
- Properties of insulating dielectrics:
- Yang X, Nielsen S, Ledwich G, (2015) Investigations of dielectric monitoring on an energised transformer oil-paper insulation system, IET Science, Measurement and Technology p102-112
- Nielsen S, Walker G, Bailey M, (2015) Development of a switch mode assisted linear amplifier for use as a high fidelity voltage source, Proceedings of the 11th IEEE International Conference on Power Electronics and Drive Systems (PEDS 2015) p188-193
- Yang X, Ledwich G, Nielsen S, (2015) Simulation study for analysis of online dielectric measurement problems on transformer insulation system, Proceedings of the 7th World Congress on Engineering Asset Management (WCEAM 2012) (Lecture Notes in Mechanical Engineering) p657-665
- Liu H, Ma L, Gu Y, Nielsen S, (2014) Numerical investigation of mechanical and thermal dynamic properties of the industrial transformer, International Journal of Computational Methods p1-12
- Yang X, Nielsen S, Ledwich G, (2014) Experimental investigations of improved dielectric condition monitoring methods on transformer oil-paper insulation system, Proceedings of the 18th IEEE International Conference on Liquid Dielectrics p130-133
- Kam S, Nielsen S, Ledwich G, (2013) A systematic review of a statistical vacuum circuit breaker model for condition monitoring, IEEE Transactions on Dielectrics and Electrical Insulation p620-627
- Yang X, Nielsen S, Ledwich G, (2013) Frequency dielectric influence of imaginary admittance on oil-paper insulation system-a case study, Proceedings of the 2013 Australasian Universities Power Engineering Conference p1-6
- Kam S, Nielsen S, Ledwich G, (2011) A circuit-breaker restrike diagnostic algorithm using ATP and wavelet transforms, Proceedings of 21st Australasian Universities Power Engineering Conference (AUPEC), 2011: Integrating Renewables into the Grid p1-6