Global warming, pollution and energy shortages are probably the most serious challenges now facing mankind. There has been an enormous upsurge of activity in developing renewable energy sources; less well-publicised are the problems of power quality (harmonics), system stability, reliability, and energy storage associated with renewable energy generation. Embedded power generators may cause voltage variations to exceed their set limits, produce voltage unbalance and also result in unwanted harmonic distortion when integrated into the network through electronic power converters.
The school carries out research work in the areas of electrical machines, drives and power conversion control. The philosophy has always been to seek not only theoretical advances in the related subjects, but also to explore innovative concepts and novel ideas for practical applications.
The power group has projects addressing all stages of the energy cycle, from generation through to transmission, storage and ultimately usage. Power electronic converters are an enabling technology for all energy conversion processes. We continue to research new converter topologies, their fundamental properties as well as their applications, such as active harmonic filtering and power factor control in transmission and distribution systems. Hybrid and unified power conditioners combining with advanced signal processing techniques such as the recursive wavelet method are developed to track and cancel harmonic disturbances and reduce flickers from micro-generators. Novel forms such as the Cuk converter and floating capacitor multilevel inverter are being investigated. New results have recently been obtained on transient responses of the Cuk converter, and various forms of modulation techniques in the multilevel inverter; this we have recently applied to control of neutral conductor currents in unbalanced three-phase four-wire power distribution systems.
Work continues on investigating the optimal structure for integrating converters with small renewable generators and intelligent control schemes for high efficiency solar photovoltaic generation systems. We have recently developed a distributed maximum power tracking technique for PV arrays that are partially shaded by obstructions. A solar power laboratory has been established for testing different types of PV devices under controlled light conditions, for developing control strategies, and for teaching purposes. Recent work on energy storage included developing neural network models and using particle swarm optimisation methods for lead acid storage batteries and fuel cells. We have close links with power companies such as AREVA and SRD Drives in UK.
New model-based techniques for maximum power generation in doubly fed induction generators for wind power are being developed. We also investigate signal-processing techniques for fault detection and system reconfiguration of wind powered induction generators. Switched reluctance machines for wave power are being investigated.
The research on Switched Reluctance Drives has been an ongoing activity in the School for an extensive period and has included seminal work which has drawn a worldwide interest and led to a number of developments of both the generic and application oriented nature.
Electrical Machines and Power Electronic Drives
Contact: Dr J Corda
The Electrical Machines and Drives research activity in the School has an internationally recognised reputation and wealth of experience which stems from extensive involvement in creating, developing and investigating novel forms of electronically controlled electromagnetic devices, as well as in seeking simple ways of understanding and explaining challenging theoretical ideas.
The Switched Reluctance Motor Drive was pioneered in the School at the end of seventies and is now well established commercially. The current research is focused on further advances in control and dynamic modelling of eddy-currents and hysteresis effects of SR machines of both rotary and linear type.
Power Converters and Applications
Contact: Dr L Zhang
The research looks into advanced converter circuit topologies, such as matrix converter and various types of multilevel inverters. The computer simulations and experimental investigations are focused on the effects of different switching strategies vs output waveform characteristics and device stress/losses.
Research in converter application is primarily concerned with the control and energy management of power generation by renewable energy sources. On-going projects include remote modelling and maximum power point tracking of photovoltaic power panels and multilevel converters for wind-powered switch reluctance generators. Active research is also in power conditioning of transmission and distribution systems for highly reliable, efficient and good quality T&D plants.
Current Researchers & Postgraduate Students:
- Ding, Xuejun
- Hu, Junfei
- Memon, Ali A.
- Yu, Jian Hua
- Waite, Michael
- Zhao Xuandi
- Zhou, Yong Ji