I, Mathew Habyarimana , declare that:(i) The research reported in this dissertation, except where otherwise indicated, is my original research.(ii) This dissertation has not been submitted for any degree or examination at any other university.(iii) This dissertation does not contain other persons' data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons.(iv) This dissertation does not contain other persons' writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: a) their words have been re-written but the general information attributed to them has been referenced: b) where their exact words have been used, their writing has been placed inside quotation marks, and referenced.(v) This dissertation does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the dissertation/thesis and in the References sections.

Large induction motors can have a high inrush and run-up current during starting, often up to ten times the rated current. In weak supplies, this could be a problem, causing system stability issues and the voltage to dip below acceptable levels. In islanded systems, the capacity could be pulled below its maximum. There are several different starting methods possible, but they are often only suitable for smaller machines. One method not investigated is the use of parallel capacitor compensation during the starting because large induction motors are very inductive during the starting sequence, so that supplying reactive power may be more effective than supplying energy. This paper first investigates several different induction motors with increasing size and assesses their compensation requirements in terms of the reactive power requirement during starting. It is shown that they do generally become more inductive as they increase in size. It is illustrated, using simulations, that using parallel capacitors during starting can significantly reduce the starting current. The concept is tested using a small experimental motor. Series inductors are added to the motor to make it more inductive and look more like a larger machine. The experimental results confirm that the method works. It is also found that the parallel capacitors require series filters to prevent harmonic current, and these can be realized using inductors in series with the compensation capacitors. Point-on switching using solid-state relays was tested, and these can reduce the transient switch-on current over the first voltage cycle.

A solar system using PV arrays to convert solar radiation into direct current was a preferred renewable energy source compared to others. Fluctuations in a commercial grid power supply depended greatly on peak power demand load. It was, therefore, more convincing to utilise a PV array system to meet peak time demand. In this paper the design of a hybrid system using mains and a PV array to meet peak power demand is discussed; the system is completely automatic through design of an automatic source selector with a pre-scheduled panel cleaning system through use of a microcontroller. A LCD displays selection of source and provides for the overriding of automatic source selection; manual switching is included. During peak power demand, solar power and/or battery power would be used; at other times mains will be the power source. Moreover, emergency switching to solar or battery during mains failure was also provided. The MPPT design controlling a PWM signal for a boost converter to achieve maximum output is also discussed. The automated design makes it user-friendly. Although initial costs are high, this hybrid system could reduce the load on commercial grids during peak power demand.

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