I have a strong research interest in mathematical modelling of power electronic circuits that are connected to AC power supply networks. The aim of this modelling is two-fold; for the development of improved control strategies, and for assessing harmonic current and voltage levels, taking into full account the characteristics of the ac supply network and other electronic devices or loads that are connected to it. This modelling approach began with HVdc converters, and has been extended to a number of FACTs devices, and modelling of loads for active harmonic filter design. It is naturally applicable to renewable energy and distributed generation technologies, where the power source is likely to be connected to the AC system via power electronics. This type of plant has high controllability, but zero inertia, posing unique control problems.