Modelling and analysis of grid integrated TSCAOI generators for renewable distributed generation systems

Behaviour of 3-phase cage induction machines, operated in two series-connected and one isolated (TSCAOI) phase winding configuration at variable speeds to generate single-phase electricity, has been investigated in detail for standalone applications. However, integration of TSCAOI configured 3-phase cage induction machines into single-phase distributed power systems is yet to be investigated. This paper therefore presents a model to investigate the behaviour of grid-connected TSCAOI generator systems and proposes a control strategy to regulate the amount of electricity generation at unity power factor under different operating conditions. Additionally, for further simplifying the overall system, a slip estimation method is proposed to enable the speed-sensorless operation of the generator. In order to validate the system feasibility, a prototype grid-connected TSCAOI generator is to be regulated, with balanced operation, to generate electricity to the grid at unity power factor. Good agreement between theoretical and experimental results under various operating conditions indicates that the generator can be successfully regulated by the proposed control scheme and are expected to be suitable for applications, such as small-scale wind and micro-hydro distributed generation systems.