This thesis presents a novel approach to the control of power flow for the autonomous operation of islanded micro-grids. A novel architecture embodying the idea is developed, and its performance is tested on balanced and unbalanced three-phase systems. Experimental tests are conducted on a balanced laboratory scale setup to verify the performance of the proposed technique.;The developed power flow controller makes use of a new adaptive estimation unit (AEU), which estimates the amplitude, phase and frequency of the fundamental component of the potentially non-stationary power signal as well as the associated active and reactive power. The AEU is based on a sinusoid-tracking algorithm (STA), which was recently proposed as an improved phase-locked loop (PLL). Low-pass and washout filters are used in the proposed control method to adjust the amount of power flow through the inverter and synchronous generator to the load after islanding. The estimated frequency and amplitude by the AEU are used to adjust the governor and field controller of the synchronous generator, respectively. Since the AEU estimates the power signal properties of each phase independently, the proposed method is applicable to unbalanced micro-grids as well.;The proposed technique is tested on a number of balanced and unbalanced systems. The results show that without the controller, the power sources will not properly share the power with one another after islanding. By using the controller, the power flow from the power sources to the load is under control. The proposed method offers significant advantages, especially in multi-machine based micro-grids. It is shown that the proposed method has advantages over currently employed techniques that are based on D-Q PLLs.;This thesis starts with a discussion on the motivation behind the development of the proposed method. It then presents an account of the developed methodology and its performance under a few exemplifying conditions. Discussions are presented to assess the performance of the proposed technique in comparison with existing technology. Laboratory experiments conducted to assess the practicality of the proposed method are presented next. An overall evaluation of the present work in the context of existing technology, its limitations and proposed future directions are presented at the end.
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