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Sole dependence on diesel energy has imposed a wide array of problems upon the operation of off-grid power systems in Northern Canada. Hybrid Renewable Energy Systems (HRES) have been vehemently emerging as a feasible alternative to the existing diesel-based generation facilities. To maximize the intended benefits, proper component selection, optimum sizing of the grid configuration and performance evaluation in the economic, environmental and reliability paradigms become decisive steps in their designing process. This paper presents a HOMER software-based gird optimization study to optimally retrofit a remote off-grid power system in Northern Canada. Topologies like Battery-Diesel, PV-Diesel and PV-Diesel-Battery were assessed under different scenarios to find the optimum retrofit for a primarily diesel-based generation facility. Results reveal the competence of PV-Diesel-Battery topology at high renewable penetration levels in achieving the envisioned benefits. Around a renewable penetration level of 21%, fuel savings up to 22% is achievable along with 0-0.5% reductions in Levelized cost of electricity compared to the existing diesel-based power system. While diversifying the energy mix, the PV-Diesel-Battery topology considerably curbs the environmental degradation caused by the diesel-only operation and ensures the reliability, availability and security of the power supply.

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The rising demand for electricity, economic benefits, and environmental pressures related to the use of fossil fuels are driving electricity generation mostly from renewable energy sources. One of the main challenges in renewable energy generation is uncertainty involved in forecasting because of the intermittent nature of renewable sources. The demand also varies according to the time of day, the season, the location, the climate, and the availability of resources. Microgrids offer a potential solution for the integration of small-scale renewable energy sources and loads along with energy storage systems and other non-renewable sources. However, intermittent generation and varying demand need to be matched to provide stable power to consumers. Therefore, it is crucial to design an energy management system to effectively manage the energy sources and supply loads for reliable and efficient operation. This paper reviews different techniques proposed in the literature to achieve the objectives of a microgrid energy management system. The benefits of existing energy management systems and their challenges are also discussed. The challenges associated with uncertainties and methods to overcome them are critically reviewed.

Incorporation of renewable sources and energy storage can contribute to reduce fuel consumption in diesel generation-based remote off-grid power systems. This thesis proposes methodologies for improved management of available generating and storage resources to reduce costs and emissions and investigates the coordination of energy management with power management functions essential for stable operation of the isolated power systems.Firstly, a test system is developed considering a case of retrofitting an existing diesel power system with photovoltaic (PV) generation and battery energy storage. A sizing study conducted using HOMER software with weather and load data for Northern Canada resulted in a PV-Diesel-Battery topology with high PV penetration levels. Next, the energy management functions are developed incrementally in three steps. First, a computationally efficient energy management system (EMS) is implemented to optimize the system operation while incorporating multiple operational requirements essential to remote power systems. Then, a demand response (DR) model that requires minimal bi-directional interactions and therefore implementable without sophisticated communication infrastructure is developed and integrated with the EMS. Thirdly, a computationally efficient two-stage model predictive control process is developed to compensate for forecast uncertainties. Finally, the power management functions necessary to achieve a logical real-time operation are implemented and coordinated with the energy management functions in a hierarchical architecture. Also, an operation evaluation framework is suggested to assess the viability of the optimum operation routines under dynamic conditions.After adding PV and energy storage to an existing diesel-only system and optimizing the operation with the DR integrated EMS, over 60% cost and emission reductions are achieved for a representative summer day compared to the diesel-only operation. The cost and emission reductions achieved for a representative winter day are 31% and 11%, respectively. During the intra-day operation, the proposed uncertainty management framework navigates the system judiciously and achieves cost and emission performance closer to that is obtainable when perfect forecast information is available in a iii computationally efficient manner. Numerous tests verify the correct operation of the proposed power management strategies and the utility of the operation evaluation framework while demonstrating the importance of coordination of the energy and power management functions. iv Use of Copyrighted Material I like to confirm the approval from all the authors and hereby acknowledge the use of the following publications during the preparation of this thesis. Only the contents of the publications where I am the first author are included in this thesis. Publications in Elsevier Journals-R. Kaluthanthrige and A. D. Rajapakse, "Two-stage framework for optimizing the operation of remote off-grid power systems under uncertainties," Int. J. Electr.