Sharif Digital Repository

Nowadays, due to the increasing importance and penetration of microgrids, solving the microgrid optimal sizing problem has become more important. The current utility grid and conventional energy sources are mainly ac, however, increasing rate of the replacement of the ac load with dc load lead to a more efficient dc system. So choosing the optimal type of microgrid as a way to increase efficiency of these systems would be a serious issue. This thesis establishes a planning model which finds the optimal size and type of a microgrid to minimize total cost. Total cost includes investment, operation and reliability cost of the microgrid. Sizes of DGs, converters and transformer linking the... 

Renewable resources, because of their compatibility with the environment, accessibility, and low cost of operation, have become the center of unprecedented attention. Since the output of these resources cannot be predicted accurately, they are usually implemented in microgrids with conventional generating units and energy storage systems.Furthermore, distribution networks are integral parts of power systems, and many studies have been conducted in order to improve them. Because of high investment and operation costs of distribution networks and environmental concerns, it is necessary to conduct meticulous economic studies so that with proper investments, profitable opportunities are provided... 

In conventional planning methods for an isolated microgrid, loads’s performance is taken into account in a constant power factor. Also, Motor loads dynamics which might results in absorbing a reactive power up to a few times more than the load’s capacity isn’t considered in this methods. Another important issue in the microgrid’s stability is the microgrid’s spinning reserve. Due to the isolated microgrid’s disconnectivity and not considering these problems in small isolated microgrids, the possibility of an instability event in microgrid’s performance would rise enourmously. In this thesis, an isolated microgrid’s planning has been carried out based on a solar resource while taking into... 

Renewable energy deployment through distributed energy resources is among the central goals of future power systems. Microgrids have proven to be an economically viable soloution for distributed energy resources integration into power system and benefit the customers with uninterrupted power supply. In this context provisional microgrids have been introduced with the main goal of rapid renewable energy sources deployment. Since a considerable portion of renewable enegy resources as well as residential loads are DC and this portion is expected to grow even further, hybrid AC/DC design of provisional microgrids can improve both efficiency and economic benefit by optimal arrangement of AC/DC...