As distributed generations and renewable energy are becoming the fastest growing segment of the energy industry, the technical issues and environmental impacts have to be studied and understood. The large number of small-scale Microgrid components with their own characteristics is a big challenge for Microgrid modeling, simulation, planning and operation. The major goal of this thesis is to build a library of various Microgrid components. First of all, the thesis is going to present a detailed description of Microgrid models with moderate complexity. Next, it will present the modeling of loads, utility grid and transmission lines. Then, the paper will discuss the distributed generation models that have been developed in Matlab/Simulink including Diesel Engine, Fuel Cell, Micro Gas Turbine, Wind Turbine, Photovoltaic Cell, along with the detailed modeling of short-term storage (Battery, Pumped Hydro Storage, Flywheel, and Supercapacitor). In addition to steady-state study, the thesis will also discuss the hybrid sample systems that are built to investigate their transient responses. To enhance the simulation performance, some improvements on modeling and simulation will be introduced as well. To accommodate the high demand of renewable energy and the environment policy, the planning and operation the of Micro-source generators has been studied using HOMER. Simulation results show a case study of an optimal microgrid configuration on Ontario area in Canada. Sensitivity variables are specified to examine the effect of uncertainties, especially in a long-term planning. Also, demand side management plays an important role in the operation of Microgrid. Based on raw data, case studies are carried out to investigate and validate the demand response methods. Finally, the philosophy for Microgrid protection, especially Time-delay overcurrent protection, will be briefly introduced in both gird-connected and islanding modes. / Master of Science