Modeling And Simulation Of Hybrid Microgrid Based On Wind And Photovoltaic Generation

This thesis focuses on the research on the modeling and simulation of hybrid microgrids based on wind and solar power generation. There are insufficient experiences about the construction of microgrids since microgrids based on renewable energy are standing on the experimental stage. Thus, accurate models and effective simulations should be applied before the actual microgrid projects are implemented. According to simulation results, system structure or configuration can be modified and potential problems could be given precautions. Due to the characteristics of renewable energy a hybrid microgrid system which uses wind and solar power is presented. Mathematical models of the components of this system are established. To verify these models simulations are run by PSCAD/EMTDC, which is a power system simulation software. The simulation results provide supports for the advantages of hybrid microgrid system.A brief introduction to microgrids based on renewable energy is stated first. The consequences of simulations of microgrids and necessity of development of clean energy are discussed. Current research progresses of world microgrids development are presented in detail and research achievements and demonstration projects are also listed in this thesis.From the systematical respective the control strategies of microgrids are demonstrated on the basis of microgrid’s concept and structure. There are two operation statuses for microgrids including grid-connected and islanded operation. Each status requires different and proper control strategies. And when switching status the microgrid needs seamless operation. The basic requirements of microgrid operation are meeting load demands and keeping satisfactory power quality.Three types of wind power generator are illustrated in this thesis. As a result of its reliability and simplicity the permanent magnetic direct-drive wind power generator is applied in the hybrid microgrid system. When it is running as a grid-connected microgrid, the maximum power tracking strategy is often applied. When islanded, voltage and frequency control is primary strategy. Photovoltaic generation tends to be affected by environmental conditions such as temperature and radiation. When these conditions change, PV generation will follow the change. By implementing the maximum power point tracking (MPPT) theory, PV generation would remain high efficient to transfer power.Wind power generator, PV array, converters and inverters are all modeled and the combined microgrid system is simulated in PSCAD/EMTDC. The simulation results show that hybrid microgrid system based on wind and solar power generation is able to provide a more stable performance than sole energy based microgrid during a long-term operation period.