Research On Operation And Control Strategy Of Micro-grid

As the environmental pollution and energy crisis have become increasingly prominent, it is becoming the focus of global attention to looking for clean and renewable energy. Meanwhile, large-area power outages occur frequently in recent years due to natural disasters and partial failure, so that the vulnerability of traditional grid has been fully exposed. To solve these problems, the technology of distributed generation (DG) has caught more and more attention.Distributed generation with clean and renewable energy (such as solar energy and wind energy) as the main source supply, scatters around the users. It avoids the difficulties of long-distance transmission and it can independently bear the needs of the users when the traditional grid gets out of order. Combining distributed sources and loads into a small-sized grid is good for the combination of distributed sources and the traditional grid. This is the origin of Micro-grid. The emergence of Micro-grid can make contribution to the promotion of the renewable energy and also improve the power supply reliability of traditional grid.As the inverter is the interface of distributed source and grid, how to control the inverters is a key problem of Micro-grid research. Now the main control strategies consist of PQ control, V/f control and Droop control. The theories of these typical control strategies are analyzed deeply and the selection of model parameters are studied in this thesis.As Micro-grid is a complex system that consists of many distributed sources, it’s impossible to control the whole Micro-grid by controlling a single inverter. On the base of PQ, V/f and Droop control, it’s necessary to make overall control operations for Micro-grid. As the main operations, the theories of master-slave operation and peer-to-peer operation are analyzed deeply. Models of these two operations are established by MATLAB to verify their feasibility. According to the results of simulation, some defects are exposed.To overcome these defects, some improvement methods are raised and they are combined into a comprehensive control operation. At last, the feasibility of these methods and operation are verified by MATLAB.Considering the complexity and valuableness of Micro-grid experimental system, simulation continues to be one of the key ways to research Micro-grid deeply. So the simulation models in this thesis have a practical significance.