Research On Microgrid-connected Friendly Based On Hybrid Control Theory

With the problems of energy shortage and environmental pollution becomingmore and more serious, microgrid technology based on the new energy has been gotthe welcome of people. However，microgrid include large of various distributed power:wind power，solar power and so on. Because of the output characteristics of thesedistributed power with randomness and intermittency, which will be made the powerquality level of microgrid lower, the microgrid energy is considered as "garbage"energy for main grid, the energy is limited using for microgrid-connected strictly, andthe microgrid will be also affected by the maid grid, so the development of microgridand renewable energy power has been restricted seriously. How to choose thegrid-connected interface and how to control the microgrid-connected system and howto make the microgrid becoming a friendly supplement of the maid grid are hot topicsto researchers. The mostly aim of this thesis is that applying a new grid-connectedinterface with hybrid control theory to microgrid grid-connected operation control.In this thesis, the concept and the research background and the applicationpresent situation of microgrid and hybrid control are firstly put forward, and researchon several typical model of hybrid system, and then expound the basic idea of thehybrid control theory emphatically to establish an overall understanding. Secondly,putting forward and comparison several manners of the grid-connected operation formicrogrid indicates that the microgrid-connected can operate friendly by the voltagesource converter with proper control technology. Then, introduce the basic structureframe of microgrid grid-connected operation with the theory of hybrid control on thebased of analyzing the hybrid character of microgrid system, and analyse thesignaling system, control decision system and the controller design, focuses on thepart of the controller which include continuous controller and discrete controllerdetailed analysis, and then the model of the discrete controller is established byautomata model.Finally, it simulates a topical microgrid generating system, thedistributed generations of which include photovoltaic power generation system andwind power generation system with the capacity of200MVA, the continual systemand the separate logic actuation of which are simulated by Matlab/Simulink andMatlab/Simulink/Stateflow separately. The result of the simulation illustrates that thecontrol scheme presented in this thesis possesses notable action and fine effect to restrain harmonic, compensate reactive power, and improve the stability ofmicrogrid-connected operation. At the end of this dissertation, the main results of theresearch are summarized. The further work is pointed out as well.