The Study Of Control And Stability For Micro-grid Based On Hybrid System Theory

In this paper, the hybrid system theory is applied to the micro-grid, because there are a large number of switching devices in the micro-grid, result in hybrid behavior between continuous dynamics and switching events, therefore it is a typical hybrid system. In this paper, we study micro-grid based on hybrid system.We designed hybrid control scheme for micro-grid, and studied the stability of the micro-grid.First introduced the research background and research progress of hybrid system theory, research purpose and significance of this paper, the concept of micro grid and the control methods, and the basic knowledge of stability which this paper will use.Secondly,in this paper, interval impulsive system is applied to the micro grid. By defining the impulsive system robust event exponential input-to-state stability(robust event-e-ISS), and the theorem of the equivalence conditions of robust event-e-ISS is derived; The result above will be applied to the interval impulsive system, we define robust event-e-ISS for the system, and the theorem of the equivalence conditions of robust event-e-ISS is derived; Finally the result above will be applied to the interval impulsive switched system, then we define robust event-e-ISS for the system, and the theorem of the equivalence conditions of robust event-e-ISS is also derived. The previous theory shows that if the uncertain matrices were restricted in smaller robust area, it will increase its decay rate, and according to the theorem of robust event-e-ISS of interval impulsive switched system, we designed a interval impulsive switched control system for the VSC, and studies the ISS on load disturbance and islanding disturbance, through simulation experiment, the system in both cases have ISS.Finally the stability of micro grid system which contains multiple distributed generators is studied, we constructed a model for micro grid based on impulsive system. To enhance the stability of the micro-grid when switching to an islanding state, a two-hybrid control strategy was studied. The first layer is made of continuous local controllers control each distributed power unit, distributed power unit is designed in the integration of the linear matrix inequality technique based on the theory of Lyapunov, the purpose is to adjust the set point of distributed power subsystem to achieve the best performance and suitable running index,The second layer is coordinated through decentralized supervisory control, decentralized supervisory control is built on the basis of information fusion, which is the use of wide area measurement system aimed at disturbing situation when there is a large distribution to convert subsystem into a proper operating condition. Simulation results show that the system has good transient stability.