Interval Observer And The Application In Wind Turbine Control System

Observer design is an important project for a long time, and it has wide application in engineering practice. Various observers have been proposed, such as Luenberger observer (full-order and reduced-order), observer for affine system, adaptive observer, observer for unknown parameter, and so on. The design method is to make the estimation error system without input to be homogeneous, hence the estimation error system will be asymptotically stable. The error is not asymptotically stable when the system has uncertain inputs. Interval observer has been proposed recently for uncertain systems, such as linear system with uncertain input. It provides a range of states but not exact values. It reflected the trend of the development of the science.Wind energy generation has become to be a focus. It is non-polluting, efficient and has huge reserves around the world. Wind energy is one important replacement of non-renewable resources in the current era with energy crisis. Doubly-fed induction generator (DFIG) is one of the most used machines. The vector control technology for DFIG has been researched in many articles. There are a lot of literatures about flux observation technology which is essential for the vector control technology. The most of the current researches, such as extended Kalman filter, the adaptive observer and the sliding mode observer, etc., are based on the method of homogeneous system. The interval observer design of DFIG has never been proposed. The purpose of this thesis is to design interval observer of DFIG. In addition, the closed-loop control based on state observer is considered in the thesis. A treatment is proposed for bilinear matrix inequality (BMI).The positive system theory and internally positive representations (IPRs) of systems are produced. Then the interval observer design for one class of continuous linear time-invariant system is given. The observer-based control law of one-sided Lipschitz nonlinear systems is studied. A new research has been done for the bilinear matrix inequalities (BMIs). Finally, a Matlab numerical example validates the availability of the method. The mathematical models of doubly-fed induction motor are given and studied for the design of the interval observer. Vector control technology is introduced. Based on the above, the interval observer design for DFIG is given. It is assumed the rotor speed is a constant. The input disturbance is considered. The simulation results show the range of rotor current fluctuation. The article has been summarized in the end. Limitations of the research are presented and suggestions for future study are proposed.