| Front-end speed controlled wind turbine is put forward by German VOITH company in recent years, which is different from the traditional rigid driving mode, its transmission chain uses hydraulic torque converter, which makes the turbine directly coupled with power grid by electric excitation brushless synchronous generator, and produce electricity just like a conventional hydropower and thermal power synchronous generator. It has strong low voltage across ability and reactive power output capability, good power quality and other advantages, which has great development potential. Therefore, analysis and research on the subtle antidisturbance fault-tolerant control of front-end speed controlled wind turbine is of great practical significance to ensure safe, stable and efficient operation of the wind turbine.As a key part of front-end speed controlled wind turbine energy conversion system, the operation conditions of wind turbine generator directly affect the power quality and unit performance. Due to the wind power system works in places like plateau, wild places for a long time, and exposes to the inclement environment such as wind, frost, rain and snow and so on, in addition, it is mainly driven by complex random uncertainty natural wind, the generator is vulnerable to be influenced by external environment and multi-source disturbance inside the generator, and also prone to various faults. Because of strong coupling and strong nonlinear characteristics of the front-end speed controlled wind turbine generator, with the accumulation and spread of the disturbance and fault, it not only affects the safety, stable and efficient operation of the generator itself, but also directly affect the performance of the entire wind power system, the efficiency and quality of power supply.A front-end speed controlled wind turbine generator is selected as the research object, considering multi-source disturbance factors and fault exist at the same time, researches the subtle anti-disturbance fault-tolerant control for generator, and the effectiveness of the proposed control strategy is verified by simulation.Firstly, the basic structure and operation principle of the front-end speed controlled wind turbine generator are analyzed, based on this, the state space model of front-end speed controlled wind turbine generator with electric current and rotor angular velocity as the state is derived.Then, the multi-source disturbance of front-end speed controlled wind turbine generator are analyzed and classified. Multi-source disturbance can be divided into norm bounded random disturbance and external disturbance system, and a compound subtle anti-disturbance control method is put forward based on disturbance observer based control(DOBC), feedback control and H∞ control. For norm bounded random disturbance, H∞ control is designed to weaken the disturbance, and DOBC and feedback control method are designed based on the linear matrix inequalities(LMIs) and Lyapunov stability theory, which is used to estimate and compensate the external disturbance system. By integrating traditional controller, the closedloop systems can still remain stable and meet the H∞ control performance, even under the multi-source disturbance factors, the method can improve the control accuracy of the generator.Finally, considering the multi-source disturbance and sensor fault exist at the same time in generator, the composite hierarchical anti-disturbance fault-tolerant controller is designed, on the basis of subtle anti-disturbance control of the generator, for the sensor fault in the system, the fault diagnosis observer and feedback control is adopted to realize the fault diagnosis and fault-tolerant control. At last, the effectiveness of the designed control strategy is verified through simulation analysis. |
PDF Full Text Request