Research On Fuzzy Sliding Control In Pitch System

With development of society, the energy and environment is becoming pressing issues facing humanity. Wind power is renewable and pollution-free. It becomes a hot topic of research in the field of energy technologies. The variable pitch control technology is one of the key technologies of wind power. To carry out the study of variable pitch control technology has important practical significance.Fuzzy control is not depend on precise mathematical model. It is the biggest advantage. The selection of fuzzy control rules is more subjective and fuzzy control is vulnerable to the impact of parameter changes. Sliding Mode control is invariant to the external disturbance and parameter changes. Thus, the complementary between the fuzzy control and sliding mode variable structure control exists. To resarch the complementary and to design controller corresponding is the main contents of this thesis. Specific work has been done as follows:Firstly, in order to effectively describe the dynamic behavior of wind power generation system, it has established the mathematical model of variable pitch wind turbine system. It has provided the basis for controller design in subsequent chapters to set up the mathematical model. Based on wind turbine model, this thesis has done some simulation for the system established. PID control method is put into the simulation. The simulation provides basis for comparison of different control effects.Secondly, fuzzy control collects knowledge from experts or experiences. It does not depend on the accurate mathematical model. Wind power generation system is highly nonlinear and has characteristics of difficult establishment of the exact mathematical model. For the feature of the wind power system, this thesis has designed fuzzy controller. The fuzzy controller designed has been used in the pitch system and done simulation.Then, the wind power system has characteristics of time-varying and strong coupling. It is also susceptible to parameter variations and external disturbances. To solve this problem, sliding mode control method has been introduced in. This thesis designs the fuzzy sliding mode controller based on fuzzy control and sliding mode variable structure control. The controller retains the advantages of the fuzzy controller of independent of mathematical models. Meanwhile, it maintains the advantages of sliding mode variable structure control ’such as to reduce the system order and to simplify the complexity of the control system. At the same time, the fuzzy sliding mode control method greatly reduce the buffeting phenomenon which appears to take the sliding mode control method alone.Finally, MATLAB toolbox has been used to do simulation in wind power generation system. PID control, fuzzy control and fuzzy sliding mode control have been used in the thesis. The control effects of three different control methods in the pitch system have been compared and analyzed. To a certain extent, PID and fuzzy control play a good control effect.However, the simulation results show that the fuzzy sliding mode control can better meet the requirements of stability of output power in the case of high wind speed. It has a better dynamic performance.