Reseach And Design On Variable Pitch Control Of Large Scale Wind Trubine

With today’s social productivity development, human need more energy. Thelimited conventional energy sources, such as coal, oil and natural gas, will be depleteand difficult to regenerate. So, as a kind of environment-friendly renewable cleanenergy, wind power become more and more valued. Now, it is swift and violentdevelopment in wind power generation industry. At the same time, under growingcapacity of single generator set, the security and efficiency problems of variable pitchsystem are increasingly prominent, which makes the study of wind turbines variablepitch system more and more important. This article mainly based on doubly-fedinduction generator.First of all, based on the basic theory of aerodynamics, the mechanism and thestructure of wind turbine and its energy conversion process, the principle and structureof the variable pitch system, it is clear that the variable pitch system plays an importantpart in wind turbine. After the research of pitch regulation technology, especially theindependent variable propeller technology, I mastered the control process of variablepitch system.Second, according to the control method of main controller, I researched thedynamic property of pitch system when the main controller adopts routine control modeand modified position loop control mode. Finally, I find out the problem and their causeof formation. The wind turbine is stochastic and nonlinear. After researching the generalcontrol strategy and some intelligent control methods, I come up with the continuousdisplacement control strategy. I process the angle from main controller, then send it toPID controller. The PID controller will give out a speed to converter. At the same time,I research the relationship of acceleration and speed. With and without the acceleration,the modified position loop control strategy is better than routine control strategy.Finally, I do the modeling and simulation with Matlab/Simulink， do anexperiment under no-load state and load state，and test the system in the wind field. Itran in different speed. It was rerulted that the continuous displacement control strategyhas an advantage in solving the problem of pitch system. The electric energy is better.The wind turbine is more secure. The wind turbine gets longer life span and lowermaintenance costs.