Study On The Soft Braking Technique Of Wind Turbine

The exploitation of clean and renewable energy is the ultimate way to overcome the crisis of energy and environment which is getting worse and worse. Now, wind power technique is growing up, the sinicized process is quite speedy, most components can be sincized. The brake system is an important part of wind turbine generator, which plays an important role when the wind turbine stops. At present, the brake system of wind turbine is imported from other countries, due to its dear price and maintain cost, we must sinicize the brake system of wind turbine.It can bring fluctuations of the moving parts and gearbox torque and the wear of brake pads when the traditional brake works, so soft braking system is introduced to solve those problems. We design a soft braking hydraulic system based on analyzing the mathematic model of wind turbine braking and combined the working theory of traditional brake system. This hydraulic system can adjust high-speed switch valve on/off time by control the PLC controller's PWM output, then can control the braking force in the stop process of the wind turbine. Accordingly, the stop process of the wind turbine can be more smooth and softer, and the shock wave of gearbox can be minished, also the wind turbine can run more steady.The main research contents of the paper are as follows.In chapter 1, the background, significance and development actuality are given. Then the research status of the brake system and the abuses of the traditional mechanism brake system are introduced. At last, the main research contents and key techniques are presented.In chapter 2, the brake theory, momentum theory and hydrodynamic theory are utilized to design a soft brake hydraulic system. Then simulation of the stop process of soft brake and traditional brake system has been done on the Matlab software.In chapter 3, we design a soft brake hydraulic system of 750KW wind turbine, which includes mechanism brake, pitch brake, yawing brake and filling pressure loop.In chapter 4, the soft brake control system is designed and described, then the options of PLC controller and its software actualizing are introduced.In chapter 5, the 750KW soft brake system prototype's workshop and field test are carried on, and according to the test results, the soft brake's efficiency is analyzed.In chapter 6, the paper's research work and the outcomes are generalized, and the future investigations on soft brake system are point out.