Research Of Variable Pitch Laws For H-type Vertical Axis Wind Turbine

New energy has got extensive attention because of the climate change and environmental pollution in the world. As the representative of the new energy, wind energy has been developed and used on large scale. Wind has the characteristics of abundant storage, wide distribution, few pollution and renewability. Investment and development in wind power industry are encouraged by the policies of governments of all countries in the world. Horizontal Axis Wind Turbine is the most widely used in today's wind power plants, but it still has some inherent drawbacks such as high center of gravity, complicated structure and inconvenient maintenance. In recent years, the Vertical Axis Wind Turbine began to attract the attention of scholars. Because it can overcome the defects of HAWT easily. However, the lower efficiency and no self-starting ability have always hindered its marketization and commercialization.This paper attempts to improve the revolving torque of the wind wheel by changing the pitch angle, so that the issue of poor starting performance and low power coefficient can be solved. Firstly, the basic theory of H-type VAWT and blade element are introduced in detail. Then the force analysis formulas of the blade element are deduced The mathematical expressions of revolving torque as well as the wind power coefficient are obtained. Secondly, the paper analyzes the theory of variable pitch technology. After that, the flow chart of control rules of blade pitch is designed. The revolving torque at different azimuth angles is calculated in Matlab. And the control rules of blade pitch under different conditions are gotten by analyzing data. Followed the simulation, the hardware and software control system of H-type VAWT are designed based on the core of STC12C5A60S2 microcontroller. The performance of variable pitch model and fixed pitch model is compared on the platform. The improved self-starting performance and system efficiency with using variable-pitch laws have been validated by experimental results.