Research On Individual Variable Pitch Control Strategies Of Large-Scale Wind Turbine

With the rapid development of wind power generation technology, the wind generator single capacity are continually increased, variable speed and pitch control technology has become the main trend in today's wind power development. Especially, the control strategy of using individual pitch to stabilize the output power of generator and reduce load disturbance of wind turbine is the hot spot of large wind turbines research. Depend on National Key Technology R&D Program major project"Research and development of land and sea environment doubly fed variable speed constant frequency wind turbines", this thesis studied the independent variable pitch control strategy on 3MW doubly fed variable speed constant frequency wind turbine independent variable pitch control system. The purpose is using independent variable pitch control to reduce the unbalanced load of wind turbine, stabilize the output power of generator. The major research works are summarized in the following:Firstly, according to wind turbine variable pitch control theory and independent variable pitch control wind turbine control model; independent variable pitch control theory based on blade root loading coordinate transformation pitch angle feedback linearization is studied. Based on the summary of variable speed and variable pitch wind turbine aerodynamics and operation principle, the thesis analyzed the problems such as structural establishment of independent variable pitch, wind turbine characteristics and dynamic loading of independent blade operating, derived independent variable pitch feedback linearization control model, designed independent variable pitch control strategy based on blade root loading variable pitch angle feedback linearization. By detected the blade root loading of each blade and using Coleman coordinate transformation theory to change blade root loading into pitch angle feedback adjustment, the strategy realized the independent control of wind turbine, the main purpose is to reduce the unbalanced loading to the wind turbine caused by wind shear, tower shadow and random turbulent. Compared with PI unified variable pitch control simulation exercises, the results illustrate, independent variable pitch control strategy based on blade root loading variable pitch angle feedback linearization can realized independent pitch control and has significant effect on reducing dynamic loading of wind turbine, pitch control system has better stability and faster response time.Then, the research designed independent variable pitch control strategy based on 3MV wind turbine LPV (linear parameter variable) model reference self-adaption. According to the non-linear couple of large wind turbine multi-input and multi-output and the extra control loading impact of independent variable pitch, the thesis used LPV theory to linearize the variable control of wind power transformation system in wind turbine, established the LPV model of wind turbine independent variable pitch control system. This model can be used to test the slowly change of parameters and realized the non-linearization in wind power transformation processes of wind turbine, can effectively simulated the operation situation of wind turbine. In addition, an independent variable pitch whole turbine control strategy based on wind turbine LPV model reference self-adaption is designed using model reference self-adaption control theory. Compared with the independent variable pitch system computer simulation between LPV model reference self-adaption control and PI control, the results illustrate, the independent variable pitch system using LPV model reference self-adaption control has more gentle torque pulsation output, with small amplitude change, generator output power is around rated power, transmission system has small shock and high output efficiency, and has better advantages than PI control.Finally, a 3MW wind turbine independent variable pitch semi-physical experiment platform is established to confirm the above independent variable pitch control strategy and simulation results. By simulated the typical wind field situation, independent variable pitch control strategy is tested. There are some entities in the semi- physical simulation experiment platform, such as wind turbines operating control system, electronic drive mechanism of variable pitch system and sensor system. Others such as wind wheel, tower and generators are using Bladed simulation software powered by GH Company to simulate; the whole semi-physical simulation platform can be regard as a real variable speed variable pitch turbine. The test data shows that the individual variable pitch control strategy of large-scale wind turbine is feasible and effective.