Megawatt Permanent Magnet Direct-Drive Wind Power System Pitch Control Strategy

China’s wind power industry development is very rapid, and wind turbine is also tending to large-scale and intelligent. With the increase of the proportion of wind power generating units and wind power generation in the power grid. In order to maintain the safe and stable operation of power network, there is an urgent need to on the control strategy of the wind power generation system improved, to make wind power from large fluctuations, low reliability of bad electrical improvement for stable and reliable advantages.Large scale permanent magnet direct drive wind power generation system is a nonlinear system with large inertia and pure time delay. Pitch control is one of the key control parts in this system. Variable pitch control is not only related to the quality of output power of wind power generation system, but also to determine whether the unit can operate normally. The variable pitch control system has the characteristics of high order nonlinear and strong coupling. In order to stable output active power of wind turbine generator. At present, the traditional PID control method is used to control the pitch of the wind power field. PID control method is simple and easy to operate. But in practical application, because the wind power system is easy to be affected by the random disturbance, the accurate model of the wind power generation system is difficult to be established. So the gap between the control accuracy and the expected effect is great. The wind power consumption is extremely unfavorable, which isthe bottleneck of the power system of wind power consumption, new energy access.In this paper, based on the research of permanent magnet direct drive wind power generation system, the model of wind turbine model, transmission system model, variable pitch system model, permanent magnet synchronous generator model and converter model are established, and based on the analysis of the operation characteristics of the permanent magnet direct drive synchronous wind power generation system, the control algorithm of PID control, nonlinear optimal control and algebraic neural network control are studied. The control characteristics of each control algorithm in permanent magnet direct drive wind power generation system are obtained.And in view of the control characteristics of each control strategy, the PID control is combined with the nonlinear optimal control and the algebraic neural network, which constitute the two new control strategies. In addition, ant colony algorithm is used to optimize the parameters of PID controller. The threshold value of nonlinear optimal control and PID control is established, and the optimal PID parameters are used as the initial value of the algebraic neural network. Finally, according to the variable pitch control strategy, Design corresponding controller, using Simulink tool in MATLAB platform, the system is analyzed under two conditions of step wind speed and full wind speed. The results show that the two new control strategies proposed in this paper can obtain good control effect in the permanent magnet direct drive wind power generation system, and achieve a more stable and constant power output.