Characteristics Analyzed Of Permanent Magnet Direct Drive Wind Turbine Under Blade Imbalance

As a kind of renewable energy, wind energy has been paid extensive attention. The direct drive permanent magnet wind turbine is a developing trend in modern wind power system.Wind turbine is used to absorb energy. Energy directly import the permanent magnet synchronous generator to produce electricity through the transmission chain. Wind turbine blade is a key component to absorbwind energy. However, the blade failure will directly lead to the wind turbine blade mass imbalance and cause adverseeffect on the wholewind turbine.Therefore timely detect and exclude impeller imbalance fault are necessarily important during the wind turbine operation.It can not only extend the life of the wind turbinebut also improve the security of the running turbine.In addition,the amplitude and frequency of power which is generated by permanent magnet synchronous generator vary with the wind speed,the poweris unstable and cannot be connected to the grid.Using full power converter can slove the problem.The causes and types of blade fault is analyzed. The paper theoretical analyzes the influence of leaf mass imbalance fault on the generator stator current and electrical power. Simulation software MATLAB/Simulink is used for establish transmission system model, mathematical model of permanent magnet synchronous generator and back-to-back PWM converter control model. The model is used for simulating the operation of the unit when input the stepvelocity. The results proved that themodelis correct and the control strategy isfeasible. The model is also used for simulate the operation of the unit during the blade mass unbalance. The simulation obtained the characteristics under fault conditions of the unit. Three-phase stator current and the electric power is demoduled with the application of Hilbert transformation. With the unbalanced mass increasing, the failure level get deeper, electric power and stator current amplitude increased. The simulation result is the same as the theory analysis. It provide some reference for the impeller quality imbalance fault of the actual project cases.