风速分布差异对永磁风力发电机组故障特性的影响分析

为了更有效地辨识永磁风力发电机组的故障特征，从叶轮扫掠面内的实际风况出发，综合考虑风剪切、塔影效应产生的风速时空分布差异，并研究该差异对永磁风力发电机组故障特征的影响。首先介绍考虑风速时空分布差异后的风速模型（等效风速模型），然后基于该模型对永磁风力发电机组常见的电气和机械故障特性进行理论分析，分别推导得出考虑风速时空分布后绕组不对称故障、叶轮不平衡故障以及这2种故障复合作用下的定子电流表达式；最后利用Matlab/Simulink平台进行仿真验证。研究结果表明，与现有的基于轮毂处平均风速的故障特征相比，考虑风速时空分布差异后，永磁风力发电机绕组不对称故障特征中含有3kP(k为整数，P为叶轮转频)为主的调制频率；叶轮不平衡故障特征频率除P和3kP外，还出现了P与3kP的耦合调制；复合故障下频率成分会更复杂。

FAULT CHARACTERISTICS ANALYSIS OF PERMANENT MAGNETIC WIND TURBINES CONSIDERING WIND SPEED DISTRIBUTION DIFFERENCES

In order to identify the fault characteristics of wind turbines with permanent magnetic synchronous generators more effectively, the spatial-temporal distribution differences of wind speed caused by wind shear and tower shadow are considered comprehensively based on the actual wind condition in the swept area of the rotor disk, and the influence of these differences on the fault characteristics of wind turbines is studied. Firstly, the wind speed model considering the spatial-temporal distribution differences of wind speed （equivalent wind speed model） is introduced, and then the characteristics of the typical electrical and mechanical faults of wind turbine generator system are analyzed theoretically based on this model. The expressions of the stator current under stator winding asymmetry fault, blade imbalance fault, and the combination of these two faults are re-derived respectively considering the spatial-temporal distribution differences of wind speed. Finally, the simulation in Matlab/Simulink platform is used to verify the theory analysis. The results show that new fault characteristics will appear considering the spatial-temporal distribution differences of wind speed compared with the existing fault characteristics based on the average wind speed at the hub. The winding asymmetry fault characteristics contain the modulation frequency of 3kP （k is integer, P is the blade rotation frequency）. There exists the effect of coupling modulation of P and 3kP under the blade imbalance fault in addition to P and 3kP. The fault frequency components will be more complex under the compound fault.