基于双PQ变换的感应电机转子故障诊断

Rotor Faults Diagnosis for Induction Motors Based on the Double PQ Transformation

提出了基于双PQ变换的感应电机转子故障诊断新方法。该方法以三相基波正序电压及其希尔伯特变换构造PQ变换矩阵,用其对定子三相电流进行变换,得到电机有功功率P及无功功率Q。由于正常电机P、Q均恒定,在PQ坐标系下对应1个点;故障电机则由于P、Q中附加频率为2sfs(s为转差率,fs为电网频率)的波动分量而对应于1个椭圆。通过比较电机正常及转子断条故障运行时的P、Q在PQ坐标系下对应的模式,可以实现转子断条故障的可靠检测。选择转子断条电机在PQ坐标系下对应椭圆的长轴为故障特征,椭圆中心与空载运行点之间的距离为归一化基准值,得到了1个近似独立于电机惯量及负载等级的故障严重因子。实验结果证明了该方法的有效性。

A new rotor faults diagnosis method for induction motors based on the double PQ transformation is presented. With the positive sequence fundamental voltage components and its minus Hilbert transformation as elements, the PQ transformation matrix is constructed. The active power P and reactive power Q can be obtained through the PQ transformation of the stator currents. Due to the P and Q are both constant for healthy motor, they correspond to a dot on the PQ reference coordinate. And the P and Q of the rotor broken bar motor will correspond to an ellipse due to they comprise an additional frequency component of 2sfs （s is slip and fs is supply frequency）. By distinguishing of these two different patterns, the rotor broken bar fault can be detected. Using the major radius of the ellipse as the fault indicator and the distance between the point of no-load condition and the center of the ellipse on the PQ reference coordinate as its normalization value, the fault severity factor which is approximately independent of load level and the inertia value of the induction motors is given. Experimental results demonstrate effectiveness of the proposed method.