离心泵负载下的电机定子电流特性研究

为了探索离心泵运行工况与电机定子电流之间的关系，通过数值模拟分析了不同运行工况下的离心泵水力负载转矩特性，可知水力矩呈周期性变化，均值随着流量的增大而增大，水力矩脉动强度均方根随着运行工况偏离设计工况而增大。通过理论分析可知，转矩特征将以工频调制方式反映在电机定子电流中。通过试验测得了电机定子电流，计算了定子电流均方根，并用奇异值分解法（singular value decomposition，简称SVD）消去电网工频信号，实现反映离心泵运行状态的电流特征提取。结果表明：定子电流均方根（root mean square，简称RMS）与水力负载转矩的均方根变化特征一致。根据计算处理后的定子电流总谐波失真(total harmonic distortion，简称THD)可知，THD呈现出随离心泵运行工况偏离设计工况而增大的趋势。

Characteristics of Induction Motor Current Signature for Centrifugal Pump Load

Changes in the operating conditions of the centrifugal pump cause fluctuations in the hydraulic load torque, which stimulates current in the motor stator when transmitted to the motor through the rotor shaft system. In light of the relationship between the operating conditions of the centrifugal pump and the stator current of the motor, the hydraulic load torque characteristics of the centrifugal pump under different operating conditions are analyzed through numerical simulation. The hydraulic moment changes periodically, its mean value increases with the increase of the flow rate, and the root mean square of the hydraulic moment pulsation intensity increases as the operating conditions deviate from the design conditions. Furthermore, theoretical analysis shows that the characteristics of torque are reflected in the motor stator current by power frequency modulation. Finally, the motor stator current is measured through experiments, the root mean square of the stator current is calculated, and the power frequency signal of the power grid is eliminated by the singular value decomposition method to realize the extraction of current characteristics for centrifugal pump running state. The results show that the root mean square of the stator current is consistent with the root mean square of the hydraulic load torque. The calculation of total harmonic distortion (THD) shows that it tends to increase as the operating conditions of the centrifugal pump deviate from the design conditions.