基于Tan-Sun变换的不对称磁信号检测研究

Research on asymmetric magnetic signal detection based on Tan-Sun transform

电缆中由于三相电流之和为零而无法通过电流传感器测量出各相芯线的电流值,可利用电缆表面对称安装的3个磁传感器所测量的磁感应强度对其进行间接计算。然而当电缆的三相芯线位置不对称时,即使三相电流是平衡的,所测得的3个磁感应强度却是不平衡的,从而不利于分析与计算。为了解决上述问题,本文将Tan-Sun变换方法应用于三芯位置非对称电缆的电流检测技术中,基于Tan-Sun变换的同步相量测量技术可将3个不平衡的磁感应强度直接变换为恒定的dq轴磁感应强度,因此可进一步建立d轴磁感应强度与三相电流幅值之间的比例关系,从而实现对其三相平衡电流的有效测量。实验结果验证了所提出的电流测量方法的准确性和可行性。

The sum of three-phase currents in the power cable is zero,each of which cannot be measured by using the current transducer,but can be evaluated indirectly by using the magnetic flux intensities measured by three magnetic sensors which are installed symmetrically on the power cable surface.However,if three-phase cores of the power cable are located asymmetrically,the three measured magnetic flux intensities will be unbalanced as well even if the three-phase currents are balanced,which is not beneficial to analysis and calculation.In order to solve the above problems,Tan-Sun transform method is applied to the current detection technique for asymmetric three-core power cable in this paper.The synchronous phasor measurement technique based on Tan-Sun transform can convert three unbalanced magnetic flux intensities directly into the ones with constant values in dq-axes.Therefore,the proportional relationship between d-axis magnetic flux intensity and three-phase current amplitude can be further determined,which can be used to realize the effective measurement of three-phase balance currents.The experimental results can verify the accuracy and feasibility of the proposed current measurement method.