基于环路积分型磁阻传感阵列的电流测量方法

Current Measurement Method Utilizing Loop-Integral Magnetoresistance Array

电力系统是人类日常活动的重要基础设施,是最复杂的人工系统。为了维持电力系统稳定、可靠地运行,电力系统需要准确、可靠的状态监测,不同的状态监测情景需要有区别的测量方式以获得更精确的测量结果。目前,电力系统中电流的在线监测主要局限于室内场所的导线电流测量,对于电力系统中铜排工作电流的测量手段还较为缺乏。针对电力系统铜排电流监测的需求,以磁场作为耦合方式,需要重点解决两方面关键科学问题:1)矩形截面铜排通流电流后的磁场等效模型;2)基于通流铜排磁场的磁场测量、电流反演方案。本文基于毕奥萨伐尔定律,建立了理想情况下通电铜排磁场模型,研究了矩形截面铜排近场、远场的磁场;基于磁场计算,研究了电流传感器阵列包含的测量单元数量对电流测量的影响,优化了阵列结构;基于安培环路定律、均值算法,计算阵列电流反算结果与给定电流之间的误差,求得基于传感阵列的理论电流测量误差。在此基础上,设计了用于矩形铜排电流测量的矩形阵列、测量信息处理模块、数据通路及相关硬件电路,使用了独特的双层电路板结构以固定并定位多个隧道结磁阻效应传感单元。最后,搭建基于通电铜排的实验平台,利用阵列测量系统实现对实验室条件下铜排电流的测量。结果表明,本文设计的电流测量阵列能够实现1%以内的电流测量精度。

The power system serves as a crucial infrastructure for daily human activities and represents one of the most intricate artificial systems.To ensure the stable and reliable operation of the power system,precise and dependable state monitoring becomes imperative.Varied state monit-oring scenarios necessitate distinct measurement methods to obtain more accurate results.Currently,online monitoring of current within the power system primarily focuses on wire current measurement in indoor locations,leaving a gap in measurement methods for the working current of cop-per bars in the power system.In addressing the need for monitoring the current of the power system busbar,the utilization of the magnetic field as the coupling method demands attention to resolving two key problems:1)Developing a magnetic field model for rectangular cross-section copper busbars with current flow;2)Creating a magnetic field measurement and current inversion method based on the magnetic field of the copper bus-bar with current flow.This paper,based on Biot Savart’s law,establishes an ideal magnetic field model for copper busbars with current flow.The study delves into the magnetic fields of rectangular cross-section copper bars in both near and far fields.Through magnetic field calculations,the impact of the number of measurement units within the current sensor array on current measurement is explored,and the array structure is optim-ized.Employing Ampere’s loop law and a mean algorithm,the error between the array current back-calculation result and the given current is de-termined.Building upon this,a design is proposed,encompassing a rectangular array,a measurement information processing module,a data path,and associated hardware circuits for measuring current in a rectangular copper busbar.A unique double-layer circuit board structure is employed to secure and position multiple tunnel junction magnetoresistive effect sensing units.Ultimately,an experimental platform,utilizing electrified copper bars,is established to measure the current of a copper busbar under laboratory conditions using the array measurement system.Experi-mental results demonstrate that the current measurement array outlined in this paper achieves an accuracy of less than 1%.