Investigation of magnetic field sensing in electric power distribution networks for current and position monitoring

Abstract

The high percentage of various distributed resources integration and customer participation response demand is forcing utilities to automate the electric power distribution network in a big way. Advanced monitoring technology is foremost among the automation processes of the distribution network. However, the electric power distribution network is numerous and spread over large geographic areas, making it difficult and expensive to construct and maintain the monitoring systems.

In this thesis, magnetic field sensing technology is investigated to address the emerging monitoring requirements in electric power distribution networks. Unlike current and voltage, the magnetic field is present in space far away from conductors, allowing for online and non-contact sensing, which facilitates the installation and maintenance of the monitoring systems. Therefore, a series of magnetic field sensing-based monitoring techniques are studied and devised for critical infrastructures, including power converters, power distribution cables, and electric vehicles, all of which are associated with generation, distribution, and consumption.

On the generation side, the study of magnetic field sensing-based current monitoring systems provide the perception of real-time information related to the current in the power converters. The double circular current trace as well as the software algorithms are newly designed to achieve anti-interference capability, small DC bias current detection, and wide bandwidth impedance estimation to address the emerging monitoring requirements in the power converters.

On the distribution side, the study of magnetic field pattern-based fault monitoring systems exhibits the comprehension to assess the status of power distribution cables in real time. A magnetic field pattern is first established for the three-core distribution cable. Each type of fault changes the magnetic field pattern uniquely and immediately, leading to fast short-circuit fault detection.

On the consumption side, the diverse electrical devices have prompted the need to monitor additional non-electrical parameters. In this context, an investigation into a position monitoring system, grounded in magnetic field sensing, has been undertaken specifically for wireless electric vehicle charging. As the user base of electric vehicles within the electric power distribution network continues to grow, the significance of position monitoring becomes paramount in supplying projection data essential for informed decision-making. The position monitoring system utilizes magnetic field sensing to track the position of electric vehicles before charging. After that, the system triggers corresponding actions to optimize the charging process for efficient charging.

Finally, theoretical analysis, finite element method simulations, and prototype experimentation are performed to validate and evaluate the performance of the series monitoring approaches based on magnetic field sensing. Based on the proposed techniques, the magnetic field sensing method exhibits great potential to be extensively utilized in the electric power distribution networks for designing advanced monitoring systems.