An optical fiber Faraday effect current sensor for power system applications

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Optical fiber sensors have many inherent properties which make them ideal for applications within electric power systems. The dielectric isolation achieved in using optical fiber has fostered research in the areas of communication and sensing. This thesis focuses on the application of the optical Faraday effect in fiber for current sensing. The sensor which was constructed for this research is composed of various specialty types of fiber, spliced together to form an all-fiber system. The focus of this work is not in the theoretical verification of the Faraday effect; rather, it is the qualitative analysis of the fundamental implementation of this phenomenon for current sensing, i.e. simple polarimetric rotation as a function of magnetic field. Initially, a theoretical explanation of the Faraday effect is presented. This is followed by a detailed analysis of the output optical signal from the current sensor. A qualification of the various noise contributors of the sensing system is pre sented, and an optimal operating configuration, depending on the specific application, is identified. A study of the effects of acoustic vibration perturbations on the fiber is performed. Additionally, the performance of the optical fiber Faraday effect current sensor is compared to a high performance, commercially available, instrumentation current transducer. Specifically, the responses of the two sensors are compared in real time during various operating conditions. Concurrently, a theoretical analysis of the test circuit is performed using the electromagnetic transients program (EMTP). The output from the optical sensor and the EMTP are virtually identical. Several recommendations are made concerning the direction of research in optical fiber current sensing, and explanations are suggested for the seeming lack of interest by electric utilities to invest in this development