Experimental and theoretical analysis of an optical current sensor for high power systems

Abstract

A magneto-optical sensor, using a dual quadrature polarimetric processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire (OPGW) link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.

Development of an electrical current sensor prototype for applications in high-power lines

“…In this condition the two optical outputs originate two distinct voltage signals (S1 and S2) which have their amplitude modulated by the magnetic field and are in phase opposition. The SF-57 glass prism used has a high Verdet constant, which is approximately 20.07 rad/(m.T) at 633 nm, 7,82 rad/(m.T) at 830 nm [8] and drops substantially to 0.75 rad/(m.T) at 1570 nm [9]. This glass also has a very low intrinsic linear birefringence and a nearly zero elasto-optic coefficient.…”

Faraday Angle and Accuracy Measurement of Magneto-Optic Current Transmission Based on New Telluride Glass

“…The Faraday rotation of the azimuth angle of the output light of the optical current sensor can be quantified using different signal analysis techniques. One of the methods to detect the rotation angle is to use a polarization detection scheme, which uses two polarizers located in front of and behind the sensor [9]. The first polarizer is used to determine the initial polarization state of the light wave.…”

Error Induced by the Optical Path of a High Accuracy and High Bandwidth Optical Current Measurement System

“…The retardance ∆ is derived directly from the solution for x 3 in (10). The rotation of the reference system ϕ depends on the two conditions x 1 and x 2 from (9). By knowing the zero-field / zero-current output polarisation, the deviation caused by the additional linear birefringence in the system can be determined.…”

“…It is important to either preserve the polarisation information carefully or to gather enough information for a valid reconstruction. Proposed solutions for polarisation preservation are using full integration of the optical processing elements into the sensor head [6,7,8,9] with free-space propagation paths as well as downlink optical fibers for signal propagation [10]. The past research of MOCS and its optical errors focused strongly on all-fiber arrangements and complete preservation of the polarisation state after the modulation.…”