Research on Fiber Optic Current Transformer Cross Stripe Measurement Technique

Due to the limitations of existing fiber optic current transformers (FOCT), achieving high-precision measurement and a large measurement range simultaneously has been challenging. In this research, we propose a novel FOCT based on the cross-stripe measurement method, which effectively enhances the measurement range without compromising accuracy and enables precise current measurement across a wide dynamic range. Firstly, based on the working principle of reflective straight waveguide FOCT, we analyze the relationship between Faraday phase shift, feedback phase shift, and analog-to-digital converter in digital closed-loop systems. Subsequently, we introduce a register overflow-based cross-stripe measurement method. Secondly, we establish a simulation test platform to evaluate the dynamic performance of FOCT using indicators such as maximum measurable current change rate and steady-state noise standard deviation. The theoretical feasibility of cross-stripe measurement is demonstrated through these evaluations. Finally, an experimental platform for FOCT is constructed to verify the feasibility of our proposed cross-stripe testing scheme in terms of multicycle measuring range and accuracy aspects. Experimental results indicate that our prototype can successfully measure large currents across stripes with change rates not less than 980kA/ms and amplitudes not less than 500kA pulse currents while maintaining similar levels of accuracy compared to existing FOCTs.