Novel Noncontact Current Sensor for Wideband Disturbance Monitoring in Renewable Energy-Based Power Systems

This paper presents a Tunnel magneto-resistance-based Double air-gap Zero magnetic field (TDZ) current sensor, designed for measuring wideband disturbances in Renewable Energy Sources (RES)-based power systems. Conventional current transformers face limitations in accuracy and dynamic measurement performance due to inherent structural and material constraints. To overcome these limitations, a zero magnetic environment is designed by fusing the coil and feedback circuit with the motivation of approximating the actual magnetic field strength. Next, double air gap and closed-loop structures are formed to mitigate eccentricity errors, resulting in a 39-fold improvement in linearity compared to open-loop designs. Finally, by integrating the TDZ sensor, a wideband disturbance recorder prototype, referred to as the Grid Situational Awareness Device (GSAD), is implemented to enable high-fidelity phasor measurements. Extensive experiments validate its superior performance under steady-state, dynamic, and wideband disturbance conditions. The results demonstrate that the measurement capabilities surpass those of typical sensors, achieving a linearity of 0.03% and a full-scale accuracy of 0.038%. The frequency error and total vector error of the TDZ-GSAD are as low as 0.2 mHz and 0.039%, respectively.