This paper introduces a self-integrating Rogowski coil featuring a distributed damping resistor structure to enhance broadband current signal measurement. Traditional Rogowski coils face bandwidth limitations due to high-frequency resonance from stray capacitance. This study explores resonance suppression and bandwidth extension through circuit theory and experimental validation. A distributed parameter model based on transmission line theory shows the impact of damping resistor spacing on resonance suppression. Experiments confirm that a design with 10 kΩ resistors every 5 turns reduces gain attenuation at parasitic resonance from 32 dB to 9 dB, achieving a measurement range of 50 kHz to 200 MHz with gain fluctuations within ±1 dB.

This study delves into the response characteristics of core grounding current signals in power transformers across different operating conditions, aiming to enhance the accuracy of transformer condition assessment. Existing detection technologies often rely on single-parameter methods, which fall short in providing a comprehensive evaluation of transformer conditions. To address this limitation, this research develops a wideband circuit model based on multi-conductor transmission line theory and backed by experimental validation. The model systematically investigates the response mechanisms of core grounding current to various electrical stresses, including impulse voltages, power-frequency harmonics, and partial discharges. The findings reveal distinct response characteristics of core grounding current under different stresses. Under impulse voltage excitation, the core current exhibits high-frequency oscillatory decay with characteristics linked to voltage waveform parameters. In harmonic conditions, the current spectrum shows linear correspondence with excitation voltages, with no resonance below 1 kHz. Partial discharges induce high-frequency oscillations in the grounding current due to multi-resonant networks formed by distributed winding-core parameters. This study establishes a new theoretical framework for transformer condition assessment based on core grounding current analysis, offering critical insights for optimizing detection technologies and overcoming the limitations of traditional methods.