Optimization of Harmonic Suppression Devices Based on Current-Sensitive Materials

The neutral ungrounded configuration is widely adopted in China’s distribution networks. Evolving power system structures and parameters have significantly increased ferromagnetic resonance incidents. These phenomena degrade power quality, damage critical equipment like potential transformers, and cause frequent high-voltage fuse blowouts, severely impacting system reliability. Addressing the critical limitations of existing primary-side harmonic suppression devices—specifically insufficient heat resistance and thermal capacity leading to inadequate suppression and burnout—this study proposes an enhanced solution. The core component of the conventional varistor-based suppressor is replaced with a novel current-sensitive material. This material exhibits significantly faster resistance-response linearity and superior thermal capacity compared to traditional varistors. Rigorous thermal capacity tests confirmed the current-sensitive material’s enhanced stability and endurance under high-current and impulse conditions. Full-scale 10 kV system testing simulating critical intermittent single-phase ground faults demonstrated the device’s superior performance; it consistently suppressed the PT primary neutral current to a stable 0.195 A, significantly outperforming traditional varistor-based suppressors which exhibited current rebound to 0.884 A. Experimental validation thus confirms the substantial effectiveness and reliability of the improved harmonic suppression device.