Harmonic Filters Suppress System Resonance

In power systems and distribution networks, nonlinear loads (such as frequency converters, rectifiers, and power electronic equipment) often introduce multiple harmonics, causing current or voltage waveforms to deviate from the ideal sine wave. These harmonics may resonate with capacitor banks or inductive components in the system, leading to voltage or current amplification and potentially causing system resonance, affecting equipment stability and lifespan.

ahf harmonic filter By tuning the inductor (L) and capacitor (C) to specific harmonic frequencies during the design phase, a low-impedance path is created. For harmonics with higher frequency components that deviate from the fundamental frequency (50/60Hz), automatic harmonic filter almost forms a "short-circuit path for harmonic currents," allowing the harmonic currents to preferentially flow into harmonic filter cost instead of being "accepted" by the rest of the system.

Since the harmonic currents are guided into low harmonic vfd, they no longer propagate in the system or couple with the capacitive/inductive components of the system itself, significantly reducing the likelihood of resonance. Especially in the case of parallel capacitor banks, proper tuning of power harmonic filter or the use of detuning filtering schemes with reactors can keep the system's natural frequency away from the harmonic frequencies.