Adaptive Damping – An Improved Resonance Mitigation Scheme for Shunt Capacitors

Adding a damping unit to a shunt capacitor is an effective way to mitigate capacitor-caused resonance. However, damping units suffer from power loss issues. This shortcoming is amplified further in cases where resonance has a low possibility of occurring. In view of this, an adaptive damping method is proposed to improve the existing scheme. The damping unit is capable of mitigating resonance and eliminating the power loss under the non-resonance condition. The core idea of the proposed approach is to add a breaker so that the damping unit can be switched on or off depending on whether resonance occurs. The design of and control mechanism for the proposed switchable damping unit are presented. The performances of the new resonance mitigation scheme in terms of harmonic mitigation, loading, switching transient and cost are verified for an actual capacitor application case.