Considerations on the life performance and installation practice of shunt capacitors in the presence of harmonics generated by AC/DC converters

This paper investigates the influence of harmonic distortion on the life reduction of power capacitors when connected in parallel to power converters operating with randomly-varying loads. A probabilistic life model is employed in order to evaluate the effectiveness of standard design procedures for capacitors operating in distorted regimes. This approach is applied to a working example based on measurement data obtained from a busbar feeding a ski-lift resort. Either a capacitor bank or a system consisting of a shunt filter plus a capacitor bank is considered for reactive power compensation. It is shown that capacitor design made on the basis of voltage derating of 20% may be not sufficient to ensure satisfactory life performance.