Electricity power quality has grown from obscurity to a major issue. One of the most severe problems of power quality is harmonic distortion and its consequences. Particularly, the increasing penetration of power electronic-based loads (nonlinear loads) is creating a growing concern for a harmonic distortion in the AC power system. Then, electricity power quality is a major issue for utilities and their customers and both are quickly adopting the philosophy and the limits proposed in the new international standards (IEC, EN, BS, IEEE). Consequently, power-conditioning equipment is becoming more important for electric utilities and their customers. Up to now, various harmonic mitigation equipment or solution have been proposed. Most of them are tuned passive filters, series reactors etc. New innovative equipment such as active harmonic conditioners or active filters also plays an important or compensating the power harmonics.