Various harmonic mitigation equipments and solutions have been proposed for power quality improvement, most of them are tuned passive filters. However, the performance of a passive filter is strongly dependent on the system impedance at the harmonic frequencies which depends on the distribution network configuration and the loads. Therefore, design of passive filters involves thorough system analysis in order to obtain adequate filtering performance of the filter. New innovative equipment such as active power filters also play an important role in compensating the power harmonics. This paper presents a review of active power filter topologies, control strategies and configurations. Shunt, hybrid and series active power filters are described showing their compensation characteristics and principles of operation.