A new topology of active filter to correct power-factor, compensate harmonics, reactive power and unbalance of three-phase four-wire loads

This paper proposes a new topology of an active filter (AF) with improved control algorithm. The reactive power theory of three-phase circuits is used to obtain reference currents as control quantities for the AF. The developed improved control algorithm is first tested with a standard topology of the AF, thereafter, extended to control a new topology of four-pole AF system. The new topology of the AF system is capable to compensate harmonics and reactive power, correct power-factor and unbalance in three-phase four-wire balanced/unbalanced linear/nonlinear loads. The proposed new topology of the AF system fully compensates neutral current for nonlinear unbalanced load connected in a three-phase four-wire supply system, thereby preventing heating and bursting of neutral conductor. The new topology of the AF system is free from shoot through fault and exhibits a desired performance. The developed control algorithm is implemented using a TMS320C31 DSP system and performance of new topology of the four-pole AF system with improved control algorithm is simulated. Simulation as well as experimental results are given and discussed in detail.