Instantaneous active and reactive power (p-q) and current (Id-Iq) Control strategies for extracting the three-phase reference currents for shunt active power filters are compared, evaluating their performance under different source voltage conditions with PI and Fuzzy logic Controllers in MATLAB/SIMULINK environment and also implemented using RTDS Hardware. This book is organized as Section-1 introduces the importance of active power filters and solid state devices; section-2 provides the classifications of active power filter; section-3 provides the details of shunt active filter basic compensation principle; section-4 provides the classifications of control strategies; section-5 provides the details of selection considerations of APF's; section-6 provides the details of technical and economic considerations; section-7 provides the details of DC Link Voltage Regulation; section-8 provides the details of DC Link Voltage Regulation with PI and FLC;Simulation and real time results of p-q and id-iq control strategies with PI controller using MATLAB presented in section-9 and section-10; section-11 provides the comparative study and finally section-12 states all concluding remarks.