Fuzzy logic and Selectivity controllers for the paralleling of four-leg shunt active power filters based on Three Dimensional Space Vector Modulation

A new structure of paralleling four leg shunt active power filters is presented in order to compensate the four-wire electrical network supplying the high power of non-linear single-phase loads. An effective selectivity of control with fuzzy logic and Three Dimensional Space Vector Modulation (3D-SVM) introduced in this configuration of SAPFs to maintain the same amplitude and frequency of output current of each inverter, this is necessary to determine the numbers of inverters in service and their frequency of commutation according to the power of non-linear single-phase loads, to make operating or stopping the inverters without disturbing the performance of paralleling SAPFs. The fuzzy logic controller (FLC) and Three Dimensional Space Vector Modulation (3D-SVM) is necessary to robustness, minimizing the harmonics of source currents, reducing the magnitude of neutral current, eliminating the zero-sequence current, compensating reactive power in the four-wire distribution network, stabilizing the DC bus voltage, switching losses, and to fixe switching frequency in inverters. Also, a instantaneous real, imaginary and zero-sequence powers pq0 theory in the alpha beta omicron-axes is presented to generate the reference currents which should be injected by the paralleled four leg SAPFs.