Comparison of Current Controlling Methods for Shunt Active Power Filters to Improve Power Quality

In this digital world age, widespread use of electronics and power electronic devices, which are mainly nonlinear in nature, causes issues of power quality. The power must meet the specified limits (international standards), but the quality of power is deteriorated due to non-linear loads. Hence to improve the quality of power and enhance the performance of the power system the harmonics present must be reduced. These harmonics also distort the current and voltage waveforms, but current harmonics are very common and negatively affect consumers' economies, so a shunt active power filter (SAPF) is deploying to reduce it. The article presents two current controlling techniques (CCT) i.e., direct and indirect CCT in a 3-phase SAPF to compensate the current harmonics created by loads non-linear in nature. These two current controlling methods varies in quantity of current sensors are employed. For direct current controlling (DCC) method, both load currents and filter currents are detected whereas in ICC only the source-side current is measured. To obtain a reference current template a PI controller is applied to both techniques. The fuzzy logic controller (FLC) is used to replace the PI controller as it is not requiring the system's accurate mathematical model. FLC is also able to handle non-linearity in the system, doesn't require precise inputs, and is robust in nature. Simulation results for both the techniques with PI & FLC under steady state & transient conditions are presented.