In this work, a Three phase Transformerless Hybrid Series Active Power Filter
(THSeAF) based on Sliding Mode Control (SMC) is proposed to mitigate the
voltage and current distortions present in an electrical distribution
systems (EDS). A Sliding Mode Controller is designed by controlling the
parameters present on the load side as well as source side of the system.
Three separate voltage source converters (VSC) are used. The mod1elling of
the system is derived by considering a single-phase system by using state
space analysis. The frequency response characteristics have been derived for
the single-phase system and the stability of the system is studied. It is
observed that the system has good stability margins when the SMC is applied
at the source side compared to load side. Simulation results obtained in
PSCAD/EMTDC v4.6 have been observed for power quality issues like voltage
sags, voltage swells, voltage distortions, voltage unbalances and their
concurrent occurrence. The approach of stationary reference frame was used
for source side control and PQ theory is used for load side control. It is
observed that the proposed controller works well in obtaining a stable and
constant load voltage during these power quality issues. The difference in
settling time observed is around 4 ms for the load side and source side
control. The THD present in the load voltage is near about 1%. The SMC is
found to be robust in obtaining a constant load voltage with low THD and an
improved power factor.
Empirical Wavelet Transform Based Approach for Extraction of Fundamental Component and Estimation of Time-Varying Power Quality Indices in Power Quality Disturbances