Recursive Digital Filter Based Control for Power Quality Improvement of Grid Tied Solar PV System

This article deals with the implementation of a control approach for an active power transfer between solar photovoltaic (PV) array and the grid/ load along-with power quality (PQ) improvement by eliminating harmonics and compensating reactive power required by the load in the distribution network. The PQ problems at the point of intersection, are increasing preeminently with respect to voltage and current harmonics due to integration of renewable sources. The recursive digital filter control implemented here for PV grid interfaced system is efficient in improving PQ indices by operating round the clock and ensuring power transfer between utility grid and connected loads. The prominence of the control algorithm lies in the efficient switching of voltage source converter (VSC), by generating reference grid currents, which are obtained through indirect current control technique. The recursive digital filter is utilized for processing the load currents and extracting the active power component of them. These active power components of load currents are used for generating the reference grid currents in this system. A prototype of the system is developed in the laboratory and its performance is studied for varying loads, changing solar insolation, and voltage swell, voltage sag and voltage distortion conditions.