Dual Mode Control of Grid Tied Solar PV-DSTATCOM by Utilizing Warped Digital Filter in Distribution System

Abstract

For the efficient functioning of grid tied solar photovoltaic array in distribution system, the control algorithm is proposed here utilizing a warped digital filter. The solar photovoltaic (PV) array supplies maximum power to the grid/the load by maximum power point tracking (MPPT) technique namely a perturb and observe (P&O) method. The control is termed as a dual mode, as it performs satisfactorily during availability/unavailability of solar PV array power. When the solar PV array power is incident, the proposed system is capable of transferring active power from solar PV array to the grid/the load while improving power quality using a voltage source converter (VSC) working as a distribution static compensator (DSTATCOM). However, during cloudy days or at night, when solar power is not present, the system performs as DSTATCOM for reactive power compensation and elimination of harmonics. The control algorithm provides smooth transition between these modes of operation of the system. The control implemented using warped digital filters, is adaptive as its coefficients are updated depending upon system requirements. A feed-forward term for solar PV array power is incorporated, for the enhancement of dynamic response. A prototype of the system is developed in the laboratory and its performance is studied for varying loads, varying solar insolation conditions and change of modes between grid tied PV array and DSTATCOM.