Enhancement of power quality in a weak grid using PV-coupled DSTATCOM with modified IRPT control

Abstract The integration of power electronic devices and renewable energy sources in the grid has introduced non-linearities and harmonics in the system. The photovoltaic-based distribution static compensator (PV-DSTATCOM) enhances power quality in the grid by suppressing harmonic components, balancing grid currents under unbalanced load conditions, and stabilizing the voltage at the point of common coupling (PCC) under grid voltage disturbance. For stabilized operation of PV-DSTATCOM in such a scenario, a modified instantaneous reactive power theory (IRPT) based control strategy has been proposed. The designed control strategy is applied to a PV-DSTATCOM, coupled with a weak grid, and aims to achieve multiple control objectives. This control algorithm generates the current reference signal for switching of PV-DSTACOM. Furthermore, proposed algorithm ensures that the power output from the solar PV is first utilized by the connected loads, and balanced energy is transferred to the utility grid. The performance of the proposed controller is assessed in comparison with the conventional IRPT technique and the UVT-based control strategy. The operational efficiency of the control algorithm under dynamic conditions is demonstrated through simulations performed in MATLAB/Simulink. The simulation results have been verified using a real-time simulator, OPAL-RT. The tests are conducted for nonlinear loading, unbalanced loading, grid voltage sag, grid voltage swell, and solar PV insolation changes. The test results are satisfactory, with grid current distortion levels lying within the limits specified by IEEE Standard 519.