Low Voltage Ride-Through and Arctangent Based VSC Control with High Gain PV System for Power Quality Platform

In the presented work, a grid-tied solar PV (SPV) system with non-linear load operation has been controlled to obtain the active and reactive power flow during normal and unbalanced voltage sag conditions. During the normal voltage at a common point of connection (CPC), the active and reactive power demand of non-linear load has been met at unity power factor (UPF) by grid-tied PV system and PV arrays worked at maximum power point (MPP) by perturb & observe (P&O) algorithm. During the unbalanced voltage sag at CPC, to avoid the over-rating operation of the voltage source converter (VSC), one of the PV arrays is set to operate at non-MPP operation. The proposed arctangent-based modified least mean square (AM-LMS) algorithm offers UPF operation, lower grid current total harmonic distortion (THD), and reactive power support to the grid with ride-through conditions during unbalanced voltage sag. The AM-LMS also offers faster convergence, adjustable step-size parameters, and less computational burden to controllers. It also offers better tradeoff between dynamics and steady-state oscillations of weights of algorithm and hence provides robust control of VSC under normal and abnormal CPC voltage conditions. Based on parameter tuning, the tradeoff between convergence and stability with change in error are limitations. Such algorithms are mostly applicable to noise and error elimination from communications signals, power converters control etc. During sag, the DC-DC converter has been controlled to curtail the active power to prevent over-current operation of VSC. Based on the revised grid codes as per IEEE-1547-2018, the reactive power is supplied to the utility grid during sag conditions. The proposed AM-LMS control and grid-tied SPV system have been modelled and analyzed in MATLAB/Simulink environment.