Study of PLL less DSGTP System using band-pass filter and APC (active power coefficient) control

Abstract

This paper represents a study on a grid-tied photovoltaic (PV) system connected to a non-linear load. The system includes a PV array, a boost converter, a voltage source inverter (VSI), and a coupling inductor for grid connection. The maximum power point tracking (MPPT) mechanism based on Perturb and Observe (P&O) method which is used to control the duty ratio of the boost converter. Synchronization is achieved through a second-order band-pass filter instead of a Phase Locked Loop (PLL). However, the non-linear load causes poor current quality, leading to a high Total Harmonic Distortion (THD) in the grid current, which may affect the sinusoidal nature of the grid current and other connected loads. To address the harmonics problem, an Active Power Coefficient (APC) control technique is implemented to control the PV inverter gate pulse. The proposed model has been simulated in Matlab/Simulink, and system output parameters are analysed graphically. The simulation results indicate that the proposed approach maintains the total harmonic distortion (THD) of the grid current below 5% even in changing weather conditions, which satisfies the IEEE 519 standard.