ILST Control Algorithm of Single-Stage Dual Purpose Grid Connected Solar PV System

This paper presents a single-stage, three-phase grid connected solar photovoltaic (SPV) system. The proposed system is dual purpose, as it not only feeds extracted solar energy into the grid but it also helps in improving power quality in the distribution system. The presented system serves the purpose of maximum power point tracking (MPPT), feeding SPV energy to the grid, harmonics mitigation of loads connected at point of common coupling (PCC) and balancing the grid currents. The SPV system uses a three-phase voltage source converter (VSC) for performing all these functions. An improved linear sinusoidal tracer (ILST)-based control algorithm is proposed for control of VSC. In the proposed system, a variable dc link voltage is used for MPPT. An instantaneous compensation technique is used incorporating changes in PV power for fast dynamic response. The SPV system is first simulated in MATLAB along with Simulink and sim-power system toolboxes, and simulated results are verified experimentally. The proposed SPV system and its control algorithm are implemented in a three-phase distribution system for power quality improvement and improved utilization of VSC. The total harmonics distortions (THDs) of grid currents and PCC voltages are observed within IEEE-929 and IEEE-519 standards.