Implementation of a Modified MPPT Strategy for Solar-PV Arrays Connected to Harmonic-Polluted Grids Under Partial Shading Conditions

Solar-PV systems are ubiquitously exploited to harvest solar energy and convert it to electric energy. In grid-connected solar-PV system there are some problems that affect the generating power and the system's power quality such as partial shading problem (PS) and harmonics. The PS of solar-PV arrays causes many problems such as hot-spot trouble in which the modules under shading conduct as loads and become inverse biased. As a result of this trouble the solar-PV power & voltage curve contains multiple peaks and traditional MPPT techniques require modifications to track the point of maximum power during PS conditions. System's harmonics are generated due to switching techniques of the voltage-sourced converter (VSC), also connecting non-linear loads to the system inject harmonics to the utility grid. A model of grid-connected solar-PV arrays through VSC using PSCAD/EMTDC software is presented with a modified Incremental Conductance (INC.) technique to track the MPP in both normal and PS conditions. Also, the system's harmonics and how to reduce their effect are studied and analyzed.