Single-Phase Grid Interfaced Hybrid Solar PV and Wind System using STF-FLL for Power Quality Improvement

In this paper, a self-tuning filter-frequency locked loop (STF-FLL) based control algorithm is proposed for power quality improvement in single phase utility grid integrated to solar photovoltaic (PV) array with a permanent magnet synchronous generator (PMSG) based wind energy generation system (WEGS). The STF-FLL control is designed for effective extraction of fundamental components of load current. The proposed technique offers a high degree of insensitivity and immunity to power disturbances. The main objective of the system, is to supply active power to the load and a single phase grid, connected at point of common coupling (PCC). Moreover, it also mitigates the power quality issues like grid current harmonics distortion and provides load reactive power compensation. The grid connected voltage source converter (VSC) acts as a distribution static compensator (DSTATCOM) in the absence of power from the PV array as well as from the wind turbine and improves the power quality of the current drawn from the grid. The STF-FLL technique extracts the fundamental components of the grid voltage for grid synchronization. To achieve maximum power, a perturb and observe (PO) based maximum power point tracking (MPPT) algorithm is used. A feed-forward term for solar and wind contribution, is introduced for improving the dynamic response for the changes in solar insolation and wind speed, respectively. The implementation of proposed control is simple and the system response is fast. The behavior of system is tested under dynamic loading, variable solar insolation and changing wind speed conditions on a developed prototype in the laboratory. The performances of proposed system satisfy the objective the proposed scheme and the IEEE-519 standard.