A normalized adaptive filter for enhanced optimal operation of grid interfaced PV system

This paper proposes a grid connected single-stage photovoltaic (GPV) system using an adaptive normalized notch filter (ANNF). An unknown time-varying fundamental frequency is precisely estimated from the normalized notch filter and consequently the fundamental load component is extracted using this algorithm. The convergence of the proposed algorithm is independent of both amplitude and the frequency of the fundamental component, and therefore, this algorithm is robust to these changes in the load current. The adaptive estimation of fundamental load current with perturbations on load/grid side system is well analyzed. The proposed ANNF control strategy is not only efficient in fundamental extraction, however, it also achieves the objectives of supplying real power to the grid, load current balancing and power factor correction. An experimental setup is developed to validate the proposed control under various perturbations. Test results are found satisfactory and the THDs in grid currents are achieved within the limits advised by IEEE 519 standard