Interconnection of Solar PV System to Abnormal Grid Using Adjustable Frequency Generalized Integrator Filter Based Control

This paper provides effective power quality improvement and DC offset removal for dual stage single phase grid connected solar photovoltaic (PV) system by incorporating adjustable frequency generalized integrator (AFGI) filter. The system also complements the maximum power output of solar PV array using driftless perturb & observe (P& O) maximum power point tracking (MPPT) technique and addresses the drift problem at varying insolation levels. This control provides satisfactory frequency estimation under the conditions of distorted grid voltage and varying grid frequency. The phase locked loop (PLL) less control not only improves the system dynamics and makes it robust, but it also facilitates it to exploit the system resources during the unavailability of sun irradiance and fulfils the load requirement of reactive power as well as harmonics compensation for local loads. The system is analyzed under various dynamic conditions of grid voltage distortion, DC offset, grid voltage swell, PV power variation, load variations using a developed Simulink model. The system complies with the IEEE-519 standard, eliminating the grid current deformations and maintaining a sinusoidal shape at real time fundamental grid frequency.