Improved power quality with an adaptive grid-forming inverter control scheme in solar PV system

In this paper, an improved fractional order notch filter (IFONF)-based grid-forming inverter control scheme is employed to mitigate the harmonics in photovoltaic system applications. Moreover, a fuzzy gain tuning proportional-integral-derivative (FTPID) controller is developed for the dc-link voltage to maintain its reference value. The proposed FTPID-IFONF control scheme is executed to evaluate the active fundamental weight components (FWC) of the load currents and distorted grid voltages consequently generates the PWM pulses to the grid-forming inverter for power quality enrichment in a grid integration with photovoltaic applications. The integer order based filters have some constraints due to differentiator term and fixed integrator. For this reason, an improved design of an integer order notch filter is suggested in the proposed FTPID-IFONF controller scheme. The behavior of the proposed FTPID-IFONF control scheme is found good in-terms of elimination of dc offset, grid-synchronization, separation of fundamental components, adaptive behavior and harmonic elimination at the consumer terminals. The proposed controller is validated under several load and grid dynamic conditions such as steady-state, grid voltage sag-swell, distorted, load dynamic and removed conditions on MATLAB/Simulink platform. A prototype PV integrated with grid setup is constructed to validate the proposed system in the real-time. The FTPID-IFONF control scheme is well justified under several grid and load dynamic conditions and the harmonic distortions of the grid characteristics are found well based on the limits of IEEE-519 standards. A comparative study is also analyzed to show the effectiveness of the controller with recently published works.