Nonlinear adaptive command-filtered backstepping controller design for three-phase grid-connected solar photovoltaic with unknown parameters

A robust nonlinear control strategy, based on back-stepping, is presented to adjust the dc-link voltage from the PV system and the current which is used to control the amount of injected active or reactive power into the grid. The control system is projected using an adaptive backstepping technique taking the unknown parameters into consideration. But many times, the problems of differential expansion and the control saturation in backstepping theory are very hard and difficult, we employ a command filter to eliminate the impact of time derivative and control saturation. The devised controller is adaptive to the unknown parameters of the PV system and those parameters are estimate via the adaptive laws for the sake of guaranteeing the stability of dc-link voltage extracting from the PV solar and the appropriate amount active and reactive power injecting to the grid. The stability of the entire system is disposed on account of the Lyapunov functions (LPF). In the end, the effect of the proposed controller is measured on a grid-connected solar PV inverter system under the change of the reference values of PV system. The result of the simulation indicates excellent dynamic following performance and strong robustness with the proposed controller.