Optimized virtual impedance solar restoration droop emulated SEPIC controller under low irradiation

Abstract

This paper is focused on PV-based reduced order pade’s approximation SEPIC (single-ended primary inductor converter) virtual Impedance, restoration controller with parallel impedance emulation condition. However, the complexity of the higher-order SEPIC controller has been reduced and compared using Pade’s approximation with different reduction techniques. It covers the time response, oscillation, overshoot, dynamic performance, and controller stability. The computational time and need of the sensor are less, and better responses occur compared to the other reduction technique under the solar irradiance variation. However, in PV, the dynamic resistance is generalized by a nonlinear solar I–V (current–voltage) curve dependent on the operating point, such as irradiance, temperature, and its I–V curve. The nonlinearity effect affects the stability of the system. The SEPIC outer voltage and inner current controller with virtual impedance controller enhance the stability, and comparative response is demonstrated through the bode plot. A virtual impedance controller (VIC) cascaded with voltage restoration minimizes the voltage notching and oscillations under variation of inertia coefficients. The transient and dynamic performance of reduced order using a genetic algorithm controller has been used to demonstrate and discuss the PV-SEPIC system’s stability.