Fuzzy logic controller-based synchronverter in grid-connected solar power system with adaptive damping factor

Abstract

In recent years, renewable energy sources, specifically solar power systems, have developed rapidly owing to their technological maturity and cost effectiveness. However, its grid integration deteriorates frequency stability because of insufficient rotating masses and inertial response. Hence, a synchronverter, which is an inverter that mimics the operation of a synchronous generator, is crucial to interface solar power in a power grid. It stabilizes the power grid by emulating a virtual inertia. However, a conventional proportional-integral (PI)-based synchronverter is not equipped with an adaptive damping factor (Dp) or a digitalized smart controller to manage fast-responding solar inputs. Hence, a novel fuzzy logic controller (FLC) framework is proposed such that the synchronverter can operate in a grid-connected solar power system. In this study, Dp is controlled in real time using an FLC to achieve balance between speed and stability for frequency error correction based on frequency difference. Results of four case studies performed in Matlab/Simulink show that the proposed FLC-based synchronverter can stabilize the grid frequency by reducing the frequency deviation by at least 0.2 Hz (0.4%), as compared with the conventional PI-based synchronverter.