Small-Signal Model and Stability Control for Grid-Connected PV Inverter to a Weak Grid

This paper presents a small signal stability analysis to assess the issues facing PV (photovoltaic) inverters connected weak grid. It is revealed that cause of transient instabilities, either high-frequency or low-frequency oscillations, dominated by outer control loops and grid strength. However, most challenging oscillations are induced coupling interaction between loop controller PLL (Phase-Locked Loop) when inverter Therefore, proposes damping methodology in order enhance high system integration, while maintaining system. The method uses DC link voltage error modulate reference reactive current. proposed reduces DVC (DC controller), AVC (AC controller) (Phase-locked loop). According this study’s results, performance capability grid-connected improved flexibility design enhanced. strategy tested using PLECS simulation software (Plexim GmbH, Zurich Switzerland) results compared with conventional method.