Colloquia

Summary

The increasing penetration of renewable energy sources, primarily interfaced through inverter-based systems, introduces significant challenges in maintaining grid stability and performance under varying conditions. Tools such as MATLAB Simulink and Typhoon HIL are widely used and highly effective for validating power electronics systems; however, inverter operation is often highly sensitive to grid characteristics. Many existing studies focus on isolated scenarios, leading to custom designs for each application or unclear design decisions. This work aims to streamline the inverter design process and enable the development of inverters that are less sensitive to grid variations while staying within practical design constraints. It also lays the groundwork for a future automated control-hardware-in-the-loop (C-HIL) simulation framework. Modular inverter models are developed for C-HIL implementation, incorporating both grid-forming (GFM) and grid-following (GFL) control strategies using dqreference frame voltage and current control. An analysis of the grid’s short circuit ratio (SCR) is conducted to assess inverter performance under different grid strengths, revealing a trade-off between power quality and stability: GFL benefits from high SCR, while GFM provides better stability under low SCR conditions. The influence of an LCL filter on system dynamics is also examined. Additionally, a benchmarking study compares the robustness of SRF-PLL and DDSRF-PLL synchronization techniques in GFL inverters under weak grid conditions. Finally, the stabilizing effects of active damping are demonstrated, particularly in very weak grid scenarios.