Evaluating the Droop Control Loop of the Grid-Forming Converter in an Isolated Resistive Network

The increasing use of renewable energy sources in power systems brings challenges in ensuring voltage and frequency stability, particularly in isolated or weak grids. Grid-forming converters have emerged as an effective solution, capable of replicating the dynamic characteristics of synchronous machines. This paper presents an evaluation of droop control loop applied to a grid forming converter within an isolated resistive network. The study examines three main scenarios: the grid forming converter's steady-state response to a sudden load change, the influence of varying R/X ratio on the stability and performance of the droop control loop, and the grid forming converter behavior during a balanced three-phase fault. The results indicate that while droop control generally maintains system stability, its effectiveness is heavily impacted by the R/X ratio, with lower ratios posing greater challenges. The response of the grid forming converter during a three-phase fault also provides key insights into the limitations and strengths of droop control in networks with different line resistance or fault resistance. These outcomes offer important contributions to the refinement of control strategies for grid forming converters, supporting the development of stable and reliable power systems, particularly in microgrid environments and other isolated networks with resistive nature.