Small-signal stability modelling, sensitivity analysis and optimization of droop controlled inverters in LV microgrids

Abstract

Islanded microgrids can enhance the resilience of power systems. Their stability is subject to ongoing research. This work introduces a unique way of sensitivity analysis, parameter tuning and optimization with respect to small-signal stability of grid-forming and grid-supporting droop controlled inverters in microgrids. A large selection of parameters is incorporated and simultaneously optimized based on a genetic algorithm. The sensitivity of parameters so far not considered in literature, such as the measurement filter time constant, is analysed. Simplifications often accepted as valid, e.g. the neglect of current and voltage controller or the line dynamics, are reviewed using the optimized parameter sets and providing new insights into the accuracy of model reduction techniques. Results indicate that the stability can be enhanced drastically by simultaneously optimizing a wide range of parameters. Model simplifications often seen as valid in literature must be carefully considered, as they can result in conservative stability assessment, especially for grid-forming droop control. The results of this work are relevant for the microgrid small-signal stability analysis in numerous contexts, such as reconfiguration, topology optimization or optimal placement of inverters.