Advanced droop control with PSO-optimized FOPI dual loop for DC microgrid stability under disturbances

Abstract Impedance interactions of parallel connected DC converter attached with nonlinear load is affected the converter system stability. To mitigate the converter system stability problem, Particle swarm optimization (PSO) based dual loop droop with Fractional order PI (FOPI) controller has been designed to mitigate the converter system stability with improved the dynamic performance of converter system formed a DC microgrid. Parallel energy source converter connected PV source converter with DC microgrid system have variation in output voltages during load and source disturbance by impacted by internal parameters of converter, line parameters and nonlinear loads. The droop control (primary controller) method decentralizes the power sharing by adjusting output voltage based on load current variations. Moreover, an additional a secondary dual loop controller encompassing voltage and current loops using Fractional order proportional integral controller (FOPI), is used to eliminate the problem associated with disturbance such as solar source converter current disturbance, load current disturbance, and source voltage variation, impedance interaction enhancing microgrid stability. The converters small signal model is verbalized for state space analysis. PSO optimizes the FOPI controller’s parameters, improving disturbance rejection and ensuring stable transient responses. Different case study as impedance interaction, solar source converter current disturbance, load current disturbance, and source voltage variation has been taken to validate the performance of advanced droop control with PSO-optimized FOPI Dual Loop controller over conventional controller, droop + PI and droop + FOPI controller. The modified controller (advance droop control with PSO-based FOPI dual loop controller) demonstrates superior performance with a 0.07 s settling time, 0.038 s rise time, and 1.02% overshoot. It outperforms the droop+PI and droop+FOPI controllers, improving settling time by 82.93% and 75.26% respectively, confirming its effectiveness over conventional methods in enhancing system stability and dynamic response under disturbances.