Blended Integral-Proportional/Proportional-Integral Control for Voltage Source Converter-Based AC Microgrids

Abstract

To allow a more effective utilization of distributed energy resources (DERs) in microgrids (MGs) and avoid violating operational limits of the asset, it is important that the stability and transient behavior or response of quantities such as voltages and currents is improved and maintained at appropriate levels. This paper uses small-signal analysis to investigate the behavior of blended integral-proportional/proportional-integral (IPPI) voltage and current controllers by deriving state-space models and performing eigenvalue analysis in a voltage source converter-based microgrid (VSC-MG). The results are compared with conventional PI-based voltage and current controllers on the same VSC-MG, and show that by adjusting the blending factor for each VSC’s IPPI-based voltage and current controllers, an improvement in stability and transient behavior can be achieved. An optimization framework based on particle swarm optimization is developed to aid in selecting blending factors for stable VSC-MG operation. Simulations are performed with the aid of MATLAB/Simulink to validate the theoretical analyses.

Keywords

• AC microgrid
• boost converter
• droop control
• integral-proportional control
• particle swarm optimization
• proportional-integral control