Disturbance-rejection control for unbalanced operation of microgrids: Invariant-set approach

Area of Science:

• Electrical Engineering
• Power Systems

Background:

• Voltage imbalance significantly degrades power quality in microgrids.
• Controlling voltage unbalance is essential for reliable microgrid operation.

Purpose of the Study:

• To propose a novel tracker design for mitigating voltage imbalance in microgrids.
• To attenuate the impact of negative sequence components treated as bounded disturbances.
• To ensure stability and improve power quality under unbalanced conditions.

Main Methods:

• A microgrid model incorporating positive and negative sequence components was developed.
• Control strategy based on attracting ellipsoid-set and invariant-set principles was designed.
• The H∞ approach was utilized for tracker synthesis to minimize ellipsoid volume.
• Norm-bounded uncertainty was employed to model external disturbances.

Main Results:

• The proposed tracker effectively mitigates voltage unbalance and negative sequence effects.
• Simulations demonstrated superior accuracy and dynamic response compared to the standard H∞ method.
• The control strategy proved effective under various unbalanced scenarios and faults.

Conclusions:

• The developed tracker design offers a robust solution for voltage imbalance control in microgrids.
• The invariant-set and H∞ approach provides enhanced performance in terms of accuracy and dynamic response.
• This method significantly improves microgrid power quality and operational stability.