Small-signal modeling and robust multi-loop PID and H_∞ controllers synthesis for a self-excited induction generator

Area of Science:

• Electrical Engineering
• Control Systems
• Power Systems

Background:

• Self-excited induction generators (SEIGs) present modeling challenges due to non-linearities and uncertainties.
• Accurate mathematical models are crucial for effective controller design in SEIG systems.

Purpose of the Study:

• To develop robust multi-loop controllers for terminal voltage and stator frequency regulation in three-phase SEIGs.
• To address the inherent complexities and uncertainties in SEIG system modeling.

Main Methods:

• A small-signal-based modeling approach using preprocessed experimental data from an actual SEIG system.
• Design of three robust voltage H∞ controllers and one robust frequency controller using classical and structured H∞ synthesis.
• Integration of controllers into a multi-loop system for simultaneous voltage and frequency regulation.

Main Results:

• Validated linear small-signal models for SEIG voltage and frequency.
• Demonstrated effectiveness of robust multi-loop controllers through simulation and experimental tests.
• Achieved a good trade-off between Nominal Performance (NP) and Robust Stability (RS) margins for the nominal operating point.

Conclusions:

• The proposed small-signal modeling and robust multi-loop control strategy effectively regulates SEIG terminal voltage and stator frequency.
• The controllers ensure performance and robustness for the nominal plant and neighboring uncertainty models.
• Significant deviations in operating points can compromise the NP-RS trade-off, highlighting limitations for highly dynamic conditions.