Stability analysis of adjustable-speed induction-motor drive using genetic algorithm

Adjustable-speed induction-motor drives can experience sustained oscillations at low frequencies and light loads. It is thus advantageous to ensure their reliable operation by closely monitoring their performances against any potential loss of stability occurring during operation. This paper proposes a genetic algorithm (GA) with conserving for mapping the instability region of an induction-motor drive, by identifying all its eigenvalues with zero real-parts in one execution. Due to its simplicity, the proposed GA can also be individually executed for studying the stability impacts of any perceivable parametric variation occurring during operation. With this, the operator will be able to monitor any variation of instability region during operation, track undesirable operational variations, identify worst-case disturbances occurring during operation, synthesize appropriate preventive/ corrective remedial actions and maintain low-risk operation. The proposed GA is applied to an induction-motor drive with constant V/Hz control. Case studies are conducted by using the proposed GA for assessing the stability impacts of changing V/Hz control and changing induction-motor parameters occurring during operation.