Suitability of aggregation methods of induction motor models for voltage stability analysis

Abstract

This paper focusses on the aggregation of multiple induction motors (IM) connected in parallel on the same bus into a single equivalent model using aggregation based on transformer equivalent circuit (method 1) and on no-load and locked rotor (method 2).This has been necessitated by the strong effects that the nonlinear loads have on power system characteristics and therefore erroneous modeling of these devices continues to be an area of greater uncertainty. Though various methods of a aggregations have been used, comparison on their suitability and accuracy has not been extensively explored. Also investigated is the suitability of multi-band power system stabilizer (MB-PSS) on the aggregate motor under a fault. The accuracy of these methods is compared to densify the most appropriate. Their performance is validated by evaluating the results obtained from individual and aggregate IM on IEEE 16 Bus test system. The results shows that method 2 is accurate than method 1 in identification of the motor parameters both under steady-state and under fault condition. The MB-PSS gives better damping of the oscillatory modes with method 2 than method 1. The former method can therefore be used for accurate analysis of voltage stability in a complex power system.