New index parameter for rapid evaluation of turbo-generator subsynchronous resonance susceptibility

This paper proposes the use of a new index parameter which provides initial insight into the expected subsynchronous resonance (SSR) susceptibility of a turbo-generator without the need for detailed numerical calculations. This index parameter, derived from the modal representation of a turbo-generator shaft, is called the ‘torsional interaction susceptibility’ (TIS) and it indicates the propensity of a mode to become unstable due to torsional interaction. Calculated results are presented to show that this index parameter can be used to provide initial information about the expected SSR behaviour of a turbo-generator and to enable comparisons between the SSR behaviour of modes from different turbo-generators.