Small signal sensitivity technique for determining inter-connector transfer limits

A new simulation technique has been developed for determining oscillatory stability transfer limit of an inter- connector. The small signal sensitivity algorithm calculates the rate of change of small signal oscillatory damping with respect to the change in inter-connector power transfer. The significant level of correlation between the derivative of small signal damping and the small change in power transfer makes the determination of transfer limit possible. Empirical formulas of damping constant with respect to inter-connector power transfers are then developed. This technique has been successfully applied to determine the small signal transfer limits of the South Australia - Victoria (SA-VIC) inter-connector and Queensland-New South Wales inter-connector (QNI) in the Australian National Electricity Market (NEM). From the QNI transfer limit study, it is observed that the effect of voltage stability takes over the oscillatory stability at high power transfer. The application and limitation of this technique is further discussed.