Available transmission capability - Sell firm or interruptible?

Available Transfer Capability (ATC) is an important parameter for all companies participating in the power transaction activities. One aspect of the ATC analysis relates to the following important questions: what part of the posted ATC should be bought/sold as firm and what as an interruptible (non-firm) capacity? In the emerging competitive electricity market, this will perhaps be one of the crucial problems faced by the market participants. This problem has not been discussed in the literature yet, and is considered in this paper by calculating the optimal split between firm and interruptible ATC, using a DC load flow model and Monte Carlo optimization approach.