Determination of the interruptible load carrying capability in a generation system

A generating system, consistent with its reliability criterion, is capable of serving a firm load for which it is built. In addition to the firm load, the same generating system is capable of supporting a limited amount of interruptible load. This capability is defined as the interruptible load carrying capability (ILCC) of that system. The additional load is served by the resources acquired to serve the firm load, without affecting the reliability of the firm load. The magnitude of ILCC for a given system increases with the reliability of the system, with increased duration of interruption and with the level of reliance that is placed on the emergency operating procedures. The authors present a probabilistic approach used to calculate the ILCC of the Alberta Interconnected System (AIS). These findings helped to determine the maximum level of interruptible load service that Alberta´s electric utilities can offer their customers. The impact of various factors on ILCC is discussed and the process is illustrated with numerical results.