Disconnected pnode

The California ISO is proposing a modification to language in Section 27.1.1 to determine the closest electrically connected node for disconnected PNodes. This node will serve as the location from which the ISO will select the Locational Marginal Price (LMP) for the disconnected node. Since the start of operations under the new market design on April 1, 2009, when a Pricing Node (PNode) included in the ISO market model has been disconnected, the ISO markets have posted a "$0" Marginal Cost of Congestion (MCC). The software cannot calculate a cost of congestion when the PNode is disconnected from the system. This is because under such circumstances the Power Transfer Distribution Factor (PTDF) associated with the disconnected PNode and the binding constraint is zero. At such times, the optimization does not actually produce a price and therefore the price at that location, issued through the actual market clearing process, is undefined. After the optimization is completed the software inserts a zero value for the MCC at the disconnected PNode location.