Stage: II (Review) Status: Complete Date commenced: 28/09/2011

The review notes that but for an error made by the system operator in resolving the infeasibility, unprecedented prices would have occurred at some nodes in the lower North Island (up to $56000/MWh).

The high prices are a manifestation of numerically correct, but economically questionable outcomes of the pricing model.

A conclusion of the review is that events on the 26th September be taken as a 'near miss' warning, and that urgent changes to some aspects of the Code are required. The review also recommends a generalisation of the high spring washer resolution process to mitigate other mechanisms by which extreme prices can be derived.

Review of 26 September 2011 infeasibility situatio