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FERC makes available University Wisconsin-Madison “TIER Report” Concerning definition of Bulk-Power System Facilities

On September 12, 2009, FERC made available a report prepared by the University of Wisconsin-Madison entitled “Topological and Impedance Element Ranking (TIER) of the Bulk-Power System.”  The “TIER Report” was performed with support from the FERC Office of Electric Reliability as part of FERC’s ongoing efforts to more clearly define the facilities that comprise the bulk-power system and the criteria used to determine such facilities.


Generally, the TIER Report, which will be presented at a FERC technical conference on September 22, 2009, introduces a method for ranking branch elements in the electric grid (typically lines and transformers), with the purpose of: (1) developing a process to distinguish those facilities that should not be considered part of the Bulk-Power System from those facilities that should be considered part of the Bulk-Power System; (2) identifying the elements needed to operate each of the electric interconnections; and, (3) ranking the importance of those elements.  To view the TIER Report, click here.