Letter Regarding ISO-NE System North-South Transfer Limits


Dated: April 19, 2012

Posted in:

Authored by:

April 19, 2012

Mr. Stephen Rourke
Vice President, System Planning ISO New England, Inc.
One Sullivan Road
Holyoke, MA 01040

RE: Request Information About Impediments to Expansion of North-to-South Transfer Limits

Dear Mr. Rourke:

The New England States Committee on Electricity (NESCOE) is interested in transmission system analysis that provides information for policymakers about potential enhancements that could increase the transfer limits of the north-to-south interface and the relative costs of implementing such upgrades. NESCOE seeks ISO-NE’s assistance in identifying the most efficient way to obtain such analysis given related work ISO-NE has underway.

First, NESCOE appreciates ISO-NE’s ongoing efforts to examine the implications of increased power flows from northern New England into southern New England in the context of two studies – the Maine Power Reliability Program (MPRP): Transfer Capability Study and the Strategic Transmission Analysis. NESCOE supports ISO-NE’s intent to further analyze the transfer capability of the transmission system through these studies. NESCOE is interested in exploring with ISO-NE whether and how either study may identify potentially cost-effective transmission system enhancements and upgrades. Measures that enable more efficient use of the existing transmission system’s assets and reduce production costs could help to provide service to customers at the lowest cost over the long term and may be in ratepayers’ interest. Accordingly, NESCOE requests assistance in identifying how to obtain better information on transfer capacity than we have today.

As an example, the MPRP Transfer Capability Study identified issues associated with a substation in southeastern Massachusetts. Further analysis may determine whether upgrading the substation to be bulk power system compliant and/or other enhancements related to resolving stability-testing failures could have an impact on the MPRP transfer limits. Alternatively, the Strategic Transmission Analysis assesses the transfer capability of conceptual transmission overlays designed to accommodate the integration of significant quantities of wind energy. It is possible that modifying the scope of the Strategic Transmission Analysis in a very targeted way could produce useful information about means to make the most efficient use of the transmission system.

More specifically, NESCOE is interested in further information about system upgrades that could increase the north-to-south transfer limits at low cost, thereby increasing the ability of power to flow from an export constrained area towards load centers.

NESCOE does not have a preference about how ISO-NE might identify upgrades that would increase the north-to-south transfer limits of the system to the potential benefit of the region’s ratepayers, but is interested in obtaining further assessment of the potential in the near term. Accordingly, to the extent that ISO-NE believes it could provide a reasonably accurate estimate of the information identified above by using its professional judgment and considerable experience operating the region’s electric system and with prior studies, NESCOE would welcome information on that basis. Alternatively, if more detailed analysis is necessary or appropriate, we would appreciate ISO-NE’s views on the most effective approach to obtaining such analysis.

Respectfully Submitted,

New England States Committee on Electricity
/s/ Heather Hunt
Heather Hunt
Executive Director