Executive Summary

RLC Engineering, LLC (RLC) conducted an Interconnection System Impact Study (the "Study") under the ISO New England Inc. Open Access Transmission Tariff ("Tariff") Schedule 22-Standard Large Generator Interconnection Procedures ("LGIP") on behalf of ISO New England Inc. (ISO-NE) and Bangor Hydro Electric (BHE) for UPC Wind (UPC) to construct and interconnect a 60MW wind farm on Stetson Mountain in western Washington County, Maine.

The Stetson Mountain Wind Project (the "Project") is proposed to consist of 40, 1.5MW GE wind turbine-generators and will connect with BHE's 115-kV transmission system at the Keene Road switching station located in Chester, Maine. The Project is proposed to be in service by December, 2007.

The Study was performed in accordance with the ISO New England Operating Documents, including the Interconnection Procedures contained in Schedule 22 of the Tariff, and the ISO New England Planning Procedures 5-6, Minimum Interconnection Standard ("MIS"). Pursuant to Schedule 22, the Study was performed as an Interconnection System Impact Study ("ISIS"). The ISIS includes results: (i) assessing voltage limit violations and thermal overloads resulting from the interconnection; (ii) identifying any instability or inadequately damped response to system disturbances resulting from the interconnection; and (iii) assessing circuit breaker short circuit capability limits exceeded as a result of the interconnection.

The purpose of the Study was to:

(i) Analyze the steady-state, stability, and short circuit conditions for the Project

(ii) Determine any upgrades to the transmission system that would be required to mitigate any adverse impacts that the Project could otherwise pose on the reliability and operating characteristics of the New England transmission system in accordance with the Northeast Power Coordinating Council (NPCC) Document A-2 "Basic Criteria for Design and Operation of Interconnected Power Systems", the ISO New England Planning Procedure No. 3, "Reliability Standards for the New England Area Bulk Power System" and the ISO New England Planning Procedure No. 5-3, "Guidelines for Conducting and Evaluating Proposed Plan Application Analyses" and Bangor Hydro transmission planning criteria

(iii) Determine any upgrades required to mitigate any degradation to transmission transfer capability under ISO New England Planning Procedure No. 5-6, "Scope of Study for System Impact Studies under the Minimum Interconnection Standard"

The primary area of concern for this study is the area around BHE's Keene Road switching station in Chester, Maine. Currently the combined output from Brookfield Power (126MW) which is radial out of Keene Road switching station, and the Indeck 5 (25MW) plant located at the Enfield substation, is limited under summer conditions to avoid normal and contingency overloading of the Enfield - Graham section of Line 64. The Stetson Mountain Wind Project is proposed to be located approximately 40 miles east of the Keene Road switching station. The additional generation provided by the Project will only add to the congestion of Line 64, therefore under the Minimum Interconnection Standard the Project was dispatched against the Brookfield Power (formerly known as Great Lakes Hydro) facility in East Millinocket, Maine to maintain reliable loading in the study area.

Steady State

Steady state voltage and thermal analyses examined system performance without the proposed Project in order to establish a baseline for comparison. System performance was re-evaluated with the Project and compared with the previous baseline performance to demonstrate the impact of the Project on area transmission reliability under the guidelines of the Minimum Interconnection Standard.

Steady state analysis was evaluated at summer 2008 peak (29,775MW) and light load (12,555MW) levels. Four dispatch scenarios were created for each load forecast. An additional D5 dispatch was created for the peak load forecast only to evaluate the reactive capability of the Project. The objective of modeling these five stressed conditions was to examine the proposed
Project and the ability of the transmission system to reliably serve customer peak demand under all these system conditions.

Based upon the steady state results the Project poses no significant adverse impact on the reliability and operating characteristics of the interconnected bulk power transmission system and does not require any network upgrades beyond the interconnection station requirements of the Project at Keene Road S/S. No significant voltage or thermal violations of reliability criteria were associated with the Project when an equal amount of generation was turned off at the Brookfield Power - Powersville facility which also interconnects at Keene Road S/S.

Stability

Stability analyses evaluated the impact of the Stetson Mountain Wind Project on transmission system performance at summer 2008 peak (27,900MW) and light load (12,555MW) levels. Fault simulations established transmission system reliability performance under two dispatch scenarios for the peak load forecast and three scenarios for the light load forecast. The Project was dispatched against the Brookfield Power - Powersville facility.

The stability analysis analyzed the Project's impact on the transient stability performance of design contingencies in the vicinity of the Project and determined the Project's Low Voltage Ride Through (LVRT) performance met ISO NE criteria.

The stability results showed that the Project poses no significant adverse impact on the reliability and operating characteristics of the interconnected bulk power transmission system.

Short Circuit

Short-circuit analysis was conducted by Bangor Hydro-Electric to assess the impact of the Stetson Mountain Wind Project on the fault current levels and breaker duty in the area. The surrounding substation breakers were evaluated to determine if the transmission system changes create overduty conditions.

Short circuit duties were found to be within the ratings of the existing 115-kV system equipment. No adverse short circuit impact was found as a result of interconnecting Stetson Mountain Wind Farm.

Conclusion

The Interconnection System Impact Study revealed that the addition of the 60MW Stetson Mountain Wind Farm has no significant system impact on the reliability, stability and operating characteristics of the New England bulk power transmission system. No network upgrades are needed except those at the Keene Road substation which are directly related to the Project's interconnection.

Attachment:
Final_Draft_Report_UPC_Wind_Stetson_Rel_Com.pdf