National Grid Local System Plan

1. National GridLocal System Plan Needs Assessment/Potential Solutions PAC Meeting September 30, 2009

2. Agenda • Local System Plan (LSP) Background • Purpose • National Grid information • Planning process • LSP Project List • Study Example

3. Purpose of Local System Plan Per Attachment K – Local, the LSP is a report that: • Describes projected improvements to non-PTF that are needed to maintain system reliability • Reflects: • LSP Needs Assessments • Corresponding transmission system planning and expansion studies • Identifies: • Local Planning Process • Criteria, Data, and Assumptions

4. LSP Communication • PAC, Transmission Customers, and other Stakeholders have 30 days to provide any written comments for consideration by National Grid. • National Grid’s contact: Gabriel Gabremicael Mgr Transmission Planning, New England National Grid 40 Sylvan Road Waltham, MA 02451-1120

5. LSP Communication Continued • The ISO-NE RSP project list links to each individual TO’s LSP project list. • National Grid’s project list is located at: • http://www.nationalgridus.com/oasis/filings_studies.asp • "LSP - LTP Transmission Projects - August 2009"

6. Approach to Updates • An LSP project list is required to be updated at least annually. • National Grid intends to update the posted project list on a semi-annual basis to reflect changes on projects. • A presentation of the LSP will be made annually.

7. LSP Project List • The LSP Project List is a cumulative listing of proposed regulated transmission solutions that may meet LSP needs. • Lower voltage facilities contained in the LSP Project List pertain to facilities supplying our wholesale municipal customers. • The LSP Project List contains the status of each project: • Concept • Proposed • Planned • Under Construction • In Service

8. LSP Project List

9. Local System Planning Process • Local studies can result from: • Load Growth • Area Reliability Assessments • Point of Delivery Request from Customer • Generation Interconnection Request • A Planner – • summarizes the results from the needs assessment and provides: criteria, data and assumptions used in study • builds study cases with proposed alternatives • determines the most effective solution • summarizes the results of the solutions study

10. Criteria • All National Grid facilities that are part of the interconnected National Grid system shall be designed in accordance with the National Grid Transmission Planning Guide. • The National Grid Transmission Planning Guide is posted on our website under: • http://www.nationalgridus.com/transmission/c3-8_standocs.asp • as: • Transmission Planning Guide

11. Data and Assumptions Resources for studies: • NEPOOL Library cases for load flow and ASPEN short circuit studies • CELT Report Load forecasts for NE wide loads • Customer provided forecasted loads for local areas

12. 2009 LSP Projects

13. LSP – Massachusetts

14. LSP – Massachusetts Continued

15. LSP – Massachusetts Continued

16. LSP – Massachusetts Continued

17. LSP – Massachusetts Continued

18. LSP – Massachusetts Continued

19. LSP – Rhode Island

20. LSP – Removed From 2008 List

21. Local System Planning Process Study Example

22. Study Area – Norwell C3 & S9 lines • Norwell Area C3 & S9 115 kV transmission lines’ related Loading and Reliability concern: • Norwell area is located in the Southeastern part of Massachusetts. It is presently served via C3 and S9 115 kV transmission facilities out of Auburn Street substation in Brockton, Massachusetts. Presently, the total load served via the C3 and S9 lines is approximately 220 MW. Since, there are only two 115 kV supply lines to the area, there is loading and reliability concern during contingency loss of one of the two supply lines to the area.

23. Norwell Area Map

24. System Impact Study (SIS) – Needs Assessment • Steady State analysis: Results of N-0, N-1 analysis – To evaluate the steady-state reliability of the transmission system, summer peak load cases were used: originated from ISO-NE 2007 library base cases and load levels according to the ISO-NE CELT 2009 report, and National Grid’s 2009 PSA forecast for the area. Thermal and voltage analysis were performed for all facilities in service (N-0) and for all single contingency (N-1) applicable to the area. • Results of the steady state N-0 analysis did not show thermal and voltage related issue in accordance to National Grid Transmission Planning Guide. • Results of the steady state N-1 analysis did not show voltage related issue in accordance to National Grid Transmission Planning Guide. However, 115 kV C3 line showed possible thermal overloads during contingency loss of 115 kV S9 line for the summer peak load case of 2012. • Short-Circuit analysis: Results – will be performed only for the recommended plan • Transient Stability: Results – will be performed only for the recommended plan

25. G G Present Layout – Norwell NO.ABINGTON The 115 kV radial C3 & S9 transmission lines supply Norwell, Scituate, Plymouth Street, North Abington, Phillips Lane, and Water Street substations in the eastern portion of Brockton Power Supply Area (PSA). 2.0 C3 3.0 2.7 6.3 2.7 6.3 S9 2.6 3.0 OP. OP. OP. AUBURN. ST G 2.5 NORWELL SCITUATE PLYMOUTH.ST PHILLIPS LANE WATER.ST * The numbers in red background indicate approximate distances in miles

26. Solutions – Norwell Alternative 1: Build a transmission line interconnecting C3 & S9 lines with any nearby transmission line (e.g., 478-509) Alternative 2: For higher reliability, CBs should be placed at Water Street or Phillips Lane. Water Street is ruled out due to space constraint. In-line CBs at Phillips lane. Alternative 3: Ring bus at Phillips Lane to address reliability related issues. Alternative 4: Both breakers at Phillips Lane and Switch closed permanently at Norwell Sub to address reliability related issues.

27. Solutions – Norwell Alternative 1: Build a transmission line interconnecting C3 & S9 lines with any nearby transmission line (e.g., 478-509).

28. Solutions – Norwell Alternative 2: For higher reliability, CBs should be placed at Water Street or Phillips Lane. Water Street is ruled out due to space constraint. In-line CBs at Phillips lane.

29. Solutions – Norwell Alternative 3: Ring bus at Phillips Lane to address reliability related issues.

30. Solutions – Norwell Alternative 4: Add two breakers at Phillips Lane and Switch closed permanently at Norwell Sub to address reliability related issues.

31. Study Status • Presently alternatives have been evaluated for Steady state related analysis. • Reliability related analysis is pending. Also, cost estimates for alternatives have been requested from various departments. • Upon evaluating the alternatives, a recommendation will be made for the alternative that best addresses the area concern with the most cost effective approach.

32. Questions Questions