SOUTHWEST CONNECTICUT RELIABILITY PROJECT BY THE CONNECTICUT LIGHT AND POWER COMPANY DOING BUSINESS AS EVERSOURCE ENERGY VOLUME 4: PLANNING JUNE 2016 Connecticut Siting Council – Application SWCT Reliability Project Note: This page is intentionally left blank Connecticut Siting Council – Application SWCT Reliability Project INDEX VOLUME 4: PLANNING EX 1: ISO-NE, “Southwest Connecticut Area Transmission 2022 Needs Assessment,” June 2014, Redacted to secure Confidential Energy Infrastructure Information (CEII) EX 2: ISO-NE, “Southwest Connecticut Area Transmission 2022 Solutions Study Report,” February 2015, Redacted to secure Confidential Energy Infrastructure Information (CEII) EX 3: ISO-NE “Transmission Planning Technical Guide,” March 2, 2016 EX 4: London Economics “Analysis of the Feasibility and Practicality of Non-Transmission Alternatives (NTAs),” March 2015 Connecticut Siting Council – Application SWCT Reliability Project Note: This page is intentionally left blank Connecticut Siting Council – Application SWCT Reliability Project EXHIBIT 1: ISO-NE, “SOUTHWEST CONNECTICUT AREA TRANSMISSION 2022 NEEDS ASSESSMENT,” JUNE 2014, REDACTED TO SECURE CONFIDENTIAL ENERGY INFRASTRUCTURE INFORMATION (CEII) Connecticut Siting Council – Application SWCT Reliability Project Note: This page is intentionally left blank Connecticut Siting Council – Application SWCT Reliability Project Southwest Connecticut Area Transmission 2022 Needs Assessment REDACTED —PUBLIC VERSION © ISO New England Inc. June 2014 Table of Contents Section 1 Executive Summary ...................................................................................... 8 1.1 Study Objective ....................................................................................................................................... 8 1.2 Method and Criteria ................................................................................................................................. 8 1.3 Study Assumptions .................................................................................................................................. 9 1.4 Specific Areas of Concern ..................................................................................................................... 10 1.4.1 Frost Bridge – Naugatuck Valley Subarea Thermal and Voltage Needs ..................................... 10 1.4.2 Housatonic Valley / Norwalk – Plumree Subarea Thermal and Voltage Needs .......................... 11 1.4.3 Bridgeport Subarea Thermal and Voltage Needs ........................................................................ 11 1.4.4 New Haven - Southington Subarea Thermal and Voltage Needs ................................................ 12 1.4.5 Glenbrook – Stamford Subarea Thermal and Voltage Needs ...................................................... 12 1.4.6 Short Circuit Test Results ............................................................................................................ 12 1.4.7 Results of Generation Re-Dispatch Analysis ............................................................................... 13 1.5 Statements of Need ................................................................................................................................ 13 1.6 NERC Compliance Statement ............................................................................................................... 14 Section 2 Introduction and Background Information ............................................... 15 2.1 Study Objective ..................................................................................................................................... 15 2.2 Areas Studied ........................................................................................................................................ 15 2.3 Study Horizon ........................................................................................................................................ 18 2.4 Analysis Description ............................................................................................................................. 18 Section 3 Study Assumptions .................................................................................... 20 3.1 Steady State Model Assumptions .......................................................................................................... 20 3.1.1 Study Assumptions ...................................................................................................................... 20 3.1.2 Source of Power Flow Models ..................................................................................................... 20 3.1.3 Transmission Topology Changes ................................................................................................. 20 3.1.4 Generation Additions & Retirements ........................................................................................... 21 3.1.5 Explanation of Future Changes Not Included .............................................................................. 22 3.1.6 Forecasted Load ........................................................................................................................... 23 3.1.7 Load Levels Studied .................................................................................................................... 25 3.1.8 Load Power Factor Assumptions ................................................................................................. 26 3.1.9 Transfer Levels ............................................................................................................................ 26 3.1.10 Generation Dispatch Scenarios .................................................................................................. 27 3.1.11 Reactive Dispatch Assumptions ................................................................................................ 29 3.1.12 Demand Resources ..................................................................................................................... 30 3.1.13 Protection and Control System Devices Included in the Study Area ......................................... 30 3.1.14 Explanation of Operating Procedures and Other Modeling Assumptions ................................. 32 3.2 Stability Modeling Assumptions ........................................................................................................... 33 3.3 Short Circuit Model ............................................................................................................................... 33 3.3.1 Study Assumptions ...................................................................................................................... 33 Southwest Connecticut Area Transmission 2022 – Needs Assessment Report ISO New England Inc. ii 3.3.2 Short Circuit Model ..................................................................................................................... 33 3.3.3 Generation Additions & Retirements ........................................................................................... 33 3.3.4 Generation and Transmission System Configurations ................................................................. 34 3.3.5 Boundaries ................................................................................................................................... 34 3.3.6 Other Relevant Modeling Assumptions ....................................................................................... 34 3.3.7 Other System Studies ................................................................................................................... 34 Section 4 Analysis Methodology ................................................................................ 35 4.1 Planning Standards and Criteria ............................................................................................................ 35 4.2 Performance Criteria ............................................................................................................................. 35 4.2.1 Steady-state Criteria ..................................................................................................................... 35 4.2.1.1 Thermal and Voltage Limits .................................................................................................. 35 4.2.1.2 Solution Parameters ............................................................................................................... 36 4.2.2 Stability Performance Criteria ..................................................................................................... 36 4.2.3 Short Circuit Performance Criteria .............................................................................................. 37 4.3 System Testing ...................................................................................................................................... 37 4.3.1 System Conditions Tested ............................................................................................................ 37 4.3.2 Steady-State Contingencies / Faults Tested ................................................................................. 37 4.3.3 Generation Re-Dispatch Testing .................................................................................................. 39 4.3.4 Critical Load Level (CLL) Analysis ............................................................................................ 39 4.3.5 Stability Contingencies / Faults Tested