1 May 2003 Stage 1 Completion Project Status Polytechnic UNIVERSITY Phase Angle as an Indicator of Imminent Voltage Collapse in Electric Transmission and Distribution System

2 Project Background R&D project proposed by Polytechnic University Joint research and analysis by LIPA and Polytechnic University Two stage project –Stage 1 (analysis using simulation software) is complete –Stage 2 (site-specific field implementation and testing) Tool for on-line system monitoring Polytechnic UNIVERSITY

3 Purpose of Project Polytechnic UNIVERSITY

4 Accomplishments Stage 1 - completed The simple one-loop analysis was expanded to a 9-bus model (of the LIPA network) study using a load-flow program. The actual load-flow program used by LIPA for the Long Island network was employed. Polytechnic UNIVERSITY

5 Southold Tiana Southampton Bridgehampton Riverhead Buell Generating Hero Orient Point Tuthill Mattituck Peconic East Hampton Amagansett Installation Site Areas of Voltage Collapse Concerns East End of Long Island

6 Study Conclusions Both the 9-bus and full load flow model analyses demonstrated correlation between increased system load and increased phase angle difference between a remote load bus and a reference bus. Phase angle difference increases more rapidly with the increased system load as compared to the remote bus voltage degradation. Therefore, phase angle monitoring is likely to be a better indicator of imminent voltage collapse. There is a consistency between phase angle profiles across a range of system loads for different system power factors. Study results support decision to proceed with field testing. Polytechnic UNIVERSITY

7 Polytechnic UNIVERSITY 345 kV vs 138 kV Swing Bus; PF = 0.93pu; Load Adjusted System-Wide

8 Polytechnic UNIVERSITY 345 kV Swing Bus; PF = 0.93pu; Load Adjusted East of Holbrook Only

9 Polytechnic UNIVERSITY 345 kV Swing Bus; PF = 0.90 vs vs.0.98; Load Adjusted System-Wide

10 Stage 2 - Planned Activities Field Test –Collect phase angle information by metering voltage & currents at 4H East Garden City 345kV reference bus and at 9U Montauk 23kV load bus Develop Guideline for System Operators for a set of system conditions System Operator Training Polytechnic UNIVERSITY

11 Site Specific Implementation Polytechnic UNIVERSITY

12 Polytechnic UNIVERSITY LOCAL PC For MONITORING DIAL – UP or WEB BROWSER EXSISTING LIPA OWNED DATA NODE MODEL 5530 CURRENT AND VOLTAGE INPUTS INFO NODE MODEL 5500 GPS CLOCK 9U MONTALK DATA NODE MODEL 5530 CURRENT AND VOLTAGE INPUTS INFO NODE MODEL 5500 GPS CLOCK 4H EAST GARDEN CITY Field Installation