2002/03 SEMA/RI Export and Short-Term Upgrade Analysis

Tuesday, February 4, 2003

SEMA

SEMA / RI EXPORT SEMA / RI EXPORT

SEMAGRI

VERMONT

NH

WESTERN MASS

CONNECTICUT

SWCTNORWALK-STAMFORD

SEMARI

LINE 336

CENTRAL MASS

COMERFORD MOORE

DOWNTOWN BOSTON

BOSTON

NEMA

SOUTHERN MAINE

BHE

MAINE

Generation/Load

• Generation Capacity in SEMA/RI – SEMA: 3633 MW (WSCC), 3350 MW (SSCC)

– RI: 5890 MW (WSCC), 5414 MW (SSCC)

– SEMA/RI: 9523 MW (WSCC), 8764 MW (SSCC)

• Load– Year 2002

– SEMA: 2304 MW, RI: 2009 MW,

– SEMA/RI: 4313 MW (17.8% of NEPOOL load)

– Year 2003 (forecast)

– SEMA: 2358 MW, RI: 2056 MW

– SEMA/RI: 4414 MW

Objectives

• Determine a set of maximum concurrent transfers among SEMARI, SEMA and E-W

• Investigate the sensitivities of E-W transfers based on different NY-NE transfers

• Determine the short-term upgrades required to enhance the export capability.

Criteria

• This study concentrated on the system responses to extreme contingencies (3ph fault with delayed clearing)

• System responses are unacceptable if – Transiently unstable, or– Transient stable with undamped oscillation, or– A net source loss over 1400 MW

Recommendation – Stability Performance Analysis

• Modify or replace the following breakers to achieve Independent Pole Tripping (IPT) capability:

West Medway 111, 112 (completed) Millbury 314 (completed) Sherman Road 142 (completed) West Walpole 104, 105, 108, 109 (2003)

140 141 141A 142

143

L347 to Lake Road

Ocean State Power

L328 to W. Farnum

L3361 to ANP Blackstone

Sherman Road Substation

L333

314

1402

302

343

4357

L323 to W. Medway

L343 to Sandy Pond

L357 to W. MedwayL301/302 to Carpenter Hill and Ludlow

L314 to Sandy Pond

Millbury Substation

111 112

107 108 109

104 105 106

101 102A 102 103

L389 to W. Walpole

L325 to W. Walpole

L344 to Bridgewater

L3520 to ANP BellinghamL336 to ANP Blackstone

L357 to Millbury

L323 to Millbury

240-601 to Framingham Auto

W. Medway Substation

282-602 to Waltham Auto

107 108 109

104 105

L389 to W. Medway

L331 to Carver

L316 to HolbrookL25 to W. Medway

W. Walpole Substation

SEMA/RI Stability Limits

Before all the IPT modifications:– SEMA/RI 2400 MW– SEMA 400 MW– E-W 850 MW

• The current stability limits (West Walpole non-IPT)– SEMA/RI 2400 MW– SEMA 1350 MW– E-W 850 MW

• After all the IPT modifications– SEMA/RI 3000 MW– SEMA 2300 MW– E-W 2400 MW

Impact of various NY-NE transfers on E-W stability limits

• After the breaker upgrades, SEMARI 3000 MW, SEMA 2300 MW can be achieved simultaneous with– if NY-NE 1500 MW, then East-West 2700 MW– if NY-NE 0 MW, then East-West 2400 MW– if NY-NE -1200 MW, then East-West 1700 MW

Canal Substation

• Extreme contingencies at Canal substation cause a total source loss over 1400 MW (Canal unit 1 and 2, NB-NE tie trip)

• Canal non-IPT breakers 212, 312, 412, 112, 512 and 612

• Upgrade breakers to meet IPT requirement or reduce the backup clearing time to achieve an acceptable system response

Brayton Point substation

• Non-IPT breaker 15-300T and 03-300T

• Total source loss over 1400 MW

• Upgrade or replace 15-300T and 03-300T to meet IPT requirement.

Follow-Up Stability Analysis

• Long-term transmission expansions are required to further increase the SEMARI transfer limits

• Stability analysis of long-term alternatives is in progress right now