The Comprehensive Reliability Planning Process (CRPP) recently completed by NYISO represents a major advance in planning. It is a stakeholder process, described along with its criteria, organization, and approval process in the Reliability Needs Assessment (RNA) Support Document (NYISO, 2005, pp. 1-6). Below are the main points of the CRPP relating to this committee’s charge:
The reliability of the electrical generation and transmission system in the New York Control Area (NYCA) would be inadequate beginning in 2009 if, as is the case historically, thermally constrained transmission limits control transmission.1 The reliability criterion of loss-of-load expectation (LOLE) for the NYCA reaches 0.160 by 2009, and thus exceeds the New York State Reliability Council (NYSRC) criterion of LOLE of 0.1 or less.
The projected inadequate reliability by 2009 is a consequence of the factors listed below, in spite of new resources of about 2,890 megawatts (MW) coming online between 2005 and 2007 (including the 660 MW Neptune high-volt-age direct current (HVDC) cable from the Pennsylvania-Jer-sey-Maryland (PJM) Independent System Operator into Long Island). These compounding factors are as follows:
Projected load growth in southeastern New York State;
Increased electrical demand over the past decade of 5,000 MW in southeastern New York, only one-fourth of which was matched by net additions to generating capacity or load reduction downstate;
Scheduled retirements by early 2008 of about 2,250 MW of generating capacity and changes in neighboring power systems; and, consequently
Greater past reliance and higher projected reliance on a complex and aging transmission system.
The state’s transmission system is increasingly characterized by congestion, especially during summer peak loads, at the Upstate New York-Southeast New York (UPNY/ SENY) transmission interface, where power generated in northern and western New York state is transmitted toward the high-load centers in southeastern New York, especially New York City, Long Island, and, increasingly, Westchester County (NYCA Zones J, K, and I, respectively)—and by the complexity of the transmission system within New York City. Consideration of transmission transfer constraints, particularly at the UPNY/SENY interface (just north of Pleasant Valley, New York), is thus a key aspect of considering the projected reliability of the alternating current (AC) transmission system.
The New York Power Authority’s (NYPA’s) Poletti Unit 1 (Zone J, 885 MW) represents 39 percent, and Lovett Units 3, 4, and 5 (Zone G, 431 MW) represent 19 percent of the scheduled retirements of generating capacity by early 2008. Thus Poletti 1 and the Lovett Station’s units together total 1,315 MW and represent 58 percent of the scheduled retirements by mid-2008.
Addition of a corrective resource—an additional 250 MW of generating capacity in New York City (Zone J), beyond NYISO’s Initial Base Case—would be needed by 2009 to meet the NYCA LOLE criterion of 0.1. The additional generating capacity needed downstate increases to 1,250 MW by 2010 and to 1,500 MW by 2011.
Reactive power deficiencies in the Lower Hudson Valley (LHV) mean, however, that voltage-constraint limits2 in the transmission system, if not corrected, would control the reliability situation, rather than thermal transmission constraints. In this situation, the projected NYCA LOLE reaches 0.395 by 2008 and 2.43 by 2010. The impact if voltage constraints were to control—and if only adding more generation capacity were to be considered— would therefore be that an additional 500 MW of generating capacity would be needed in New York City (Zone J) by 2008, increasing to 1,750 MW downstate in Zones I through K by 2010 (unless an additional 1,500 MW were added in Zone J alone by 2010) (see NYISO, 2005).
The retirements of Lovett Station Units 2, 3, and 4 and Poletti Unit 1 by early 2008 therefore also result in the need in 2008 for a resource to correct reactive power, some 335 megavars (Mvar) of static VAR compensation (SVC) at Ramapo Substation (southern Zone G). By 2010, some 1,000 Mvar of SVC capacity would be needed downstate, 500 Mvar at Ramapo and 500 Mvar at Sprain Brook (southern Zone I). The inadequate NYCA system reliability beginning in 2008 or 2009 exists without the additional consideration of the hypothetical retirement of Units 2 and 3 of the Indian Point Energy Center that presently supply 2,138 MW of power and about 1,000 Mvar of reactive power downstate.
A brief scenario analysis describes the impact on NYCA system reliability of the hypothetical early retirement of the Indian Point Units 2 and 3 in 2008 and 2010, respectively. In this early-retirement scenario, the LOLE for the
Thermal limits relate to avoidance of overheating the transmission lines, a condition causing the lines to sag, and in some instances to touch vegetation, causing outages.
Voltage drop in the AC system must be tightly limited to maintain frequency and synchronous operation and to avoid physical damage both to generating equipment and equipment served as load.