Spinning Reserve From Responsive Loads

Abstract

Responsive load is the most underutilized reliability resource available to the power system today. It is currently not used at all to provide spinning reserve. Historically there were good reasons for this, but recent technological advances in communications and controls have provided new capabilities and eliminated many of the old obstacles. North American Electric Reliability Council (NERC), Federal Energy Regulatory Commission (FERC), Northeast Power Coordinating Council (NPCC), New York State Reliability Council (NYSRC), and New York Independent System Operator (NYISO) rules are beginning to recognize these changes and are starting to encourage responsive load provision of reliability services. The Carrier ComfortChoice responsive thermostats provide an example of these technological advances. This is a technology aimed at reducing summer peak demand through central control of residential and small commercial air-conditioning loads. It is being utilized by Long Island Power Authority (LIPA), Consolidated Edison (ConEd), Southern California Edison (SCE), and San Diego Gas and Electric (SDG&E). The technology is capable of delivering even greater response in the faster spinning reserve time frame (while still providing peak reduction). Analysis of demand reduction testing results from LIPA during the summer of 2002 provides evidence to back up this claim. It also demonstrates that loads are different from generators and that the conventional wisdom, which advocates for starting with large loads as better ancillary service providers, is flawed. The tempting approach of incrementally adapting ancillary service requirements, which were established when generators were the only available resources, will not work. While it is easier for most generators to provide replacement power and non-spinning reserve (the slower response services) than it is to supply spinning reserve (the fastest service), the opposite is true for many loads. Also, there is more financial reward for supplying spinning reserve than for supplying the other reserve services as a result of the higher spinning reserve prices. The LIPAedge program (LIPA's demand reduction program using Carrier ComfortChoice thermostats) provides an opportunity to test the use of responsive load for spinning reserve. With potentially 75 MW of spinning reserve capability already installed, this test program can also make an important contribution to the capacity needs of Long Island during the summer of 2003. Testing could also be done at ConEd ({approx}30 MW), SCE ({approx}15 MW), and/or SDG&E ({approx}15 MW). This paper is divided into six chapters. Chapter 2 discusses the contingency reserve ancillary services, their functions in supporting power system reliability, and their technical requirements. It also discusses the policy and tariff requirements and attempts to distinguish between ones that are genuinely necessary and ones that are artifacts of the technologies that were historically used to provide the services. Chapter 3 discusses how responsive load could provide contingency reserves (especially spinning reserve) for the power system. Chapter 4 specifically discusses the Carrier ComfortChoice responsive thermostat technology, the LIPAedge experience with that technology, and how the technology could be used to supply spinning reserve. Chapter 5 discusses a number of unresolved issues and suggests areas for further research. Chapter 6 offers conclusions and recommendations.