1. Reliability Criteria for Bulk Power System Design Richard V. Kowalski Manager, Transmission Planning ISO New England

2. Reliability Criteria for Bulk Power System Design © 2005 ISO New England Inc. 2 Reliability Standards/Criteria NERC (Planning Standards: TPL-001,004) –ftp://www.nerc.com/pub/sys/all_updl/standards/rs/TPL-001-0.pdf, TPL-002-0.pdf, TPL-003-0.pdf, TPL-004-0.pdf) NPCC (A2 – “Basic Criteria for Design and Operation of Interconnected Power Systems”) –(http://www.npcc.org/publicFiles/reliability/criteriaGuidesProcedur es/a-02.pdf) ISO New England (PP3 – “Reliability Standards For The New England Area Bulk Power Supply System”) –(http://www.iso-ne.com/rules_proceds/isone_plan/PP3_R2.doc)

3. Reliability Criteria for Bulk Power System Design © 2005 ISO New England Inc. 3 New England Reliability Standards Assure the reliability and efficiency of the New England bulk power supply system through coordination of system planning, design and operation. –Resource Adequacy –Area Transmission Requirements –Transmission Transfer Capability –Extreme Contingency Assessment –Extreme System Conditions Assessment

4. Reliability Criteria for Bulk Power System Design © 2005 ISO New England Inc. 4 Area Transmission Requirements: Key Elements - Serve load under enumerated contingency conditions Before and after any critical generator, transmission circuit, transformer, phase angle regulating transformer, HVDC pole, series or shunt compensating device has already been lost Due allowance for generator maintenance and forced outages Applicable transfers, load, and resource conditions that reasonably stress the system

5. Reliability Criteria for Bulk Power System Design © 2005 ISO New England Inc. 5 Relevance of Criteria Criteria & standards are the product of experience –http://www.nerc.com/~filez/dawg-disturbancereports.html Millions of combinations of potential system conditions: load levels, generation status, transmission outages The interconnected bulk power system is VERY complex; many tens of thousands of interacting pieces of equipment Consequences of failure (August 14, 2003) A “Normal” day –Multiple lines out of service –Over 2000 MW of unplanned generation outages A “Bad” day can be a lot worse Long repair time for some facilities (e.g. Transformers) Equipment needs to be maintained

6. Reliability Criteria for Bulk Power System Design © 2005 ISO New England Inc. 6 The Desired Outcome Planning the system to meet a wide range of reasonably stressed conditions should result a system that can be reliably and efficiently operated and maintained for reasonably foreseeable conditions