Research Papers: Gas Turbines: Electric Power

Risk-Based Assessment of Unplanned Outage Events and Costs for Combined-Cycle Plants

[+] Author and Article Information
Dale Grace

Senior Project Manager
Electric Power Research Institute,
3420 Hillview Avenue,
Palo Alto, CA 94025
e-mail: Dgrace@epri.com

Thomas Christiansen

Senior Vice President
Strategic Power Systems, Inc.,
11016 Rushmore Drive,
Suite 275,
Charlotte, NC 28277
e-mail: Christiansen@spsinc.com

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received July 3, 2012; final manuscript received August 14, 2012; published online January 8, 2013. Editor: Dilip R. Ballal.

J. Eng. Gas Turbines Power 135(2), 021801 (Jan 08, 2013) (7 pages) Paper No: GTP-12-1254; doi: 10.1115/1.4007732 History: Received July 03, 2012; Revised August 14, 2012

Unexpected outages and maintenance costs reduce plant availability and can consume significant resources to restore the unit to service. This paper describes a survey and analysis of unplanned outage events for 388 combined-cycle plants, based on 164 D/E-Class and 224 F-Class gas turbines. The 15-year timeframe included over 3000 unit-years of data. The causes and durations of forced outages and unscheduled maintenance were identified, and overall reliability and availability were established for each class of plant. Costs to restore the unit to service for each main outage cause were estimated, as were net revenues lost due to unplanned outages. A statistical approach to estimated costs and lost revenues provides a risk-based means to quantify the impact of unplanned events on plant cash flow as a function of class of gas turbine and plant subsystem. The risk-based assessment defines the range of probable costs of unplanned outage events.

Copyright © 2013 by ASME
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Grace, D. and Scheibel, J., 2001, “Technical Risks and Mitigation Measures in Combustion Turbine Project Development,” ASME Turbo Expo 2001, New Orleans, LA, ASME, Paper No. 2001-GT-0472.
Grace, D., 2008, “Combined-Cycle Power Plant Maintenance Costs,” ASME Turbo Expo 2008, Berlin, Germany, ASME Paper No. GT2008-51357. [CrossRef]
Grace, D., 2011, “Combined-Cycle Component Reliability Statistics: Technical Risk of Unplanned Outage Events,” EPRI, Palo Alto, CA, Paper No. 1023079.
Grace, D., 2011, CTCC O&M Cost Analyzer, Version 8.5, EPRI, Palo Alto, CA: 2011, Software No. 1021728.
Grace, D., 2011, SOAPP-CTWorkstation, Version 8.2, EPRI, Palo Alto, CA: Software No. 102165.


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Fig. 1

Unplanned outage rates for E-Class and F-Class combined cycle plants

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Fig. 3

Average cost to return to service per event for F-Class plants

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Fig. 2

Average cost to return service per event for E-Class plants

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Fig. 5

Lost net revenue: F-Class plant

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Fig. 4

Lost net revenue: E-Class plant

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Fig. 6

Average risk-adjusted annual cost of unplanned outages: E-Class plant

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Fig. 7

Average risk-adjusted annual cost of unplanned outages: F-Class plant

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Fig. 8

Probability curve fit to frequency versus individual event maintenance cost



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