Analysis of combined cycle operating patterns

The world´s biggest new generating plant construction boom is drawing to a close. Natural gas fired combined cycle plants constituted the large majority of these additions. The developers who initially proposed these plants commonly expected them to enter service as base-loaded electricity suppliers with capacity factors near 80%. These projections, however, failed to account for many of the dramatic changes that have taken place in the ensuing years. The installed base of power generation increased by over 190 GW between 1999 and 2003, a 20% increase in only four years. During the same period, peak load demand rose by only 7%. The resulting excess of capacity has forced combined cycle power plants to compete for intermediate operations in many parts of the country. At the same time, natural gas prices have both risen dramatically and exhibited increased volatility, challenging the profitability of combined cycle plants. These factors in combination, present a very difficult environment in which to predict future plant operating level. This paper examines the historical operating patterns of combined cycle power plants and also how these patterns have changed in recent years. A fundamental power system simulation model is used to predict future operations. Using the fundamental model to predict the maintenance and parts needs for the entire fleet of units without needing to expressly consider the uncertainty inherent in each individual unit´s forecast operation is explored and discussed. Finally, the impact of these changes in combined cycle operating pattern is discussed from both an equipment owner standpoint, and the original equipment manufacturer (OEM) parts and services supplier. The advantages of sharing operating data are illustrated by some of the new products that have been introduced because of improved operating knowledge.