Assessment of cycling costs of combined cycle units for frequency regulation

Abstract

Operation flexibility is a prerequisite to ensure the success of a power market operation. Due to the variable generation mix, generation units that are flexible to meet the challenge of ramping and provide operation reserve are important in today's system operations. Generators participating in frequency regulation and other ancillary services might lose energy market revenue due to reserved margins, thus regulation performance should be evaluated and paid for. The actual value of operation flexibility is dependent on the system characteristics and the market mechanism. Using the information available in energy management system and combined cycle power plants, this study proposes a simple and practical method to estimate the variant fuel cost increase of combined cycle units to provide frequency regulation service in an island power system. Based on actual operation data, analysis results testify the fact that the efficiency of the combined cycle units is reduced at lower loads and the units are subjected to different fuel cost increases at distinct operation configurations. The proposed method is justifiable and applicable for assessing variant costs incurred in providing energy system flexibility.