Simple Approach to Estimate the Capacity Credit of Wind Electric Conversion Systems and Its Economic Aspect

Abstract

In this study, an effort has been made to develop a simple approach to estimate the capacity credit under variable load condition. It is based on replacing the annual load duration curve by a stepped function and calculating the capacity credit for each of the load steps. A weighted average of these values using the probability of the various load steps is proposed as an estimate of the overall capacity credit. As a next step, capacity credit is incorporated in a simple economic study with wind and coal-fired plants. Systems with different wind penetration levels are compared with the system with only conventional power plant (coal) in terms of various parameters such as annual energy production, generation cost and annual system CO2 emission etc. keeping the total system capacity constant. Findings and Conclusions: A simplified approach to assess the capacity credit of wind electric conversion systems (WECS) and its economic aspect has been presented. Results for weighted capacity credit show a pattern for all wind penetration values. Weighted capacity credit values decrease as penetration increases in the system. Also, weighted capacity credit value increases as the wind regime improves. Although this approach can be refined, it enables a rapid initial assessment of the capacity credit that can be used for planning purposes. As a next step, capacity credit is incorporated in a simple economic study with wind and coal-fired plants. Systems with different wind penetration levels are compared with the system with only conventional power plant (coal) in terms of various parameters such as annual energy production, generation cost and annual system CO2 emission etc. keeping the total system capacity constant. Results show that although the system's total annual energy production decreases with an increase in wind penetration, system generation cost / MWh is lower than the system with only coal fired plants. Also, there is a considerable decrease in CO2 emission with increasing in wind penetration.