Wind power modelling and the determination of capacity credit in an electric power system

Wind is an important energy source and is regarded as a valuable alternative to traditional electric power-generating sources. There is an increasing interest in the development and use of wind energy as a substitute for more conventional energy because of its high potential and minimum impact on the environment. Generating capacity from wind power behaves quite differently than that from more conventional generating sources, as the wind is highly variable and is both site and terrain specific. These conditions dictate the need to develop suitable models and procedures to assess the reliability implications associated with integrating wind power in electric power systems.

This paper presents an approach to modelling wind power in generating-capacity reliability studies using an autoregressive moving average (ARMA) time series. The technique is illustrated by application to a representative test system using wind data from a site in Saskatchewan, Canada. The test system is used to illustrate the effect on the system risk of adding increasing amounts of wind capacity to a conventional generating system. The risk is assessed using the loss of load expectation and loss of energy expectation indices. The generating capacity credit attributable to wind power is expressed in terms of the increase in system peak load-carrying capability at the criterion risk level. These analyses are extended to consider multiple wind sites with dependent and independent wind regimes.