Power system reliability impacts of wind generation and operational reserve requirements

Abstract

Due to its variability, wind generation integration presents a significant challenge to power system operators in order to maintain adequate reliability levels while ensuring least cost operation. This paper explores the trade-off between the benefits associated to a higher wind penetration and the additional operational reserve requirements that they impose. Such exploration is valued in terms of its effect on power system reliability, measured as an amount of unserved energy. The paper also focuses on how changing the Value of Lost Load (VoLL) can be used to attain different reliability targets, and how wind power penetration and the diversity of the wind energy resource will impact quality of supply (in terms of instances of unserved energy). The evaluation of different penetrations of wind power generation, different wind speed profiles, wind resource diversity, and different operational reserve requirements, is conducted on the Chilean Northern Interconnected System (SING) using statistical modeling of wind speed time series and computer simulation through a 24-hour ahead unit commitment algorithm and a Monte Carlo simulation scheme. Results for the SING suggest that while wind generation can significantly reduce generation costs, it can also imply higher security costs to reach acceptable reliability levels.Keywords: Wind power, uncertainty modeling, variable generation, reserve requirements, value of lost load. RESUMENDebido a su variabilidad, la integración de generación eólica presenta desafíos significativos para los operadores de los sistemas eléctricos a la hora de mantener niveles de confiabilidad adecuados asegurando, de forma simultánea, una operación a mínimo costo. Este artículo explora los beneficios asociados a una mayor penetración de generación eólica y los requerimientos adicionales de reservas operacionales que esta impone. Dicha exploración se realiza en términos de los efectos de la energía eólica en la confiabilidad del sistema, medida como cantidad de energía no servida. El artículo, además, se enfoca en cómo es que al cambiar el costo de falla se puede motivar el alcance de diferentes metas de confiabilidad, y cómo la penetración y diversidad del recurso eólico impactan la calidad de servicio (en términos de instancias de energía no servida). La evaluación de diferentes niveles de penetración, diferentes perfiles de velocidad de viento, diversidad del recurso eólico y distintos requerimientos de reservas operacionales, se lleva a cabo en el Sistema Interconectado del Norte Grande (SING) chileno usando modelos estadísticos de velocidad de viento y simulación computacional mediante un algoritmo de pre-despacho y un esquema de Monte Carlo. Los resultados para el SING sugieren que mientras la generación eólica puede reducir significativamente los costos de generación del sistema, también implica mayores costos de seguridad para alcanzar niveles de confiabilidad adecuados.

Regulating Reserve Dynamic Scheduling and Optimal Allocation in Systems with a Large Share of Wind-Power Generation

“…The operating impact of wind-power generation, as well as the corresponding additional grid-balancing requirements, have been studied widely [8][9][10][11]. The report in Reference [12] concluded that the impact of wind-power variability is relatively small in the regulation time scale (minutes), larger during the load-following time scale (minutes to hours), and more significant for the unit commitment/scheduling time scale (day).…”