Three-stage Variability-based Reserve Modifiers for Enhancing Flexibility Reserve Requirements under High Variable Generation Penetrations

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Area control error (ACE), Flexibility reserves, Variable generation (VG), Operating reserves, Uncertainty, Variability

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Daniel Felix Ritchie School of Engineering and Computer Science, Electrical and Computer Engineering


The electric power system has continuously evolved in order to accommodate new technologies and operating strategies. As the penetration of integrated variable generation in the system increases, it is beneficial to develop strategies that can help mitigate their effect on the grid. Historically, power system operators have held excess capacity during the commitment and dispatch process to allow the system to handle unforeseen load ramping events. As variable generation resources increase, sufficient flexibility scheduled in the system is required to ensure that system performance is not deteriorated in the presence of additional variability and uncertainty. This paper presents a systematic comparison of various flexibility reserve strategies. Several of them are implemented and applied in a common test system, in order to evaluate their effect on the economic and reliable operations. Furthermore, a three stage reserve modifier algorithm is proposed and evaluated for its ability to improve system performance.

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