Review of frequency response strategies in renewable-dominated power system grids: Market adaptations and unit commitment formulation

Abstract

• Conducts an extensive literature review on frequency-constrained optimization in power systems dominated by high renewable energy source (RES) penetration. • Examines various UC and stochastic unit commitment (SUC) approaches, including scenario sampling, chance-constrained optimization, and robust optimization methods. • Highlights the challenges and opportunities associated with integrating RES in low-inertia power systems, particularly in weakly interconnected networks like those in sub-Saharan Africa. • Provides insights into market adaptations and the economic valuation of inertia, emphasizing the need for regulatory frameworks that support RES and distributed energy resources (DERs) participation in frequency response services. • Identifies research gaps and suggests future research directions for improving the integration and optimization of RES in power systems, emphasizing the importance of comprehensive frequency response models and robust scheduling algorithms. This study provides a thorough analysis of unit commitment (UC) formulations in the context of low-inertia power systems, which are increasingly prevalent as the transition to Renewable Energy Sources (RES) gain momentum. Given the move towards more sustainable energy models, incorporating RES presents unique challenges in maintaining grid stability due to their inherent lack of synchronous inertia. This review examined the intricacies of modelling energy market designs and UC strategies to tackle these challenges. The study explores the expansion of frequency response services, emphasizing the increasing dependence on ancillary services, particularly in markets with a substantial presence of RES, attention is focused on the unique operating challenges in regions like Sub-Saharan Africa, where dispersed grid networks and generation inadequacies compound the problem. The paper delves into different methodologies and modelling approaches used in frequency-constrained optimization, shedding light on the strengths and weaknesses of current practices. A crucial outcome of our study is that the use of uniform frequency response models to deduce post-fault frequency parameters will not give adequate results in sparsely connected power system networks. Also, studies primarily focus on generation adequacy and the reliability criterion of the largest generator outage, overlooking the potential impact of network constraints and congestions in their formulation. Our analysis provides valuable insights into creating market frameworks that optimize energy and ancillary services, ensuring a stable and efficient grid operation in a power system dominated by RES. Based on our findings, it is essential to establish electricity market frameworks that can effectively maximize the utilization of energy resources and address the specific regional challenges associated with frequency regulation services in the future.

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