Economic operation and transactive energy management for microgrids with distributed energy resources

Abstract

Over the last decade, the increasing penetration of distributed energy resources (DERs) provides a clean and efficient solution to combat the climate change and reduce the dependence on fossil fuel. The trending adoption of microgrids as the new operation paradigm brings about many economic and environmental benefits as well as the flexibility of self-organized system operation. Recently, plenty of research works have been carried out on the operation and management of microgrids. However, some limitations are noted in these works with respect to e.g. the economic operation of microgrids, especially considering the complexities of components, e.g., battery degradation and renewable forecasting errors. This thesis aims to address aforementioned challenges by developing advanced methods and solutions that can enhance both the economic operation and transactive energy management within a single microgrid and among multiple microgrids. Due to the high penetration of DERs, the economic operation of a microgrid is confronted with several challenges. First of all, since it is difficult to accurately forecast the production output of renewables well beforehand, the short-term economic dispatch is essentially an uncertainty-embedded decision-making problem. In addition, it is hard to characterize the degradation process of battery storage systems, and therefore it is challenging to formulate the battery degradation cost function. In this regard, a novel real-time degradation model is specially developed for lithium-ion battery energy storage systems to resemble the battery material degradation as much as possible. Microgrids located within the same geographical areas can be interconnected when making energy scheduling decisions. Cooperative management can be beneficial and economic for microgrids to complement each other in terms of matching the power supply with the demand at the minimum cost. However, challenges lie in the mechanism design for proactive participations into the cooperation. To enable transactive energy trading within multiple microgrids, a comprehensive peer-to-peer (P2P) energy sharing framework is proposed. In this framework, the social welfare of microgrids is maximized, and both the power flow loss and shadow price are involved. To enable the transactive management in alignment with existing electricity market timeline, a hierarchical P2P market with different timescales is proposed for microgrids to further explore their flexibilities. In the proposed tri-level P2P transaction market, the day-ahead market provides preliminary energy schedule decisions; the intra-day market is introduced to generate corrective actions to complement day-ahead decisions; the real-time regulation market can further guarantee the short-term balance of power supply-and-demand. Furthermore, the possible communication failures in the cyber network are innovatively taken into account and a communication failure-robust algorithm is accordingly designed. To summarize, the high penetration of DERs virtually imposes various challenges to the operation and management of microgrids from technical, economic and security perspectives. Throughout this thesis, new energy management and operation strategies with different advantages are developed for microgrids with DERs to address these challenges accordingly. With the achievements in this thesis, future works including the further enhancement and validations of the developed strategies through real-world implementations can be carried out.