Energy Balancing of Power System Considering Periodic Behavioral Pattern of Renewable Energy Sources and Demands

Renewable Energy Sources (RESs), such as wind and photovoltaic systems, represent environmentally sustainable options for power generation. However, the inherent variability in the output energy of RESs poses a significant challenge to their seamless integration into the power grid. Furthermore, fluctuations in consumer activity amplify the risks associated with power imbalances. To ensure the stable operation of power systems, it is critical to enhance their ability to manage fluctuations caused by renewable sources and dynamic demand. This paper introduces a pioneering concept for robust energy balancing designed to mitigate energy imbalances resulting from fluctuating generation and demand mismatches. This paper proposes system conditions for a power system to continue safe operation under any power levels of fluctuating generation and demand considering worst-case analysis. In other words, our theorem provides the boundary between a system that can continue its safe operation under any power levels of fluctuating generators and loads and a system that may experience power/energy imbalance due to the fluctuations of generators and loads. These two types of energy balancing conditions, named Supply-Dominated Energy Balancing (SDEB) and Demand-Dominated Energy Balancing (DDEB), apply worst-case operations for fluctuating power devices and best-case operations for controllable power devices. These two conditions jointly provide sufficient conditions for a power system to operate safely under any power level of fluctuations. The key idea behind these energy balancing concepts is the consideration of periodic behavioral patterns of fluctuating sources and loads and their upper and lower bound envelopes, enabling us to analyze the long-term system behavior by analyzing one-cycle operations. In addition, the extracted non-trivial upper-bound and lower-bound envelopes of fluctuating sources and loads offer a novel interpretation of the collaboration between storage systems and controllable sources/loads in energy balancing and provide insights into the minimum sizes required for these devices to sustain safe and uninterrupted power system operation. Finally, the application of the proposed SDEB and DDEB conditions to actual power generation and consumption data is demonstrated. In general, worst-case-based theoretical discussions tend to yield a result that is far apart from a practical situation. However, it is found that the difference between our result and another cost-based practical approach is relatively small, which reveals the potential of the proposed approach to work with more realistic constraints, preferences, etc., in practical situations.