Predictive Optimization of Hybrid Energy Systems with Temperature Dependency

Abstract

Hybrid Energy Systems (HES), amalgamating renewable sources, energy storage, and conventional generation, have emerged as a responsive resource for providing valuable grid services. Subsequently, modeling and analysis of HES has become critical, and the quality of grid services hedges on it. Currently, most HES models are temperature-agnostic. However, the temperature-dependent factors can significantly impact HES performance, necessitating advanced modeling and optimization techniques. With the inclusion of temperature-dependent models, the challenges and complexity of solving optimization problem increases. In this paper, the electro-thermal modeling of HES is discussed. Based on this model, a nonlinear predictive optimization framework is formulated. A simplified model is developed to address the challenges associated with solving nonlinear problems. Further, projection and homotopy approaches are proposed. In the homotopy method, the NLP is solved by incrementally changing the C-rating of the battery. Simulation-based analysis of the algorithms highlights the effects of different battery ratings, ambient temperatures, and energy price variations. Finally, comparative assessments with a temperature-agnostic approach illustrates the effectiveness of electro-thermal methods in optimizing HES.

Figures (11)

• Figure 1: Schematic diagram of hybrid energy system.
• Figure 2: Battery's ECM with enclosure and HVAC.
• Figure 3: Illustrating the different methods presented herein, including the iterative homotopy approach based on the battery's C-rating.
• Figure 4: Input data: NE-ISO energy price and solar irradiance at 15-minute intervals for a day (24 hours).
• Figure 5: Impact of variation in $\Delta T_{\text{Batt}}$ on overall revenue and HVAC cost at ambient temperature of $20^{o}$ C, 0.5C battery.