Comprehensive reliability evaluation and enhancement of distributed energy systems: Unlocking risk-resistant potential of building virtual thermal storage with uncertainty in renewable resources and equipment failures

Ensuring uninterrupted and high-quality energy supply is essential for distributed energy systems (DESs) to maintain public safety and deliver their intended benefits, underscoring the need for robust reliability evaluation. Building virtual thermal storage (VTS), utilizing the envelope and internal mass, has proven effective in alleviating supply stress by flexibly adjusting demand but receives far less attention in reliability issues. By regarding buildings only as passive loads in reliability evaluations, the risk-resistant potential of VTS is often underestimated, leading to overly conservative designs and controls for DESs. This study therefore proposed a novel reliability evaluation method that considers the risk-resistant potential of building thermal storage under multiple operational risks, i.e., uncertain renewable power and equipment failures. A state incidence matrix-improved sequential Monte Carlo framework was developed to dynamically quantify the impacts of these risks and VTS behavior, modeled using a physics-informed hybrid approach. A bi-level post-shortage scheduling mechanism for reliability enhancement was further proposed to prioritize critical supplies by fully unlocking VTS potential. The proposed reliability evaluation and enhancement methods were validated using a reference office building served by a representative DES. Results demonstrate that the proposed methods effectively enhance reliability, reducing annual energy shortages to 26.90 h and 693.50 kWh under a 60 % grid-fed-in rate, which achieves an 80.12-88.18 % improvement compared to conventional evaluations. It is also found that reasonably relaxing indoor temperature constraints contributes to this enhancement. This study offers valuable insights into optimizing demand management for more resilient building and energy engineering.