This article examines the trade space between the resilience and cost of an island microgrid. The article presents two models for the resilience and the cost of the microgrid. The resilience model considers the invulnerability and recoverability of the microgrid and represents the power balance of the microgrid, energy storage, and maintenance policies. The cost model adapts the levelized cost of energy measure to the context of island microgrids. We conduct experiments to investigate two microgrid architecture decisions of how much excess generation capacity and redundancy to provide. The experiments show that redundancy of generative sources provides greater resilience for similar cost, and resilience improves quickly as excess power capacity is added while the cost grows more slowly. Case studies for island microgrids show how a redesign of the microgrid can improve resilience without increasing costs. The article contributes to the literature a model for decisions makers to evaluate the tradeoffs between resilience and cost for island microgrids that must depend on their own distributed energy resources.

Designing complex, socio-technical, cyber-physical systems has become increasingly challenging in recent years. Interdependencies between engineering domains can lead to emergent behavior that is difficult to predict and manage. The recent shift toward model-based design has demonstrated significant advantages for minimizing these challenges (McDermott et al. 2020. Benchmarking the benefits and current maturity of model-based systems engineering across the enterprise. results of the model-based systems engineering (MBSE) maturity survey, part 1: Executive summary. Technical Report SERC-2020-SR-001, Systems Engineering Research Center.). Further, the early identification of safety and security design weaknesses in safety-critical systems leads to reduced redesign costs in later design phases (Yang and EI-Haik, 2003. Design for Six Sigma. McGraw-Hill, New York City; Clausing and Frey, 2005. Improving system reliability by failure-mode avoidance including four concept design strategies. Systems Engineering, 8(3), pp. 245–261.). As a result, this article contributes the Multidisciplinary Early Design Risk Assessment Framework (MEDRAF) methodology for early combined safety and security assessment based on interdisciplinary dependency models of a system. The focus is on factors contributing to the estimation of the probabilities of successful attacks on system components. The Zero Trust paradigm is applied in which all humans, hardware, and processes interacting with the system are considered to pose a security risk. A calculation of security-related probability estimates is presented which is dependent on the current global security environment. Subsequently, security and safety probability estimates are combined to present an overall safety-security risk calculation using hybrid safety-security trees. The risk values help designers assess the loss of specific key components and safety functions. The methodology is demonstrated with a case study of a spent fuel pool cooling system in a nuclear reactor. The results of the case study show that the risk of losing one key system component doubles when combining security and safety compared to only assessing safety events. This paper is based on a paper presented at the CIE 2020 conference (Papakonstantinou et al., 2020. Towards a zero trust hybrid security and safety risk analysis method. In International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, American Society of Mechanical Engineers.).

This article develops a method to model, analyze, and design military microgrids with the objective to improve their resilience in the face of disconnections from the larger electrical grid. Military microgrids provide power to installation and base facilities to enable base mission objective accomplishments that are related to national security. Previous research, tools, and methods for microgrid design and assessment do not adequately address resilience in terms of accomplishing mission objectives and instead primarily focus on economic outcomes. This article proposes a novel metric to quantify microgrid resilience in terms of its ability to minimize the impact of power disruption on missions supported by the microgrid. The metric is used in a novel design method to ensure an islanded military microgrid can continue operations while disconnected for a two-week duration. Our model examines the ability to continue mission operations subject to various microgrid disruptions as well as equipment reliability.

The ability to provide uninterrupted power to military installations is paramount in executing a country’s national defense strategy. Microgrid architectures increase installation energy resilience through redundant local generation sources and the capability for grid independence. However, deliberate attacks from near-peer competitors can disrupt the associated supply chain network, thereby affecting mission critical loads. Utilizing an integrated discrete-time Markov chain and dynamic Bayesian network approach, we investigate disruption propagation throughout a supply chain network and quantify its mission impact on an islanded microgrid. We propose a novel methodology and an associated metric we term “energy resilience impact” to identify and address supply chain disruption risks to energy security. The proposed methodology addresses a gap in the literature and practice where it is assumed supply chains will not be disrupted during incidents involving microgrids. A case study of a fictional military installation is presented to demonstrate how installation energy managers can adopt this methodology for the design and improvement of military microgrids. The fictional case study shows how supply chain disruptions can impact the ability of a microgrid to successfully supply electricity to critical loads throughout an islanding event.