Increase System Resilience Research Articles

Resilience Improvement of Microgrid Cluster Systems Based on Two-Stage Robust Optimization

For microgrids in deep and remote sea areas, ocean currents are widely used as an emerging power generation resource. Implementing ES systems is crucial for smooth power output and grid stability. The stability of power output from sea current energy generation faces challenges due to speed fluctuations. Enhancing resilience requires addressing transmission line failures caused by extreme seabed conditions, and ensuring operational security. An ES configuration method considering line faults based on two-stage robust optimization is presented in this paper. First, in order to simultaneously consider planning and operation, a defender–attacker–defender (DAD) model was established. Additionally, the capacity, rated power, and charging/discharging power of ES during operation were jointly optimized through the column-and-constraint generation (C&CG) algorithm. In addition, the rationality and effectiveness of the proposed method were demonstrated through experiments on modified IEEE six-bus and fifty-seven-bus systems. The results show that a distributed ES configuration increased system resilience by 54.60% and reduced abandoned power rate by 57.06% compared with the situation without ES configuration.

Sensitivity of development goals to water scarcity of Iraq and transboundary regions

Iraq and its transboundary regions have significant challenges from water scarcity in combination with other social and environmental factors. There are short- and long-term implications for vulnerable demographics, such as youth. With Iraq's dependence on upstream water management, there is a need to address several critical factors of transboundary watersheds such as the Haditha, Mosul, Dokan, and Euphrates-Tigris basin. This paper develops the use of particular social, hydrological, and other environmental factors in a risk register of basins and vulnerable populations, where societal priorities vary across scenarios of hydrology and water. Social data (i.e., gridded youth population data) and hydrological observations (i.e., precipitation, temperature, root zone soil moisture, and Normalized Difference Vegetation Index (NDVI)) are obtained from publicly available satellite-based Earth observations and global models. Risk is defined and quantified as the disruption of basin order and spatial plots are provided to improve understanding of the spatial distribution of water scarcity challenges in the region with regard to vulnerable populations. The results feature identification of the most and least disruptive scenarios including: 1) population density is lowest in basins exposed to the highest air temperatures, 2) an urban-to-rural migration pattern (such as prompted by a public health crisis) would significantly disrupt basin order, and 3) populations with greatest exposure to extreme hydrological conditions of water scarcity are found in the southern basins of Iraq in or near the Al-Muthanna governorate. The impacts of this work are to steer future investments that mitigate risk of disrupted system orders and to increase system resilience of vulnerable populations to water scarcity.

Reinforcing resilience for integrated design of green and grey infrastructure with real-time control rules by considering system failures

The mutual benefits of real-time control and green and grey infrastructure for urban drainage system (UDS) renovations have drawn great attention. However, risks emerged due to equipment and structural failures, and no studies considered such failures while optimizing the renovation scheme. To address this issue, this study proposed a multi-criteria optimization method for the integrated design of green and grey infrastructure with real-time control rules, where the economic cost and system performance under normal and exceptional conditions were optimized simultaneously. Failure probabilities of equipment and structure were quantified using homogeneous Poisson process models, and failure losses were estimated with the aid of a machine learning-based surrogate model. This approach was tested with a combined UDS in China. Results indicate that: (1) More investment does not necessarily increase system resilience to failures. Equipment and structural failures can significantly lower the effectiveness of grey infrastructure and real-time control. Therefore, solutions with more investments in grey infrastructure, which indicate higher costs, experience greater failure losses. (2) System resilience to failures can be significantly improved while maintaining other objectives when compared with the traditional design scheme. The proposed method allows for a new perspective in addition to the cost-and-resilience two-objectives design of UDS renovations, especially for systems threatened by various failures.

Trends in Hybrid Renewable Energy System (HRES) Applications: A Review

Microgrids and hybrid renewable energy systems play a crucial role in today’s energy transition. They enable local power generation and distribution, reducing dependence on large centralized infrastructures, can operate independently or connected to a grid, and can provide backup power, thus increasing system resilience. In addition, they combine multiple renewable energy sources, such as solar, wind, hydro, and biomass, to maximize the efficiency and reliability of the supply, and are also adaptable to location-specific conditions, taking advantage of locally available energy resources and reducing the need for energy imports. Moreover, they contribute to decarbonization goals by offering a cleaner and more sustainable alternative. In this article, a documentary review is presented on the interaction of Homer Pro software 3.16.2 (July 2023), used for the design of hybrid renewable energy systems (HRES), with other methods of optimization or sizing. Allusion is made to the type of architecture in the most prominent clean and fossil source configurations, the levelized cost, net annual cost, and maintenance and capital investment cost. A comparison is made among the works reported in the last five years regarding the use of this software tool, based on load demand, geographical area, renewable energy sources, fossil sources, and objective functions, applied to the educational, rural, and industrial sectors. It is shown that India is one of the countries that has reported the most number of HRES techno-economic environmental analysis works, and that the case studies have focused approximately 47% on rural areas, 20% on educational agencies, 14% on commerce and industry, and 29% on urban buildings.

Proactive care for frailty.

Many providers aspire to scale up proactive care that prevents escalation of health and care needs, delays onset of disability, and reduces demand for emergency department attendance or admission to hospital or care home. NHS England offers guidance on personalised and coordinated multi-professional support and interventions for people with moderate or severe frailty. This article reflects on the growing international evidence for an integrated proactive approach for older people with frailty and why investing in high-quality, joined-up care for older people across the whole system improves outcomes for people, reduces demand for services, increases system resilience, and delivers economic and societal benefits. Facing up to frailty requires creative whole system workforce planning and development that will be challenging to deliver in the current financial and recruitment context yet all the more worthwhile as scaling up proactive care has the potential to be a game changer.

A net-zero emissions strategy for China’s power sector using carbon-capture utilization and storage

Decarbonized power systems are critical to mitigate climate change, yet methods to achieve a reliable and resilient near-zero power system are still under exploration. This study develops an hourly power system simulation model considering high-resolution geological constraints for carbon-capture-utilization-and-storage to explore the optimal solution for a reliable and resilient near-zero power system. This is applied to 31 provinces in China by simulating 10,450 scenarios combining different electricity storage durations and interprovincial transmission capacities, with various shares of abated fossil power with carbon-capture-utilization-and-storage. Here, we show that allowing up to 20% abated fossil fuel power generation in the power system could reduce the national total power shortage rate by up to 9.0 percentages in 2050 compared with a zero fossil fuel system. A lowest-cost scenario with 16% abated fossil fuel power generation in the system even causes 2.5% lower investment costs in the network (or $16.8 billion), and also increases system resilience by reducing power shortage during extreme climatic events.

A novel method to assess urban multimodal transportation system resilience considering passenger demand and infrastructure supply

With the continuous construction of urban infrastructure, urban multi-modal transportation system (UMTS) has gradually become complex and intertwined, which makes the system more uncertain and vulnerable, especially under disruptions. Improving the resilience of UMTS is critical to maintaining urban reliability and sustainability. This paper aims to build effective models to assess the resilience of UMTS. To develop the resilience assessment model, we provide a comprehensive, dynamic index that considers passenger demand and infrastructure supply. Three transportation modes are considered: bus, subway and taxi, and a cascading failure model is simulated. Data from Singapore are collected to analyse resilience indicators’ characteristics and explore relationship between resilience indicators and node measures. The results indicate that 1) when stations experience failure, it has the greatest impact on the accessibility of the transportation network, followed by efficiency and connectivity; 2) system resilience is negatively related to the node degree and node betweenness centrality of the attacked station; 3) beyond a certain threshold, continuing to increase stations’ additional capacity does not significantly increase system resilience. The proposed resilience index can be used as an optimization goal during system design and recovery. The conclusions and recommendations can inform the management and improvement of urban transportation system resilience.

Optimal isolated microgrid topology design for resilient applications

Meshed microgrids have been used in a plethora of specialised applications that demand increased system resilience, from data centres to the international space station. When resilience maximisation is the desideratum, topology design is the fundamental factor determining the overall system performance. Very few published papers on this problem are found in literature and they take into consideration partial available topologies, or they fail to quantify resilience or assess microgrid stability. To address these gaps on microgrid topology planning (MTP), this paper proposes a holistic optimal topology design framework, comprised of six stages: (a) graph generator to extract all possible connected, non-isomorphic networks for a given number of nodes, (b) optimal asset positioning upon each generated graph using mixed-integer linear programming, (c) small-signal stability assessment and (d) post-outage flow matrix calculation for each microgrid to quantify repercussions from fault/damage of all interconnecting lines, (e) quantification of resilience metrics originally applied to distribution systems to assess vulnerability and criticality of each line, along with classic graph-theoretical indicators and finally, (f) aggregation of said metrics to rank the produced microgrid topologies. The proposed methodology is evaluated through detailed discrete simulations to assess its efficacy and the dynamic stability of the optimal microgrid topology.

An Interlinking Converter for Renewable Energy Integration into Hybrid Grids

With the rise in global warming, distributed generators (DGs) based on renewable energy sources have become increasingly important in the power sector. Due to their small size and the capacity to 'island' while providing most of their loads during situations, microgrids provide an excellent framework to build smart grids, which increases system resilience. Given that renewable-based DGs dominate microgrids and are defined by their statistical properties and unpredictable power, sustaining load-generation balance is a significant challenge. Although microgrids are now widely used and researched, there is still considerable contention over whether they should use alternating current (AC) or direct current (DC), with the majority opinion leaning toward a combination of the two. nIn order to facilitate the flexible incorporation of renewable energy into hybrid grids, this article offers an interlinking converter design. The suggested converter may be configured as a DC-DC converter, a DC-AC inverter, or a DC-DC/AC multiport converter thanks to its one AC port and two DC ports, making it a versatile option for combining multiple DC and AC sources. Flexible conversion, high power density, low leakage currents, and tunable power flow are all features validated by the MATLAB/SIMULINK simulation results, proving the idea.

Impacts of varying network parameters on the vulnerability and resilience of interdependent critical infrastructure systems

ABSTRACT Critical infrastructure systems are complex and subjected to evolving risks and hazards, which makes anticipating their behavior difficult. To prioritize among actions that increase system resilience, it is critical to understand their impacts on parameters defining a network and on anticipated network performance. In this paper, the authors investigate the impacts of variations in three parameters on network vulnerability: component vulnerabilities, service interdependency redundancies, and system link configuration. The advances of this work compared to prior studies include: 1) The impacts of parameters varied across a range of values at the component level are evaluated considering component functionality and connectivity; 2) quantitative analyses of component performance as parameters vary are investigated based on system redundancies; and 3) probabilistic system interdependencies are analyzed through a Bayesian network that considers component pathways. Results quantify effects of changes in component vulnerabilities and dependencies and are used to discuss impacts on system resilience.

On-Orbit Servicing System Architectures for Proliferated Low-Earth-Orbit Constellations

On-orbit servicing (OOS) presents new opportunities for refueling, inspection, repair, maintenance, and upgrade of spacecraft (s/c). OOS missions for s/c in a geostationary orbit (GEO) are currently underway. However, there are currently no plans for OOS of low-Earth-orbit (LEO) s/c, aside from technology demonstrations, because of their shorter design life and lower cost. Designing OOS systems for LEO constellations differs from that of GEO-based systems; this difference is attributed to LEO’s proliferation of satellites, environmental effects (J2 nodal precession, drag), and different constellation patterns. Satellite constellations in LEO are becoming more distributed due to increased access, distributed risk, flexibility, and cost. OOS of s/c may enable the reduction of requirements on subsystems such as safety and the need for redundancy. These requirement reductions will enable lower risks, lower costs, and increased system resilience. This paper analyzes the benefits of OOS in proliferated LEO constellations. Several OOS system architectures are modeled in various scenarios, and we will evaluate the utility tradespace in which OOS is beneficial. OOS provides higher utility over the comparative alternative of using spare satellites in some scenarios. The utility of OOS provides even greater utility when accepting higher failure rates of satellites, which can be mitigated by an OOS system compared to the comparative alternative of orbital spares.

Towards improved understanding of cascading and interconnected risks from concurrent weather extremes: Analysis of historical heat and drought extreme events

Weather extremes can affect many different assets, sectors and systems of the human environment, including human security, health and well-being. Weather extremes that compound, such as heat and drought, and their interconnected risks are complex, difficult to understand and thus a challenge for risk analysis and management, because (in intertwined systems) impacts can propagate through multiple sectors. In a warming climate, extreme concurrent heat and drought events are expected to increase in frequency, intensity and duration, posing growing risks to societies. To gain a better understanding of compound extremes and associated risks, we analyze eight historical heat and drought extreme events in Europe, Africa and Australia. We investigated and visualized the direct and indirect impact paths through different sectors and systems together with the impacts of response and adaptation measures. We found the most important cascading processes and interlinkages centered around the health, energy and agriculture and food production sectors. The key cascades result in impacts on the economy, the state and public services and ultimately also on society and culture. Our analysis shows that cascading impacts can propagate through numerous sectors with far reaching consequences, potentially being able to destabilize entire socio-economic systems. We emphasize that the future challenge in research on and adaptation to concurrent extreme events lies in the integration of assets, sectors and systems with strong interlinkages to other sectors and with a large potential for cascading impacts, but for which we cannot resort to historical experiences. Integrating approaches to deal with concurrent extreme events should furthermore consider the effects of possible response and adaptation mechanisms to increase system resilience.

System-friendly process design: Optimizing blue hydrogen production for future energy systems

While the effects of ongoing cost reductions in renewables, batteries, and electrolyzers on future energy systems have been extensively investigated, the effects of significant advances in CO2 capture and storage (CCS) technologies have received much less attention. This research gap is addressed via a long-term (2050) energy system model loosely based on Germany, yielding four main findings. First, CCS-enabled pathways offer the greatest benefits in the hydrogen sector, where hydrogen prices can be reduced by two-thirds relative to a scenario without CCS. Second, advanced blue hydrogen technologies can reduce total system costs by 12% and enable negative CO2 emissions due to higher efficiencies and CO2 capture ratios. Third, co-gasification of coal and biomass emerged as an important enabler of these promising results, allowing efficient exploitation of limited biomass resources to achieve negative emissions and limit the dependence on imported natural gas. Finally, CCS decarbonization pathways can practically and economically incorporate substantial shares of renewable energy to reduce fossil fuel dependence. Such diversification of primary energy inputs increases system resilience to the broad range of socio-techno-economic challenges facing the energy transition. In conclusion, balanced blue-green pathways offer many benefits and deserve serious consideration in the global decarbonization effort.

Strengthening Health Systems for Climate Adaptation and Health Security: Key Considerations for Policy and Programming.

Strengthening Health Systems for Climate Adaptation and Health Security: Key Considerations for Policy and Programming.

Supplementation of ex situ produced bioflocs improves immune response against AHPND in Pacific whiteleg shrimp (Litopenaeus vannamei) postlarvae.

The emergence of Vibrio diseases, including acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio spp., had resulted in heavy losses in global shrimp production. Biofloc technology is a closed aquaculture system developed as one of the sustainable solutions to increase system resilience in the shrimp industry. In this study, biofloc was formed externally (ex situ biofloc) with probiotics Bacillus sp. strain BME and Bacillus sp. strain BCE, diatom microalgae Chaetoceros calcitrans, and a consortium of nitrifying bacteria, in the ratio of 1:1:6:6 as a starter. The study showed that the ex situ biofloc supplementation in Pacific whiteleg shrimp (L. vannamei) postlarvae culture can increase the shrimp culture performance (shrimp survival and growth), reduce Vibrio counts in the water and shrimp body, and provide stimulation of the shrimp immune response through humoral immune responses, such as pattern recognition protein (C-type lectin) and melanization process (proPO). Overall, the results indicate that the supplementation of ex situ biofloc provided protection to shrimp under Vibrio infection, regardless of the timing of addition (before, simultaneously, or after addition of Vibrio sp. strain VPA). This suggests that the ex situ biofloc can be effective as a preventive and a supportive treatment against potential AHPND infection in L. vannamei postlarvae culture. Taken together, the ability of the ex situ biofloc to modulate immune-related gene expression and resistance of L. vannamei against potentially AHPND-causing Vibrio sp. strain makes it an effective aquaculture technology for infectious disease control in shrimp production with high-density and minimal water exchange culture. KEY POINTS: • Supplementation of ex situ produced biofloc in shrimp postlarvae culture. • Ex situ biofloc reduces Vibrio counts in the water and shrimp body. • Ex situ biofloc stimulates shrimp humoral immune responses and survival.

Network hardening and optimal placement of microgrids to improve transmission system resilience: A two-stage linear program

This paper aims to develop a linear two-stage optimization problem based on an attacker-defender resilient planning (AD-RP) model to improve the power system's operational and infrastructural resilience in the face of low-probability high-impact events. In the developed model, attackers are natural phenomena that can cause the most severe damage to system performance, and defenders are actions that minimize system vulnerabilities. In the first stage, a stochastic model depending on Monte-Carlo simulation is developed to present a new index for selecting the most vulnerable transmission system components. This index is designed based on combining the worst possible case of attack, disaster statistical analysis, system structure and fragility curves. In the second stage, as defense operations, the hardening of vulnerable lines and microgrids placement in the proper places are carried out considering investment budget constraints. Minimizing load shedding and ensuring the resilience of the transmission network are the main objectives behind the second stage. In this regard, a comprehensive metric for the evaluation of the transmission system resilience is introduced. Thanks to a mixed-integer programming problem, the effectiveness of the proposed AD-RP model in increasing system resilience is demonstrated in the IEEE 30-bus and 118-bus test systems.

Developing a framework to enhance the seismic resilience of the electricity distribution system feeding the healthcare system

Delivering electricity to hospitals is vital for maintaining hospitals' functionality. Given the seismic vulnerability of electrical substations, providing effective rehabilitation plans for repairing these systems seems necessary for a resilient healthcare system. Studies concerning interdependent systems' functionality have not thoroughly addressed the interdependency of healthcare and electrical distribution systems. A framework to identify the effectiveness of different post-disaster rehabilitation plans for electrical substations to enhance the resilience of the healthcare system electricity is developed in this study, which increases the recoverability of the healthcare system after an earthquake. The vulnerability analysis for electrical facilities is done using modified fragility functions, considering the effects of aging as well. The geographical information system is used for assigning patients to hospitals given several patients' decision criteria. The framework uses a stochastic discrete event simulation to determine the effectiveness of different rehabilitation scenarios for five days after an earthquake occurs while using patients’ waiting time as the performance measure. Finally, the proposed framework is applied to Ghazvin city in the north-west of Iran. The results show that the best scenario would increase system resilience by 85%, highlighting the importance of identifying and implementing the best scenario.

Strategies for Controlling Microgrid Networks with Energy Storage Systems: A Review

Distributed Energy Storage Systems are considered key enablers in the transition from the traditional centralized power system to a smarter, autonomous, and decentralized system operating mostly on renewable energy. The control of distributed energy storage involves the coordinated management of many smaller energy storages, typically embedded within microgrids. As such, there has been much recent interest related to controlling aspects of supporting power-sharing balance and sustainability, increasing system resilience and reliability, and balancing distributed state of charge. This paper presents a comprehensive review of decentralized, centralized, multiagent, and intelligent control strategies that have been proposed to control and manage distributed energy storage. It also highlights the potential range of services that can be provided by these storages, their control complications, and proposed solutions. Specific focus on control strategies based upon multiagent communication and reinforcement learning is a main objective of this paper, reflecting recent advancements in digitalization and AI. The paper concludes with a summary of emerging areas and presents a summary of promising future directions.

Ex-post evaluation of Interruptible Load programs with a system optimisation perspective

The deployment of demand response in reserve markets has been widely discussed. Interruptible Load programs contract demand capacity from consumers in exchange for fixed and variable payments. System operators contract these resources to increase system resilience and use them for economic purposes. Although common, no ex-post evaluations of the program’s performance and efficiency exists in the literature. To fill this gap, the paper presents a procedure to evaluate the optimal usage of these resources from a system operator perspective. A Mixed Integer Linear Problem is set to minimise the overall cost of the system using the participant demand resources in the tertiary reserve market, while ensuring that all technical and regulatory constraints are fulfilled in the evaluation. The proposed method describes a series of metrics to compare the optimal performance with the current scenario, and we draw a set of conclusions and policy recommendations from it. We apply the method to the Spanish Interruptible Load program. Our results show that during the five and a half years of the program, demand resources could have provided savings to the system of up to 23% of the cost of tertiary reserve.

Toward More Resilient Urban Stormwater Management Systems—Bridging the Gap From Theory to Implementation

Many publications include references to reliability, risk and resilience, specifically within the context of climate change and rapid urbanization. However, there is a considerable gap between theory and actual implementation by drainage professionals. As such, most drainage professionals will not have an appreciation of a drainage system's response to events in excess of its original design event. This gap is compounded by the desire toward evaluating components such as “critical infrastructure” for events significantly more severe than ever contemplated. This paper, reflecting the combined wisdom and thoughts of various drainage professionals across Canada involved with the creation of the Canadian drainage standards (CSA W204 and W210), provides a treatise of risk and resilience based on the application of the dual drainage principle. It provides a discussion of key factors including climate change; densification; shape, intensity, duration and spatial extent of storm events, as a function of the normalized capacity or drain down/emptying time of the various components of the drainage system. Commentaries are offered, highlighting the role of appropriate setbacks and freeboard, and focusing on those aspects that have historically been ignored. Avenues to increase system resilience are presented including an evolution in passive and active flow controls, the potential beneficial role of natural systems and low impact development practices as a function of system sensitivity, discussing how options may vary across Canada.