scholarly journals Assessing the Vulnerability of Power Systems Using Multilevel Programming: A Literature Review

2021 ◽  
Vol 20 (38) ◽  
pp. 99-117
Author(s):  
Juan Pablo Hernandez Valencia ◽  
Jesus Maria Lopez-Lezama ◽  
Bonie Johana Restrepo Cuestas

Vulnerability studies can identify critical elements in electric power systems in order to take protective measures against possible scenarios that may result in load shedding, which can be caused by natural events or deliberate attacks. This article is a literature review on the latter kind, i.e., the interdiction problem, which assumes there is a disruptive agent whose objective is to maximize the damage to the system, while the network operator acts as a defensive agent. The non-simultaneous interaction of these two agents creates a multilevel optimization problem, and the literature has reported several interdiction models and solution methods to address it. The main contribution of this paper is presenting the considerations that should be taken into account to analyze, model, and solve the interdiction problem, including the most common solution techniques, applied methodologies, and future studies. This literature review found that most research in this area is focused on the analysis of transmission systems considering linear approximations of the network, and a few interdiction studies use an AC model of the network or directly treat distribution networks from a multilevel standpoint. Future challenges in this field include modeling and incorporating new defense options for the network operator, such as distributed generation, demand response, and the topological reconfiguration of the system.f the system.

Author(s):  
Daniel Alberto Zuniga Vazquez ◽  
Feng Qiu ◽  
Neng Fan ◽  
Kevin Sharp

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3432 ◽  
Author(s):  
Fabio Bignucolo ◽  
Manuele Bertoluzzo

The ongoing diffusion of solid-state DC/DC converters makes possible a partial migration of electric power systems from the present AC paradigm to a future DC scenario. In addition, the power demand in the domestic environment is expected to grow considerably, for example, due to the progressive diffusion of electric vehicles, induction cooking and heat pumps. To face this evolution, the paper introduces a novel electric topology for a hybrid AC/DC smart house, based on the solid-state transformer technology. The electric scheme, voltage levels and converters types are thoroughly discussed to better integrate the spread of electric appliances, which are frequently based on internal DC buses, within the present AC distribution networks. Voltage levels are determined to guarantee high safety zones with negligible electric risk in the most exposed areas of the house. At the same time, the developed control schemes assure high power quality (voltage stability in the case of both load variations and network perturbations), manage power flows and local resources according to ancillary services requirements and increase the domestic network overall efficiency. Dynamic simulations are performed, making use of DIgSILENT PowerFactory software, to demonstrate the feasibility of the proposed distribution scheme for next-generation smart houses under different operating conditions.


Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5326
Author(s):  
Pawel Pawlus ◽  
Rafal Reizer ◽  
Michal Wieczorowski

Areal 3D analysis of surface texture gives more opportunities than a study of 2D profiles. Surface topography evaluation, considered as 3D dimensional analysis in micro or nanoscales, plays an important role in many fields of science and life. Among many texture parameters, those connected with height are the most often used. However, there are many other parameters and functions that can provide additional important information regarding functional behaviour of surfaces in different applications. The knowledge about the functional importance of various surface properties is low. This review tries to fill this gap. Surface texture parameters are presented in various groups: height, spatial, hybrid, functional, feature, and others. Based on experiences of the present authors and literature review, the relationships among various surface parameters and functional properties are described. A proposal of a selection of parameters on the basis of their functional significations is provided. Considerations for future challenges are addressed.


2020 ◽  
Vol 2 (11) ◽  
Author(s):  
Erica Honeck ◽  
Arthur Sanguet ◽  
Martin A. Schlaepfer ◽  
Nicolas Wyler ◽  
Anthony Lehmann

AbstractNature forms interdependent networks in a landscape, which is key to the survival of species and the maintenance of genetic diversity. Nature provides crucial socio-economic benefits to people, but they are typically undervalued in political decisions. This has led to the concept of Green Infrastructure (GI), which defines an interlinked network of (semi-)natural areas with high ecological values for wildlife and people, to be conserved and managed in priority to preserve biodiversity and ecosystem services. This relatively new concept has been used in different contexts, but with widely diverging interpretations. There is no apparent consensus in the scientific literature on the methodology to map and implement GI. This paper serves as an informed primer for researchers that are new to GI mapping understand the key principles and terminology for the needs of their own case-study, and as a framework for more advance researchers willing to contribute to the formalization of the concept. Through a literature review of articles on creating GI networks, we summarized and evaluated commonly used methods to identify and map GI. We provided key insights for the assessment of diversity, ecosystem services and landscape connectivity, the three ‘pillars’ on which GI identification is based according to its definition. Based on this literature review, we propose 5 theoretical levels toward a more complex, reliable and integrative approach to identify GI networks. We then discuss the applications and limits of such method and point out future challenges for GI identification and implementation.


Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 328 ◽  
Author(s):  
Zifan Zhang ◽  
Zhidong Wang ◽  
Zhifeng Chen ◽  
Gan Wang ◽  
Na Shen ◽  
...  

As the largest global renewable source, hydropower is a useful supplement to mountainous distribution networks with abundant water resources, and shoulders a large portion of the regulation duty in many power systems. In particular, in the form of decentralized energy sources located to their customers, small hydropower (SHP) improve grid stability by diversifying the electricity system and reducing power loss. The mountainous distribution networks supplied by small hydropower are closed-loop design but open-loop operation, which easily causes the tripping of tie line even further the off-grid operation of small hydropower system. Once the tie line trips, the current countermeasures—such as hydropower shutdown and load shedding—do not fully guarantee the reliability of power supply and the utilization efficiency of hydropower. This paper studies the amplitude-frequency characteristics of SHP off-grid, according to the typical integration of hydropower in South China, a SHP on-grid/off-grid model is established based on the Power Systems Computer Aided Design (PSCAD) platform. It is found that due to the inertia of SHP, the amplitude-frequency characteristics of SHP island system are relatively slow, and the process of non-synchronization with the main grid is gradually expanded. The characteristic of SHP has a certain degree of synchronization with the main grid in the initial island operates stage, which helps to find a novel grid connection method. This paper further proposes the strategy of using fast busbar automatic transfer switch (BATS), which quickly connect the trip-off SHP to the distribution network under the condition of permitting distributed energy grid-connected. The PSCAD simulation results show that proposed strategy has a limited impact on the power grid and prove the effectiveness of the method.


Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1732
Author(s):  
Thapelo C. Mosetlhe ◽  
Yskandar Hamam ◽  
Shengzhi Du ◽  
Eric Monacelli

Pressure control in water distribution networks (WDNs) provides an avenue for improving both their sustainability and reliability. The complexities of the networks make the problem more challenging as various situational operations must be accounted for to ensure that the entire system performs under recommended conditions. In general, this problem is addressed by the installation of pressure reducing valves (PRVs) in WDNs and determining their appropriate settings. Researchers have proposed the utilization of several control techniques. However, the limitations of both computational and financial resources have compelled the researchers to investigate the possibility of limiting the PRVs while ensuring their control is sufficient for the entire system. Several approaches have been put forward to mitigate this sub-problem of the pressure control problem. This paper presents a review of existing techniques to solve both the localization of PRVs and their control problems. It dwells briefly on the classification of these methods and subsequently highlights their merits and demerits. Despite the available literature, it can be noted that the solution methods are yet to be harmonized. As a result, various avenues of research areas are available. This paper further presents the possible research areas that could be exploited in this domain.


2020 ◽  
Vol 39 (3) ◽  
pp. 3839-3851
Author(s):  
Arun Nambi Pandian ◽  
Aravindhababu Palanivelu

Optimal placement of FACTS devices attempts to improve power transfer, minimize active power loss, enhance voltage profile and improve voltage stability, thereby making the operation of power systems more flexible and secured. The classical methods experience difficulties in solving the FACTS placement problem (FPP) with discontinuous functions and may diverge or result oscillatory convergence. Besides the number of FACTS devices for placement should be given as an input while solving the problem. The solution methods then attempts to forcefully place all the specified number of devices in the power system, but in reality, the system may require an optimal number of FACTS for placement. The application of swarm-intelligence based optimization algorithms strives to overcome the drawbacks of classical methods. This paper presents a new solution method for FACTS placement problem using improved harmony search optimization (IHSO) with a newly suggested dissonance mechanism that avoids badly composed music, with a view of avoiding the sub-optimal solutions. Besides, the method requires to specify only the maximum number of FACTS devices for placement and places only the optimal number of devices within the specified maximum number of devices. The paper also includes simulation results of three IEEE test systems for exhibiting the superiority of the proposed method.


IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 177761-177773 ◽  
Author(s):  
Paulo Neis ◽  
Marco A. Wehrmeister ◽  
Marcos F. Mendes

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