System Congestion Research Articles

수요자원 인센티브를 통한 태양광발전 출력제한 대응 ESS 최적운영스케줄링에 관한 연구

The installation of energy storage system (ESS) is increased to solve the instability of the transmission system due to variable renewable energies such as Photovoltaic power generation (PV) and wind power generation. Meanwhile, recently, PV output is frequently curtailed since PV output produced after the ESS charging is finished causes transmission line congestion. For this congestion, it is common to increase line capacity or allocate the output curtailment for each power plant. However, since the unsettled loss occurs due to the output curtailment, the power plant operator should be given an incentive to induce the output curtailment for a specific time. Therefore, in this paper, the ESS optimal operation scheduling using the demand response transaction mechanism as an incentive is presented. From the perspective of PV operator with ESS, the charge/discharge capacity is determined in units of 15 minutes reflecting the PV curtailment and the demand response trading mechanism through mixed-integer linear programming. Uncertainty in the D-Day actual PV power output is considered as three scenarios such as Day-ahead forecasting PV power output and Day-ahead forecasting PV power output scenario with mean absolute percentage errors. Through optimal operation scheduling of ESS, transmission line overload and system congestion are suppressed by ESS charging and PV operators can secure additional benefits through the demand response trading mechanism without PV curtailment. Namely, total expected benefits can be maximized by the proposed method. As a result, an additional expansion of transmission lines or the introduction of a new incentive system can be avoided by the flexibility of PV operators.

Dynamical efficiency for multimodal time-varying transportation networks

Spatial systems that experience congestion can be modeled as weighted networks whose weights dynamically change over time with the redistribution of flows. This is particularly true for urban transportation networks. The aim of this work is to find appropriate network measures that are able to detect critical zones for traffic congestion and bottlenecks in a transportation system. We propose for both single and multi-layered networks a path-based measure, called dynamical efficiency, which computes the travel time differences under congested and free-flow conditions. The dynamical efficiency quantifies the reachability of a location embedded in the whole urban traffic condition, in lieu of a myopic description based on the average speed of single road segments. In this way, we are able to detect the formation of congestion seeds and visualize their evolution in time as well-defined clusters. Moreover, the extension to multilayer networks allows us to introduce a novel measure of centrality, which estimates the expected usage of inter-modal junctions between two different transportation means. Finally, we define the so-called dilemma factor in terms of number of alternatives that an interconnected transportation system offers to the travelers in exchange for a small increase in travel time. We find macroscopic relations between the percentage of extra-time, number of alternatives and level of congestion, useful to quantify the richness of trip choices that a city offers. As an illustrative example, we show how our methods work to study the real network of a megacity with probe traffic data.

Dysautonomia and Implications for Anosmia in Long COVID-19 Disease.

Long COVID-19 patients often reported anosmia as one of the predominant persisting symptoms. Recent findings have shown that anosmia is associated with neurological dysregulations. However, the involvement of the autonomic nervous system (ANS), which can aggregate all the long COVID-19 neurological symptoms, including anosmia, has not received much attention in the literature. Dysautonomia is characterized by the failure of the activities of components in the ANS. Long COVID-19 anosmia fatigue could result from damage to olfactory sensory neurons, leading to an augmentation in the resistance to cerebrospinal fluid outflow by the cribriform plate, and further causing congestion of the glymphatic system with subsequent toxic build-up in the brain. Studies have shown that anosmia was an important neurologic symptom described in long COVID-19 in association with potential COVID-19 neurotropism. SARS-CoV-2 can either travel via peripheral blood vessels causing endothelial dysfunction, triggering coagulation cascade and multiple organ dysfunction, or reach the systemic circulation and take a different route to the blood–brain barrier, damaging the blood–brain barrier and leading to neuroinflammation and neuronal excitotoxicity. SARS-CoV-2 entry via the olfactory epithelium and the increase in the expression of TMPRSS2 with ACE2 facilitates SARS-CoV-2 neurotropism and then dysautonomia in long COVID-19 patients. Due to this effect, patients with anosmia persisting 3 months after COVID-19 diagnosis showed extensive destruction of the olfactory epithelium. Persistent anosmia observed among long COVID-19 patients may be involved by a cascade of effects generated by dysautonomia leading to ACE2 antibodies enhancing a persistent immune activation.

A Novel Approach Using TCSR FACTS Controller for Mitigation of Congestion in a Multi-machine Power System

A Novel Approach Using TCSR FACTS Controller for Mitigation of Congestion in a Multi-machine Power System

Plentiful electricity turns wholesale prices negative

In 2020, average wholesale electricity prices in the United States fell to $21/MWh, their lowest level since the beginning of the 21st century. Low natural gas prices and the proliferation of low marginal cost resources like wind and solar had already established a trend toward lower wholesale prices, and this trend was exacerbated by declining electricity demand due to the Covid-19 pandemic in 2020. Negative real-time hourly wholesale prices occurred in about 4% of all hours and wholesale market nodes across the United States, but these were not distributed evenly. Regional clusters emerged, for example, in the Permian Basin in western Texas, and in Kansas and western Oklahoma in the Southwest Power Pool (SPP), negative prices accounted for more than 25% of all hours. Negative electricity prices result either from local congestion of the transmission system leading supply to exceed demand locally or due to system-wide oversupply. Looking at the latter condition in SPP, we find that all major generator types contribute to this excess supply, because of limited ramping flexibility or self-scheduled out-of-market unit commitments. Additional monetary production incentives such as renewable energy credits or tax credits also enable negative bids; indeed, negative prices predominantly occur when demand levels are low and wind production levels are high. Frequent negative prices can inform the value of additional renewable energy investments at specific locations, the need for transmission and storage development, and opportunities load growth or adaptation.

Effect of Heavy Rainstorm and Rain-Induced Waterlogging on Traffic Flow on Urban Road Sections: Integrated Experiment and Simulation Study

AbstractAs a typical type of adverse weather, heavy rainfall can result in congestion and productivity loss in the urban transportation system, which has been a severe problem for cities and attrac...

Characterization of rain specific attenuation and frequency scaling technique for satellite communication systems in a tropical location

Increased demand for satellite system applications and congestion of the lower frequency bands has mandated the foray into higher frequency spectrum which is more susceptible to rain-induced attenuation. This research explores the characterization of rain specific attenuation and frequency scaling technique for satellite communication system in Akure (7.17°N, 5.18°E, 358 m), Nigeria. Two-year archived rain-attenuation data on Ku-Band satellite link over the earth-space path of Akure was used for the study. Concurrent measurement of rainfall parameters and Eutelsat W4/W7 satellite radio beacons was carried out at the Department of Physics, Federal University of Technology Akure, between January 2017 and December 2018 using Tektronix Y400 NetTek spectrum analyzer. Estimated and measured rain attenuation statistics were compared, and exact determination of the power law coefficients which support the computation of explicit attenuation from measured rain rate was carried out. Recommended frequency scaling technique was also employed to investigate the magnitude of rain-induced attenuation at higher frequency bands. Results show that, at 0.01 percentage exceedance window, combined estimated and measured rain attenuation have respective magnitudes of about 13.09 dB and 21.43 dB. Also, estimated and scaled attenuation at 16 GHz, 20 GHz, 30 GHz and 40 GHz are about 21.97 dB, 31.78 dB, 56.64 dB, 77.23 dB and 28.36 dB, 33.95 dB, 42.17 dB, 46.07 dB respectively.

Bone-destructive osseous arteriovenous fistula at the jugular bulb mimicking a glomus jugular tumor

BackgroundSome reports have described intraosseous arteriovenous fistulas showing osteolytic changes, but an osseous arteriovenous fistula (AVF) at the jugular bulb showing extensive bone destruction is a very rare disease. Case descriptionA 60-year-old man presented with pulsatile tinnitus and right facial nerve palsy. Radiological imaging showed a large homogenously enhanced osteolytic lesion at the right jugular foramen. A cerebral angiogram showed a high-flow vascular lesion of the jugular bulb associated with retrograde sinus reflux, resulting in venous congestion of the deep venous system. These findings led us to misdiagnose this lesion as a glomus jugular tumor. However, combined arterial and venous angiography after transarterial embolization revealed the precise angioarchitecture, and we finally diagnosed this lesion as a high-flow osseous AVF at the jugular bulb. We performed transvenous embolization using a triple catheter technique. The lesion was successfully obliterated, and the 6-months angiogram showed no recurrence. ConclusionA rare case of high flow osseous AVF at the jugular bulb associated with osteolytic changes in the surrounding bony structure is reported. Although many hypervascular lesions at the jugular bulb are glomus tumors, bone destructive osseous AVF at the jugular bulb should be considered.

Electric vehicle charging management using location-based incentives for reducing renewable energy curtailment considering the distribution system

There have recently been an increasing number of variable renewable energy curtailment cases to manage power system stability problems caused by the overproduction of variable renewable energy. Variable renewable energy curtailment can be a factor that hinders the development of the power industry by reducing the economic viability of variable renewable energy operators and the efficiency of energy use. In this study, an economic curtailment methodology using electric vehicles to mitigate energy waste and economic losses is proposed. Charging point operators participate in incentive-based demand response programs with their charging station loads under curtailment situations. A location-based incentive algorithm considering distribution system constraints is proposed to avoid distribution system congestion. A response model based on random arrival electric vehicles considering demand and price elasticity, time pressure, and charging pressure is developed. The proposed methodology is verified through case studies based on the environment of Jeju Island in Korea. The case study results show that the proposed methodology can use energy more economically and effectively than conventional variable renewable energy curtailment methodology.

Optimal Rescheduling of Generators to Alleviate Congestion in Transmission System: A Novel Modified Whale Optimization Approach

Optimal Rescheduling of Generators to Alleviate Congestion in Transmission System: A Novel Modified Whale Optimization Approach

Integrated operational planning model, considering optimal delivery routing, incentives and electric vehicle aggregated demand management

The use of electric vehicles is being promoted to address emerging concerns about global warming associated with emissions from fossil fuels. Besides, in the context of parcel delivery deep growth related to e-commerce, electric vehicle is becoming an alternative to conventional fossil fuel technology. Intrinsically, the charging process implies the interdependence between the transportation and electric power systems. This paper presents a new multistage optimization-based approach that allows linking delivery routing and aggregated demand management in the transportation and electric power systems, respectively. For the routing and charging of each independent electric vehicle, battery degradation, acceleration- and speed-dependent power consumption, penalty for delivery delay, tolls, fixed charging prices and incentives for availability time are considered. An electric vehicle demand aggregator is used to guarantee the synergy between systems. Incentives are included to motivate electric vehicles to remain at charging intersections. However, attractive incentives can create electric power system congestion due to simultaneous charges on nodes. Thus, an iterative decongestion methodology is developed. The resulting model is divided into three stages: delivery allocation, delivery routing for each independent electric vehicle and optimal energy management by electric vehicle demand aggregator. The resulting optimization problem is cast as a mixed-integer linear programming model for the first two stages and a linear programming model for the third stage. Numerical results demonstrate the effectiveness of the proposed model on a real 284-intersection map with a set of 100 electric vehicles, showing that incentives allow electric vehicle demand aggregator to achieve cost savings of 8.5%.

Проблема домашнего насилия в пандемию COVID-19: кто виноват и что делать?

The article presents the analysis of the problem of domestic violence on the basis of domestic and foreign statistical data and the research results. Attention is focused on the aggravation of this problem during the pandemic of the new coronavirus infection COVID-19 in many countries of the world. The situation of uncertainty, a long stay in a confined space, the fear of contracting a new coronavirus infection, the inability to receive adequate medical care due to the congestion of the healthcare system, loss of financial stability, disruption of the usual rhythm of life led to the escalation of psychological tension. This resulted in the increase of domestic violence. The important role in resolving the situation and helping the victims of domestic violence under quarantine conditions was performed by specialized state and non-governmental organizations. Their activities underwent the structural, financial, and technological changes in the post-Covid-19 period. At the same time, in Russia there is a need of adopting a new federal law on combating domestic violence which will reduce the number of domestic crimes and increase the family values.

Intestinal Microbial-tissue Complex and Chronic Heart Failure (part 1): Pathogenesis

Antigenic and metabolic integration of the intestinal microbiota into the homeostasis of the human body is a factor that claims to play a key role in the pathogenesis of cardiovascular diseases. It acquires special significance against the background of the decrease in blood circulation and congestion in the digestive system during chronic heart failure. Aim of the review is analysis and synthesis of studies results on the role of intestinal microbiocenosis in the pathogenesis of heart remodeling and chronic heart failure. The search for articles was conducted in databases eLIBRARY.RU and Medline for the key terms "gut microbiota (microbiome, microbiocenosis)", "dysbiosis (dysbacteriosis)", "excessive bacterial growth syndrome", "lipopolysaccharide (endotoxin)", "trimethylamine-N-oxide" in combination with the terms "heart failure", "myocardial remodeling", "myocardium" in Russian and English, respectively. We selected articles containing the results of clinical and experimental studies published from 1995 to 2020. Review articles were considered only on the subject of the cited original publications. Most researchers have established the relationship between chronic heart failure and dysfunction and changes in the qualitative and quantitative composition of intestinal microbiocenosis. As negative changes, it is customary to note the proliferation of gram-negative opportunistic bacteria with concomitant endotoxinemia and a decrease in the pool of commensal microbiota. The available data suggest that the participation of the intestinal microbial-tissue complex in the pathogenesis of chronic heart failure and heart remodeling is realized through the activation of a local and then systemic inflammatory response, accompanied by cardiodepressive action of pro-inflammatory cytokines and universal proliferation factors, an imbalance of matrix metalloproteinases and their inhibitors, the initiation of apoptosis, fibrosis, and loss of contractile myocardium. Besides, a decrease in the production of short-chain and polyunsaturated fatty acids and vitamins by the commensal microbiota may be associated with changes in the electrical properties of cardiomyocyte membranes, a decrease in the systolic function of the left ventricle of the heart, and an increase in the risk of sudden cardiac death. It's also shown that the direct cardiotoxic effect of microbial molecules (lipopolysaccharides, peptidoglycans, trimethylamine-N-oxide, etc.), which interact with the receptors of cardiomyocytes and microenvironment cells, can cause the development of myocardial remodeling and its dysfunction. Recent studies have established mechanisms of myocardial remodeling mediated by microbial molecules, which may be associated with new strategies for the treatment and prevention of heart failure.

Congestion management of power systems by optimizing grid topology and using dynamic thermal rating

The integration of high-level renewable energy, increased load demand, and the aging of the transmission network have all exacerbated the congestion of the transmission system. This requires transmission service providers to make full use of the existing transmission infrastructure by using cost-effective new transmission technologies, thereby taking full advantage of the inherent flexibility of the system. Dynamic thermal rating (DTR) is one of several technologies that can help address challenges with transmission operation, especially congestion management. Optimal transmission switching (OTS) and DTR technologies together provide flexible methods to enhance the performance of the power system and maximize the use of existing transmission system. In this study, a probabilistic multi-objective based congestion management procedure is proposed using OTS strategies considering the maximization of system reliability and minimization of the total generation cost. Additionally, the prevention of islanding is considered to ensure the feasibility of transmission switching status. The uncertainties associated with load demand and wind power generation are handled in this study using the points estimation method (PEM). The formulated optimization problem is solved using the multi-objective teacher learning based optimization (MOTLBO) algorithm. As the studied problem is a nonlinear constrained multi-objective optimization problem with conflicting objectives, the Pareto-optimality is used to find the set of optimal solutions. The best compromise solution among the Pareto set is chosen by a fuzzy decision-making approach. Several case studies are simulated on the modified IEEE RTS-96 system. The simulation results show that transmission system reconfiguration while considering the DTR leads to the enhancement of the system performance as compared to static line rating (SLR). For example, the generation cost has dropped by 6.78% when utilizing the DTR as compared to the SLR.

Spatial demand forecasting based on smart meter data for improving local energy self‐sufficiency in smart cities

The use of distributed energy resources (DERs) in a city contributes to the net zero CO2 of a city. However, the spatially uneven distribution of power demand and surplus electricity causes congestion in the grid system, making wide-area operation difficult. The concept of local energy self-sufficiency via energy management, in which batteries or electric vehicles are charged using power generated by DERs and discharged to neighbouring consumers, is expected to be a way to avoid grid conjunction while maximizing the use of DERs. For efficient local energy self-sufficiency, it is necessary to identify where and when future power surpluses and shortages will occur within a city and optimize battery operation according to demand. Forecasts that focus only on representative points of a city may be less reproducible in diversity in the power demand transition for individual consumers in local parts of cities. Electricity smart meters that monitor power demand every 30 min from each consumer are expected to help predict the spatiotemporal distribution of power demand to achieve efficient local energy self-sufficiency. The significance of reflecting regional characteristics in forecasting spatiotemporal distribution of power demand is demonstrated using actual data obtained by smart meters installed in Japanese cities. The results suggest that the forecast approach, which considers the daily periodicity of power demand and weather conditions, obtains high prediction accuracy in predicting power demand in meshed local areas in the city and derives results precisely reproducing the spatiotemporal behaviours of power demand.

La conformidad: Negociar, pactar, rebajar y... ¿Renunciar a derechos para agilizar el proceso?

This work aims to analyze the conformity in the Spanish procedural system. But not exclusively. It pretends that the reader gets an idea that even though the conformity (as well as other forms of negotiated justice) is an advantageous and agile solution, also has a more uncertain side since it implies wavering guarantees and fundamental rights. Without disregarding the negotiations that take place (mainly, in the USA) that can be constraining to extremes that are hardy ethical or not at all. Not everything is acceptable for facilitating the process. This study will allow us to verify the problems of the justice system (slowness and congestion), as well as to analyze an instrument of procedural facilitation such as the conformity, to review its functioning, and for understanding what happens in the USA and in Chile, countries that have been chosen because the former is a conformity-based system, and the latter has an important Criminal Procedure Code and aims at distancing from the plea bargaining.

Entrance Location Planning of HOV Lanes in Multi-lane Highway Considering System and HOV Lane State

The high-occupancy vehicle (HOV) lane is an effective traffic demand management that encourages carpooling. In this study, we examine entrance location planning of HOV lanes. A highway commuting system containing HOV lanes is proposed. Commuters make travel choices based on the principle of minimum commuting time, i.e., the system is in the user equilibrium state. By planning the HOV lanes’ entrance location, the manager indirectly influences the commuters’ travel choices, thus achieving the predetermined management goals. In this study, an optimization model is developed where the decision variable is the entrance location of the HOV lane, and the conditional constraint of user equilibrium is satisfied. The objective function is a weighted average of a system state indicator and an HOV lane state one. Numerical examples show that the proposed method solves the location planning problem of the HOV lane entrance. The quantitative results reveal that the system congestion is relieved when the HOV lane entrance is close to the city center, and the traffic condition of the HOV lane is improved when the entrance is close to the city’s edge.

A new congestion cost allocation method in a deregulated power system using weighting of contractual preferences and geographical location of users

The restructuring of a power system from its monopolistic market to a deregulated system introduces important power flow considerations such congestion in the transmission system due to economic factors like competition in generation. Transmission congestion leads to additional cost for the transmission operator. This paper elaborates a method allocation of this cost amongst users based on their individual utilization of transmission assets. The congestion is relieved by influencing the choices of the consumers in the energy market. The paper proposes a cost allocation scheme based on power flow tracing method, by distinguishing the part of the cost related to the consumers’ market preferences, as opposed to the cost due to their geographical locations in the network before weighting them into a unique cost. This can bring about more transparency and efficiency with regard to payments made by producers and consumers, and also guides them towards choices that alleviate congestions in network.

Understanding CBO's Medicare for All Cost Estimates

In December 2020, the Congressional Budget Office (CBO) released a comprehensive report analyzing the costs of a single-payer healthcare system of the kind usually referred to as “Medicare for All” (M4A). The report has not yet received as much public attention as it deserves, most likely because of ongoing controversies in the aftermath of November’s presidential election. CBO’s M4A federal cost estimates are significantly lower than those produced in other studies (including my own). The CBO report also provides much information about M4A not readily found elsewhere. In particular, the report illuminates the extent to which M4A would increase congestion in the US healthcare system and would likely lead to more denials of sought-after care. The purpose of this policy brief is to highlight the most significant information and findings in the CBO report and to explain how CBO’s estimates diverge from mine and those in other studies.

Femoral Vein Pulsatility: What Does It Mean?

In this report, the clinical evolution of a 72-year-old patient transferred to the surgical intensive care unit after cardiac surgery is described. The presence of a pulsatile Doppler signal of the common femoral vein was noted after surgery. On postoperative day 5, diuretics in addition to a combination of inhaled epoprostenol and milrinone were associated with normalization of femoral vein pulsatility. The observations seen in peripheral venous flow reinforce the hypothesis that pulsatility of the common femoral vein represents an associated echocardiographic sign of right ventricular dysfunction and may be used to monitor systemic venous congestion. Pulsatility in the venous system may be improved by reducing volume overload and improving right ventricular function.