Hierarchical distributed framework for optimal dynamic load management of electric vehicles with vehicle-to-grid technology

The tendency towards carbon dioxide reduction greatly stimulates the popularity of electric vehicles against conventional vehicles. However, electric vehicle chargers represent a huge electric burden, which affects the performance and stability of the grid. Various optimization methodologies have been proposed in literature to enhance the performance of the distribution grids. However, existing techniques handle the raised issues from individual perspectives and/or with limited scopes. Therefore, this paper aims to develop a distributed controller-based coordination scheme in both medium and low voltage networks to handle the electric vehicles’ charging impact on the power grid. The scope of this work covers improving the network voltage profile, reducing the total active and reactive power, reducing the load fluctuations and total charging cost, while taking into consideration the random arrivals/departures of electric vehicles and the vehicle owners’ preferred charging time zones with vehicle-to-grid technology. Simulations are carried out to prove the success of the proposed method in improving the performance of IEEE 31-bus 23 kV system with several 415 V residential feeders. Additionally, the proposed method is validated using Controller Hardware-in-the-Loop. The results show that the proposed method can significantly reduce the issues that appear in the electric power grid during charging with minor changes in the existing grid. The results prove the successful implementation of different types of charging, namely, ultra-fast, fast, moderate, normal and vehicle-to-grid charging with minimum charging cost to enhance the owner’s satisfaction level

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

An efficient design of LC-compensated hybrid wireless power transfer system for electric vehicle charging applications

Wireless power transfer (WPT) is the technology of transferring the electric power through a time-varying electric or magnetic field acting as a transmission medium. A combination between the inductive power transfer (IPT) and the capacitive power transfer (CPT) has been recently developed to benefit from the merits of both systems in order to realize high power transfer with high efficiency through large air gaps and misalignment distances. The output power capability of the existing designs is still limited and needs further enhancement. In this paper, a new hybrid inductive and capacitive wireless power transfer model is proposed, analyzed and simulated. The inductive part composes of a circular spiral coil integrated with a helical coil and supported with cross shape ferrite bars in order to enhance the magnetic coupling ability. The capacitive part consists of four cylindrically evacuated square plates compatible with the inductive part size to facilitate the combination process. Firstly, the system structure is designed using Maxwell-3D simulation tool, then an equivalent circuit model is derived in detail to explicate the working principle. Secondly, a 10.1 kW hybrid system is designed and simulated using MATLAB/Simulink and ANSYS/Simplorer. Excluding the inverter and the rectifier internal losses and considering only the AC losses of the coils represented in their parasitic resistance, a high resultant efficiency equal to 99.37% at a resonant frequency of 1 MHz is achieved. Generally, the results show that the hybrid system could perform better under different air gaps and misalignments than the inductive and the capacitive systems separately

Enhanced performance of substation dynamics during large induction motor starting using SVC

Static Var Compensators (SVC) have been widely used to separately improve each of voltage variation performance and steady state power factor of industrial substations. However, these two functions are interdependent, power factor improvement tends to do better voltage regulation. In this paper, a newly starting method with SVC for large induction motors is suggested. This method provides a controllable amount of reactive power precisely according to the requirement of the load. A combined controller consists of slow susceptance control besides fast acting voltage control will give SVC the ability to achieve power factor correction, and will present a constant voltage characteristic during large induction motor starting. An ideal compensator approach is proposed for both power factor correction and optimum voltage regulation. A case study of 1.4 MW large induction motor starting is presented with different starting methods. A comparative study is conducted to simulation results using Electrical Transient Analyzer Program (ETAP) for different starting cases. Finally, the simulation results provide bases for the safe and reliable operation and would insure a robust design of practical substation. Keywords: Motor starting, ETAP, Induction motor, Power factor, Stativ var compensator, Voltage regulatio

A Gaussian random walk salp swarm algorithm for optimal dynamic charging of electric vehicles

Salp swarm algorithm (SSA) is one of the recently developed meta-heuristic optimization algorithms. Since SSA outperforms other swarm-based algorithms, it has recently been employed in various applications, including feature selection, neural network training and renewable energy systems. In this paper, an improved salp swarm algorithm based on a Gaussian random walk is proposed, which enhances the algorithm’s performance particularly for multidimensional constrained global optimization problems. The integration of a Gaussian random walk into the algorithm balances between its exploration and exploitation capabilities. Furthermore, the proposed algorithm introduces a new re-dispersion strategy in the case of stagnation at local optimum points, which considerably enhances exploration. The performance of the proposed algorithm is evaluated using a set of twenty-three benchmark test functions and is compared to the performance of prevalent metaheuristic algorithms. Statistical analysis is performed using Wilcoxon signed-rank test, and the results reveal considerable improvement over the competing algorithms. Then, 21 real-world optimization problems are used to further evaluate the efficacy of the proposed algorithm. The winners of the CEC2020 Competition on Real-World Single Objective Constrained Optimization, SASS, sCMAgES, EnMODE, and COLSHADE algorithms, are used as four comparable algorithms in the real-world optimization problems. The convergence curves and simulations provide very competitive performance compared to the comparative algorithms. The proposed algorithm is used to address one of the most challenging real-world constrained problems in power system applications, namely, determining the optimal charging schedule for electric vehicles at charging stations. The results reveal that the proposed algorithm outperforms other existing algorithms in terms of increasing the charging revenues and achieving maximum power grid stability

Prognostic and diagnostic anthropometric biomarkers of sarcopenia in a cohort of Egyptian patients with hepatitis C-induced liver cirrhosis

Abstract Background Chronic hepatitis C (HCV) infection is a leading cause of liver cirrhosis (LC) worldwide with decompensation-related clinical sequelae. Sarcopenia is currently recognized as a fundamental complication of LC owing to various mechanisms. This study aimed to assess the role of anthropometric measures of sarcopenia in predicting the outcome of LC as assessed by the Child-Turcotte-Pugh (CTP) grade. Results A cross-sectional study was carried out on 80 patients with HCV-related LC with different CTP grades. The diagnosis of sarcopenia was based on the 2018 definition of sarcopenia according to the European Working Group on Sarcopenia in Older People (EWGSOP). Muscle strength was assessed by hand grip strength (HGS) and lower leg extension strength (LES). Assessment of muscle mass was performed by measuring mid-calf circumference (MCC) and mid-arm muscle circumference (MAMC). HGS varied significantly between the different CTP grades, being highest in CTP grade C. Additionally, the number of patients diagnosed with “definitive sarcopenia” using either HGS/MCC or LES/MCC varied significantly between CTP grades, being highest in CTP grade C. Conclusions HGS is a better predictor of worse outcomes of liver cirrhosis than LES. The combination of MCC and HGS or LES is a potentially promising noninvasive prognostic biomarker of liver disease

On the development of flywheel storage systems for power system applications: A survey

Energy storage systems cannot be considered energy sources but having the ability of storing and discharging energy. They have a vital rule in the reliability and power quality of power systems. There are several energy storage systems (e.g. compressed air storage, battery, supercapacitors, hydrogen storage and flywheels) which can be selected according to the application requirements. Flywheels are used in electric power systems for frequency support, uninterruptible power supply, voltage sag mitigation, flexible AC transmission and power leveling. The flywheel energy storage system consists of a flywheel, an electric machine and a power conversion system. In this paper, energy storage systems used in power system applications are surveyed focusing on flywheel energy storage systems. © 2012 IEEE

A design example of an 8-pole radial AMB for flywheel energy storage

High speed flywheel energy storage systems normally use magnetic bearings to reduce friction loss. Bearing load consists of radial forces with or without axial forces according to drive configuration and requirements. The magnetic bearing system may be passive magnetic bearing (PMB), active magnetic bearing (AMB) or superconducting magnetic bearing (SMB) according to the required application. In this paper, a design example for an 8-pole radial AMB used for flywheel energy storage is presented. The design details along with finite element simulations are given to verify the design requirements. Finite element analysis is also used to obtain the bearing parameters. Based on calculated system parameters, a Matlab model is built to simulate the magnetic bearing in different cases. © 2012 IEEE

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

Background: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit