Nonsy load flow: Smart grid load flow using non-synchronized measurements

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper presents a novel algorithm for load flow analysis in smart grids, using non-synchronized measurements collected at the main substation and at the terminals of Distributed Generators (DGs) and microgrids. This allows the use of already available measurements along with a proper communication system to calculate the magnitude and phase angle of nodal voltages, power flow in each branch, power injected by each electricity source, and system losses. The proposed non-synchronized measurements-based load flow (Nonsy load flow) algorithm is based on the conventional backward-forward sweep and it considers the synchronization angles as unknown variables to be calculated. Simulation studies on a smart grid model with several DG units and microgrids validate the performance of the proposed method. In all the studied cases, the load flow results are accurate and the unknown synchronization angles are precisely calculated as a byproduct of the algorithm without any significant extra computational effort. The calculated synchronization angles can satisfy the need of other smart grid applications requiring synchronized measurements

A Practical Integrated Fault Location Method for Electrical Power Distribution Networks

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Future distribution systems are expected to be self-healing systems which can manage the faults and quickly restore the customers from outage. As the basic function of fault management systems, fault location methods play an important role in reducing the outage time and related costs. This paper aims to present a practical method that provides precise and reliable estimations of the fault location. The method is an integration of a voltage sag-based method and an impedance-based method. Following to any permanent fault, the proposed method first uses the voltage sag magnitudes measured by a limited number of meters to find the closest node to the fault. Then, it investigates the lines connected to the node selected and uses an impedance-based method to find the exact fault location. The method proposed can be applied to large-scale distribution systems having several laterals and load taps. Simulations are on a practical distribution system are performed to test the method performance. The simulation study includes a comparative analysis with two other recent methods reported in the literature. The results show the better accuracy of the proposed method even with measurement inaccuracies and load data errors

All-cause mortality following a cancer diagnosis amongst multiple sclerosis patients: A Swedish population-based cohort study

Background and purpose: A reduced cancer risk amongst patients with multiple sclerosis (MS) has been reported. Theoretically, this could represent a genuine reduction in risk or, alternatively, 'diagnostic neglect', where cancer is undiagnosed when symptoms are misattributed to MS. Objective: Assess all-cause mortality risk following a cancer diagnosis in patients with MS compared with a cohort without MS. Patients: A cohort of MS patients (n = 19 364) and a cohort of the general population (n = 192 519) were extracted from national Swedish registers from 1969 to 2005. All-cause mortality after cancer in MS was compared with the general population. Poisson regression analysis was conducted in the MS and non-MS cohorts separately. The models were adjusted for follow-up duration, year at entry, sex, region and socioeconomic index. The two cohorts were combined and differences in mortality risk were assessed using interaction testing. Results: The adjusted relative risk (and 95 confidence interval) for all-cause mortality following a cancer diagnosis in MS patients (compared with MS patients without cancer) is 3.06 (2.86-3.27; n = 1768) and amongst those without MS 5.73 (5.62-5.85; n = 24 965). This lower magnitude mortality risk in the MS patients was confirmed by multiplicative interaction testing (P < 0.001). Conclusions: A consistent pattern of lower magnitude of all-cause mortality risk following cancer in MS patients for a range of organ-specific cancer types was found. It suggests that cancer diagnoses tend not to be delayed in MS and diagnostic neglect is unlikely to account for the reduced cancer risk associated with MS. The lower magnitude cancer risk in MS may be due to disease-associated characteristics or exposures. © 2015 EAN

Legg-Calvé-Perthes disease and the risk of injuries requiring hospitalization

Background and purpose Previous studies have suggested that Legg-Calvé-Perthes disease (LCPD) is associated with repetitive trauma, coagulation problems and anatomical abnormalities of the blood supply to the femoral head. The hypothesis that repetitive trauma can affect the blood supply of the femoral head, leading to LCPD, is supported by an animal model. For evidence of an increased risk of repetitive trauma, we investigated whether patients with LCPD have a higher risk for severe injuries requiring hospitalization. Patients and methods We identified 2579 patients with LCPD in Sweden during the period 1964-2005. 13,748 individuals without LCPD were randomly selected from the Swedish general population, matched by year of birth, sex and region (control group). Cox proportional hazard regression estimated the risks. Results Compared to the control group, patients with LCPD had a modestly raised hazard ratio (HR) of 1.2 (95% CI 1.1-1.3) for injury requiring hospitalization. The risks were slightly higher for soft tissue injuries (HR = 1.3, 95% CI:1.1-1.4) than for fractures (HR = 1.1, 95% CI: 1.0-1.3) and more pronounced among females. Compared to the control group, the higher risk for injury only applied to the lower extremities (HR = 1.2, 95% CI: 1.0-1.4) in patients with LCPD. Interpretation Patients with LCPD are vulnerable to injuries which could be interpreted as a marker of hyperactive behavior. It could also implicate that anatomical changes in the bone formation or blood supply of the femoral head - increasing its sensibility for trauma - contribute to the etiology of LCPD. © Copyright: ©Nordic Orthopaedic Federation

Dietary patterns and risk of squamous-cell carcinoma and adenocarcinoma of the esophagus and adenocarcinoma of the gastric cardia: A population-based case-control study in Sweden

We conducted a large population-based case-control study in Sweden to examine the association of dietary patterns and the development of cancers from the esophagus or gastroesophageal junction. In total 185 patients with esophageal adenocarcinoma, 165 with esophageal squamous-cell carcinoma, 258 with gastric cardia adenocarcinoma, and 815 randomly selected population controls underwent face-to-face interviews. Exploratory factor analysis was used to identify possible dietary patterns. Multivariate logistic regression with adjustments for age, sex, years of education, body mass index, physical activity, symptomatic gastroesophageal reflux, smoking, and total energy intake was used to estimate odds ratios (ORs) and their 95% confidence intervals (CIs). We identified three major dietary patterns in this population, for example, "healthy diet" (high in vegetables, tomato, fruits, fish, and poultry), "Western diet" (high in processed meat, red meat, sweets, high-fat dairy, and high-fat gravy), and "alcohol drinker" (high in intakes of beer, liquor, and French fries). We found that a healthy diet tended to moderately decrease the risk of all three cancers under study, although none of the associations was statistically significant. A high score of Western diet was associated with increased risks of gastric cardia adenocarcinoma (high 3rd fertile vs. low 1st quartile, OR = 1.8, 95% CI = 1.1-2.9, P for trend = 0.04) and esophageal adenocarcinoma (high 3rd fertile vs. low 1st fertile, OR = 1.6, 95% CI = 0.9-3.1, P for trend = 0.13), whereas a dietary pattern characterized by high beer and liquor intake (alcohol drinker) significantly increased the risk of squamous-cell carcinoma of the esophagus (3rd fertile vs. low 1st fertile, OR = 3.5, 95% CI = 1.9-6.3, P for trend < 0.0001). Our study confirms the important role of diet in the carcinogenesis of esophageal and cardia cancer. Copyright © 2006, Lawrence Erlbaum Associates, Inc

Multi-Objective Optimal Placement of Recloser and Sectionalizer in Electricity Distribution Feeders

© 2019 IEEE. Electricity distribution feeders, due to their geographical dispersion, are subjected to faults caused by adverse weather, vegetation growth, etc., resulting in long outages for customers. Overhead switching devices (i.e. reclosers, sectionalizers, disconnectors and etc.) are known as the most practical solutions to limit the outage area, and consequently increase the distribution system reliability. This paper presents a Multi-Objective Particle Swarm Optimization (MOPSO) algorithm for Optimal Placement of Recloser and Sectionalizer to minimize customers' outage cost and increase system reliability with an optimal investment. The algorithm determines the number and optimal locations of reclosers and sectionalizers to fulfill the objectives. The obtained results on the standard 85-node distribution feeder validate the effectiveness of the proposed method

Simultaneous optimal placement and sizing of DSTATCOM and parallel capacitors in distribution networks using multi-objective PSO

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. The increase in electricity demands has increased the dimension and loading of today radial distribution feeders, which in turn would result in more losses and voltage drops. Such issues together with the demand for higher power quality has raised a need for modern power system management techniques such as using power electronic devices. Among, DSTATCOM is introduced as an effective solution for reactive power control in power distribution level. To make a better use of DSTATCOM in improving the network power quality, it should be sized and placed in accordance with parallel capacitors. A multi-objective optimization method is proposed in this paper to find the optimal location and size of DSTATCOM and parallel capacitors simultaneously. The cost of power losses, voltage profile and voltage stability are selected as objectives to be improved. The obtained results on the IEEE 33-node test system indicate that the proposed method satisfies the defined objectives and considerably improves the network operational characteristics

Influences of nitrogen and potassium top dressing on yield and yield components as well as their accumulation in rice (Oryza sativa)

This research was conducted to investigate the effects of different rates of nitrogen (N) and potassium (K) top dressing on grain yield and yield components of rice (Oryza sativa cv. Tarrom) and to investigate N and K content of upper leaves analyzed at ten different times. A pot experiment was carried out on a completely randomized design with seven replications under greenhouse conditions at the Experiment Station of Sari Agricultural Sciences and Natural Resources University, Iran, during the growing season in 2008. Nitrogen was applied in the form of urea (46% N) at the rates of 0, 23 and 46 kg N ha-1 and potassium in the form of potassium chloride (60% K2O) at the rates of 0, 30 and 60 kg K2O ha- 1. Results indicated that panicle length, plant height, number of tiller, number of grain per panicle, hollow grain percentage, grain and biological yield were significantly affected by N and K fertilization. Maximum grain yield (75.46 g pot-1) occurred at 23 kg N ha-1 and 30 kg K2O ha-1. At flowering stage, Kcontent of stems were higher than leaves, and N content in flag leaves was higher than other plant parts