scholarly journals RAILWAY SYSTEM IMPACT ON VOLTAGE QUALITY AT THE LEVEL OF THE CROATIAN TRANSMISSION NETWORK

2020 ◽  
Vol 69 (2) ◽  
pp. 19-23
Author(s):  
Denisa Galzina ◽  
Eraldo Banovac ◽  
Tomislav Tomiša
Keyword(s):  
Harmonic Distortion ◽  
Quality Measurement ◽  
Theoretical Description ◽  
Transmission Network ◽  
Two Phase ◽  
Voltage Unbalance ◽  
Railway Systems ◽  
Voltage Quality ◽  
Railway System ◽  
The Impact

Railway systems are single-phase loads, connected to two-phase of the three-phase supply network. Therefore, they negatively affect the voltage quality, primarily the voltage unbalance. In addition to voltage unbalance, railway systems inject current harmonics into the network due to controllable diode or thyristor drives used to operate the train. The paper gives a short theoretical description of the harmonic distortion and the voltage unbalance as well as the results of the voltage quality measurement. Moreover, the paper shows the impact of the railway system on the transmission network in the case that the facilities are connected to the 110 kV voltage level.

scholarly journals THE IMPACT OF INNOVATIVE TECHNOLOGIES ON THE EFFICIENCY OF RAILWAY SYSTEM MANAGEMENT

2021 ◽  
pp. 68-75
Author(s):  
Irina Sabirova ◽  
◽  
Keyword(s):  
Transport Systems ◽  
System Management ◽  
Systems Management ◽  
Management Tools ◽  
Innovative Technologies ◽  
Intelligent Transport ◽  
Railway Systems ◽  
Railway Industry ◽  
Railway System ◽  
The Impact

The article discusses the issues of introducing innovative technologies into the railway management system. The object of the study is the efficiency of management of railway systems. The subject of the research is innovative technologies and their impact on the effectiveness of railway systems management. The purpose of the work is to conduct a theoretical analysis of the impact of innovations on the efficiency of railway systems management and, using the example of large foreign railway systems, to determine the main factors of innovation efficiency. The scientific novelty of the presented work lies in the analysis of foreign experience in the development of effective management tools for railway systems in the context of innovation. The paper concludes that the future of the railway industry directly depends on the degree of its digitalization and technologization, the introduction of intelligent transport systems and active integration into the global space of innovative development.

scholarly journals An Analysis of Voltage Quality in a Nanogrid during Islanded Operation

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 614 ◽  
Author(s):  
Jakob Nömm ◽  
Sarah Rönnberg ◽  
Math Bollen
Keyword(s):  
Short Circuit ◽  
Harmonic Distortion ◽  
Quality Data ◽  
Voltage Unbalance ◽  
Voltage Distortion ◽  
Voltage Quality ◽  
Islanded Operation ◽  
Harmonic Voltage ◽  
Even Harmonics

Voltage quality data has been collected in a single house nanogrid during 48 weeks of islanded operation and 54 weeks of grid-connected operation. The voltage quality data contains the voltage total harmonic distortion (THD), odd harmonics 3 to 11 and 15, even harmonics 4 to 8, voltage unbalance, short-term flicker severity (Pst) and long-term flicker severity (Plt) values, and voltage variations at timescales below 10 min. A comparison between islanded and grid-connected operation values was made, were some of the parameters were compared to relevant grid standard limits. It is shown that some parameters exceed the defined limits in the grid-standards during islanded operation. It was also found that the islanded operation has two modes of operation, one in which higher values of the short circuit impedance, individual harmonic impedance, harmonic voltage distortion and voltage unbalance were reached.

scholarly journals Power Quality Measurement and Active Harmonic Power in 25 kV 50 Hz AC Railway Systems

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5698
Author(s):  
Yljon Seferi ◽  
Steven M. Blair ◽  
Christian Mester ◽  
Brian G. Stewart
Keyword(s):  
Power Quality ◽  
Quality Measurement ◽  
Electrical Energy ◽  
Active Power ◽  
Time Interval ◽  
Time Varying ◽  
Electrical Networks ◽  
Measurement Instruments ◽  
Railway Systems ◽  
The Impact

Railway electrical networks rated at 25 kV 50 Hz are characterised by significant levels of voltage and current harmonics. These frequency components are also time varying in nature due to the movement of trains and changing operational modes. Processing techniques used to evaluate harmonic results, although standardised, are not explicitly designed for railway applications, and the smoothing effect that the standard aggregation algorithms have on the measured results is significant. This paper analyses the application accuracy of standardised power quality (PQ) measurement algorithms, when used to measure and evaluate harmonics in railway electrical networks. A shorter aggregation time interval is proposed for railway power quality measurement instruments, which offers more accurate estimated results and improved tracking of time varying phenomena. Harmonic active power present in railway electrical networks is also evaluated in order to quantify the impact it has on the energy accumulated by electrical energy meters installed on-board trains. Analysis performed on 12 train journeys shows significant levels of non-fundamental active power developed for short periods of time. As an energy meter will inadvertently absorb the financial cost of non-fundamental energy produced by other trains or other external power flows, results are provided to support recommendations for future standards to measure only fundamental frequency energy within train energy measurement meters.

scholarly journals Voltage Harmonic Suppression by Means of Grid-Connected Converters Using only Local Measurements

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2515 ◽  
Author(s):  
Ya Zhang ◽  
Maurice Roes ◽  
Marcel Hendrix ◽  
Jorge Duarte
Keyword(s):  
Control Method ◽  
Frequency Estimation ◽  
Estimation Error ◽  
Harmonic Distortion ◽  
Current Control ◽  
Harmonic Suppression ◽  
Voltage Quality ◽  
Local Measurements ◽  
Grid Connected Converters ◽  
The Impact

A single-phase grid-connected converter is considered in this paper in the presence of harmonic problems introduced non-linear loads. In order to compensate the harmonics caused by the loads, a local voltage support scheme is proposed. This is an added feature because its implementation is in parallel with a conventional current control method. Distinctively, the measurements of the grid or load current are not needed since the scheme is based on only local measurements. On top of a fundamental part for desired power injection, the converter output current comprises a harmonic part for compensation. Thus, the grid current harmonic distortion is minimized and the enhancement of the local voltage quality is achieved. A comprehensive model analysis indicates that the proposed strategy can help to attenuate harmonics of the local voltage without compromising on the quality of the fundamental current injection. Experimental results validate the effectiveness of the proposed control scheme. Moreover, the impact of grid frequency estimation error on the control strategy’s performance is quantified theoretically and experimentally.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

scholarly journals A next step in disruption management: combining operations research and complexity science

2021 ◽  
Author(s):  
Mark M. Dekker ◽  
Rolf N. van Lieshout ◽  
Robin C. Ball ◽  
Paul C. Bouman ◽  
Stefan C. Dekker ◽  
...  
Keyword(s):  
Operations Research ◽  
Complexity Science ◽  
Rolling Stock ◽  
Accurate Information ◽  
Disruption Management ◽  
Railway Systems ◽  
Decentralized Decision Making ◽  
Control Situations ◽  
Management Techniques ◽  
The Impact

AbstractRailway systems occasionally get into a state of being out-of-control, meaning that barely any train is running, even though the required resources (infrastructure, rolling stock and crew) are available. Because of the large number of affected resources and the absence of detailed, timely and accurate information, currently existing disruption management techniques cannot be applied in out-of-control situations. Most of the contemporary approaches assume that there is only one single disruption with a known duration, that all information about the resources is available, and that all stakeholders in the operations act as expected. Another limitation is the lack of knowledge about why and how disruptions accumulate and whether this process can be predicted. To tackle these problems, we develop a multidisciplinary framework combining techniques from complexity science and operations research, aiming at reducing the impact of these situations and—if possible—avoiding them. The key elements of this framework are (i) the generation of early warning signals for out-of-control situations, (ii) isolating a specific region such that delay stops propagating, and (iii) the application of decentralized decision making, more suited for information-sparse out-of-control situations.

scholarly journals The Effect of Health Shock and Basic Medical Insurance on Family Educational Investment for Children in China

2021 ◽  
Vol 18 (10) ◽  
pp. 5242
Author(s):  
Pu Liao ◽  
Zhihong Dou ◽  
Xingxing Guo
Keyword(s):  
Negative Impact ◽  
Medical Insurance ◽  
Generation Model ◽  
Two Phase ◽  
Parental Health ◽  
Health Shock ◽  
Basic Medical Insurance ◽  
Child Education ◽  
The Impact ◽  
Basic Medical

This paper explores the role of basic medical insurance in protecting family investment in child education. First, this paper establishes a two-phase overlapping generation model to theoretically analyse the impact of basic medical insurance on investment in child education under the influence of the impact of parental health. The results show that health shock reduces parental investment in child education, and medical insurance significantly alleviates the negative impact of parental health shock on investment in child education. Furthermore, this paper establishes a two-way fixed effect regression model based on the data of China Family Panel Studies (CFPS) in 2014 and 2016 to empirically test the above results. The results showed that parental health shocks negatively affect investment in child education, and paternal health shock has a more significant impact than maternal health shock. However, medical insurance significantly reduces this negative impact, provides security in investment in child education, and promotes the improvement of human capital.

Quality measurement of refrigerant two-phase flow in refrigeration cycles

2021 ◽  
Vol 77 ◽  
pp. 101880
Author(s):  
Mitsuhiro Fukuta ◽  
Shota Morishita ◽  
Katsuya Nishihata ◽  
Masaaki Motozawa ◽  
Naoya Makimoto
Keyword(s):  
Two Phase Flow ◽  
Quality Measurement ◽  
Phase Flow ◽  
Two Phase

scholarly journals Exploring the impact of a decision support algorithm to improve clinicians’ chemotherapy-induced peripheral neuropathy assessment and management practices: a two-phase, longitudinal study

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Robert Knoerl ◽  
Emanuele Mazzola ◽  
Fangxin Hong ◽  
Elahe Salehi ◽  
Nadine McCleary ◽  
...  
Keyword(s):  
Decision Support ◽  
Peripheral Neuropathy ◽  
Management Practices ◽  
Management Strategies ◽  
Clinic Visit ◽  
Evidence Based ◽  
Two Phase ◽  
Assessment Index ◽  
Patient Reported ◽  
The Impact

Abstract Background Chemotherapy-induced peripheral neuropathy (CIPN) negatively affects physical function and chemotherapy dosing, yet, clinicians infrequently document CIPN assessment and/or adhere to evidence-based CIPN management in practice. The primary aims of this two-phase, pre-posttest study were to explore the impact of a CIPN clinician decision support algorithm on clinicians’ frequency of CIPN assessment documentation and adherence to evidence-based management. Methods One hundred sixty-two patients receiving neurotoxic chemotherapy (e.g., taxanes, platinums, or bortezomib) answered patient-reported outcome measures on CIPN severity and interference prior to three clinic visits at breast, gastrointestinal, or multiple myeloma outpatient clinics (n = 81 usual care phase [UCP], n = 81 algorithm phase [AP]). During the AP, study staff delivered a copy of the CIPN assessment and management algorithm to clinicians (N = 53) prior to each clinic visit. Changes in clinicians’ CIPN assessment documentation (i.e., index of numbness, tingling, and/or CIPN pain documentation) and adherence to evidence-based management at the third clinic visit were compared between the AP and UCP using Pearson’s chi-squared test. Results Clinicians’ frequency of adherence to evidence-based CIPN management was higher in the AP (29/52 [56%]) than the UCP (20/46 [43%]), but the change was not statistically significant (p = 0.31). There were no improvements in clinicians’ CIPN assessment frequency during the AP (assessment index = 0.5440) in comparison to during the UCP (assessment index = 0.6468). Conclusions Implementation of a clinician-decision support algorithm did not significantly improve clinicians’ CIPN assessment documentation or adherence to evidence-based management. Further research is needed to develop theory-based implementation interventions to bolster the frequency of CIPN assessment and use of evidence-based management strategies in practice. Trial registration ClinicalTrials.Gov, NCT03514680. Registered 21 April 2018.

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