scholarly journals Optimized Design of Modular Multilevel DC De-Icer for High Voltage Transmission Lines

Electronics ◽  
2018 ◽  
Vol 7 (9) ◽  
pp. 204 ◽  
Author(s):  
Jiazheng Lu ◽  
Qingjun Huang ◽  
Xinguo Mao ◽  
Yanjun Tan ◽  
Siguo Zhu ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Engineering Application ◽  
Optimized Design ◽  
Multilevel Converter ◽  
Power Outage ◽  
Total Cost ◽  
Technical Performance ◽  
Promising Solution

Ice covering on overhead transmission lines would cause damage to transmission system and long-term power outage. Among various de-icing devices, a modular multilevel converter based direct-current (DC)de-icer (MMC-DDI) is recognized as a promising solution due to its excellent technical performance. Its principle feasibility has been well studied, but only a small amount of literature discusses its economy or hardware optimization. To fill this gap, this paper presents a quantitative analysis and calculation on the converter characteristics of MMC-DDI. It reveals that, for a given DC de-icing requirement, the converter rating varies greatly with its alternating-current (AC) -side voltage, and it sometimes far exceeds the melting power. To reduce converter rating and improve its economy, an optimized configuration is proposed in which a proper transformer should be configured on the input AC-side of converter under certain conditions. This configuration is verified in an MMC-DDI for a 500 kV transmission line as a case study. The result shows, in the case of outputting the same de-icing characteristics, the optimized converter is reduced from 151 MVA to 68 MVA, and the total cost of the MMC-DDI system is reduced by 48%. This conclusion is conducive to the design optimization of multilevel DC de-icer and then to its engineering application.

scholarly journals Optimized Design of Modular Multilevel DC De-Icer for High Voltage Transmission Lines

2018 ◽  
Author(s):  
Jiazheng Lu ◽  
Qingjun Huang ◽  
Xinguo Mao ◽  
Yanjun Tan ◽  
Siguo Zhu ◽  
...  
Keyword(s):  
High Voltage ◽  
Transmission Lines ◽  
Engineering Application ◽  
Optimized Design ◽  
Power Outage ◽  
Technical Performance ◽  
Promising Solution ◽  
High Voltage Transmission

Ice covering on overhead transmission lines would cause damage to transmission system and long-term power outage. Among various de-icing devices, modular multilevel converter (MMC) based DC de-icer (MMC-DDI) is recognized as a promising solution due to its excellent technical performance. Its principle feasibility has been well studied, but few literature discuss its economy or hardware optimization, thus the designed MMC-DDI for high voltage transmission lines is usually too large and too expensive for engineering applications. To fill this gap, this paper presents a quantitative analysis on the converter characteristics of MMC-DDI, and calculates the minimal converter rating and its influencing factors. It reals that, for a given de-icing requirement, the converter rating varies greatly with its AC-side voltage. Then an optimization configuration is proposed to reduce the converter rating and improve its economy. The proposed configuration is verified in a MMC-DDI for a 500kV transmission line as a case study. The result shows, in the case of outputting same de-icing characteristics, the optimized converter rating is reduced from 151 MVA to 68 MVA, and total cost of MMC-DDI is reduced by 48%. This analysis and conclusion are conductive to the optimized design of multilevel DC de-icer, then to its engineering application.

Long Term Structural Integrity Considerations for Abandoned Pipelines

2016 ◽  
Author(s):  
Shane Finneran ◽  
T. J. Prewitt ◽  
Joel Kaufman
Keyword(s):  
Transmission Lines ◽  
Structural Integrity ◽  
Large Diameter ◽  
Metal Loss ◽  
Finite Element Analyses ◽  
Load Bearing Capacity ◽  
Soil Subsidence ◽  
Structural Capacity

There has been increasing interest across the industry to better understand the possible long term risks associated with out of service pipelines. In Canada, the Canadian Energy Pipeline Association (CEPA), Petroleum Technology Alliance of Canada (PTAC), and the National Energy Board (NEB), have undertaken multiple studies to identify and assess the threats related to pipeline abandonment. [1][2][3] The primary hazards typically identified across industry for pipeline abandonment are associated with long term corrosion degradation, potential for creation of water conduits, possible environmental impacts, and potential for pipeline collapse and associated soil subsidence. Unfortunately, little guidance is presently available to the industry for determining remaining structural capacity of a heavily corroded pipeline to establish likelihood, and possible timeline, of collapse, nor for determining possible subsidence magnitudes associated with large diameter transmission lines. This paper presents a technical case study for an assessment approximating the remaining strength of an abandoned pipeline subject to long term corrosion degradation, considering both general metal loss, and randomized pitting and perforation growth. The work presented used a combination of finite element analyses, and existing industry models for determining load bearing capacity of an abandoned pipeline under varying levels of degradation.

scholarly journals Long-Term Power Outage and Preparedness of the Population of a Region in the Czech Republic—A Case Study

2021 ◽  
Vol 13 (23) ◽  
pp. 13142
Author(s):  
Štěpán Kavan ◽  
Olga Dvořáčková ◽  
Jiří Pokorný ◽  
Lenka Brumarová
Keyword(s):  
Czech Republic ◽  
Actual State ◽  
Power Outages ◽  
Power Outage ◽  
The Czech Republic ◽  
The World ◽  
Nonparametric Correlation ◽  
World Point

The power outages that have occurred in recent years around the world point to widespread problems with consequences for the lives and health of the population, but also material damage. This is a case study that focuses on the evaluation of the preparedness of the population of a selected region in the Czech Republic for a long-term power outage. This article deals with a case study that focuses on the evaluation of the preparedness of the population of the Karlovy Vary region in the field of emergency survival. Part of the study is the evaluation of the respondents’ answers, which provides an overview of the actual state of preparedness for power outages on a sample group of respondents in the Karlovy Vary region. The research method used was a survey using questionnaires. The obtained information was subsequently statistically evaluated by nonparametric correlation using Kendall’s taub. From the presented results of the survey, it is clear that the inhabitants of smaller municipalities are better prepared for a power outage and can create basic conditions for emergency survival.

Unattended Sensors in Marine Environments

2015 ◽  
pp. 285-308
Author(s):  
Rizal Mohd Nor ◽  
Mikhail Nesterenko
Keyword(s):  
Temperature Sensor ◽  
Architectural Design ◽  
World Wide ◽  
Oxygen Sensor ◽  
Satellite Transmitter ◽  
Total Cost ◽  
Commercial Off The Shelf ◽  
Embedded Pc

This chapter discusses the use of unattended sensors and its use in marine environment. The authors present challenges of designing a marine sensor in harsh environments and a case study in implementing a marine sensor to study hypoxia. Hypoxia is a world-wide anthropogenic phenomenon related to pollution. The authors describe the construction of an inexpensive sensor buoy system, Oxybuoy, designed for long-term unattended oxygen sensor measurements. The technology is available to construct such sensor buoys. The authors showed a prototype based on commercial off-the shelf components: an embedded PC, an optical dissolved oxygen sensor, a temperature sensor, a Wi-Fi transmitter and a satellite transmitter. Its total cost is around $5,000 to construct, program and test a proof of concept of such sensor. The authors describe the buoy's architectural design and three experiments that the authors carried out to demonstrate its viability.

Unattended Sensors in Marine Environments

2019 ◽  
pp. 396-419
Author(s):  
Rizal Mohd Nor ◽  
Mikhail Nesterenko
Keyword(s):  
Temperature Sensor ◽  
Architectural Design ◽  
World Wide ◽  
Oxygen Sensor ◽  
Satellite Transmitter ◽  
Total Cost ◽  
Commercial Off The Shelf ◽  
Embedded Pc

This chapter discusses the use of unattended sensors and its use in marine environment. The authors present challenges of designing a marine sensor in harsh environments and a case study in implementing a marine sensor to study hypoxia. Hypoxia is a world-wide anthropogenic phenomenon related to pollution. The authors describe the construction of an inexpensive sensor buoy system, Oxybuoy, designed for long-term unattended oxygen sensor measurements. The technology is available to construct such sensor buoys. The authors showed a prototype based on commercial off-the shelf components: an embedded PC, an optical dissolved oxygen sensor, a temperature sensor, a Wi-Fi transmitter and a satellite transmitter. Its total cost is around $5,000 to construct, program and test a proof of concept of such sensor. The authors describe the buoy's architectural design and three experiments that the authors carried out to demonstrate its viability.

Caregivers' Perceptions of Speech-Language Pathologist Talk About Child Language and Literacy Disorders

2020 ◽  
Vol 29 (4) ◽  
pp. 2049-2067
Author(s):  
Karmen L. Porter ◽  
Janna B. Oetting ◽  
Loretta Pecchioni
Keyword(s):  
Language And Literacy ◽  
Collective Case Study ◽  
Study Approach ◽  
School Aged Children ◽  
Speech Language Pathologist ◽  
Therapy Goals ◽  
Semistructured Interviews ◽  
Types Of Information

Purpose This study examined caregiver perceptions of their child's language and literacy disorder as influenced by communications with their speech-language pathologist. Method The participants were 12 caregivers of 10 school-aged children with language and literacy disorders. Employing qualitative methods, a collective case study approach was utilized in which the caregiver(s) of each child represented one case. The data came from semistructured interviews, codes emerged directly from the caregivers' responses during the interviews, and multiple coding passes using ATLAS.ti software were made until themes were evident. These themes were then further validated by conducting clinical file reviews and follow-up interviews with the caregivers. Results Caregivers' comments focused on the types of information received or not received, as well as the clarity of the information. This included information regarding their child's diagnosis, the long-term consequences of their child's disorder, and the connection between language and reading. Although caregivers were adept at describing their child's difficulties and therapy goals/objectives, their comments indicated that they struggled to understand their child's disorder in a way that was meaningful to them and their child. Conclusions The findings showed the value caregivers place on receiving clear and timely diagnostic information, as well as the complexity associated with caregivers' understanding of language and literacy disorders. The findings are discussed in terms of changes that could be made in clinical practice to better support children with language and literacy disorders and their families.

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