Icing Effects on Power Lines and Anti-icing and De-icing Methods

Icing on power lines may lead to compromise safety and reliability of electric supply network. Prolong icing can lead to power breakdown and collapse of towers. Since power transmission lines are mostly overhead and could face the direct impact of icing, and it is one of the main challenges faced by power distribution companies in cold regions. When the ice accretion crosses the safety limit then deicing action can be carried out. We can find number of deicing methods that are used in different parts of the world. However, all of these deicing techniques have their own advantages and disadvantages on implementation. It is one of the most difficult as well as dangerous process to perform deicing on power lines. If a fault is detected and that has been occurred due to icing or during routine maintenance, extra care must be taken in order to ensure safety of the personals when performing de-icing of lines. However, as technology evolved, new ways and techniques are adopted with the help of sensors that give quick feedback to control room in the national grid via wireless communication network for real time action. In the thesis we have discussed atmospheric icing impacts on power lines in the cold regions across the world. A literature review has been done for anti-icing and deicing methods that are currently adopted in the power distribution network. Methods that are used against ice buildups have also been analyzed. This work also shows the impacts of icing and deicing techniques presently adopted, and also throws light on their pros and cons during maintenance operations. It provides an overview of the evolving technology trends that are practiced to ensure the availability of existing power transmission system in cold climate regions

A review of infrared thermography applications for ice detection and mitigation

Ice accretion on various onshore and offshore infrastructures imparts hazardous effects sometimes beyond repair, which may be life-threatening. Therefore, it has become necessary to look for ways to detect and mitigate ice. Some ice mitigation techniques have been tested or in use in aviation and railway sectors, however, their applicability to other sectors/systems is still in the research phase. To make such systems autonomous, ice protection systems need to be accompanied by reliable ice detection systems, which include electronic, mechatronics, mechanical, and optical techniques. Comparing the benefits and limitations of all available methodologies, Infrared Thermography (IRT) appears to be one of the useful, non-destructive, and emerging techniques as it offers wide area monitoring instead of just point-based ice monitoring. This paper reviews the applications of IRT in the field of icing on various subject areas to provide valuable insights into the existing development of an intelligent and autonomous ice mitigation system for general applications

Image analysis methods in the measurement of ice loads on structures

The icing of marine vessels and offshore structures causes significant reductions in their efficiency and creates unsafe working conditions. Ice detection and removal play important roles to reduce the risk of hazards and increase operational efficiency. Ice detection and measurement on structures are a challenge in marine industries, due to a lack of studies in this field. In this research, image processing methods are developed to measure ice loads on structures. Image processing algorithms are used to detect the ice accumulated on the structures and then the ice loads are calculated. The combination of thermal and visual imaging is suggested to detect ice, in order to reduce drawbacks occurring in these types of imaging. Also, the ice load is calculated on a known structure based on the structure information and the ice detection results. Experiments are conducted to verify the results of ice load measurements obtained by the algorithms. Ice loads are calculated in a variety of situations, such as using different imaging types, changing camera positions and angles of view and using different ice load values. The calculated ice load results show good coherence with the actual values obtained by measuring the samples which are used in the experimental setups

Experimental Investigations on Transient Surface Water Transport and Ice Accreting Processes Pertinent to Aircraft Icing Phenomena

In the present study, an multi-transducer (sparse array) ultrasonic pulse-echo (MTUPE) technique was developed to quantify the transient surface behaviors of the water film flow driven by boundary layer airflow. The instantaneous surface waves riding on the free surface of the water film flow were characterized based on the measured time series of the water film thickness. Based on the time expansions of the measured thickness profiles of the surface water film flow, a instability transition, from periodical two-dimensional waves to pebbled waves of an obviously non-periodic nature, was observed. Then, the temporally-resolved spatial wave structures in the wind-driven water film flow were reconstructed, which provide more details of the surface morphologies and evolutions of the surface waves in the wind-driven water film flow. A strategy, based on the use of frequency dependent ultrasonic attenuation, was investigated that has the potential to characterize and differentiate between different types of ice that can form on aircraft during winter operations. The measurement methodology and system were validated using the data for acoustic attenuation in water. The data for two types of ice, rime-like and glaze-like, are in agreement with results from previous measurements. There is a significant difference seen in the ultrasonic attenuation characteristics between the two types of ice. It would appear that there is potential to add attenuation data to on-aircraft ice detection systems which could then potentially enable ice-type specific based de-icing to be implemented. Such optimized de-icing could have a potential for reducing winter weather operational costs, and ensure safety is maintained, or even improved. A comprehensive experimental study was also conducted to quantify the transient surface water transport and dynamic ice accreting process over a wing surface at different icing conditions. The experiments were conducted in the Icing Research Tunnel available at Iowa State University (ISU-IRT). While the transient behaviors of the surface water transport over an NACA 23012 airfoil with realistic initial ice roughness at the airfoil leading edge were investigated using an innovative digital image projection-correlation (DIPC) technique, the unsteady heat transfer and phase changing processes under different icing conditions were examined in details based on the measured surface temperature maps over the ice accreting surfaces by using an infrared thermal imaging system. The objective of this study is to elucidate the underlying physics of surface water transport and ice accretion to improve our understanding of the important microphysical processes pertinent to aircraft icing phenomena to develop more effective and robust anti-/de-icing strategies to ensure safer and more efficient aircraft operations in cold weather

Outdoor Insulation and Gas Insulated Switchgears

This book focuses on theoretical and practical developments in the performance of high-voltage transmission line against atmospheric pollution and icing. Modifications using suitable fillers are also pinpointed to improve silicone rubber insulation materials. Very fast transient overvoltage (VFTO) mitigation techniques, along with some suggestions for reliable partial discharge measurements under DC voltage stresses inside gas-insulated switchgears, are addressed. The application of an inductor-based filter for the protective performance of surge arresters against indirect lightning strikes is also discussed

Hybrid Advanced Optimization Methods with Evolutionary Computation Techniques in Energy Forecasting

More accurate and precise energy demand forecasts are required when energy decisions are made in a competitive environment. Particularly in the Big Data era, forecasting models are always based on a complex function combination, and energy data are always complicated. Examples include seasonality, cyclicity, fluctuation, dynamic nonlinearity, and so on. These forecasting models have resulted in an over-reliance on the use of informal judgment and higher expenses when lacking the ability to determine data characteristics and patterns. The hybridization of optimization methods and superior evolutionary algorithms can provide important improvements via good parameter determinations in the optimization process, which is of great assistance to actions taken by energy decision-makers. This book aimed to attract researchers with an interest in the research areas described above. Specifically, it sought contributions to the development of any hybrid optimization methods (e.g., quadratic programming techniques, chaotic mapping, fuzzy inference theory, quantum computing, etc.) with advanced algorithms (e.g., genetic algorithms, ant colony optimization, particle swarm optimization algorithm, etc.) that have superior capabilities over the traditional optimization approaches to overcome some embedded drawbacks, and the application of these advanced hybrid approaches to significantly improve forecasting accuracy

Structural Health Monitoring (SHM) and Determination of Surface Defects in Large Metallic Structures using Ultrasonic Guided Waves

Ultrasonic guided wave (UGW) is one of the most commonly used technologies for non-destructive evaluation (NDE) and structural health monitoring (SHM) of structural components. Because of its excellent long-range diagnostic capability, this method is effective in detecting cracks, material loss, and fatigue-based defects in isotropic and anisotropic structures. The shape and orientation of structural defects are critical parameters during the investigation of crack propagation, assessment of damage severity, and prediction of remaining useful life (RUL) of structures. These parameters become even more important in cases where the crack intensity is associated with the safety of men, environment, and material, such as ship’s hull, aero-structures, rail tracks and subsea pipelines. This paper reviews the research literature on UGWs and their application in defect diagnosis and health monitoring of metallic structures. It has been observed that no significant research work has been convened to identify the shape and orientation of defects in plate-like structures. We also propose an experimental research work assisted by numerical simulations to investigate the response of UGWs upon interaction with cracks in different shapes and orientations. A framework for an empirical model may be considered to determine these structural flaws

Continuous Autonomous UAV Inspection for FPSO vessels

This Master's thesis represents the preliminary design study and proposes the unmanned aerial vehicle (UAV) -based inspection framework, comprising several multirotors with automatic charging and deployment for 24/7 integrity inspection tasks. This project has three main topics. First one describes the operational environment and existing regulations that cover use of UAVs. It forms the basis for proposal of the relevant use-case scenarios. Third part comprises two chapters, where design of concept and framework is being based on the previous factors. It shows that before implementation of fully autonomous inspection system, there is a need to cover both regulatory and technical gaps. It can be explained by the fact that there does not exist any autonomous inspection system today. Thus, this project can be seen as a base for future development of the UAV-based inspection system, as it focuses on creation of a general framework

Analysis of a seeder-feeder and freezing drizzle event

Surface icing can cause dramatic consequences on human activities. What is more, numerical weather prediction models are not very accurate in determining freezing drizzle, which creates uncertainty when forecasting this type of weather phenomenon. Therefore, it is essential to improve the forecast accuracy of these models for such phenomena to mitigate risks caused by unforeseen freezing drizzle events. On 5 February 2012, an episode of freezing drizzle took place in the Guadarrama Mountains, at the center of the Iberian Peninsula. This episode was preceded by weak snowfall. After the freezing drizzle, moderate snowfall was recorded in the study area. This event was simulated using the Weather Research and Forecasting model. Through this analysis, we identified the meteorological factors at both synoptic scale and mesoscale that caused this episode. Wind perpendicular to an orographic barrier-generated updrafts and retention of moisture upwind, which caused orographic clouds to appear on the north side of the Guadarrama Mountains. Atmospheric stability prevented cloud formation at midlevels at the time of the freezing drizzle, which maintained cloud top temperatures warmer than −15ºC during the episode. The entrance of moisture and instability at midlevels caused cloud top temperatures substantially colder than −15º C, which coincided with snow in the mountain range. Cloud top temperature and thickness control the efficiency of the glaciation process, thereby determining the type of precipitation at the surface. Freezing drizzle risk and in-cloud icing algorithms were developed with the aim of predicting similar events in the study area, which could mitigate impacts on human activities.This paper was supported by the following grants: TEcoAgua, METEORISK PROJECT (RTC-2014-1872-5), Granimetro (CGL2010-15930) and CGL2011-25327 of MINECO, and LE220A11-2 and LE003B009 awarded by the Junta de Castilla y León

Joint University Program for Air Transportation Research, 1984

The research conducted during 1984 under the NASA/FAA sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology, Ohio University, and Princeton University. Completed works, status reports, and bibliographies are presented for research topics, which include navigation, guidance, control and display concepts. An overview of the year's activities for each of the schools is also presented