scholarly journals Concepts and Methods to Assess the Dynamic Thermal Rating of Underground Power Cables

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2591
Author(s):  
Diana Enescu ◽  
Pietro Colella ◽  
Angela Russo ◽  
Radu Florin Porumb ◽  
George Calin Seritan
Keyword(s):  
Computational Methods ◽  
Risk Estimation ◽  
Renewable Energy Sources ◽  
Thermal Conditions ◽  
Weather Conditions ◽  
Operating Conditions ◽  
International Standards ◽  
Power Cable ◽  
Power Cables ◽  
Thermal Limits

With the increase in the electrical load and the progressive introduction of power generation from intermittent renewable energy sources, the power line operating conditions are approaching the thermal limits. The definition of thermal limits variable in time has been addressed under the concept of dynamic thermal rating (DTR), with which it is possible to provide a more detailed assessment of the line rating and exploit the electrical system more flexibly. Most of the literature on DTR has addressed overhead lines exposed to different weather conditions. The interest in the dynamic thermal rating of power cables is increasing, considering the evolution of computational methods and advanced systems for cable monitoring. This paper contains an overview of the concepts and methods referring to dynamic cable rating (DCR). Starting from the analytical formulations developed many years ago for determining the power cable rating in steady-state conditions, also reported in International Standards, this paper considers the improvements of these formulations proposed during the years. These improvements are leading to include more specific details in the models used for DCR analysis and the computational methods used to assess the power cable’s thermal conditions buried in soil. This paper is focused on highlighting the path from the initial theories and models to the latest literature contributions. Attention is paid to thermal modelling with different levels of detail, applications of 2D and 3D solvers and simplified models, and their validation based on experimental measurements. A salient point of the overview is considering the DCR impact on reliability aspects, risk estimation, real-time calculations, forecasting, and planning with different time horizons.

scholarly journals Experimental Validation of a Heat Transfer Model in Underground Power Cable Systems

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1747 ◽  
Author(s):  
Paweł Ocłoń ◽  
Janusz Pobędza ◽  
Paweł Walczak ◽  
Piotr Cisek ◽  
Andrea Vallati
Keyword(s):  
Experimental Validation ◽  
Thermal Conditions ◽  
Test Stand ◽  
Temperature Fields ◽  
Transfer Model ◽  
Power Cable ◽  
Power Cables ◽  
Temperature Changes ◽  
Steady State Temperature ◽  
Underground Power Cable

This paper presents the laboratory test stand that is used for experimental validation of underground power cable system models. Determination of temperature distribution in the vicinity of the cable is the main goal of the study. The paper considers a system of three power cables, situated in the in-line arrangement, and buried in sand. Three electrical heaters of special construction are used in order to simulate the heat flux that is generated in the power cables during their operation. The test stand is designed to be placed in a thermoclimatic chamber, which allows testing the system in various thermal conditions when the ambient temperature changes by 20 °C to 30 °C. Numerical computations of the steady-state temperature fields are performed using the finite element method.

scholarly journals Ampacity of power cables exposed to solar radiation – recommendations of standards vs. CFD simulations

2018 ◽  
Vol 70 ◽  
pp. 03004 ◽  
Author(s):  
Stanislaw Czapp ◽  
Marian Czapp ◽  
Seweryn Szultka ◽  
Adam Tomaszewski
Keyword(s):  
Heat Transfer ◽  
Solar Radiation ◽  
International Standards ◽  
Power Cable ◽  
Power Cables ◽  
Ambient Conditions ◽  
Cfd Simulations ◽  
Factors Influencing ◽  
Free Air ◽  
Computational Fluid Dynamics Cfd

Ampacity of power cables strictly depends on the ambient conditions. It is very important whether a cable is buried in soil, installed in the air or placed in ducts. When a cable is installed in free air, potential solar radiation has the dominant impact on the prospective ampacity. International standards indicate how to calculate ampacity of power cables exposed to solar radiation, however the standards’ recommendations are characterised by some simplifications. In order to consider many complex factors influencing ampacity of power cables, and modelling advanced heat transfer phenomena, a Computational Fluid Dynamics (CFD) can be used. This paper presents a comparison of ampacity calculation of an example power cable for two approaches – first: according to international standards; second: with a CFD employed. Differences in results obtained for these two approaches are commented.

Testing Submergible Power Cables for Oil Well Applications

1981 ◽  
Vol 54 (1) ◽  
pp. 51-60
Author(s):  
Jon W. Martin
Keyword(s):  
Electrical Properties ◽  
Field Testing ◽  
Power Cable ◽  
Oil Well ◽  
Power Cables ◽  
Degradation Mechanisms ◽  
Cable Insulation ◽  
Thermal Limits ◽  
The World

Abstract A downhole simulator can be used to test oil well power cable, providing results more quickly and economically than can be obtained from field testing. Electrical properties of the cable can be monitored durng the test. Thermal limits can be established. Field degradation mechanisms can be reproduced. TRW uses the facility to evaluate oil well cable designs and to test new cable insulation and protection materials. From this experience, submergible cables have been improved to meet the most severe downhole conditions being encountered throughout the world.

Analysing integration issues of the microgrid system with utility grid network

2021 ◽  
Vol 22 (1) ◽  
pp. 113-127
Author(s):  
Mulualem Tesfaye ◽  
Baseem Khan ◽  
Om Prakash Mahela ◽  
Hassan Haes Alhelou ◽  
Neeraj Gupta ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Control Mode ◽  
Voltage Source ◽  
Modulation Scheme ◽  
Main Challenge ◽  
Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

scholarly journals Performance Evaluation of Neural Network-Based Short-Term Solar Irradiation Forecasts

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3030
Author(s):  
Simon Liebermann ◽  
Jung-Sup Um ◽  
YoungSeok Hwang ◽  
Stephan Schlüter
Keyword(s):  
Neural Network ◽  
Goodness Of Fit ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Solar Irradiation ◽  
Weather Data ◽  
Short Term ◽  
Climate Conditions ◽  
Lstm Network ◽  
The Time Domain

Due to the globally increasing share of renewable energy sources like wind and solar power, precise forecasts for weather data are becoming more and more important. To compute such forecasts numerous authors apply neural networks (NN), whereby models became ever more complex recently. Using solar irradiation as an example, we verify if this additional complexity is required in terms of forecasting precision. Different NN models, namely the long-short term (LSTM) neural network, a convolutional neural network (CNN), and combinations of both are benchmarked against each other. The naive forecast is included as a baseline. Various locations across Europe are tested to analyze the models’ performance under different climate conditions. Forecasts up to 24 h in advance are generated and compared using different goodness of fit (GoF) measures. Besides, errors are analyzed in the time domain. As expected, the error of all models increases with rising forecasting horizon. Over all test stations it shows that combining an LSTM network with a CNN yields the best performance. However, regarding the chosen GoF measures, differences to the alternative approaches are fairly small. The hybrid model’s advantage lies not in the improved GoF but in its versatility: contrary to an LSTM or a CNN, it produces good results under all tested weather conditions.

scholarly journals Polyethylene Nanocomposites for Power Cable Insulations

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 24 ◽  
Author(s):  
Ilona Pleşa ◽  
Petru Noţingher ◽  
Cristina Stancu ◽  
Frank Wiesbrock ◽  
Sandra Schlögl
Keyword(s):  
Electrical Performance ◽  
Power Cable ◽  
Power Cables ◽  
Structure Property ◽  
Thermoplastic Polymers ◽  
Water Tree ◽  
Tree Resistance ◽  
Structure Property Relationships ◽  
Aging Mechanisms ◽  
Comprehensive Study

This review represents a comprehensive study of nanocomposites for power cables insulations based on thermoplastic polymers such as polyethylene congeners like LDPE, HDPE and XLPE, which is complemented by original results. Particular focus lies on the structure-property relationships of nanocomposites and the materials’ design with the corresponding electrical properties. The critical factors, which contribute to the degradation or improvement of the electrical performance of such cable insulations, are discussed in detail; in particular, properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, space charge, electrical and water tree resistance behavior and electric breakdown of such nanocomposites based on thermoplastic polymers are described and referred to the composites’ structures. This review is motivated by the fact that the development of polymer nanocomposites for power cables insulation is based on understanding more closely the aging mechanisms and the behavior of nanocomposites under operating stresses.

scholarly journals A Flexible Load Control Strategy for Distribution Network to Reduce the Line Losses and to Eliminate the Transmission Congestion

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Beibei Wang ◽  
Xiaoqing Hu ◽  
Peifeng Shen ◽  
Wenlu Ji ◽  
Yang Cao ◽  
...  
Keyword(s):  
Power Distribution ◽  
Distribution Systems ◽  
Renewable Energy Sources ◽  
Distribution Network ◽  
Test System ◽  
Operating Conditions ◽  
Load Control ◽  
Transmission Congestion ◽  
Heavy Load ◽  
Flexible Load

There are many uncertain factors in the modern distribution network, including the access of renewable energy sources and the heavy load level. The existence of these factors has brought challenges to the stability of the power distribution network, as well as increasing the risk of exceeding transmission capacity of distribution lines. The appearance of flexible load control technology provides a new idea to solve the above problems. Air conditioners (ACs) account for a great proportion of all loads. In this paper, the model of dispatching AC loads in the regional power grid is constructed, and the direct load control (DLC) method is adopted to reduce the load of ACs. An improved tabu search technique is proposed to solve the problem of network dispatch in distribution systems in order to reduce the resistive line losses and to eliminate the transmission congestion in lines under normal operating conditions. The optimal node solution is obtained to find the best location and reduction capacity of ACs for load control. To demonstrate the validity and effectiveness of the proposed method, a test system is studied. The numerical results are also given in this article, which reveal that the proposed method is promising.

Multiphysics Design and Analysis Simulations for Power Electronic Device Wirebonds

2003 ◽  
Author(s):  
Patrick W. Wilkerson ◽  
Andrzej J. Przekwas ◽  
Chung-Lung Chen
Keyword(s):  
Heat Dissipation ◽  
Electronic Device ◽  
Electronic Devices ◽  
Thermal Conditions ◽  
Simulation Software ◽  
Operating Conditions ◽  
Power Electronic ◽  
Stress Concentrations ◽  
Multiphysics Simulation ◽  
Multiphysics Simulations

Multiscale multiphysics simulations were performed to analyze wirebonds for power electronic devices. Modern power-electronic devices can be subjected to extreme electrical and thermal conditions. Fully coupled electro-thermo-mechanical simulations were performed utilizing CFDRC’s CFD-ACE+ multiphysics simulation software and scripting capabilities. Use of such integrated multiscale multiphysics simulation and design tools in the design process can cut cost, shorten product development cycle time, and result in optimal designs. The parametrically designed multiscale multiphysics simulations performed allowed for a streamlined parametric analysis of the electrical, thermal, and mechanical effects on the wirebond geometry, bonding sites and power electronic device geometry. Multiscale analysis allowed for full device thermo-mechanical analysis as well as detailed analysis of wirebond structures. The multiscale simulations were parametrically scripted allowing for parametric simulations of the device and wirebond geometry as well as all other simulation variables. Analysis of heat dissipation from heat generated in the power-electronic device and through Joule heating were analyzed. The multiphysics analysis allowed for investigation of the location and magnitude of stress concentrations in the wirebond and device. These stress concentrations are not only investigated for the deformed wirebond itself, but additionally at the wirebond bonding sites and contacts. Changes in the wirebond geometry and bonding geometry, easily changed through the parametrically designed simulation scripts, allows for investigation of various wirebond geometries and operating conditions.

scholarly journals Development of an operation strategy for hydrogen production using solar PV energy based on fluid dynamic aspects

2017 ◽  
Vol 7 (1) ◽  
pp. 141-152 ◽  
Author(s):  
Ernesto Amores ◽  
Jesús Rodríguez ◽  
José Oviedo ◽  
Antonio de Lucas-Consuegra
Keyword(s):  
Hydrogen Production ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Water Electrolysis ◽  
Weather Conditions ◽  
Energy Sources ◽  
Electrolysis Cell ◽  
Operation Strategy ◽  
Solar Pv ◽  
Alkaline Water Electrolysis

AbstractAlkaline water electrolysis powered by renewable energy sources is one of the most promising strategies for environmentally friendly hydrogen production. However, wind and solar energy sources are highly dependent on weather conditions. As a result, power fluctuations affect the electrolyzer and cause several negative effects. Considering these limiting effects which reduce the water electrolysis efficiency, a novel operation strategy is proposed in this study. It is based on pumping the electrolyte according to the current density supplied by a solar PV module, in order to achieve the suitable fluid dynamics conditions in an electrolysis cell. To this aim, a mathematical model including the influence of electrode-membrane distance, temperature and electrolyte flow rate has been developed and used as optimization tool. The obtained results confirm the convenience of the selected strategy, especially when the electrolyzer is powered by renewable energies.

scholarly journals The Use of Drone Photo Material to Classify the Purity of Photovoltaic Panels Based on Statistical Classifiers

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 483
Author(s):  
Tomasz Czarnecki ◽  
Kacper Bloch
Keyword(s):  
Renewable Energy Sources ◽  
Base Material ◽  
Weather Conditions ◽  
High Rate ◽  
Solar Panels ◽  
Soil Dust ◽  
Photovoltaic Panels ◽  
Statistical Classifiers ◽  
Study Results ◽  
The Subject

The subject of this work is the analysis of methods of detecting soiling of photovoltaic panels. Environmental and weather conditions affect the efficiency of renewable energy sources. Accumulation of soil, dust, and dirt on the surface of the solar panels reduces the power generated by the panels. This paper presents several variants of the algorithm that uses various statistical classifiers to classify photovoltaic panels in terms of soiling. The base material was high-resolution photos and videos of solar panels and sets dedicated to solar farms. The classifiers were tested and analyzed in their effectiveness in detecting soiling. Based on the study results, a group of optimal classifiers was defined, and the classifier selected that gives the best results for a given problem. The results obtained in this study proved experimentally that the proposed solution provides a high rate of correct detections. The proposed innovative method is cheap and straightforward to implement, and allows use in most photovoltaic installations.

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