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This paper aims to propose a novel methodology for optimal voltage source converter (VSC) station installation in hybrid alternating current (AC)/direct current (DC) transmission networks.

In this analysis, a unified power flow model has been developed for the optimal power flow (OPF) problem for VSC-based high voltage direct current (VSC-HVDC) transmission network and solved using a particle swarm optimization (PSO) algorithm. The impact of the HVDC converter under abnormal conditions considering N-1 line outage contingency is analyzed against the congestion relief of the overall transmission network. The average loadability index is used as a severity indicator and minimized along with overall transmission line losses by replacing each AC line with an HVDC line independently.

The developed unified OPF (UOPF) model converged successfully with (PSO) algorithm. The OPF problem has satisfied the defined operational constraints of the power system, and comparative results are obtained for objective function with different HVDC test configurations represented in the paper. In addition, the impact of VSC converter location is determined on objective function value.

A novel methodology has been developed for the optimal installation of the converter station for the point-to-point configuration of HVDC transmission. The developed unified OPF model and methodology for selecting the AC bus for converter installation has effectively reduced congestion in transmission lines under single line outage contingency.

This research paper aims to investigate the change detection filter technique with a decision tree-based event (fault type) classifier for recognizing and categorizing power system disturbances on the high-voltage DC (HVDC) transmission link.

A change detection filter is used to the average and differential current components, which detects the point of fault initiation and records a change detection point (CDP). The half-cycle differential and average currents on both sides of the CDP are sent through the signal processing unit, which produces the respective target. The extracted target indices are sent through a decision tree-based fault classifier mechanism for fault classification.

In comparison with conventional differential current protection systems, the developed framework is faster in fault detection and classification and provides great accuracy. The new technology allows for prompt identification of the fault category, allowing electrical grids to be restored as quickly as possible to minimize economic losses. This novel technology enhances efficiency in terms of reducing computing complexity.

Setting a threshold value for identification is one of the limitations. To bring the designed system into stability condition before creating faults on it is another limitation. Reducing the computational burden is one of the limitations.

Creating a practical system in laboratory is difficult as it is a HVDC transmission line. Apart from that, installing rectifier and converter section for HVDC transmission line is difficult in a laboratory setting.

The suggested scheme’s importance and accuracy have been rigorously validated for the standard HVDC transmission system, subjected to various types of DC fault, and the results show the proposed algorithm would be a feasible alternative to real-time applications.

The purpose of this paper is to shed light to the concept of solar electricity transfer from North Africa to Europe in the frame of Article 9 of the European Renewable Energy Sources (EU-RES) Directive 28/2009/EC, to explain why efforts have not been successful up to now and to provide recommendations on how to proceed.

The authors have compared the “Supergrid” concept that was pursued by some institutions in the past years with the original “TRANS-CSP” concept developed by the German Aerospace Centre in 2006. From this analysis, the authors could identify not only major barriers but also possible ways towards successful implementation.

The authors found that in contrast to the Supergrid approach, the original concept of exporting dispatchable solar power from concentrating solar thermal power stations with thermal energy storage (CSP-TES) via point-to-point high voltage direct current (HVDC) transmission directly to European centres of demand could be a resilient business case for Europe–North Africa cooperation, as it provides added value in both regions.

The analysis has been made in the frame of the BETTER project commissioned by the Executive Agency for Competitiveness & Innovation in the frame of the program Intelligent Energy Europe.

One of the major implications found is that due to the time lost in the past years by following a distracted concept, the option of flexible solar power imports from North Africa to Europe is not any more feasible to become part of the 2020 supply scheme.

To make them a viable option for post-2020 renewable energy systems for electricity development in Europe, a key recommendation of the project is to elaborate a detailed feasibility study about concrete CSP-HVDC links urgently.

The analysis presented here is the first to give concrete recommendations for the implementation of such infrastructure.

The purpose of this paper is to estimate the influence of long‐term, whole‐body exposure of rats to strong, static electric field with physical parameters generated nearby high voltage direct current (HVDC) transmission lines on the intensity of reactive oxygen species generation analyzed indirectly, basing on the measurement of malone dialdehyde level, as well as on the activity of enzymatic antioxidant defence system.

In rats exposed to static electric field with intensity of 16, 25 and 35 kV/m, respectively, or sham‐exposed eight hours daily for 56 days, in the obtained plasma, erythrocytes lysates and liver homogenates the activity of some antioxidant enzymes as well as the concentration of malone dialdehyde were determined with use of spectrophotometric and kinetic methods.

It was observed that long‐term exposure of rats to static electric field causes only temporary compensatory changes in the concentration of malone dialdehyde and transient changes in the activity of enzymatic antioxidant system, both in blood and in liver tissue in the form of temporary inhibition of activity of most antioxidant enzymes during exposure cycle, with subsequent compensatory increase in this activity after the end of exposure cycle, enabling maintenance of prooxidant‐antioxidant balance in the organism of experimental animals and inhibition of peroxidation process.

Presented data indicate that construction of air HVDC transmission lines, according to actual compulsory regulations, enables serious health hazards related to persistent disturbances of prooxidant‐antioxidant balance to be avoided.

In the experiment it was confirmed, for the first time, that long‐term exposure to strong static electric field causes transient compensatory changes of prooxidant‐antioxidant balance in living organisms.

The purpose of this study is to develop a new approach for simulating the ion flow field with the floating conductors based on the existing inversion method.

The space charge keeps charging the floating conductors until the dynamic balance is reached. The corresponding floating potential boundary condition is linearized as the combination of the equipotential constraints and natural boundary condition, which can be directly imposed in the inversion process.

The numerical results demonstrate that the modified inversion algorithm performs well in the ion flow field with the floating conductors and the floating potential converges within five steps’ iterations. The proposed approach is applied to investigate the effect of the grounded line to the floating conductors in the practical high voltage direct current (HVDC) transmission lines.

The modified inverse algorithm provides a general way to deal with the Kapzov hypothesis and the floating boundary condition simultaneously within one loop, which can be applied to the multiphysics systems with different kinds of irregular boundary conditions.

Gas insulated systems, such as gas insulated lines (GIL), use insulating gas, mostly sulfur hexalfluoride (SF₆), to enable a higher dielectric strength compared to e.g. air. However, under high voltage direct current conditions, charge accumulation and electric field stress may occur, which may lead to partial discharge or system failure. Therefore, numerical simulations are used to design the system and determine the electric field and charge distribution. Although the gas conduction shows a more complex current–voltage characteristic compared to solid insulation, the electric conductivity of the SF₆ gas is set as constant in most works. The purpose of this study is to investigate different approaches to address the conduction in the gas properly for numerical simulations.

In this work, two approaches are investigated to address the conduction in the insulating gas and are compared to each other. One method is an ion-drift-diffusion model, where the conduction in the gas is described by the ion motion in the SF₆ gas. However, this method is computationally expensive. Alternatively, a less complex approach is an electro-thermal model with the application of an electric conductivity model for the SF₆ gas. Measurements show that the electric conductivity in the SF₆ gas has a nonlinear dependency on temperature, electric field and gas pressure. From these measurements, an electric conductivity model was developed. Both methods are compared by simulation results, where different parameters and conditions are considered, to investigate the potential of the electric conductivity model as a computationally less expensive alternative.

The simulation results of both simulation approaches show similar results, proving the electric conductivity for the SF₆ gas as a valid alternative. Using the electro-thermal model approach with the application of the electric conductivity model enables a solution time up to six times faster compared to the ion-drift-diffusion model. The application of the model allows to examine the influence of different parameters such as temperature and gas pressure on the electric field distribution in the GIL, whereas the ion-drift-diffusion model enables to investigate the distribution of homo- and heteropolar charges in the insulation gas.

This work presents numerical simulation models for high voltage direct current GIL, where the conduction in the SF₆ gas is described more precisely compared to a definition of a constant electric conductivity value for the insulation gas. The electric conductivity model for the SF₆ gas allows for consideration of the current–voltage characteristics of the gas, is computationally less expensive compared to an ion-drift diffusion model and needs considerably less solution time.

In the 1930s, chlorofluorocarbons (CFCs) were developed as safe, non-reactive alternatives to toxic and explosive refrigerants and propellants such as ammonia, chloromethane, and sulfur dioxide. American engineer Thomas Midgley famously demonstrated these properties by inhaling Freon (CFC-12) and blowing out a candle with it. He was presented with many awards for his discoveries, such as the Perkin, Priestley, and William Gibbs medals. In today's jargon, CFCs might have been called an eco-innovation, because they provided solutions to several environmental issues. However, CFCs solved environmental problems by creating others. In 1974, Sherwood Rowland and Mario Molina published their pathbreaking research that demonstrated CFCs were depleting the ozone layer. In 1989, the Montreal Protocol, which regulates a global phaseout of CFCs, entered into force. A few years later, in 1995, Rowland and Molina received the Nobel Price in Chemistry. The new substitutes for CFCs, hydrofluorocarbons (HFCs), have no known effects on the ozone layer but are extremely potent greenhouse gases (GHGs) and thus subject to the Kyoto Protocol.

This teaching case intends to be a tool for academic purposes as a way to show the different assessments an investor should make and the many problems he/she may face, when evaluating a megaproject. It reviews the experience of two large corporations in Chile, intending to build a major hydroelectric generation project in Chile while facing major opposition from environmental NGOs and other stakeholders. Although in the view of many industry experts and consultants Hidroaysén was a good and necessary project, the environmental implications and some of the project’s stakeholders created a deadlock.

This teaching case was written with the idea of being used as a tool for classes in order to discuss the implications of environmental issues in big projects. The research was based on particular information of the project, financial data of the companies involved, and other public sources (news, interviews, etc.).

The conclusion of this case is that private initiatives, without the right alignment of political actors and civil society, could face the risk of being blocked and not being executed.

COP21 guidelines for responsive investment could be a guideline to follow, aligning private interest with development for countries in the third world.

We offer a way to analyze external impacts on a project of this kind, that using a common framework (COP21 guidelines) could avoid risks taking all considerations into the project.

The purpose of this study is to elucidate the effects of electric-arc-induced ablation on the corrosion behavior of pipeline steel in neutral and high pH environments.

Electrochemical testing, an atmospheric-pressure immersion experiment and various techniques (e.g. scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy) were used to examine the effects of electric-arc-induced ablation on the corrosion behavior of pipeline steel in neutral and high pH environment.

Electric-arc-induced ablation occurred preferentially in areas of inclusion. The corrosion resistance of an ablation pit was lower than that of non-ablation areas. In the neutral soil solution, general corrosion was the dominant corrosion that affected pipeline steel; the effect of ablation was small but pitting corrosion could still be induced. In a high pH environment, the samples without ablation were passivated, whereas the samples with ablation pits could not be passivated; the ablation pits were likely to develop pitting corrosion.

Electric-arc-induced ablation can reduce the corrosion resistance of pipeline steel under high-voltage direct current interference.

This chapter presents a South American perspective on the environmental and financial sustainability of energy integration incorporating recent financial lessons from the United States and Europe. An illustrative project called UNASUR-GRID is presented to highlight new thinking on funding ecologically sensitive development (post-carbon electricity generation) and regional energy sovereignty via a new regional development bank for the Union of South American Nations (UNASUR) called Bank of the South, Banco del Sur (BDS) ^1,2 . Sustainable BDS finance rules are presented that aim to break the link between development funding, environmental damage, and sovereign debt owed to banks outside the region, tapping into alternative finances to buffer the region against changes in global financial flows from core nations in the Great Recession.

The author attended presidential meetings of MERCOSUR and UNASUR supplementing this with presidential declarations comparing these with ongoing development planning from IIRSA, also interviewing a COSIPLAN representative. He also cooperated (as an independent researcher) with the Ecuadorian Central Bank research group called ‘New Architectures for Regional Finance’ (NAFR) and conducted technical interviews at South American energy institutes specialising in integration.

Development finance must reflect changes in both energy supply and demand while replacing fossil fuel inputs in electricity generation. Demand planning is necessary to attain sovereignty over a post-carbon electricity supply while maintaining dependability.

Successful energy cooperation is more than just energy infrastructure (UNASUR-GRID), cross-border confidence building is also required, reinforced by commercial treaties for energy exports and imports. Public and private national and regional energy companies need real incentives to trade internationally (improving competition) or renationalisation of supply and distribution may be necessary.

Highly original, this chapter incorporates government, UN and civil NGO inputs into primary research. BDS policy sources include government, ministerial and presidential speeches with interviews and participation in meetings with social movements. For indigenous ecological and social economic concepts such as Sumak Kawsay, the author has travelled extensively in South America and was an active participant at the first World People’s Conference on Climate Change and the 2010 Rights of Mother Earth (World Conference on Indigenous Peoples, 2014) in Cochabamba, Bolivia, along with ecologists and tribal representatives.