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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.

Self-commuted voltage source converter (VSC) can significantly extend the flexibility and operability of an HVDC system and be used to implement the concept of multi-terminal HVDC (MTDC) grid. To take full advantage of MTDC systems, its overall behaviour must be characterized in quasi static and dynamic states. Based on the numerous literatures, a dedicated two-level VSC model and its local controllers and DC grid voltage regulators are developed for this purpose. Furthermore, the requirement of the system to guarantee all the physical constrains must be well assessed and concrete demonstrations must be provided by numerical simulations.

First, a two-level VSC model and its local controllers and DC grid voltage regulators are developed. Then, DC cable models are investigated and their characteristics are assessed in the frequency domain. Those developed models are combined to form a three-terminal HVDC grid system on Matlab/Simulink platform. To analyze the stability of this electrical system, the dynamics of the system against variations of power dispatch are observed.

To analyze the stability of this electrical system, the dynamics of the system against variations of power dispatch are observed. The differences in the DC grid voltage dynamics and the power flow of the converter stations coming from the embedded primary controls are analysed, and the technical requirements for both cases are assessed.

In this paper, the dynamic stability of an MTDC system has been analysed and assessed through an adequate simulation model, including its control scheme and the cable models. The interest of the improved PI model for cables is highlighted.

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.

This paper aims to clarify voltage sourced converter’s (VSC’s) influence rules on the alternating current (AC) short-circuit current and identify the key factors, so as to propose the short-circuit current suppression strategy.

This paper investigates the key factors which impact the short-circuit current supplied by the VSC based on the equivalent current source model. This study shows that the phase of the VSC equivalent current source is mainly affected by the type of fault, whereas the amplitude is mainly decided by the control mode, the amplitude limiter and the electrical distance. Based on the above influence mechanism, the dynamic limiter with short-circuit current limiting function is designed. The theoretical analysis is verified by simulations on PSCAD.

The short-circuit current feeding from VSC is closely related to the control mode and control parameters of the VSC, fault type at AC side and the electrical distance of the fault point. The proposed dynamic limiter can make VSC absorb more reactive power to suppress the short-circuit current.

The dynamic limiter proposed in this paper is limited to suppress three-phase short-circuit fault current. The future work will focus more on improving and extending the dynamic limiter to the fault current suppression application in other fault scenarios.

The research results provide a reference for the design of protection system.

The key influence factors are conducive to put forward the measures to suppress the fault current, eliminate the risk of short-circuit current exceeding the standard and reduce the difficulty of protection design.

High-temperature (HT°) motors are made with inorganic coils wound with a ceramic-coated wire. They must be carefully designed because the HT° insulating materials have a lower breakdown voltages than the polymers used for insulating standard machines.

The voltage distribution between stator coils is computed with high-frequency (HF) equivalent circuits that consider the magnetic couplings and the stray capacitances. Two time scales are used for getting a fast computation of very short voltage spikes. For the first step, a medium time scale analysis is performed considering a simplified equivalent circuit made without any stray capacitance but with the full PWM pattern and the magnetic couplings. For the second step, a more detailed HF equivalent circuit computes voltage spikes during short critical time windows.

The computation made during the first step provides the critical time windows and the initial values of the state variables to the second one. The rise and fall time of the electronic switches have a minor influence on the maximum voltage stress. Conversely, the connection cable length and the common-mode capacitances have a large influence.

HF equivalent circuits cannot be used with random windings but only to formed coils that have a deterministic position of turns.

The proposed method can be used designing of HT° machine windings fed by PWM inverter and for improving the coils of standard machine used in aircraft’s low-pressure environments.

The influence of grounding system of the DC link is considered for computing the voltage spikes in the motor windings.

In the event of a DC short-circuit fault in a flexible DC power grid, the high peak value of the fault current puts forward more stringent requirements on the DC circuit breaker. The existing fault current cutoff mainly focuses on changing the topology structure. To suppress the development of fault current and reduce the investment cost of the DC grid, this paper aims to propose a dual-loop active current-limiting control based on energy difference.

Firstly, the equivalent circuit at fault is established, and the parameters related to the fault current are analyzed. Then, the relationship between the output voltage change of the bridge arm and the difference between the AC and DC energy is deduced. Finally, the experimental results are discussed on the real-time simulation platform Opal-RT.

The proposed current-limiting measures can greatly reduce the fault current, reduce the breaking current of the circuit breaker and increase the capacitor voltage during the fault period, which is beneficial to the stability of the AC system. It is verified that the proposed method is also applicable to a certain high-resistance fault.

This paper applies the method of AC fault to DC fault and deduces the relationship between energy difference and voltage variation corresponding to different step lengths based on digital simulation. In addition, two variables are used as control structure parameters to reduce the probability of system misoperation.

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.

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.

For the dramatically developed high voltage direct current (HVDC) power transmission, HVDC cables play a vital role in the power transmission across seas and connections with renewable power sources. However, the condition monitoring of HVDC cables is still a challenging research topic. This paper aims to understand the influence of external factors, namely, current, cavity location and material properties, on partial discharge (PD) characteristics in HVDC cable in a numerical way referring to the refined Niemeyer’s model.

The influences of the three external factors are studied by a proposed numerical model for DC PDs based on the modification of a conventional PD model for AC voltage via a finite element analysis method.

The external factors can influence the discharge magnitude and discharge repetition rate via affecting the electrical conductivity of the material: DC PD is more frequent and with higher discharge magnitude when the cavity is closer to the conductor or the current through the conductor is higher. Both DC PD repetition rate and average discharge magnitude in long-term aged material are lower than virgin material. The effect of discharge on insulation degradation becomes decreasingly significant.

The current work is based on the numerical modelling of DC PDs. Further experimental validations and comparisons are essential for improving the model.

The studies of the influence factors for PDs under HVDC voltage can benefit the research and practical power transmission on DC PDs, contributing the design and test of DC PDs in HVDC cables, exploring the understandings of the DC PDs’ mechanism.

This paper, to the best of author’s knowledge, first studies the influence factors on DC PDs based on the numerical modelling work.