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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 paper proposes an ANN based adaptive damping control scheme for the unified power flow controller (UPFC) to damp the low frequency electromechanical power oscillations. In this paper a novel damping control strategy based on the time‐domain analysis of system transient energy function (TEF) is proposed and implemented by using well tuned conventional PI controllers to obtain the preliminary training data for the design of the proposed controllers. The multi‐layered feed forward neural network with error back‐propagation training algorithm is employed in this study. Models of UPFC and ANN controllers suitable for incorporating with the transient simulation programs are derived and tested on a revised IEEE nine‐bus test system. Comprehensive simulation results demonstrate the great potential of using UPFC in damping control and the excellent performance of the proposed control scheme.

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.

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.

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.

High voltage direct current (HVDC) cable is an important part in the electric power transmission and distribution systems. However, very little research has been carried out on partial discharge under direct current (DC) conditions. Niemeyer’s model has been widely used under alternating current (AC) conditions. This paper aims to intend to modify the Niemeyer’s model considering both electric field and charge dynamics under DC conditions, and therefore proposes a numerical model describing partial discharge characteristics in HVDC cable.

This paper intends to understand partial discharge characteristics under DC conditions through numerical modelling. Niemeyer’s model that has been widely used under AC conditions has been modified, taking both electric field and charge dynamics under DC conditions into consideration. The effects of loading level or current through the conductor, cavity location and material properties on partial discharges have also been studied.

Electrical conductivity is important in determining the characteristics of partial discharge under DC conditions and discharges tend to happen in short when the cavity field exceeds the inception level under the parameter values studied in the paper.

Building the numerical model is the purpose of the paper, and there is lack in experiment and the comparison between the simulation results and experiment.

The proposed model provides the numerical model describing partial discharge in HVDC cable and helps understand the partial discharge mechanism under DC voltage.

To the best of the author’s knowledge, this paper is a very early research on the numerical modelling work on partial discharge under DC voltage.

In high-voltage direct current (HVDC) cable systems, space charges accumulate because of the constant applied voltage and the nonlinear electric conductivity of the insulating material. The change in the charge distribution results in a slowly time-varying electric field. Space charges accumulate within the insulation bulk and at interfaces. With an operation time of several years of HVDC systems, typically the stationary electric field is of interest. The purpose of this study is to investigate the influence of interfaces on the stationary electric field stress and space charge density.

An analytic description of the stationary electric field inside cable insulation is developed and numerical simulations of a cable joint geometry are applied, considering spatial variations of the conductivity in the vicinity of the electrodes and interfaces.

With increasing conductivity values toward the electrodes, the resulting field stress decreases, whereas a decreasing conductivity results in an increasing electric field. The increased electric field may cause partial discharge, resulting in accelerated aging of the insulation material. Thus, interfaces and surfaces are characterized as critical areas for the reliability of HVDC cable systems.

This study is restricted to stationary electric field and temperature distributions. The electric field variations during a polarity reversal or a time-varying temperature may result in an increased electric conductivity and electric field at interfaces and surfaces.

An analytical description of the electric field, considering surface effects, is developed. The used conductivity model is applicable for cable and cable-joint insulations, where homo- and hetero-charge effects are simulated. These simulations compare well against measurements.

Taking into consideration the current human need for agricultural produce such as rice that requires water for growth, the optimal consumption of this valuable liquid is important. Unfortunately, the traditional use of water by humans for agricultural purposes contradicts the concept of optimal consumption. Therefore, designing and implementing a mechanized irrigation system is of the highest importance. This system includes hardware equipment such as liquid altimeter sensors, valves and pumps which have a failure phenomenon as an integral part, causing faults in the system. Naturally, these faults occur at probable time intervals, and the probability function with exponential distribution is used to simulate this interval. Thus, before the implementation of such high-cost systems, its evaluation is essential during the design phase.

The proposed approach included two main steps: offline and online. The offline phase included the simulation of the studied system (i.e. the irrigation system of paddy fields) and the acquisition of a data set for training machine learning algorithms such as decision trees to detect, locate (classification) and evaluate faults. In the online phase, C5.0 decision trees trained in the offline phase were used on a stream of data generated by the system.

The proposed approach is a comprehensive online component-oriented method, which is a combination of supervised machine learning methods to investigate system faults. Each of these methods is considered a component determined by the dimensions and complexity of the case study (to discover, classify and evaluate fault tolerance). These components are placed together in the form of a process framework so that the appropriate method for each component is obtained based on comparison with other machine learning methods. As a result, depending on the conditions under study, the most efficient method is selected in the components. Before the system implementation phase, its reliability is checked by evaluating the predicted faults (in the system design phase). Therefore, this approach avoids the construction of a high-risk system. Compared to existing methods, the proposed approach is more comprehensive and has greater flexibility.

By expanding the dimensions of the problem, the model verification space grows exponentially using automata.

Unlike the existing methods that only examine one or two aspects of fault analysis such as fault detection, classification and fault-tolerance evaluation, this paper proposes a comprehensive process-oriented approach that investigates all three aspects of fault analysis concurrently.