Feasibility Assessment of Plug and Play Model Predictive Control for use in DC Grids

Distributed control techniques can allow Transmission System Operators (TSOs) to coordinate their responses via TSO-TSO communication, providing a level of control that lies between that of centralised control and communication free decentralised control of interconnected power systems. Recently the Plug and Play Model Predictive Control (PnPMPC) toolbox has been developed in order to allow practitioners to design distributed controllers based on tube-MPC techniques. In this paper, some initial results using the PnPMPC toolbox for the design of distributed controllers to enhance AGC in AC areas connected to Multi-Terminal HVDC (MTDC) grids, are illustrated, in order to evaluate the feasibility of applying PnPMPC for this purpose.

Open Source Telecommunications Framework for Time-Series Data from Smart Grid Sensors.

This paper presents a framework for a telecommunications interface which allows data from sensors embedded in Smart Grid applications to reliably archive data in an appropriate time-series database. The challenge in doing so is two-fold, firstly the various formats in which sensor data is represented, secondly the problems of telecoms reliability. A prototype of the authors' framework is detailed which showcases the main features of the framework in a case study featuring Phasor Measurement Units (PMU) as the application. Useful analysis of PMU data is achieved whenever data from multiple locations can be compared on a common time axis. The prototype developed highlights its reliability, extensibility and adoptability; features which are largely deferred from industry standards for data representation to proprietary database solutions. The open source framework presented provides link reliability for any type of Smart Grid sensor and is interoperable with existing proprietary database systems, and open database systems. The features of the authors' framework allow for researchers and developers to focus on the core of their real-time or historical analysis applications, rather than having to spend time interfacing with complex protocols.

Synchronous Islanding Control in the Presence of Hydro-electric Generation

This paper introduces a novel load sharing algorithm to enable island synchronization. The system model used for development is based on an actual system for which historical measurement and fault data is available and is used to refine and test the algorithms performance and validity. The electrical system modelled is selected due to its high-level of hydroelectric generation and its history of islanding events. The process of developing the load sharing algorithm includes a number of steps. Firstly, the development of a simulation model to represent the case study accurately - this is validated by way of matching system behavior based on data from historical island events. Next, a generic island simulation is used to develop the load sharing algorithm. The algorithm is then tested against the validated simulation model representing the case study area selected. Finally, a laboratory setup is described which is used as validation method for the novel load sharing algorithm.

Strengthening timber beams with near surface mounted carbon fiber reinforced polymer rods

Many timber structures may require strengthening due to either decay and aging or an increase of load. This paper presents an experimental study in which eleven timber beams were tested, including three unstrengthened reference beams and eight beams strengthened with NSM CFRP bars. The test parameters include the position of NSM (tensile face or the bottom of the sides), the number of CFRP bars (1 or 2), and additional anchorage of NSM CFRP bars (steel wire U anchors or CFRP U strips). The test results show that the ultimate flexural strength of the timber beams were increased by 14%∼85% with an average of 47% due to NSM CFRP bar strengthening. Their deflection corresponding to the peak load was increased by 33% in average.

Improved shear strength model for FRP-strengthened RC beams accounting for adverse FRP-steel interaction

RC beams shear-strengthened with externally-bonded FRP side strips or U-strips usually fail by debonding. As such debonding occurs in a brittle manner at relatively small shear crack widths, some of the internal steel stirrups may not have reached yielding at beam shear failure. Consequently, the internal steel stirrups cannot be fully utilized. This adverse shear interaction between internal steel stirrups and external FRP strips may significantly reduce the benefit of shear-strengthening FRP but has not been considered by any of the existing FRP strengthening design guidelines. In this paper, an improved shear strength model capable of accounting for the effect of the above shear interaction is first presented, in which the unfavorable effect of shear interaction is reflected through a reduction factor (i.e. shear interaction factor). Using a large test database established in the present study, the performance of the proposed model as well as that of three other shear strength models is then assessed. This assessment shows that the proposed shear strength model performs better than the three existing models. The assessment also shows that the inclusion of the proposed shear interaction factor in the existing models can significantly improve their performance.

Effects of unconfined concrete strength on FRP confinement of concrete

Research has shown that fibre reinforced polymer (FRP) wraps are effective for strengthening concrete columns for increased axial and flexural load and deformation capacity, and this technique is now used around the world. The experimental study presented in this paper is focused on the mechanics of FRP confined concrete, with a particular emphasis on the influence of the unconfined concrete compressive strength on confinement effectiveness and hoop strain efficiency. An experimental programme was undertaken to study the compressive strength and stress-strain behaviour of unconfined and FRP confined concrete cylinders of different concrete strength but otherwise similar mix designs, aggregates, and constituents. This was accomplished by varying only the water-to-cement ratio during concrete mixing operations. Through the use of high-resolution digital image correlation to measure both axial and hoop strains, the observations yield insights into the mechanics of FRP confinement of concretes of similar composition but with varying unconfined concrete compressive strength.

Novel manually made NSM FRP (MMFRP) bars for shear strengthening of RC beams

This paper presents an experimental study evaluating the effectiveness of the Near Surface Mounted (NSM) technique with innovative manually made FRP bars (MMFRP) for shear strengthening of RC beams. RC beams designed to fail in shear were tested in three-point bending. To delay the onset of MMFRP bar debonding, a new anchorage is also developed and tested. This paper reports the results of a series of tests on simply supported rectangular RC beams, strengthened in shear with MMFRP bar either with or without the proposed anchorage. The load-deflection responses of all test beams are plotted, in addition to selected strain results. Performance and the failure modes of the test beams are presented and discussed in this paper. The proposed MMFRP bars and end anchorage enhanced the shear capacity between 25 to 48% over the control specimen. Furthermore, the adoption of the proposed end anchorage of MMFRP bars significantly enhanced the ductility of the test specimens.

Risk-aware Planning in BDI Agents

The ability of an autonomous agent to select rational actions is vital in enabling it to achieve its goals. To do so effectively in a high-stakes setting, the agent must be capable of considering the risk and potential reward of both immediate and future actions. In this paper we provide a novel method for calculating risk alongside utility in online planning algorithms. We integrate such a risk-aware planner with a BDI agent, allowing us to build agents that can set their risk aversion levels dynamically based on their changing beliefs about the environment. To guide the design of a risk-aware agent we propose a number of principles which such an agent should adhere to and show how our proposed framework satisfies these principles. Finally, we evaluate our approach and demonstrate that a dynamically risk-averse agent is capable of achieving a higher success rate than an agent that ignores risk, while obtaining a higher utility than an agent with a static risk attitude.

Modelling Duqu 2.0 Malware using Attack Trees with Sequential Conjunction

In this paper we identify requirements for choosing a threat modelling formalisation for modelling sophisticated malware such as Duqu 2.0. We discuss the gaps in current formalisations and propose the use of Attack Trees with Sequential Conjunction when it comes to analysing complex attacks. The paper models Duqu 2.0 based on the latest information sourced from formal and informal sources. This paper provides a well structured model which can be used for future analysis of Duqu 2.0 and related attacks.

IEEE C37.118-2 Synchrophasor Communication Framework

Synchrophasors have become an important part of the modern power system and numerous applications have been developed covering wide-area monitoring, protection and control. Most applications demand continuous transmission of synchrophasor data across large geographical areas and require an efficient communication framework. IEEE C37.118-2 evolved as one of the most successful synchrophasor communication standards and is widely adopted. However, it lacks a predefined security mechanism and is highly vulnerable to cyber attacks. This paper analyzes different types of cyber attacks on IEEE C37.118-2 communication system and evaluates their possible impact on any developed synchrophasor application. Further, the paper also recommends an efficent security mechanism that can provide strong protection against cyber attacks. Although, IEEE C37.118-2 has been widely adopted, there is no clear understanding of the requirements and limitations. To this aim, the paper also presents detailed performance evaluation of IEEE C37.118-2 implementations which could help determine required resources and network characteristics before designing any synchrophasor application.

Contextual Intrusion Alerts for SCADA Networks

The complexity of modern SCADA networks and their associated cyber-attacks requires an expressive but flexible manner for representing both domain knowledge and collected intrusion alerts with the ability to integrate them for enhanced analytical capabilities and better understanding of attacks. This paper proposes an ontology-based approach for contextualized intrusion alerts in SCADA networks. In this approach, three security ontologies were developed to represent and store information on intrusion alerts, Modbus communications, and Modbus attack descriptions. This information is correlated into enriched intrusion alerts using simple ontology logic rules written in Semantic Query-Enhanced Web Rules (SQWRL). The contextualized alerts give analysts the means to better understand evolving attacks and to uncover the semantic relationships between sequences of individual attack events. The proposed system is illustrated by two use case scenarios.

k-fold Subsampling based Sequential Backward Feature Elimination

We present a new wrapper feature selection algorithm for human detection. This algorithm is a hybrid featureselection approach combining the benefits of filter and wrapper methods. It allows the selection of an optimalfeature vector that well represents the shapes of the subjects in the images. In detail, the proposed featureselection algorithm adopts the k-fold subsampling and sequential backward elimination approach, while thestandard linear support vector machine (SVM) is used as the classifier for human detection. We apply theproposed algorithm to the publicly accessible INRIA and ETH pedestrian full image datasets with the PASCALVOC evaluation criteria. Compared to other state of the arts algorithms, our feature selection based approachcan improve the detection speed of the SVM classifier by over 50% with up to 2% better detection accuracy.Our algorithm also outperforms the equivalent systems introduced in the deformable part model approach witharound 9% improvement in the detection accuracy

Impact of energy-using product policies

Energy-using products (EuPs), such as domestic appliances, audio-visual and ICT equipment contribute significantly to CO2 emissions, both in the domestic and non-domestic sectors. Policies that encourage the use of more energy efficient products can therefore generate significant reductions in overall energy consumption and hence, CO2 emissions. To the extent that these policies cause an increase the average production cost of EuPs, they may impose economic costs on producers, or on consumers, or on both. In this theoretical paper, an adaptation of a simple vertical product differentiation model – in which products are characterised in terms of their quality and their energy consumption – is used to analyse the impact of the different EuP polices on product innovation and to assess the resultant economic impacts on producers and consumers. It is shown that whereas the imposition of a binding product standard for energy efficiency unambiguously reduces aggregate profit and increases the average market price in the absence of any learning effects, the introduction or strengthening of demand-side measures (such as energy labelling) may reduce, or increase, aggregate profit. Even in the case where the overall impact is unambiguously negative, the effects of product innovation and learning can be in either direction.

Avaliação do impacto da marcha com canadianas no dispêndio energético: análise comparativa entre jovens e idosos

Introdução: As canadianas são utilizadas em múltiplos quadros clínicos em que existe compromisso da marcha. No entanto, é fulcral considerar as diferentes exigências metabólicas associadas a cada auxiliar e tipo de marcha. Objetivo: Avaliar o dispêndio energético (DE) na marcha normal (MN), com uma canadiana e com duas canadianas a 3 pontos e a 3 pontos modificada em jovens e idosos. Metodologia: Estudo analítico transversal, composto por 21 indivíduos. As variáveis analisadas foram o volume de oxigénio inspirado (VO2), volume de dióxido de carbono expirado (VCO2) e quociente respiratório (QR), obtidas através do sistema portátil (Cosmed K4b2, Cosmed, Roma, Itália). Resultados: Os participantes tinham idades entre 18 e 75 anos (11 jovens e 10 idosos). Os idosos apresentaram valores significativamente mais elevados que os jovens no DE na marcha com uma canadiana a 3 pontos (p=0,009) e com duas canadianas a 3 pontos (p=0,008), enquanto nas restantes marchas não houve diferenças estatisticamente significativas (p>0,05). A MN e a marcha com duas canadianas a 3 pontos foram os tipos de marcha com maior DE nos jovens, e nos idosos. Nos jovens, a MN apresentou 19% a 45% maior DE do que as restantes marchas, enquanto nos idosos verificou-se que todas as marchas (à exceção de uma canadiana a 3 pontos modificada) apresentaram um maior DE (entre 7 e 16%) comparativamente à MN. Conclusão: Os idosos apresentaram valores significativamente mais elevados de DE que os jovens nas marchas uma e duas canadianas a 3 pontos. Na MN e na marcha uma canadiana a 3 pontos modificada existe uma tendência para os jovens apresentarem valores de DE superior aos idosos. A medição do DE fornece uma indicação precisa da eficiência da marcha, sendo útil como suporte para a decisão clínica e para uma adequada reabilitação.

A influência da marcha com tripé nos parâmetros metabólicos em jovens e idosos

Introdução: Os parâmetros metabólicos durante a marcha normal e a sua regulação são importantes devido ao metabolismo oxidativo ser o principal meio através do qual o organismo humano gera energia para realizar as atividades do quotidiano. Nem sempre a marcha é realizada de forma independente e necessita do apoio de auxiliares de marcha, como o tripé, que tem por função ampliar a base de sustentação e melhorar o equilíbrio. Objetivo: Analisar a influência de utilização de um tripé na marcha, na despesa energética em jovens e idosos saudáveis Métodos: Realizou-se um estudo observacional transversal numa amostra de 21 voluntários, com idade entre 18 a 25 anos e mais ou igual a 60 anos. Realizaram-se as avaliações com o Cosmed K4b2 (Cosmed, Rome, Italy), sendo através do mesmo que os dados foram recolhidos. Foi utilizado o teste de Friedman, com P <0,05. Resultados: Os resultados obtidos para o gasto energético nos jovens foram inferiores aos valores obtidos pelos idosos. Relativamente ao metabolismo energético o substrato energético utilizado pelos jovens foi o proteico e o lipídico pelos idosos. Entre sexos foram os homens quem tiveram um maior gasto energético. Conclusão: O uso do tripé durante a marcha não influencia o gasto energético em adultos jovens e/ou idosos saudáveis.