I denna rapport utreds hur systemdesignen av lågspänningsfördelningen för järnvägen kan kostnadseffektiviseras. I dagsläget har det utarbetats en norm kring systemdesignen som tenderar att efterbildas från år till år vilket har medfört brist på innovation inom området. Syftet med arbetet var att designa två typstationer med signalställverken M11 respektive M95, där placering samt nominell storlek av UPS:er skulle fastställas för att tillhandahålla en kostnadseffektiv lösning. Dessutom skulle kablage dimensioneras för typstationerna samt se över möjligheten att ersätta UPS:er med likriktarsystem. Stationerna baserades på två redan existerande driftplatser, Fagersta C (M11) och Skänninge (M95). Slutligen skulle olika energilagringsalternativ för UPS-system jämföras för att tillhandahålla det lämpligaste alternativet. Genom simuleringar och beräkningar i bland annat datorprogrammet El-Vis har lågspänningsfördelningen dimensionerats för typstationerna. Arbetet visar på att ett distribuerat UPS-system är att föredra ur ett ekonomiskt perspektiv gentemot ett centraliserat UPS-system. Vidare har det konstaterats att likriktarsystemet Rectiverter kan ersätta UPS:er samt att ackumulatorer är det mest passande energilagringsalternativet. / This report identifies how the system design of low voltage power distribution of the railway can be more cost effective. In the current situation there is a norm on the system design that tends to be replicated each year. This has brought a lack of innovation in the field. The purpose of the thesis was to come up with two model stations with the interlocking system M11 respectively M95, where the positioning and nominal size of the UPS:s would be determined to provide a cost effective solution. Furthermore, the cable dimensioning of the model stations was computed as well as the possibility of replacing UPS-systems with rectifier-systems. The model stations were based on two already existing operating sites, Fagersta C (M11) and Skänninge (M95). Lastly, different energy storage alternatives for UPS-systems were compared to acquire the most appropriate choice. Through simulations and calculations in, inter alia, the computer program El-Vis, the low voltage power distribution was dimensioned for the model stations. The thesis shows that a distributed UPS-system is preferred in an economical point of view compared to a centralized UPS-system. Furthermore, the thesis establishes that the rectifier system Rectiverter can replace UPS:s. It also states that accumulators are the most suitable alternative for energy storage.

Road transport mobility continues to be a challenge to the City of Johannesburg (CoJ)’s economy in general. Traffic signals, their remote monitoring and control systems are the current implemented Intelligent Transport Systems (ITS), but daily systematic faults and maintenance uncertainties on such systems decrease the effectiveness of traffic engineers’ intersections optimization techniques. Inefficient electrical power supply to such ITS is a challenge, with conditional power cuts and fluctuations, uncertainties on traffic control system faults. Another factor leading to the problem is the communication channel which is using traditional modems which are not reliable. Reporting through both customer complaints and such unreliable remote monitoring systems makes maintenance to be ineffective. In this dissertation, the factors leading to the faults and uncertainties are considered. The proposed solution considers the important concerns of ITS, such as electrical power source performance optimization technique, road traffic control systems compatibility and communications systems / Electrical and Mining Engineering / M. Tech. (Electrical Engineering)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis contributes to the analysis, project and implementation of discrete-time controllers based on the Internal Model Principle, aiming to improve the performance of three-leg three-phase PWM inverters with insulating output transformer usually found in the output stage of medium power double-conversion UPS. Initially, an investigation about issues concerning to the discrete-time models of three-phase inverters with space vector modulation and the LC filter have been carried out. This investigation shows the impact of different switching sequences, sampling instants and filter cut-off frequency on the harmonic spectrum of sampled variables used for feedback. This is a concern when the switching frequency is low to limit the switching losses as in medium and high power UPS. In this way, this thesis proposes sampling methods that make possible to reduce the low order harmonics on the interest variables, which is relevant when state feedback is used. These methods allow to obtain discrete-time average linear models useful for the controller design. In addition, the saturation of the insulating transformer is addressed in details. The dc component arising from the digital implementation and from the circuit measures non idealities, and then amplified by an inadequate choice of the controller, may lead the transformer to saturate. In order to solve this problem, and in accordance with the Internal Model Principle, internal models adequate to the plant under consideration as well as discrete-time voltage controllers in stationary and synchronous frames which are not prone to amplify the dc component, are proposed. Another goal of this thesis is the improvement of the UPS output voltage transient response due to linear and non linear load steps. This is obtained considering the sampling methods before mentioned, combined with internal models with reduced number of poles and low sampling rate. It is demonstrated that it is possible to improve significantly the output voltage transient responses, as well as to satisfy the rigorous classification of the standard IEC62040-3 for UPS without degrading the steady state performance. In addition, these control structures have enough stability margins, as proved in each case, and they results in simple and attractive solutions to be implemented in 8 or 16 bits fixed-point arithmetic microcontrollers and DSP with reduced memory space. The feasibility of the proposed solutions is verified with experimental results demonstrating both transient and steady-state performances. Finally, a comparative analysis of the proposed control structures, over the light of the standard IEC62040-3, is presented. / A presente tese de doutorado contribui para a análise, projeto e implementação de controladores discretos baseados no Princípio do Modelo Interno, com o intuito de aprimorar o desempenho de inversores trifásicos PWM a três braços com transformador isolador usualmente utilizados no estágio de saída de UPS de dupla conversão de média potência. Inicialmente se realiza uma investigação sobre os aspectos relacionados à obtenção do modelo discreto de inversores trifásicos com modulação space vector e do filtro de saída. Essa investigação mostra o impacto de diferentes seqüências de comutação, instantes de amostragem e freqüência de corte do filtro no conteúdo harmônico das variáveis amostradas usadas para realimentação. Isso é uma preocupação quando a freqüência de comutação é baixa para limitar as perdas em UPS de média e alta potência. Nesse sentido essa tese propõe métodos de amostragem que possibilitam reduzir as harmônicas de baixa ordem nas variáveis de interesse o que adquire importância quando se realiza a realimentação dos estados da planta. Esses métodos permitem a obtenção de modelos médios lineares úteis para o projeto do controlador. Além disso, a saturação do transformador de isolação é analisada em detalhe. A componente contínua oriunda da implementação digital e das não idealidades dos circuitos de medição, e amplificada por uma escolha inadequada do controlador, pode levar o transformador à saturação. Com o intuito de solucionar esse problema, e de acordo com a teoria do Princípio do Modelo Interno, são propostos modelos internos adequados à planta em questão bem como controladores discretos de tensão em eixos estacionários e síncronos, que não tem tendência a amplificar a componente contínua. Outro dos objetivos dessa tese é o aprimoramento da resposta transitória das tensões de saída da UPS na presença de degraus de carga linear e não linear. Isso é obtido considerando-se os métodos de amostragem mencionados acima, combinado com modelos internos com número de pólos e taxa de amostragem reduzidos. Demonstra-se que é possível aprimorar significativamente a resposta transitória das tensões de saída bem como satisfazer a exigente classificação da norma IEC62040-3 para UPS, sem degradar o desempenho de regime permanente. Além disso, essas estruturas de controle possuem suficiente margem de estabilidade, como provado em cada caso, e estas resultam em soluções simples e atrativas para serem implementadas em microcontroladores e DSP de aritmética de ponto fixo, com palavras de 8 e 16 bits e capacidade reduzida de memória. A viabilidade prática das propostas realizadas é verificada com resultados experimentais em regime permanente e transitório. Finalmente, apresenta-se uma análise comparativa das estruturas de controle propostas, sob o enfoque da norma IEC62040-3.

Roslagsbanans signalanläggningar har flera olika lösningar för dess strömförsörjning i form av standarder för batterier och likriktare. Denna lösningsvariation har försvårat för underhållspersonalen att åtgärda de fel som uppstått och därmed fördröjt trafiken, dvs trafikstörningar. Roslagsbanan försörjs delvis av lokala elnät där avbrott emellanåt förekommer. Dessa avbrott inträffar ofta när elnätsleverantörerna underhåller sitt ortnät vilket kan ske även under rusningstrafik. Avbrotten kan även orsakas inom signalanläggningarna när stora spänningsvariationer förekommer, t.ex. när stora induktiva- eller kapacitiva laster slås av. Dessa problem analyseras och åtgärdsförslag tas fram i denna rapport. De befintliga likriktarna och batterierna samt förslag till ersättningsprodukter som behövs för detta säkerhetssystem har sammanställts i denna rapport. För att skapa en hållbar, robust och miljövänlig strömförsörjning till Roslagsbanans signalanläggningar undersöktes i detta arbete strömspikar, avbrottsfri kraftförsörjning samt dessutom möjligheten att ansluta solceller som kompletterande åtgärd. I signalutrustningen vid Roslags Näsby stationsområde detekterades och undersöktes förekomsten av strömspikar. Två åtgärdsförslag för att komma till rätta med dessa strömspikar togs fram. Förslagen var ett lågpassfilter och en metalloxidvaristor som båda var för sig reducerar strömspikarna. Lågpassfiltret dämpar insignalernas spänning och strömförsörjning vid kraftiga förändringar i frekvensen och metalloxidvaristorn reducerar strömflödet vid överspänningar. Ytterligare undersökningar av transienterna i Roslags Näsbys och de övriga signalanläggningarna på Roslagsbanan bör utföras. Resultaten av de genomförda undersökningarna om avbrottsfri kraftförsörjning och solceller visade däremot att utrustningarna inte bör installeras i de nuvarande signalanläggningarna. Solceller var inte implementerbara eftersom effektbehovet av signalanläggningarna var större än den takyta som fanns tillgänglig för solcellerna. Arbete och investeringar för ett avbrottsfritt kraftförsörjningsunderhåll och installation av denna utrustning var mer krävande i jämförelse med dess nytta för signalanläggningarnas tillförlitlighet, dvs ingen åtgärd i nuläget. Förslag på ersättningsprodukter i form av likriktare och batterier lades fram till arbetsgivarna för att skapa en standard för Roslagbanans kraftförsörjning framåt. / Roslagsbanan's signal systems have several different solutions for its power supply in the form of several standards for batteries and rectifiers. This solution variation has made it difficult for maintenance staff to correct the errors that occurred and thus delayed traffic, i.e. traffic disturbances. Roslagsbanan is partly supplied by local power grids where interruptions occur occasionally. These interruptions often occur when the network service providers maintain their home network, which may also occur during rush hour traffic. The interruptions can also be caused by the signal systems them self when large voltage variations occur, e.g. when large inductive or capacitive loads are switched off. These problems are analysed, and action proposals are presented in this report. The existing rectifiers and batteries as well as proposals for replacement products that are needed for this safety system have been compiled in this report. To create a sustainable, robust and environmentally friendly power supply to Roslagsbanan’s signal systems, this work investigated transients, uninterruptible power supply, as well as the possibility of connecting solar cells as a complementary arrangement. An investigation of the signal equipment at Roslags Näsby station area showed presence of transients. Two proposals to reduce these transients were presented. The proposals were a low pass filter and a metal oxide varistor, both individually reduces transients. The low pass filter attenuates the voltage and current of the signal when the strong frequency changes occurs and the metal oxide varistor reduces the current flow at overvoltages. Further investigations of the transients in Roslags Näsbys and the other signal facilities on the Roslagsbanan should be performed. On the other hand, the results of the investigations on uninterruptible power and solar cells showed that the equipment should not be installed in the current signal systems. Solar cells were not implementable because the power requirement of the signal systems was greater than the current ceiling area for the solar cells. The work and investment for uninterruptible power supply maintenance and installation were more demanding in comparison to its usefulness for the reliability of the signal systems. Proposals for replacement products were submitted to employers to create a standard for Roslagbanan's power supply onwards. / Сигнални систем на железници која се зове Рослагсбана садржи више различитих решења за своје напајање у облику неколико стандарда за батерије и исправљаче. Варијација различитих решења проузроковала je потешкоће у отклањању новонасталих грешака служби које се баве одржавањем и изазвала је застој у железничком саобраћају. Рослагсбана се напаја електричном енергијом из локалних мрежа на којима може доћи до прекида. Прекид напајања електричном енергијом може бити изазван наглим променама напона у сигналним системима и уколико локални дистрибутер изводи радове на одржавању електричне мреже. Проблеми који могу настати променама напона се анализирају и испитују у овом извештају. Попис исправљача и батерија као и њихова стандардна решења су обрађени и представљени у циљу стварања одрживог и дугорочног решења за системску сигнализацију. Анализирани су високонапонски шпицеви, системи за непрекидно напајање електричном енергијом (УПС) и могућност прикључивања соларних панела. У сигналном систему на станици Рослас Насби измерени су високонапонски шпицеви. Како би се дошло до најбољег и најповољнијег решења анализирана су два предлога за њихово уклањање. Један предлог за уклањање био је ниско пропусни филтер док је за редукцију предложен метал- оксидни одводник пре напона (МОВ). Ниско пропусни филтер смањује јачину струје и напона уколико фреквенција пређе одређену претходно утврђену границу, док МОВ редукује ток струје уколико дође до скока напона. Пре имплементације било ког од наведених решења треба извршити накнадна испитивања у вези са напонским шпицевима. Резултати указују да имплементација УПС-а и соларних панела није могућа. Могућност соларних панела да произведу довољну количину енергије која је потребна за одређени систем није сразмерна површини система која би могла да се прекрије соларним панелима. Трошкови одржавања и прикључивања УПС система су већи у поређењу са значајем које би систем имао од самог УПС система. Предлог стандардних батерија и исправљача који је представљен послодавцу коригован је како би се дошло до стандардног решења за све предстојеће пројекте.