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  • 51.
    Ali, Muhammad Taha
    et al.
    National University of Science and Technology Islamabad, Pakistan.
    Anwar, Ali
    Tayyab, Umais
    Iqbal, Yasir
    Tauqeer, Tauseef
    Nasir, Usman
    Design of High Efficiency Wireless Power Transmission System at Low Resonant Frequency2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a novel design of a wireless power transmission system which transfers an appreciable amount of electrical power wirelessly using low resonant frequency, with an excellent efficiency, and has a very low cost implementation. The designs of induction coils at both source and receiver sides are also presented in this paper. The mechanism for power transmission is through electro-magnetic induction. Also an immense knowledge of electronics was applied in order to design the source and receiver between which this transfer took place. In order to realize this method an AC-AC converter, and AC-DC rectifier were used at source and receiver sides respectively along with the resonant circuits. The work was carried out by the experimental setup and results demonstrate that proposed system design can successfully transfer the amount of power that can be used in many practical applications.

  • 52.
    Ali, Muhammad Taha
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Ghandhari, Mehrdad
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Harnefors, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Effect of control parameters on infliction of sub-synchronous control interaction in DFIGs2016Ingår i: 2016 IEEE International Conference on Power and Renewable Energy (ICPRE), IEEE conference proceedings, 2016, s. 72-78, artikel-id 7871175Konferensbidrag (Refereegranskat)
    Abstract [en]

    This research work deals with the analysis of sub-synchronous control interaction (SSCI) in doubly-fed induction generators (DFIGs). The time-invariant model of the DFIG is linearized to perform eigenvalue analysis and to obtain the participation factor of each state variable for unstable modes. The sensitivity of system eigenvalues related to sub-synchronous modes is analyzed with respect to all the proportional and integral parameters of the controllers in the rotor-side-converters and grid-side-converters. The major contribution of this research work is the outcomes based on eigenvalue analysis that clearly point out the control parameters to which sub-synchronous modes are highly sensitive. The effect of series compensation level on DFIG system and on the sensitivity of converter control parameters is also studied.

  • 53.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Baudette, Maxime
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Statnett.
    Utilizing synchrophasor-based supplementary damping control signals in conventional generator excitation systems2018Ingår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 157, s. 157-167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A supplementary function of Excitation Control Systems (ECSs) for synchronous generators is that of a Power System Stabilizer (PSS). The PSS implementation in these ECSs only allows the use of a limited type of pre-defined local input measurements and built-in PSS algorithms. To adapt existing ECSs to take advantage of synchrophasors technology, this paper proposes and implements a prototype wide-area damping controller (WADC) that provides synchrophasor-based damping input signals to existing ECSs. The developed WADC comprise (i) a real-time mode estimation module, (ii) synchrophasor’s communication latency computation module, and (iii) phasor-based oscillation damping algorithm executing in a real-time hardware prototype controller.

    Through Real-Time Hardware-in-the-Loop (RT-HIL) simulations, it is demonstrated that synchrophasor-based damping signals from the WADC can be utilized together with a commercial ECS, thus providing new options for selection of the best feedback signal for oscillation damping.

  • 54.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Baudette, Maxime
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Løvlund, S
    Gjerde, J.O
    Synchrophasor Network, Laboratory and Software Applications Developed in the STRONg2rid Project2014Ingår i: PES General Meeting Conference & Exposition, 2014 IEEE, IEEE conference proceedings, 2014, s. 1-5Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the activities carried out in one of the work packages of the Nordic Energy Research funded project Smart Transmission Grid Operation and Control (STRONg2rid). The main objective of the work package is to deploy a state-of-the-art software and hardware for developing power system operation, protection, control and automation applications. Several PMUs have been deployed at partner universities and a network of synchrophasors has been set up. In addition the Smart Transmission System Laboratory (SmarTS-Lab) has been established. This laboratory serves as a test-bench to develop and verify smart transmission grid technologies. A software development kit (S3DK) was developed within the project. The S3DK has been used to implement PMU-based applications and deploy them in different targets, including smart phones and tablets. Several tools and software applications which utilize synchrophasor measurements (from the laboratory or the deployed university PMU network) to perform power system monitoring, sub-synchronous power oscillation detection, etc., have been developed and are presented herein.  

  • 55.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Kilter, Jako
    Tallinn University of Technology-Estonia.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Experiences with Steady-State PMU Compliance Testing using Standard Relay Testing Equipment2014Ingår i: Electric Power Quality and Supply Reliability Conference (PQ), 2014, IEEE conference proceedings, 2014, s. -110Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the results of steady state compliance testing of phasor measurement units (PMUs) from three different vendors in a laboratory environment. Testing is performed by providing three phase voltage and current injections to the VT and CT inputs of the PMUs through Freja-300 stand-alone protection relay test set. Testing is performed according to the standard “IEEE C37.242-2013 - IEEE Guide for Synchronization, Calibration, Testing, and Installation of Phasor Measurement Units (PMUs) for Power System Protection and Control”. The paper discusses the test setup, testing process and overall test results of this project. The limitations of stand-alone testing equipment and recommendations for utilizing real-time hardware-in-the-loop simulation for thorough testing of PMUs are also presented. 

  • 56.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Leelaruji, Rujiroj
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Over-current relay model implementation for real time simulation & Hardware-in-the-Loop (HIL) validation2012Ingår i: IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society, Montreal, QC: IEEE conference proceedings, 2012, s. 4789-4896Konferensbidrag (Refereegranskat)
    Abstract [en]

    Digital microprocessor based relays are currently being utilized for safe, reliable and efficient operation of power systems. The overcurrent protection relay is the most extensively used component to safeguard power systems from the detrimental effects of faults. Wrong settings in overcurrent relay parameters can lead to false tripping or even bypassing fault conditions which can lead to a catastrophe. Therefore it is important to validate the settings of power protection equipment and to confirm its performance when subject to different fault conditions. This paper presents the modeling of an overcurrent relay in SimPowerSystems (\textsc {matlab}/Simulink). The overcurrent relay has the features of instantaneous, time definite and inverse  definite minimum time (IDMT) characteristics. A power system is modeled in SimPowerSystems and this overcurrent relay model is incorporated in the test case. The overall model is then simulated in real-time using Opal-RT's eMEGAsim real-time simulator to analyze the relay's performance when subjected to faults and with different characteristic settings in the relay model. Finally Hardware-in-the-Loop validation of the model is done by using the overcurrent protection feature in Schweitzer Engineering Laboratories Relay SEL-487E. The event reports generated by the SEL relays during Hardware-in-the-Loop testing are compared with the results obtained from the standalone testing and software model to validate the model.

  • 57.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Statnett.
    A Hybrid Synchrophasor and GOOSE-Based Power System Synchronization Scheme2016Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 4, s. 4659-4668Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The design and real-time hardware-in-the-loop implementation of a hybrid synchrophasors and GOOSE-based automatic synchronization algorithm are presented in this paper. Automatic synchronization is performed by utilizing the synchrophasor measurements from two commercial phasor measurement units (PMUs), while the coordinated control commands to automatic voltage regulator and/or turbine governor control and trip command to the circuit breaker are issued using IEC 61850-8-1 GOOSE messages. The algorithm is deployed inside the PMU using the protection logic equations, and direct communication between the PMUs is established to minimize the communication latencies. In addition, the algorithm is tested using a standard protection relay test-set, and automatic test sequences are executed to validate its performance. It is concluded that the hybrid synchrophasor and GOOSE-based automatic synchronization scheme ensures minimum communication latencies, reduces equipment cost, facilitates interoperability, and performs automatic reconnection adequately.

  • 58.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    Statnett SF, Oslo, Norway.
    Experimental Performance Assessment of a Generator's Excitation Control System using Real-Time Hardware-in-the-Loop Simulation2014Ingår i: Industrial Electronics Society, IECON 2014 - 40th Annual Conference of the IEEE, IEEE conference proceedings, 2014, s. 3756-3762Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents methods and results for experimental performance assessment using Real-Time Hardware-in-the-Loop (RT-HIL) simulation of an Excitation Control System (ECS) for both terminal voltage regulation and power oscillation damping. The ECS configured for this study is Unitrol 1020 from ABB and its performance is assessed for both Automatic Voltage Regulator (Auto) and Field Current Regulator (Manual) modes. RT-HIL simulation is performed by using Opal-RT’s eMEGAsim RT Simulator using a power system model including a synchronous generator. Finally, the Power System Stabilizing feature of Unitrol 1020 is calibrated and assessed.  

  • 59.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Statnett.
    Impact of Time-Synchronization Signal Loss on PMU-based WAMPAC Applications2016Ingår i: IEEE PES General Meeting 2016, IEEE , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper experimentally assesses the impact of loss of time-synchronization signal on synchrophasor-based Wide-Area Monitoring, Protection and Control applications. Phase Angle Monitoring (PAM), anti-islanding protection and power oscillation damping applications are investigated. Power system models are executed using a real-time simulator with commercial PMUs coupled to them as hardware-in-the-loop. The experiments conclude that a phase angle monitoring application shows erroneous power system state whereas the operating time of an anti-islanding protection application increases due to the loss of time-synchronization signal input to PMUs. In addition, the performance of an oscillation damping controller degrades in the absence of time-synchronization input to the PMUs.

  • 60.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Implementation of Conventional and Phasor Based Power System Stabilizing Controls for Real-Time Simulation2014Ingår i: Industrial Electronics Society, IECON 2014 - 40th Annual Conference of the IEEE, IEEE conference proceedings, 2014, s. 3770-3776Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the implementation of three different types of Power System Stabilizers (PSS) and a Static Var Compensator with a supplementary Phasor Power Oscillation Damper (POD) control for real-time simulation. The Klein-Rogers-Kundur model is used as test case and the PSS and Phasor-POD’s performance is evaluated for both large and small disturbances.  Modeling is performed in the MATLAB/Simulink environment and is executed in real-time using Opal-RT’s eMEGAsim Real-Time Simulator. The simulation results and the developed model will be used to deploy hardware prototype based on embedded controllers to provide power oscillation damping. Real-time software in the loop (SIL) approach is used for validating developed models as a first logical step towards development of a prototype hardware controller.

  • 61.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Methodologies for Power Protection Relay Testing: From Conventional to Real-Time Hardware-in-the-Loop (HIL) Simulation Approaches2013Ingår i: 10th International Conference on Power System Transients, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Performance testing of the protection relays ensures that a particular protection scheme will operate reliably and fast enough to disconnect a faulty zone from the rest of the network, thus mitigating the effect of fault on the power system. It is therefore important to validate the settings of power protection equipment and to confirm its performance when subject to different fault conditions. Traditionally, commissioning engineers make use of standalone protection relay test sets for analyzing the performance of relays when subjected to different voltage and current injections. With the advent of digital simulators the model of the power system can be executed in real-time and protection relays can be interfaced as hardware-in-the-loop to evaluate their performance when subjected to different faults in the simulated power system. This gives an added value of analyzing the overall behavior of the power system coupled with the relay performance under faulty conditions. In addition, the utilization of GOOSE messages for status, control and protection purposes puts an extra requirement to completely test the IEC 61850 capabilities of the protection relays.

    This article illustrates two different techniques namely standalone testing and real-time hardware-in-the-loop testing used for protection relays performance verification. Both techniques are evaluated for hardwired and IEC 61850-8-1 (GOOSE) signals. The instantaneous overcurrent protection feature of Schweitzer Engineering Laboratories Relay SEL-421 is used for complete standalone and RT-HIL testing. For RT-HIL testing, the test case is modeled in MATLAB/Simulink and executed in real-time using Opal-RT's eMEGAsim real-time simulator. The event reports generated by standalone and RT-HIL testing for both hardwired and GOOSE signals is used to verify the tripping times achieved. Finally the performance of hardwired and GOOSE tripping times are compared and the overall standalone and RT-HIL techniques are evaluated.

  • 62.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    PERFORMANCE EVALUATION OF PROTECTION FUNCTIONS FOr IEC 61850-9-2 PROCESS BUS USING REAL-TIME HARDWARE-IN-THE-loop simulation approach2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the evolution of Process Bus (IEC 61850-9-2), there is a need to assess the performance of protection schemes using process bus against those where traditional copper wires are implemented. Differential protection is the fundamental and most commonly used protection for transformers, motors and generators. In this paper a power system is modelled in SimPowerSystems and is executed in real-time using Opal-RT’s eMEGAsim real-time simulator. Hardware-in-the loop validation of a process bus implementation for differential protection for a two winding transformer is done by using the differential protection feature in ABB’s RED-670 relay. The event reports generated by the ABB relay during Hardware-in-the-Loop testing are compared for three different scenarios i.e. complete process bus, hybrid process bus and complete traditional topology.   

  • 63.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Statnett.
    RT-HIL Implementation of Hybrid Synchrophasor and GOOSE-based Passive Islanding Schemes2015Ingår i: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 31, nr 3, s. 1299-1309Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Real-time hardware-in-the-loop performance assessmentof three different passive islanding detection methodsfor local and wide-area synchrophasor measurements is carriedout in this paper. Islanding detection algorithms are deployedwithin the phasor measurement unit (PMU) using logic equations.Tripping decisions are based on local and wide-area synchrophasorsas computed by the PMU, and trips are generated usingIEC 61850-8-1 generic object-oriented substation event messages.The performance assessment compares these islanding detectionschemes for the nondetection zone and operation speed underdifferent operating conditions. The testbench that is demonstratedis useful for a myriad of applications where simulation exercises inpower system computer-aided design software provide no realisticinsight into the practical design and implementation challenges.Finally, different communication latencies introduced due tothe utilization of synchrophasors and IEC 61850-8-1 GOOSEmessages are determined.

  • 64.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Løvlund, Stig
    Gjerde, J.O
    Open Source SCADA Implementation and PMU Integration for Power System Monitoring and Control Applications2014Ingår i: PES General Meeting | Conference & Exposition, 2014 IEEE, IEEE conference proceedings, 2014, s. -5Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the implementation of an Open Source SCADA system in a laboratory and discusses methods for PMU data integration into SCADA. SCADA BR is a web-browser based SCADA that enables the user to access monitoring, control and automation equipment over multiple protocols. For implementation, protection relays from SEL are configured as DNP3 outstations to act as slaves and SCADA BR which is installed in one of the workstations in the laboratory acts as master. The evaluation of SCADA BR has been performed by executing a power system model in a real-time simulator and coupling its analog outputs with the protection relays. The integration of PMU measurements in the SCADA system and their use for monitoring is discussed. The limitations of the SCADA systems to fully utilize PMU data are also presented.

  • 65.
    Almas, Muhammad Shoaib
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik. Statnett.
    Singh, Ravi Shankar
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Jonsdottir, Gudrun Margret
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Vulnerability of Synchrophasor-based WAMPAC Applications’ to Time Synchronization Spoofing2018Ingår i: IEEE Transactions on Smart Grid, ISSN 1949-3053, E-ISSN 1949-3061, Vol. 9, nr 5, s. 4601-4612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper experimentally assesses the impact of time synchronization spoofing attacks (TSSA) on synchrophasor-based Wide-Area Monitoring, Protection and Control applications. Phase Angle Monitoring (PAM), anti-islanding protection and power oscillation damping applications are investigated. TSSA are created using a real-time IRIG-B signal generator and power system models are executed using a real-time simulator with commercial phasor measurement units (PMUs) coupled to them as hardware-in-the-loop. Because PMUs utilize time synchronization signals to compute synchrophasors, an error in the PMUs’ time input introduces a proportional phase error in the voltage or current phase measurements provided by the PMU. The experiments conclude that a phase angle monitoring application will show erroneous power transfers, whereas the anti-islanding protection mal-operates and the damping controller introduces negative damping in the system as a result of the time synchronization error incurred in the PMUs due to TSSA.The proposed test-bench and TSSA approach can be used to investigate the impact of TSSA on any WAMPAC application and to determine the time synchronization error threshold that can be tolerated by these WAMPAC applications.

  • 66.
    Alsén, Caroline
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik.
    Kostnadsfördelar med IoT för hissystem2016Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Internet of things är idag en utveckling som starkt går framåt för att göra samhället mer tekniskt styrt, modernt och för att underlätta för människor. Det finns många branscher och arbetsområden för denna teknik och hissbranschen är en utav dessa. I denna rapport utreds de fördelar som finns med Internet of things inom hissövervakning. Företaget Safeline Sweden AB har tagit fram en produkt för att underlätta övervakningen av hissar på avstånd. En utredning av denna produkt och dess kostnadsfördelar togs fram, för att sedan kunna ta fram en affärsmodell för Safelines nya produkt IMS. Genom intervjuer med potentiella kunder kunde information tas fram angående dagens läge inställningen till ny teknik. Den informationen som kom fram under dessa intervjuer användes för att skapa en affärsmodell som ska användas som grund för en affärplan för Safeline.En affärsmodell skapades för Safeline Sweden AB och deras nya produkt IMS. I affärmodellen framgår det bland annat hur företaget bör lansera den nya produkten, hur kundrelationer ska skapas, utvecklas och behållas. Utifrån intervjuerna valdes det att IMS bör säljas som en systemlösning då det anses vara det bästa för att det ska vara attraktivt och prisvärt för kunderna.

  • 67. Alvarez, Jesus
    et al.
    Sola, Laura
    Cretich, Marina
    Swan, Marcus
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikro- och nanosystemteknik.
    Volden, Tormod
    Chiari, Marcella
    Hill, Daniel
    A Real Time Immunoassay in Alumina Membranes2014Ingår i: SENSORS, 2014 IEEE, IEEE conference proceedings, 2014, s. 1760-1763Konferensbidrag (Refereegranskat)
    Abstract [en]

    To date, photonic biosensing with porous membranes has produced slow responses and long sensing times, due to the narrow (less than 100 nm) closed end pores of the membranes used. Recently, polarimetry was used to demonstrate analyte flow through, and real time biosensing in, free-standing porous alumina membranes. Here, we demonstrate how an improved functionalization technology, has for the first time enabled a real-time immunoassay within a porous membrane with a total assay time below one hour. With the new approach, we show a noise floor for individual biosensing measurements of 3.7 ng/ml (25 pM), and a bulk refractive index detection limit of 5×10-6 RIU, with a standard deviation of less than 5%. The membranes, with their 200 nm pore diameter enabling targeted delivering of analytes to bioreceptors immobilized on the pore walls, therefore provide a route towards rapid and low cost real-time opto-fluidic biosensors for small sample volumes.

  • 68.
    Alvehag, Karin
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Impact of dependencies in risk assessments of power distribution systems2008Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [sv]

    Samhället blir allt mer elberoende och leveranssäkerhet av el är av yttersta vikt. Medan underinvesteringar leder till ett oacceptabelt antal elavbrott medför dock överinvesteringar för höga kostnader för samhället. Utmaningen är därför att hitta en samhällsekonomisk lönsam risknivå. I en riskanalys måste inte bara hänsyn tas till sannolikheten för elavbrott utan också avbrottens konsekvenser.

     

    En riskanalys kan genomföras från antingen kundernas eller nätägarens perspektiv beroende på om det är kundernas konsekvenser eller nätägarnas konsekvenser av elavbrott som tas med i analysen. Konsekvenser av elavbrott mäts oftast i avbrottskostnader. Exempel på avbrottskostnader som drabbar nätägaren är goodwill-förluster och ersättning till kunder som har haft långa elavbrott. Exempel på avbrottskostnader som drabbar kunder är förlorade försäljningsintäkter för handel- och tjänsteföretag och uteblivna möjligheter till uppvärmning och belysning för hushåll. Avhandlingens syfte är att utveckla metoder för riskanalys av eldistributionsnät utifrån kundperspektivet. Centralt i detta perspektiv är realistiska uppskattningar av kundavbrottskostnader.

     

    För att kunna genomföra en riskanalys från kundperspektivet krävs tre modeller: en kundavbrottskostnadsmodell, en belastningsmodell och en tillförlitlighetsmodell. Kundavbrottskostnadsmodellen beskriver konsekvenserna, eller kostnaderna, för kunderna av elavbrott. Belastningsmodellen modellerar icke-levererad energi och effekt på grund av elavbrott. Tillförlitlighetsmodellen beskriver fel- och lagningsprocessen för de olika komponenterna i elnätet. De tre modellerna kan kombineras i en kostnad/nytta-analys för att beskriva konsekvenserna för kunder av olika investeringsalternativ.

     

    I denna avhandling utvecklas tre nya modeller som tar hänsyn till tidsberoenden i kundavbrottskostnader, belastning samt komponenters fel- och lagningsprocess. Tidpunkten för avbrottet har stor betydelse för vilka konsekvenserna blir för kunderna. Vidare är oväder, som ofta orsakar elavbrott, i regel mer koncentrerade till vissa årstider. Dessa fakta medför att det kan finnas en korrelation mellan höga kundavbrottskostnader och en ökad risk för elavbrott. I Sverige är vinterstormar vanligast och på vintern är även belastningen och avbrottskostnaden som högst. Genom att ta hänsyn till tidsberoenden fångas korrelationer mellan höga avbrottskostnader och en ökad haveririsk.

     

    Med hjälp av de tre utvecklade modellerna genomförs riskanalyser av två fiktiva distributionsnät. Resultaten från analyserna visar att det ger en stor inverkan på den uppskattade kundavbrottskostnaden och den icke-levererade energin om hänsyn tas till tidsvariationer. För att utvärdera risken för extrema kostnader används två riskverktyg från finansbranschen: Value-at-risk och Conditional Value-at-risk. En slutsats från tillämpningen av riskverktygen är att tidsberoenden är speciellt viktiga att beakta om fokus ligger på de extrema händelser som ger upphov till extrema kostnader.

  • 69.
    Alvehag, Karin
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Quality regulation of Distribution Networks2009Rapport (Övrigt vetenskapligt)
  • 70.
    Alvehag, Karin
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Risk-based methods for reliability investments in electric power distribution systems2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Society relies more and more on a continuous supply of electricity. However, while underinvestments in reliability lead to an unacceptable number of power interruptions, overinvestments result in too high costs for society. To give incentives for a socioeconomically optimal level of reliability, quality regulations have been adopted in many European countries. These quality regulations imply new financial risks for the distribution system operator (DSO) since poor reliability can reduce the allowed revenue for the DSO and compensation may have to be paid to affected customers.This thesis develops a method for evaluating the incentives for reliability investments implied by different quality regulation designs. The method can be used to investigate whether socioeconomically beneficial projects are also beneficial for a profit-maximizing DSO subject to a particular quality regulation design. To investigate which reinvestment projects are preferable for society and a DSO, risk-based methods are developed. With these methods, the probability of power interruptions and the consequences of these can be simulated. The consequences of interruptions for the DSO will to a large extent depend on the quality regulation. The consequences for the customers, and hence also society, will depend on factors such as the interruption duration and time of occurrence. The proposed risk-based methods consider extreme outage events in the risk assessments by incorporating the impact of severe weather, estimating the full probability distribution of the total reliability cost, and formulating a risk-averse strategy. Results from case studies performed show that quality regulation design has a significant impact on reinvestment project profitability for a DSO. In order to adequately capture the financial risk that the DSO is exposed to, detailed risk-based methods, such as the ones developed in this thesis, are needed. Furthermore, when making investment decisions, a risk-averse strategy may clarify the benefits or drawbacks of a project that are hard to discover by looking only at the expected net present value.

  • 71.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    A Stochastic Weather Dependent Reliability Model for Distribution Systems2008Ingår i: 2008 10TH INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS, New York, USA: IEEE , 2008, s. 243-250Konferensbidrag (Refereegranskat)
    Abstract [en]

    In power system planning and operation, accurate assessment of reliability worth is essential for making informed decisions. One common simplification when modeling power system reliability is assuming constant failure rates and non time-varying restoration times. However, historical outages show differently; failure rates and restoration times for especially overhead lines are dependent upon time-varying factors as, for instance, weather conditions. When modeling this time dependence a two or three-state weather model is often used. The reliability model proposed in this paper does in contrast use the stochastic nature of the severe weather intensity and duration to model variations in failure rate and restoration time. Further, the model also considers when severe weather is likely to occur during the year by using a non-homogeneous Poisson process (NHPP). A time-sequential Monte Carlo technique is applied to a radial distribution system. By combining the proposed reliability model with a time-dependent interruption cost model, the effect of the inclusion of time-varying failure rates and restoration times is investigated and found to be of importance when assessing reliability worth.

  • 72.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    An activity-based interruption cost model for households to be used in cost-benefit analysis2007Ingår i: Proceedings of Power Tech 2007, 2007, s. 1611-1616Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper develops an interruption cost model for households that, as well as outage duration uses activity patterns, outdoor temperature and daylight to describe the impact of different electrical power outages. For households the interruption costs usually measure the inconvenience associated with interrupted activities and uncomfortable indoor temperature due to the outage. Further, the model also captures the large variations in interruption costs for identical outages among households. The model is applied to a test system, and using a Monte Carlo technique the total interruption cost is studied. The results imply that both the time of occurrence and the distributed nature of residential interruption costs have a significant impact on ECOST.

  • 73.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Comparison of cost models for estimating customer interruption costs2012Ingår i: Proceedings in Probabilistic Methods Applied to Power Systems (PMAPS), 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Customer interruption costs are functions of many different factors such as interruption duration, timing and customer sector. Various cost models with different number of outage and customer characteristics included have been proposed during the years. This paper compares the customer interruption cost assessments of seven different cost models in a case study.Time sequential Monte Carlo simulations are used to simulate the customers’ benefits of increased reliability in a test system. The investigated cost models’ estimations of the Expected Customer Interruption Cost (ECOST) are compared and used in a costbenefitanalysis. Results show that the ECOST results are so different that the cost model choice affects the outcome of the cost-benefit analysis. Only when using some of the cost models the investigated reinvestments are estimated to be socioeconomically beneficial.

  • 74.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Considering extreme outage events in cost-benefit analysis of distribution systems2008Ingår i: Proceedings of Australasian Universities Power Engineering Conference (AUPEC), 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    To find an acceptable level of reliability in distribution systems, cost-benefit analysis using customer interruption costs can be applied. In a case study of a test distribution system, investment in cables instead of overhead lines, aimed to increase reliability, is investigated. In addition to considering average values of reliability indices, tools for risk analysis in the financial industry, value-at-risk (VaR) and conditional value-at-risk (CVaR), are also used for the evaluation. Applying these tools allows for extreme events to be given more weight in the investment decision-making process. Even though these kind of events are very infrequent, the consequences are devastating and extreme cases should be included in cost-benefit analysis. By the help of VaR and CVaR the case study shows that cables can cause higher customer interruption costs for some load points in the system during extreme years.

  • 75.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Evaluation of quality regulation incentives for distribution system reliability investments2011Ingår i: Utilities Policy, ISSN 0957-1787, E-ISSN 1878-4356Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Designing a quality regulation that results in an adequate level of reliability in a distribution system is indeed a challenging task for the regulator. If the regulation is not well designed a socioeconomically beneficial reinvestment project is not beneficial for the DSO, and hence is not selected. This paper proposes an evaluation method for quality regulation designs. The proposed method is applied in a case study to evaluate what incentives for investments in distribution system reliability two different quality regulation designs give. One design is similar to the Swedish quality regulation that will apply from 2012 and the other design is similar to the current Norwegian quality regulation. The effect on network investment decisions when the two designs are modified to give optimal incentives for reliability on system level is also investigated. The case study result shows that even though the quality regulation on system level is designed to give incentives for socioeconomically beneficial investments, these investments may not be beneficial for the regulated DSO if the reward/penalty on the system level is capped too low.

  • 76.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Financial risk assessment for distribution system operators regulated by quality regulation2010Ingår i: Proceedings of Probabilistic Methods Applied to Power Systems (PMAPS), 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the reregulated electricity market, performance-based regulations accompanied by quality regulations are gaining ground. The quality regulation results in new financial risks for the distribution system operators (DSOs) which calls for risk assessment methods that can simulate what costs a certain regulation implies for the DSO. When, for example, guaranteed standards for worst-served customers is combined with a reward and penalty scheme the methods must be able to predict both customer and system reliability. This paper presents a new risk assessment methodology based on time sequential Monte Carlo simulations that can handle both of these levels of reliability to simulate the total regulation cost due to an arbitrary quality regulation. Since most quality regulations are corrected ex-post for each year, variations in yearly reliability can cause large variations in the total regulation cost. Instead of only considering the average total regulation cost the developed methodology uses risk tools from the financial industry to also measure the costs of more extreme years. Doing so gives the DSOs a better understanding of the financial risks they are exposed to. The developed risk assessment methodology is used to evaluate different investment alternatives in a case study.

  • 77.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Quality regulation impact on investment decisions in distribution system reliability2012Ingår i: 9th International Conference on the European Energy Market, EEM 12, IEEE , 2012, s. 6254646-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Performance-based regulations accompanied by quality regulations are gaining ground. Quality regulations imply new financial risks for the distribution system operator (DSO). In fact, the development of the regulatory model has been identified as a key factor in operations planning for a DSO. Lifetimes of distribution system components are very long and how the quality regulation might develop in the future is unknown. This paper develops a method - the regulation impact method - that can be used to investigate how changes in the quality regulation parameters affect the economic performance of an investment strategy. The proposed regulation impact method is based on net present value calculations of the total reliability cost. The new method is applied to the current Swedish quality regulation in a case study. In the case study, possible future parameter changes and their effect on the DSO's financial risk when adopting different investment strategies are investigated. With the new method it is possible to analyze how robust an investment strategy is to changes in quality regulation design.

  • 78.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Risk-based method for distribution system reliability investment decisions under performance-based regulation2011Ingår i: IET Generation, Transmission & Distribution, ISSN 1751-8687, Vol. 5, nr 10, s. 1062-1072Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the reregulated electricity market there is a growing interest in performance-based regulation accompanied by quality regulation for electric distribution networks. This paper develops a new risk-based method for reliability investment decisions when the distribution system operator (DSO) is exposed to financial risks defined by a quality regulation. As quality regulation design becomes more complex, more detailed risk management methods are needed in order to adequately capture the financial risk the DSO is exposed to. The proposed method applies a Monte Carlo simulation technique in order to assess the risks of the considered reinvestment projects. By using the proposed method the impacts that different risk strategies (risk-neutral/risk-averse) and risk models (non-time-varying/time-varying) have on which reinvestment project is selected is investigated in a case study. This is investigated for two different quality regulation designs. The result show that primarily the quality regulation design but also the risk model formulation and risk strategy have a major impact on which reinvestment project is selected.

  • 79.
    Alvehag, Karin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    The impact of risk modeling accuracy on cost-benefit analysis of distribution system reliability2011Ingår i: Proceedings of the 17th Power System Computational Conference (PSCC), Power Systems Computation Conference ( PSCC ) , 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper develops a new risk-based cost-benefit analysis method for distribution system reliability applications. In the conventional cost-benefit analysis, decisions are based on expected values which correspond to assuming that society is risk-neutral. Furthermore, input variables are assumed to be uncorrelated. In contrast to previous work this paper incorporates risk into the analysis by using time-sequential Monte Carlo simulations. By using the proposed method the impact that different risk strategies (risk-neutral/risk-averse) and risk models (non-time-varying/time-varying) have on the result of a cost-benefit analysis is investigated in a case study. Results show that when incorporating time-dependent failure rates, restoration times, customer interruption costs, and loads (correlated input data) a different reinvestment project is selected compared to when these time dependencies are ignored. This result holds regardless if decisions are made based on a risk-averse or a risk-neutral strategy.

  • 80. Ambat, Sooraj K.
    et al.
    Chatterjee, Saikat
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Hari, K. V. S.
    Progressive fusion of reconstruction algorithms for low latency applications in compressed sensing2014Ingår i: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 97, s. 146-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, it has been shown that fusion of the estimates of a set of sparse recovery algorithms result in an estimate better than the best estimate in the set, especially when the number of measurements is very limited. Though these schemes provide better sparse signal recovery performance, the higher computational requirement makes it less attractive for low latency applications. To alleviate this drawback, in this paper, we develop a progressive fusion based scheme for low latency applications in compressed sensing. In progressive fusion, the estimates of the participating algorithms are fused progressively according to the availability of estimates. The availability of estimates depends on computational complexity of the participating algorithms, in turn on their latency requirement. Unlike the other fusion algorithms, the proposed progressive fusion algorithm provides quick interim results and successive refinements during the fusion process, which is highly desirable in low latency applications. We analyse the developed scheme by providing sufficient conditions for improvement of CS reconstruction quality and show the practical efficacy by numerical experiments using synthetic and real-world data.

  • 81.
    Amelin, M.
    et al.
    KTH, Tidigare Institutioner.
    Söder, L.
    KTH, Tidigare Institutioner.
    On Monte Carlo simulation of electricity markets with uncertainties in precipitation and load forecasts2001Ingår i: Power Tech Proceedings, 2001 IEEE Porto, 2001, Vol. 1, s. 6-1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Long-term planning of a power system requires that the electricity market can be simulated. One important aspect that should be simulated is that the owners of hydro power plants with reservoirs (generally referred to as dispatchable hydro power) are forced to base their scheduling on uncertain forecasts on precipitation and load. It is inevitable that this lack of perfect information has an impact on the operation costs and reliability of the system. Hence, a simulation of an electricity market should include this property of dispatchable hydro, power. This paper shows how the consequences of hydro power planning based on uncertain forecasts can be incorporated in a Monte Carlo model by using random water value errors

  • 82.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Impact of Trading Arrangements on Imbalance Costs2009Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det finns idag planer på en storskalig utbyggnad av vindkraften i bådeSverige och i grannländerna. Samtidigt finns det utveckling mot ökadpriskänslighet hos konsumenterna. Dessa två förändringar är delvis koppladetill varandra, eftersom större volymer vindkraft medför ökade prisvariationerbåde på spotmarknaden och på reglermarknaden, vilket gör det önskvärt medkonsumenterna som i högre grad är aktiva på elmarknaden.I den här rapporten studeras olika aspekter av regelverket för elhandeln, somhar betydelse för hur effektivt en elmarknad med stora volymer vindkraft ochökad förbrukningsflexibilitet fungerar. Studien bygger på en ny simuleringsmodell, som beräknar priset i de olika faserna i elhandeln givet utbuds- ochefterfrågekurvor baserade på de prognoser som finns tillgängliga vid varjetillfälle. Denna modell har sedan tillämpats på ett antal testsystem, somförvisso är fiktiva, men vars grundläggande egenskaper påminner om deförhållanden som man kan hitta på den nordiska elmarknaden.Följande aspekter av elmarknadens utformning har studerats:• Planeringshorisont. Med planeringshorisonten avses väntetiden från attaktörerna lämnat bud till spotmarknaden fram till själva leveranstimmen.Konsekvensen av att förkorta planeringshorisonten är att man för mindreprognosfel, i synnerhet när det gäller vindkraftprognoser. Resultaten frånfallstudien visar att en kortare planeringshorisont har ett värde för de flestaaktörer på elmarknaden. Om en sådan förändring av elmarknaden är lönsamberor emellertid på om värdet av de förbättrade prognoserna är större än deadministrativa kostnaderna.• Prissättning av balanskraft för vindkraft. Idag tillämpas tvåprisavräkning för produktion och enprisavräkning för konsumtion på den nordiskaelmarknaden. Ett alternativ vore att betrakta vindkraft som negativförbrukning och räkna in vindkraftens obalanser i de balansansvarigaaktörernas konsumtionsobalanser. Detta skulle medföra minskadeobalanskostnader för vindkraftsägare, men resultaten från fallstudien visar attskillnaderna är små jämfört med att behandla vindkraft som övrig produktion.Förklaringen till detta är att obalanskostnaderna trots allt endast utgör någraprocent av vindkraftsägarnas intäkter från såld el.• Ökad förbrukningsflexibilitet. I den här rapporten studeras konsekvenserna av att införa en typ av kontrakt, som gör det möjligt för elleverantörenatt under ett begränsat antal timmar per år initiera lastminskningar hos vissakonsumenter. I fallstudien visade sig denna typ av kontrakt vara gynnsammaför samtliga aktörer (även sådana som inte själva var balansansvariga förnågon konsumtion). Den ökade förbrukningsflexibiliteten ledde också till enökad leveranssäkerhet i de studerade systemen. Dessa fördelar måstenaturligtvis vägas mot kostnaderna för att introducera sådana kontrakt ochför den nödvändiga infrastrukturen

  • 83.
    Amelin, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Simulation of Trading Arrangements Impact on Wind Power Imbalance Costs2008Ingår i: 2008 10TH INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS, NEW YORK: IEEE , 2008, s. 25-31Konferensbidrag (Refereegranskat)
    Abstract [en]

    Uncertain wind power forecasts is a disadvantage in an electricity market where the majority of the trading is performed several hours before the actual delivery. This paper presents a model which can be used to study how changes in the trading arrangement-in particular changing the delay time between closure of the spot market and the delivery period or changing the imbalance pricing system-would affect different players in the electricity market. The model can be used in Monte Carlo simulation, which is demonstrated for an example system.

  • 84.
    Amelin, Mikael
    KTH, Tidigare Institutioner, Elkraftteknik.
    Small-scale Renewable Energy Sources for Rural Electrification. Possibilities and Limitations1998Rapport (Övrigt vetenskapligt)
  • 85.
    Amelin, Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Englund, Calle
    Fagerberg, Andreas
    Balansering av vindkraft och vattenkraft i norra Sverige2009Rapport (Övrigt vetenskapligt)
  • 86.
    Amelin, Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Hersoug, Ellef
    Options for Rural Electrification in Developing Countries. A Case Study in Kasulu, Tanzania.1997Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 87.
    Amelin, Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Knazkins, Valerijs
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Estimation of maximum power consumption in the grid area of Fortum, Stockholm2005Konferensbidrag (Refereegranskat)
  • 88.
    Amelin, Mikael
    et al.
    KTH, Tidigare Institutioner.
    Söder, Lennart
    KTH, Tidigare Institutioner.
    A fast multi-area economic hydro-thermal power system model1999Ingår i: NAPS, 1999Konferensbidrag (Refereegranskat)
  • 89.
    Amelin, Mikael
    et al.
    KTH, Tidigare Institutioner.
    Söder, Lennart
    KTH, Tidigare Institutioner.
    Cost estimations for power sources in rural electrification schemes1999Ingår i: ICEET, 1999, s. 98-105Konferensbidrag (Refereegranskat)
  • 90.
    Amelin, Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Söder, Lennart
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem.
    Taking Credit: The Impact of Wind Power on Supply Adequacy-Experience from the Swedish Market2010Ingår i: IEEE POWER ENERGY MAG, ISSN 1540-7977, Vol. 8, nr 5, s. 47-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article presents some general concepts about capacity credit values, which are illustrated by theoretical examples as well as practical experience from the Swedish electricity market. The capacity credit of a wind generating unit (or a block of generating units) represents the contribution of the unit to the supply adequacy of the system. The capacity credit of a power plant is an abstract quantity based on probability calculations and requires knowledge of the probability distributions for available generation capacity and load. To secure the reliability of supply, the Swedish system operator was given the responsibility to purchase annual contracts for a "power reserve".

  • 91.
    Amelin, Mikael
    et al.
    KTH, Tidigare Institutioner.
    Söder, Lennart
    KTH, Tidigare Institutioner.
    The Strata Tree: A Useful Tool for Simulation of Electricity Markets2002Ingår i: PMAPS 2002, Naples, Italy, 2002Konferensbidrag (Refereegranskat)
  • 92.
    Anand, Srinivasan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Shahid, Naeem
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Swillo, Marcin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    InP-Based Photonic Crystal Waveguide Technology for Filtering and Sensing Applications2011Ingår i: 2011 13TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON), NEW YORK: IEEE , 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Photonic crystal (PhC) components in InP-based materials are of practical importance not only for their unique properties but also for integration with conventional optoelectronic components on InP substrate. Several PhC devices in the substrate approach such as filters, lasers, and waveguides have been demonstrated [1,2] and this has been possible due to the development of deep etching of PhCs in InP [3].

  • 93.
    Andersson, Daniel
    et al.
    Radarbolaget, Gävle.
    Wallin, Kjell
    Radarbolaget, Gävle.
    Javashvili, Otar
    Högskolan i Gävle, Radio Center Gävle.
    Beckman, Claes
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    M-Sequence UWB Radar for Industrial Applications2010Ingår i: Program of GigaHertz Symposium 2010, March 9-10, at Lund University, 2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Ultra Wideband Radar has the potential of dramatically improving the control and surveillance of industrial processes in confined areas. An example is the application of UWB radar for surveillance of furnaces for heath treatment of steel billets developed by Radarbolaget in Gävle.

    In our installation at AB Sandvik Materials Technology, we have shown that by using a non-destructive UWB Radar technique it is possible to visualize in real-time the ongoing process inside the furnace behind a 0.5 m thick ceramic wall. Since the operating temperature inside the furnace is 1200 °C, there is today no other known method capable of visualizing the process for the operator of the furnace. The system is therefore designed to sustain high temperatures and powerful electromagnetic disturbances while performing measurement with wide dynamics and high stability.

    The design of this radar is based on the idea of transmitting a continuous m-sequence and then detecting the correlated impulse response (see figure below). The wide bandwidth is a requirement for obtaining high spatial accuracy and resolution but puts further requirements on the design of the antennas and the electronics. Our results show that with this technique it is possible to determine the deformation of the steel billets inside the furnace with an accuracy of less than 5 mm. The radar system is also able to detect deformations in the furnace wall

    The m-sequence radar has many advantages over other UWB radar technologies since it e.g. does not require many analogue components. Its performance is a result of the choice of code length, sampling rate and averaging. However, the resolution is still limited by the impulse response of the analogue antenna (ringing).

    In this paper system parameters that affect the overall performance of an m-sequence radar are reviewed and means of enhancing its performance are discussed.

  • 94.
    Andersson, Göran
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Ilic, Marija D.
    Madani, Vahid
    Novosel, Damir
    Network Systems Engineering for Meeting the Energy and Environmental Dream2011Ingår i: Proceedings of the IEEE, ISSN 0018-9219, E-ISSN 1558-2256, Vol. 99, nr 1, s. 7-14Artikel i tidskrift (Refereegranskat)
  • 95.
    Andersson, Magnus
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Espinosa-Arronte, Beatriz
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    van der Beek, C. J.
    Nikolaou, M.
    Lidmar, J.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Wallin, M.
    A vortex solid-to-liquid transition with fully anisotropic scaling2009Ingår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 150, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The vortex solid-to-liquid transition has been studied in heavy ion irradiated untwinned single crystals of YBa2Cu3O7-delta with an inclined applied magnetic field. For magnetic fields tilted at angles about 45 degrees away from the columnar defects, we find that the electric resistivity in the vortex liquid regime approaches zero with power laws in the reduced temperature T - T-c that have different exponents in all three spatial directions. Since the symmetry in the problem has been broken in two non-collinear directions by i) the direction of the columnar defects and ii) the direction of the applied magnetic field, our findings give evidence for a new type of critical behavior with fully anisotropic critical exponents. A possible view of the vortex topology for the transition is also suggested.

  • 96.
    Andrijevic, Goran
    et al.
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Magnusson, Håkan
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Kämpe, Andreas
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Olsson, Håkan
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    Multistandard receiver for home networking and digital media2004Ingår i: 22ND NORCHIP CONFERENCE, PROCEEDINGS, NEW YORK: IEEE , 2004, s. 131-134Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a fully integrated multistandard receiver architecture that fulfills coming media and networking needs of homes. The receiver uses a dual-IF architecture to cover receive bands from 170 MHz to 920 MHz and the Industrial, Scientific and Medical (ISM) band at 2.4GHz. Key performance values meet the DVB-T, Zigbee, Bluetooth and 802.11b requirements (Sensitivity -72.5dBm. available SNR=28dB. Noise Figure 6.7dB. Adjacent Channel Protection Ratio-ACPR=-44dB, IIP3 = -11 dBm).

  • 97. Andriyanova, I.
    et al.
    Rathi, Vishwambhar
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Tillich, J. -P
    Binary weight distribution of non-binary LDPC codes2009Ingår i: 2009 IEEE International Symposium on Information Theory, IEEE , 2009, s. 65-69Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper is the first part of an investigation if the capacity of a binary-input memoryless symmetric channel under ML decoding can be achieved asymptotically by using non-binary LDPC codes. We consider (l.r)-regular LDPC codes both over finite fields and over the general linear group and compute their asymptotic binary weight distributions in the limit of large blocklength and of large alphabet size. A surprising fact, the average binary weight distributions that we obtain do not tend to the binomial one for values of normalized binary weights ω smaller than 1-2-l/r. However, it does not mean that non-binary codes do not achieve the capacity asymptotically, but rather that there exists some exponentially small fraction of codes in the ensemble, which contains an exponentially large number of codewords of poor weight. The justification of this fact is beyond the scope of this paper and will be given in [1].

  • 98.
    Anh, Nguyen Tua
    et al.
    KU Leuven.
    Vanfretti, Luigi
    KTH, Skolan för elektro- och systemteknik (EES), Elektriska energisystem. Statnett SF.
    Van Hertem, Dirk
    KU Leuven.
    A Quantitative Method to Determine ICT Delay Requirements for Wide-Area Power System Damping Controllers2015Ingår i: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, ISSN 0885-8950, Vol. 30, nr 4, s. 2023-2030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a quantitative method to determine delay requirements of the information and communication technology (ICT) system supporting wide-area power oscillation damping (WAPOD) controllers. An allowable time delay for the ICT infrastructure named “equivalent time delay (ETD)” is defined. The ETD is calculated by numerically comparing the damping behavior of the system when local input signals (LI) and remote input signals (RI) are used in the damping controller. The use of a WAPOD is only justified when its response outperforms that of a controller using local inputs. Therefore, the total time delay in the control loop must be below the calculated ETD. As such, the ETD serves as a design criteria to determine ICT latency requirements. The selection of an effective RI signal can be carried out by considering the maximum delays (ETDs) of different wide-area measurements. A damping improvement ETDx% has been proposed using the same methodology indicating a minimum outperformance of the remote signals. The proposed method is demonstrated using the well-known Klein-Rogers-Kundur multi-machine power system and the Vietnamese power system model.

  • 99.
    Annergren, Björn
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Log Classification using a Shallow-and-Wide Convolutional Neural Network and Log Keys2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Ett dataset som består av loggar som beskriver resultat av test från en bygg- och testprocess, använt i en miljö med kontinuerlig integration, används för att automatiskt kategorisera loggar enligt olika feltyper. Två olika sorters indata evalueras, ord och loggnycklar, där icke- ordnade dokumentmatriser används som dokumentrepresentationer för att avgöra loggnycklars användbarhet. Experimentet använder multinomial naiv bayes, MNB, som klassificerare och multiklass-supportvektormaskiner, SVM, för att avgöra prestandan för de olika sorternas indata. Experimentet indikerar att loggnycklar är ekvivalenta med ord medan loggnycklar har mycket mindre ordboksstorlek. Tre olika multi-lager-perceptroner evalueras på loggnyckel-dokumentmatriser och får något högre exakthet i krossvalideringen jämfört med SVM. Ett grunt-och-brett faltningsnätverk, CNN, designas med tidsmässiga sekvenser av loggnycklar som dokumentrepresentationer. De topppresterande modellerna av varje modellarkitektur evalueras på ett testset, utom för MNB-klassificerarna då MNB har dålig prestanda under krossvalidering. Evalueringen av testsetet indikerar att CNN:en är bättre än de andra modellerna.

  • 100.
    Antelius, Mikael
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Fischer, Andreas
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Roxhed, Niclas
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Hermetic integration of liquids in MEMS by room temperature, high-speed plugging of liquid-filled cavities at wafer level2011Ingår i: Proceedings IEEE International Conference on Micro Electro Mechanical Systems (MEMS), IEEE , 2011, s. 356-359Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper reports a novel room temperature hermetic liquid sealing process based on wire bonded "plugs" over the access ports of liquid-filled cavities. The method enables liquids to be integrated already at the fabrication stage. Test vehicles were manufactured and used to investigate the mechanical and hermetic properties of the seals. A helium leak rate of better than 1E-10 mbarL/s was measured on the successfully sealed structures. The bond strength of the "plugs" were similar to standard wire bonds on flat surfaces.

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