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  • 101. Bartusch, C.
    et al.
    Alvehag, Karin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Further exploring the potential of residential demand response programs in electricity distribution2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 125, p. 39-59Article in journal (Refereed)
    Abstract [en]

    Smart grids play a key role in realizing climate ambitions. Boosting consumption flexibility is an essential measure in bringing the potential gains of smart grids to fruition. The collective scientific understanding of demand response programs argues that time-of-use tariffs have proven its merits. The findings upon which this conclusion rests are, however, primarily derived from studies covering energy-based time-of-use rates over fairly short periods of time. Hence, this empirical study set out with the intention of estimating the extent of response to a demand-based time-of-use electricity distribution tariff among Swedish single-family homes in the long term. The results show that six years after the implementation households still respond to the price signals of the tariff by cutting demand in peak hours and shifting electricity consumption from peak to off-peak hours. Studies conducted in the Nordic countries commonly include only homeowners and so another aim of the study was to explore the potential of demand response programs among households living in apartment buildings. The demand-based tariff proved to bring about similar, but not as marked, effects in rental apartments, whereas there are virtually no corresponding evidences of demand response in condominium apartments.

  • 102.
    Baudette, Maxime
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Fast Real-time Detection of Sub-Synchronous Oscillations in PowerSystems using Synchrophasors2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Recent concerns about the environment have resultedinto large investments in renewable energies for electricityproduction, especially wind power. The integration of renewablesources of energy raises however several problemswhich have not yet been completely understood nor studied.Oscillatory events around 13 Hz have been recorded inthe US by Oklahoma Gas & Electric (OG&E). Such a highfrequency is very different from the traditional and wellstudied Inter-area oscillations, it is also beyond the measurementcapabilities of most of the existing measurementequipments and monitoring tools.

    This Thesis focuses on the development and implementationof algorithms for oscillation detection which can supportreal-time monitoring tools. It proposes a real-timemonitoring tool that exploits synchronized phasor measurementsfrom PMUs, which allow real-time analysis of higherfrequency events, filling the lack of such monitoring applicationin the power systems area. This tool was built as aprototype for real-time applications which utilize real-timePMU data for enhanced monitoring and control of powergrids.

  • 103.
    Baudette, Maxime
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Del Rosario, Gerard
    IREC.
    Ruiz Alvarez, Albert
    IREC.
    Dominguez Garcia, Jose Luis
    IREC.
    Al-Khatib, Iyad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Shoaib Almas, Muhammad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Gjerde, Jan Ove
    Statnett SF.
    Validating a real-time PMU-based application for monitoring of sub-synchronous wind farm oscillations2014In: 2014 IEEE PES Innovative Smart Grid Technologies Conference, 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    This paper presents validation experiments performed on a Phasor Measurement Unit (PMU) based fast oscillation detection application. The monitoring application focuses on the detection of sub-synchronous oscillations, utilizing real-time measurements from PMUs. The application was first tested through Hardware-In-the-Loop (HIL) simulation. Validation experiments were carried out with a different set-up by utilizing a micro grid laboratory. This second experimental set-up as well as the results of the validation experiments are presented in this paper.

  • 104. Beerten, J.
    et al.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems. Technical University of Denmark (DTU), Denmark.
    Van Hertem, D.
    A new approach to HVDC grid voltage control based on generalized state feedback2014In: 2014 IEEE PES General Meeting | Conference & Exposition, IEEE Computer Society, 2014, no October, p. 6939418-Conference paper (Refereed)
    Abstract [en]

    In this paper, a new approach to DC voltage control in a High Voltage Direct Current (HVDC) grid is introduced. In an HVDC grid, the power sharing after a converter outage can be influenced by the droop control values. However, when relying on a local feedback signal, the DC voltage drops in the system hamper a straight-forward definition of the power sharing. The use of a common DC voltage signal for the control can solve some of the problems. However, it disregards some of the benefits that are associated with the use of a local voltage control, such as the tendency of a controller using local voltage feedback signals to solve problems locally which can reduce the stress on the AC system. Furthermore, it provides no direct means to obtain different system responses for different converter outages. The control approach presented in this paper aims at improving the DC voltage droop control by combining the local voltage signal available at the converter terminals with remote voltage signals at different locations in the DC system by means of communication. The local voltage feedback control is used for a fast, reliable system response. The introduction of the remote voltage signals in the control allows to differentiate the system response for different converter outages. Simulation results show the validity of the proposed control scheme.

  • 105.
    Beerten, Jef
    et al.
    University of Leuven (KU Leuven).
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Belmans, Ronny
    University of Leuven (KU Leuven).
    Influence of DC voltage droop settings on AC system stability2012In: Proceedings on 10th International Conference on AC and DC Power Transmission, Institution of Engineering and Technology, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents a methodology to study the impact of different DC voltage droop settings on the AC system stability. When several Voltage Source Converters (VSC) in a DC system jointly control the DC voltage by means of droop control, an outage of one converter results in an abrupt change of the active power set-points of several other converters. This relative power change is related to the relative droop settings of the other converters. In this paper, the influence of the power sharing on the AC system stability is discussed by means of a singular value decomposition.

  • 106.
    Benedicto Martínez, Pedro
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Study of Interaction between Spot Market and Market for Balancing Services2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Around the world, there are a number of policies encouraging penetration of wind generation in the electricity industry. The proposed large increase in the penetration of wind generation has raised concerns about the continued security and reliability of the operation of the network. The Market participants who are willing to provide the balancing services offer their services to the Transmission System Operator, TSO. In case of any system imbalances, the offers are listed in a merit order list and the cheapest offer will be selected. This selection is regardless of balancing service provider’s nationality. If congestion happens, some other offers will be used to relieve congested line. This results in different prices for balancing services in different areas.

    This methodology is based on the corrective actions in the market for balancing services given the dispatch information from the spot market. With the increased penetration of wind generation into the electricity industry, the demand for balancing services is increasing. Under these windy scenarios, it might be more efficient to use preventive actions in the spot market rather than doing corrective actions in the Market for balancing services. This master thesis aims at showing the advantages of this new paradigm of the organization of the electricity market based on preventive actions. With this purpose, an integrated model of the electricity market was built in GAMS software and run for different scenarios and configurations of the grid. Comparisons are made at the end of this document in order to point out the superiority of this new approach over the traditional corrective model.

  • 107.
    Bengtsson, Sebastian
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    ESTIMATION OF ELECTROMECHANICAL OSCILLATIONS IN THE NORDIC POWER SYSTEM USING SYNCHROPHASOR MEASUREMENT DATA2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Unstable electromechanical dynamics, or electromechanical modes, may cause large amplitude oscillations that may lead to system break-ups or partial blackouts. Thus, the monitoring and study of these modes are of prominent importance and can be of great help for system operators and planning engineers. In this thesis ambient data analysis has been applied on both simulated and synchronized phasor data from Phasor Measurement Units (PMUs) installed at the distribution network of the Nordic power system at Tampere, Lund and Luleå to estimate frequencies and damping ratios of electromechanical modes in the systems. Different spectral estimators (Yule-Walker, Multitaper and Welch) have been used and their performance has been evaluated. Damping estimates were obtained using an autoregressive Yule-Walker model and the half-power point method. Emphasis on general handling and preprocessing of PMU data is made throughout the thesis. The performed analysis indicates that within the measurement locations available, two main inter-area modes in the Nordic power system can be estimated at approximately 0.4 Hz and 0.5 Hz. In addition relevant system dynamics in the frequency range of 0.6-1.0 Hz can also be observed. Ambient data analysis techniques have great potential for monitoring electromechanical oscillations in power systems. However, there are issues related to data quality that need to be systematically addressed, especially when it comes to calculating accurate damping estimates, in the presence of undamped low amplitude sinusoids and forced oscillations.

  • 108.
    Bergström, Mats
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Customer Outage Reduction Using AMR Data2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Due to a new law that enforces distribution companies to install AMR (Automatic Meter Reading) meters, new possibilities are opened. Not only the primary purpose of AMR meters, i.e. measure the consumption at the customer side, can be beneficial but also outage management which can help reduce the unavailability of a grid. These meters have been further developed lately and new areas of use are under investigation.

    Distribution automation is a term that normally connects to middle voltage level substations. This technology is used to monitor and remotely control power distribution, where for example outage management is an important part. Historically, implementation of distribution automation at low voltage level has never been interested since investments have been given priority to middle voltage level which covers more customers.

    This thesis investigates the possibilities to use AMR meters in order to reduce customer outages, identify limits in present construction and suggest necessary modifications to improve the performance of the system. A reliability analysis of the different proposed solutions and a sensitivity analysis of the most attractive solution are also included. An investment analysis is performed, to get an idea how much the investment would cost on an implementation The result from the thesis has shown, that one of the proposed solutions which consists of a number of breakers implemented strategically in a grid, not contribute to any major improvements. The investment cost is relatively high, and the reliability analysis has shown that the amount of outages increase, while the average repair time of interrupted customers decrease. If the breakers are less expensive and their fault rate reduced, a new investigation may be of interest in the future.

  • 109.
    Bertling, Lina M.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    On evaluation of RCM for maintenance management of electric power systems2005In: 2005 IEEE POWER ENGINEERING SOCIETY GENERAL MEETING, 2005, p. 2638-2640Conference paper (Refereed)
    Abstract [en]

    This panel presentation aims to propose a possible solution for how to evaluate the effect of RCM as a tool for maintenance management. The starting point is a general understanding of the RCM methodology. Further on, a quantitative approach for relating the impact of component maintenance on system reliability and total cost is introduced. The method, referred to as reliability-centred asset maintenance method (RCAM) is being developed within a research group at KTH in Sweden. Finally the presentation comments on ongoing research to evaluate the introduction of RCM. The aim of RCM is to optimize the maintenance achievements in a systematic way.

  • 110.
    Bertling, Lina M.
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Allan, R.
    Eriksson, Roland
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    A reliability-centered asset maintenance method for assessing the impact of maintenance in power distribution systems2005In: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679, Vol. 20, no 1, p. 75-82Article in journal (Refereed)
    Abstract [en]

    This paper proposes a method for comparing the effect of different maintenance strategies on system reliability and cost. This method relates reliability theory with the experience gained from statistics and practical knowledge of component failures and maintenance measures. The approach has been applied to rural and urban distribution systems. In particular, a functional relationship between failure rate and maintenance measures has been developed for a cable component. The results show the value of using a systematic quantitative approach for investigating the effect of different maintenance strategies.

  • 111.
    Bertling, Lina M.
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Allan, R
    Eriksson, Roland
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    A reliability-centred asset maintenance method for assessing the impact of maintenance in power distribution systems2005In: 2005 IEEE Power Engineering Society General Meeting, 2005, p. 2649-2649Conference paper (Refereed)
    Abstract [en]

    This paper proposes a method for comparing the effect of different maintenance strategies on system reliability and cost. This method relates reliability theory with the experience gained from statistics and practical knowledge of component failures and maintenance measures. The approach has been applied to rural and urban distribution systems. In particular, a functional relationship between failure rate and maintenance measures has been developed for a cable component. The results show the value of using a systematic quantitative approach for investigating the effect of different maintenance strategies.

  • 112. Biggar, D.
    et al.
    Hesamzadeh, Mohammad R.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Designing transmission rights to facilitate hedging2013In: 2013 10th International Conference on the European Energy Market (EEM), IEEE , 2013, p. 6607320-Conference paper (Refereed)
    Abstract [en]

    In a liberalised wholesale electricity market risk-averse market participants need some form of financial instrument to offset the risks of spot price variation across locations and across time. Some liberalised wholesale electricity markets seek to facilitate transactions across separately-priced nodes by making available an instrument known as a Financial Transmission Right (or FTR). But FTRs are flawed as a hedging instrument. They do not necessarily make available the full set of funds required to allow market participants to hedge locational price differences. Furthermore, conventional FTRs, which are associated with a volume which is fixed in advance, are not useful for hedging transactions where the volume depends on market conditions at the time. This paper proposes introducing a new form of transmission right which mimics the operation of a 'cap' hedge contract. This transmission right can be combined into a portfolio which provides the natural backing for the price-dependent volume-varying hedge that most market participants require. We consider that this new design of transmission rights offers promise as an approach for facilitating hedging and improving market outcomes in wholesale electricity markets.

  • 113. Biggar, D. R.
    et al.
    Hesamzadeh, Mohammad Reza
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    The Economics of Electricity Markets2014Book (Other academic)
    Abstract [en]

    Around the world, the electricity industry is in the process of undergoing a fundamental transition. Twenty years ago, electricity was primarily generated at large, industrial-scale generating plants, and transported in one direction to consumers via the transmission and distribution networks. The large generators were typically closely integrated into the operation of the transmission and distribution networks. Electricity consumers, on the other hand, were treated as essentially passive. This paradigm has changed and will change further. Around the world, a number of regions have chosen to introduce competition and competitive markets into the generation of electricity. In most of these regions, the operation of generation and transmission is coordinated through market mechanisms. This required a substantial change in the way the electricity industry is organised and operated.

  • 114. Biggar, Darryl R.
    et al.
    Hesamzadeh, Mohammad R.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Modeling the Hedging Decisions of a Generator with Market Power2011Conference paper (Refereed)
    Abstract [en]

    The incentive on an electricity generatingfirm to exercise market power depends strongly on thevolume the firm has pre-sold in the forward or hedge markets.Therefore, in order to forecast the effect of mergersand other market developments on market power outcomes,it is essential to model the hedging decisions ofdominant generating firms. This paper shows that a dominantfirm’s profit-maximizing choice of hedge level dependson the extent to which the hedge price varies withthe firm’s hedging decision. In the case in which the hedgeprice is independent of the firm’s hedge level, the optimalchoice of hedging is an “all or nothing” decision. In thiscase, there is no equilibrium level of hedging in purestrategies. This outcome may explain the observed lack ofhedge market liquidity in wholesale electricity marketswith substantial market power. We also model the equilibriumhedging outcome in a two-stage Cournot oligopolyand show that, even if the hedge price is independent of thehedging decisions of the firms, a rational expectationsequilibrium can exist with high levels of hedging if thereare enough firms in the market.

  • 115. Biggar, Darryl R.
    et al.
    Hesamzadeh, Mohammad R.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Towards a Theory of Optimal Dispatch in the Short Run2011Conference paper (Refereed)
    Abstract [en]

    In a typical liberalized wholesale electricity market, the output of controllable units is determined at regular intervals through a dispatch process. However, since the physical limits of power systems must be respected down to time scales shorter than the dispatch interval, in practice system operators must also be able adjust the output of controllable units over very short time frames - typically through the procurement and dispatch of reserves, ancillary services or balancing services. To date, the procurement and dispatch of balancing services has been guided by heuristics and rules of thumb. Yet the approach to the dispatch of balancing services can have a significant impact on the pre-contingent or system normal dispatch of the power system. In principle, improvements in the efficiency of the dispatch of balancing services could significantly improve the efficiency of the utilization of power system assets. This paper observes that the dispatch of balancing services should correspond to optimal dispatch in a dispatch process with a very short dispatch interval. We also identify a set of conditions which the procurement and dispatch of balancing services should satisfy and compare those conditions to the current arrangements for ancillary services in the Australian National Electricity Market.

  • 116.
    Björnsson, Gudmundur
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Short Term Hydropower Planning in the Icelandic System2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The format the text is saved as is unreadable, so i retyped it to my best ability.

     This master thesis contains my work of studies of a short term planning model, with the time span of one week, or 168 hours. The models are based on the future hydropower system in pjorsa- and Tungnaa- river system, located in the south part of Iceland.

    The purpose ot this thesis is to formulate and develop one week operation schedules for this future power generation system, which for a given inflow-and load forecast returns a good schedule for each power stations in the system.

    The planning problem is formulated as a mathematical programming problem. The models used to describe and implement the system under study are a piecewise linear models. For piecewise linear models the breakpoints of the model are the local best-efficiency points. The objective is to return operation plan for each power station in the system, where the the volume of stored water in the end of the planning period is maximized through optimal discharge plans. It is needed to supply contracted load, regulation- and balance power for each hour during the planning period under study.

    Two test cases are made for each model in this theises. The former case describe winter operation, with high consumptions and lower natural inflow to the reservoirs. In the latter case the consumption is low and river inflow high and is meant to describe summer time operation.

    Obtained results show that piecewise linear model gives more realistic results when the load consumption is high and the inflow is low. During summer time, with low load and high inflow. The piecewise linear models schedule more often discharge not on local best-efficiency points. This behavior can be decreased by insertion a penalty cost of discharge changes. 

  • 117.
    Bogodorova, Tetiana
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Sabate, Marc
    Aplicaciones en Informática Avanzada.
    Leon, Gladys
    Aplicaciones en Informática Avanzada.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Halat, Milenko
    Aplicaciones en Informática Avanzada.
    Heyberger, Jean-Baptiste
    RTE, France.
    Panciatici, Patrick
    RTE, France.
    A Modelica Power System Library for Phasor Time-Domain Simulation2013In: 2013 4th IEEE/PES Innovative Smart Grid Technologies Europe (ISGT EUROPE), IEEE conference proceedings, 2013, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Power system phasor time-domain simulation is often carried out through domain specific tools such as Eurostag, PSS/E, and others. While these tools are efficient, their individual sub-component models and solvers cannot be accessed by the users for modification. One of the main goals of the FP7 iTesla project [1] is to perform model validation, for which, a modelling and simulation environment that provides model transparency and extensibility is necessary.1 To this end, a power system library has been built using the Modelica language. This article describes the Power Systems library, and the software-to-software validation carried out for the implemented component as well as the validation of small-scale power system models constructed using different library components. Simulations from the Modelica models are compared with their Eurostag equivalents. Finally, due to its standardization, the Modelica language is supported by different modelling and simulation tools. This article illustrates how Modelica models can be shared across different simulation platforms without loss of information and maintaining consistency in simulation results.

  • 118.
    Bogodorova, Tetiana
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Turitsyn, Konstantin
    Massachusetts Institute of Technology, USA.
    Voltage Control-Based Ancillary Service using Thermostatically Controlled Loads2016In: 2016 IEEE Power and Energy Society General Meeting (PESGM), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    This paper discusses the possibility of providing voltage control-based ancillary services using thermostatically controlled loads (TCLs). The idea is to change the voltage at the point of common coupling in order to control power consumption of the TCLs through time. This allows to utilize the most common type of loads in the grid to provide ancillary services. These services differ from usual demand response strategies that operate on short to medium time scales. In this paper the authors propose a controller that regulate the power consumption by minimizing the power consumption error signal and by taking physical restrictions into account. Voltage restrictions arise due to the small window of voltage variability about the nominal value of the controlled voltage. In addition, capacitor bank switching interactions with motor and thermostatically controlled loads is discussed.

  • 119.
    Boone, Andrew
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Simulation of Short-term Wind Speed Forecast Errors using a Multi-variate ARMA(1,1) Time-series Model2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The short-term (1 to 48 hours) predictability of wind power production from wind power plants in a power system is critical to the value of wind power. Advanced wind power prediction tools, based on numerical weather prediction models and designed for power system operators, are being developed and continuously improved. One objective of the EU-supported WILMAR (Wind power Integration in Liberalised electricity MARkets) project is to simulate the stochastic optimization of the operation of the Nordic and German power systems, in order to estimate the value of potential improvements of wind power prediction tools. For power system simulations including wind power, a model must be developed to simulate realistic wind speed predictions with adjustable accuracy, in which the correlations between wind speed prediction error at the spatially distributed wind power plants is accurate. The simulated wind speed predictions are then converted to aggregate wind power predictions for regions within the Nordic and German power systems. A Wind Speed Forecast Error Simulation Model, based on a multi-variate ARMA(1,1) time-series model, has been developed in Matlab. The accuracy of the model in representing real wind speed predictions in Denmark has been assessed, and various errors resulting from practical limitations of input data have been quantified.

  • 120.
    Borquez Caballero, Rodrigo Edgardo
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Calculating the Distance to the Saddle-Node Bifurcation Set2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A power system will experience voltage collapse when the loads increase up to a certain critical limit, where the system physically cannot support the amount of connected load. This point identified as a Saddle- Node Bifurcation (SNB), corresponds to a generic instability of parameterized differential equation models and represents the intersection point where different branches of equilibria meet. At this point the jacobian matrix of the system is singular and the system loses stability bringing the typical scenario of voltage collapse. To prevent voltage instability and collapse, the computation of the closest distance from a present operating point to the saddle-node bifurcation set can be used as a loadability index useful in power system operation and planning. The power margin is determined by applying the iterative or direct method described in [16]. Numerical examples of both methods applied to IEEE 9-bus system and IEEE 39-bus system shows that the iterative method is more reliable although it requires a longer computation time. The stability of the system is negatively affected in two ways when generators reach their reactive power limits: the voltage stability margin

    is deteriorated, or immediate voltage instability and collapse is produced.

  • 121.
    Bortot, Baptiste
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Gas for Balancing of Variable Power Generation: A Systemic Case Study2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing share of variable renewable generation, balancing electric powersystems could become a major concern for system operators because of their variableand hardly predictable nature. However, gas technologies appear as a solutionto provide this flexibility, but the impacts on the gas power system have hardly beeninvestigated.

    In this thesis, consulting reports on the subject matter, regulator suggestions andgas-electricity interaction models in scientific literature are studied and four sourcesare identified to be used for balancing: linepack, storage facilities, liquefied natural gasand intraday gas supply from adjacent areas. Then, a gas-electricity model for flexibility supply is designed and three case studies are simulated in order to analyze bothgas and electric power systems’ behaviors. In these case studies, electricity generation,contribution of gas sources and costs are analysed.

    The study concludes that critical situations on gas market that can occur, e.g. incases of large variation in the net electricity demand and limited availability of linepackand storage facilities, the need of intraday modulation can exceed the possibilities toprovide for it. Then, gas cannot be supplied to power plants during peak periods, andmore gas than necessary is used during off-peak periods. The case studies also showthat day-ahead forecast errors in variable renewable generation can be handled mucheasier than variations by the gas system but leads to higher costs.

  • 122.
    Boulanger, Isabelle
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Lillgrund Wind Farm Modelling and Reactive Power Control2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The installation of wind power plant has significantly increased since several years due to the recent necessity of creating renewable and clean energy sources. Before the accomplishment of a wind power project many pre-studies are required in order to verify the possibility of integrating a wind power plant in the electrical network. The creation of models in different software and their simulation can bring the insurance of a secure operation that meets the numerous requirements imposed by the electrical system. Hence, this Master thesis work consists in the creation of a wind turbine model. This model represents the turbines installed at Lillgrund wind farm, the biggest wind power plant in Sweden. The objectives of this project are to first develop an accurate model of the wind turbines installed at Lillgrund wind farm and further to use it in different kinds of simulations. Those simulations test the wind turbine operating according to different control modes. Also, a power quality analysis is carried out studying in particular two power quality phenomena, namely, the response to voltage sags and the harmonic distortion. The model is created in the software PSCAD that enables the dynamic and static simulations of electromagnetic and electromechanical systems. The model of the wind turbine contains the electrical machine, the power electronics (converters), and the controls of the wind turbine. Especially, three different control modes, e.g., voltage control, reactive power control and power factor control, are implemented, tested and compared. The model is tested according to different cases of voltage sag and the study verifies the fault-ride through capability of the turbine. Moreover, a harmonics analysis is done. Eventually the work concludes about two power quality parameters.

  • 123.
    Boullanger, Benjamin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Modeling and simulation of future railways2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis project aims at improving a train power system program which simulates the interaction between a predefined train power supply system structure and a train traffic schedule. The simulator, called TPSS (Train Power System Simulator), is used for training TPSA (Train Power System Approximator) which is included in a larger investment planning program where the welfare of the society is to be maximized. The development of the railway power system implies wise investments that should last a long time. In order to make the good decisions, the consequences of different power system configurations related to the future train traffic demands have to be studied. Aiming at an investment planning in the long term, models and methods used by the simulator for the railway power system and the electric traction devices are of great importance. In this thesis electrical and mechanical models are presented and improvements are discussed thereafter. Moreover methods were modified to improve the accuracy and reduce the simulator running time. Indeed reduction of the computation time is really important when a great variety of cases are studied. In addition some further controls are implemented to obtain more workable and more realistic outcomes. Some bugs are fixed and the former models are changed aiming at a faster computation time and a better quality of the results. Comparisons between the different simulator versions are presented along the report to illustrate the benefits of the changes. Finally a global examination showing impacts of all improvements is performed. As explained the program TPSS intends to participate in a long term investment planning suggestion. The program.s outcomes of several simulations would be extracted to train a Neural Network. The latter will aim at approximating outcomes for other cases avoiding too many simulations and thus saving time.

  • 124. Boyko, Alexander
    et al.
    Matevosyan, Julija
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    The Russian wind of change2007In: Power engineer (Stevenage), ISSN 1479-8344, E-ISSN 1741-0517, Vol. 21, no 2, p. 44-47Article in journal (Refereed)
    Abstract [en]

    Wind power in Russia is lagging behind many other European countries due to low cost of conventional power along with meteorological and geographical restraints. The majority of wind farm in Russia tend to be much smaller capacity than their counterparts in countries such as Germany, the United States, India and Denmark. Wind turbines installed in Russia are often purchased second-hand from Germany or Denmark and have a much lower capacity. Some Russian companies produce their own wind turbines but they are mostly of a small capacity and are designed for personal use. Most of the stations in these regions are diesel power stations (DPS) with up to 25 MW and they require vast quantities of diesel, which needs to be transported from other regions. Government financial and legislative support is required to enable wind power development in Russia and a close collaboration with foreign wind power companies is needed to acquire manufacturing and projection experience.

  • 125.
    Boyra, Jon
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    State of the art of actual pitch systems and analysis of electrical pitch systems for wind turbines2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 126.
    Brask, Martin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    MODELLING OF THE POWER SYSTEM OF GOTLAND INPSS/E WITH FOCUS ON HVDC LIGHT2008Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose with this project is to develop a model of the whole power system of Gotland in the power system simulation software PSS/E. A model of the whole power system of Gotland has earlier been used in the power system simulation software Simpow but now there is a need to develop a model in PSS/E.

    In the power system of Gotland there are several components that need to be modelled such as lines, loads, transformers, shunt impedances, synchronous machines, asynchronous machines, an HVDC Classic link and an HVDC Light link. These components are modelled in the Simpow model and needs to be converted to the PSS/E model. The aim is to develop a model in PSS/E that is as equal as possible to the model in Simpow. Especially the HVDC Light link at Gotland has been investigated in the project.

    A problem with converting data from Simpow to PSS/E is that the models of several components differ in Simpow and PSS/E. Lines and shunt impedances can be modelled in the same way but the models for loads, transformers, synchronous machines, asynchronous machines, the HVDC Classic link, and the HVDC Light link differ in Simpow and PSS/E. The models in Simpow are converted to the models in PSS/E in an as equal way as possible. The results in PSS/E are analyzed and compared with the Simpow model.

    In the project we have also made a test of fault simulations in time-domain simulations in PSS/E. The aim with this test is to verify the PSS/E calculations when a three-phase or a single-phase fault is applied. The reason for that is that PSS/E only calculates using positivesequence components and therefore only is able to calculate exact during circumstances of symmetrical loads and faults. The result shows that the calculations for both symmetrical and unsymmetrical faults in PSS/E are correct concerning the positive-sequence components. A drawback in PSS/E is, however, that we do not have any information concerning the negativeand zero-sequence  components, which results in that we cannot calculate the three phasequantities. 

  • 127.
    Brolin, Magnus
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Estimation of hydropower system equivalentsIn: IEEE Transactions on Power Systems, ISSN 0885-8950, E-ISSN 1558-0679Article in journal (Refereed)
  • 128. Brostrom, Elin
    et al.
    Alvehag, Karin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Calculation of Residential Interruption Costs caused by Adverse Weather using Monte Carlo Methods2008Conference paper (Refereed)
    Abstract [en]

    The main contribution of this paper is a residential interruption cost model that aims to capture households? inconvenience due to power outages caused by adverse weather. Commonly, the customer interruption cost is modelled to be a function of the outage duration. However, other factors also affect the interruption cost. For example, the cost for a household increases if public services also are affected by the outage. The number of public services that a household cannot use is often correlated to the total number of customers affected by the outage. This relationship is explored in the proposed cost model in order to consider the impact of widespread and long-lasting outages caused by, for example, adverse weather. An adverse weather model gives wind and ice loads. These loads in combination with a vulnerability model for components in a transmission system and a restoration time model give the outage duration. In a case study, the impact of adverse weather on a meshed test system with residential customers is studied using Monte Carlo simulations. It is concluded that more surveys investigating the increased costs for households due to long-lasting and widespread outages are needed.

  • 129. Brostrom, Elin
    et al.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    ON TRANSMISSION RESTORATION EVALUATION AFTER ICE STORMS USING MONTE CARLO TECHNIQUES2006In: CRIS 2006 in Alexandria, USA, 2006Conference paper (Refereed)
  • 130.
    Broström, Elin
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ice Storm Modelling in Transmission System Reliability Calculations2007Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    In this thesis a new technique of modelling non-dimensioning severe weather for power system reliability calculations is developed. The model is suitable for both transmission and distribution networks and is based on geographically moving winds and ice storms. The modelled weather has severity levels that vary with time and change continuously as the weather passes a region. Different weather situations are represented with scenarios. For each scenario the weather parameters, such as size, strength, speed and direction can vary. A stochastic method for choosing parameters is also described. This method is based on probabilities for different weather situations for Swedish conditions. A stochastic vulnerability model for the components is required for each scenario to connect the risk of failure to the weather situation. The model developed here connects the direct wind impact with the impact from the ice storm which is given by an ice accretion model. It is assumed that the probability for an individual segment to break down due to the impact of a given weather depends on load functions for wind and ice together with the vulnerability model for components. It is possible to estimate the outage risk as well as the time difference between mean times to failure in different lines. Monte Carlo methods, where many scenarios are simulated, are used in the case studies. Studies of the system vulnerability is a future work of this project but in one small case study the probability for outage in a load point is estimated. To be able to estimate repair times after a severe weather the reliability calculations are extended with a restoration model which gives distributions of down times for the broken components. The situations after the ice storm that are studied are so severe that gathering of all or almost all possible restoration resources is required to restore the system. Restoration times for different components are not assumed to be independent; on the other hand they are assumed to be strongly correlated. The restoration process is dependent on staff situation, distance between location of spare parts and the breakdown, forecasts, availability of roads and distance to other breakdowns; this is included in the model. A method for simulation of non-Gaussian correlated random numbers is developed to include the correlations during the restoration process. The case studies show the impact of the different weather situations on the components and the following restoration times for the broken components.

  • 131.
    Broström, Elin
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ahlberg, Jesper
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Modelling of ice storms and their impact applied to a part of the Swedish Transmission network2007In: 2007 IEEE LAUSANNE POWERTECH, VOLS 1-5, NEW YORK: IEEE , 2007, p. 1593-1598Conference paper (Refereed)
    Abstract [en]

    In this paper a technique of modelling severe weather for power system reliability calculations is developed. The model is based on geographically moving winds and precipitation and is suitable for transmission network. A scenario represents a weather situation with given parameters. Besides the weather model a stochastic vulnerability model for the components is required for each scenario that connects the risk of failure to the weather situation. In order to mitigate severe consequences of future ice storms in an efficient way it is essential to be able to estimate the consequences based on assumptions of the technical system and the severity of possible storms. It is assumed that the probability of a failure due to a given weather depends on load functions for wind and ice together with the component vulnerability model which is based on the design of the components. The wind load is direct and the ice load is given by a known ice accretion model. Conclusions about the reliability of the studied lines under ice storms are presented as well as a graph of the critical conditions for the studied lines with ice thickness on the x-axis and gust wind on the y-axis. The numerical examples show the impact of different weather situations on a part of the Swedish Transmission network using data both from real weather situations in Sweden and the weather model.

  • 132.
    Broström, Elin
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ice Storm Impact on Power System Reliability2007In: 12 th International Workshop on Atmospheric Icing on Structures (IWAIS 2007), Yokohama, Japan, 2007Conference paper (Refereed)
    Abstract [en]

    Ice storms are freezing rain that coats everything in ice, often in combination with heavy wind. The aim of the methods developed in this paper is to estimate the risk of failure due to ice storms. This includes a severe weather model, a new method for choosing weather parameters and a component vulnerability model. The weather model is based on how a low pressure behaves and consists of functions that describe the wind and precipitation parts of the weather. An ice accretion model is used to estimate the ice loads. The method for choosing weather parameters is useful for Monte Carlo simulations where the effects of many different weather situations are studied. In the stochastic component vulnerability model the failure rates are based on how an increased ice load influences the critical wind. Swedish weather conditions and transmission components are used in the case study and the loads and their impact are estimated for many different weather situations.

  • 133.
    Broström, Elin
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Modelling of Ice Storms for Power Transmission Reliability Calculations2005In: Proceedings 15th Power Systems Computation Conference PSCC2005, Liège, Belgium: PSCC , 2005Conference paper (Refereed)
    Abstract [en]

    This paper describes a new technique of modelling adverse weather for power system reliability calculations. The reliability calculation is based on a Monte-Carlo technique where each scenario represents a certain weather situation with certain parameters. For each scenario a model of the adverse weather is needed and in this paper a model based on geographically moving winds and ice storms is developed. The benefit of this is that it is possible to estimatethe time difference between mean times to failure indifferent lines, not only the outage risk. For each scenario a weather impact model is also required, where the risk of transmission outage is connected to the weather situation.The here-developed model connects the direct wind impact with the integrating impact from the ice storm. The developed method is applied to a numerical example.

  • 134.
    Brännlund, Greta
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Evaluation of two peak load forecasting methods used at Fortum2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 135.
    Bureau, Cédric
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Developing a harmonic power flow software in distributed generation systems2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main topic of this thesis is harmonic power flow and its use in a simulation software that I have developped. The idea of the software is to combine distribution grids' description, non-linear load models and power flow methods. Nowadays, power electronics is more and more present in electric devices in distributed generation systems. Those power electronics systems can emit or absorb harmonics that can damage the devices in the grid. Thus, it is important to be able to estimate harmonic behaviour in the grid in order to be able to prevent the possible problems that could occur.The main contribution of this internship is the precise expression of the needs and goals of the software, and an implementation of its structure. In this thesis, It is explained howthe grid's components and non-linear devices are modelled in the software in order to beable to represent the distribution system. There is also a study the possible input of this software and create a symbolic representation of the grid that is helpful when it comes toload flow calculation. Then, the different load flow and harmonic load flow algorithms that are presented in the literature are analysed and compared them together in order to determine the methods that should be implemented in the future software.Two of the implemented fundamental load flows with a single-phase system are tested.Thus, it also validates the input reading and the grid representation construction. The software developped is a first implementation of a more global software that will require further studies. Indeed, the developpement stage will be done by external contractors or computer science specialists, that will insist on parallelization of algorithms and software optimization, in order to have a software as efficient and fast as possible.

  • 136.
    Cairo, Ignasi
    et al.
    IREC.
    Del Rosario, Gerard
    IREC.
    Dominguez, J.L.
    IREC.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Al-Khatib, Iyad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Baudette, Maxime
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Almas, M. Shoaib
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Equipos para medidas precisas de fase en tension corriente para redes inteligentes2013In: Automatica e Instrumentación, ISSN 0213-3113, no 451, p. 87-90Article in journal (Other (popular science, discussion, etc.))
  • 137.
    Canon, Alexandre
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Impact of Bidding Zone Configuration on the French Electricity Network2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At the beginning, the rst operation concern of electricity transmission networks is to

    ensure the security of power system. These interconnections are also used for the purpose

    of exchanging electricity from one country to another. They have a central role

    to achieve the integrated European electricity market by allowing electricity supplier

    to sell energy to a customer in another EU country. This enables market players to

    trade electricity depending on opportunities and prices in various bidding areas in Europe.

    The interconnections contribute therefore to the eectiveness of the European

    electricity market. The volume of trade is however limited by the physical limitations of

    the transmission lines, which are determined by the TSOs through cross border capacity

    calculations and assigned to the actors based on dierent market mechanisms (e.g.

    capacity allocation).

    The fast development of renewable energy sources has increased the imbalances between

    supply and demand. This further increases constraints on transmission lines, including

    the interconnections between neighboring countries. In order to manage this problematic

    situation, the modication of the bidding areas conguration is often considered as

    a solution. Dierent studies developed methods based on nodes aggregation or minimization

    of re-dispatching costs to dene the price areas. However, the impact of this

    kind of measure on the overall system is not well studied.

    This master thesis work presents a general methodology to study the impact of a new

    bidding zone conguration in the French electrical network from a market point of view.

    In order to dene a relevant bidding zone conguration in the system, physical ows on

    the lines are determined and the two ends of binding links are located in two dierent

    bidding zones. Then, electricity price, social welfare evolution and modication of the

    ows due to the new generation pattern are presented in order to evaluate and analyze

    the impact of the new bidding zone conguration on the market.

    The modelling limits are analyzed in order to evaluate the proposed approach.

  • 138. Carvajal-Carreño, W.
    et al.
    García, A. P. C.
    Fernández-Cardador, A.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Efficient driving algorithms for non-disturbed and disturbed trains with the CBTC signalling system2015In: 2015 International Conference on Models and Technologies for Intelligent Transportation Systems, MT-ITS 2015, IEEE conference proceedings, 2015, p. 418-425Conference paper (Refereed)
    Abstract [en]

    Trains with automatic train operation (ATO)-communication-based train control (CBTC) have the capability to follow a predesigned or calculated speed profile and also can change the control command at any point of the route. This paper presents the advances in the research about designing driving profiles for ATO trains under the CBTC signalling system. Two algorithms based on simulation are proposed, one for the offline design of single undisturbed train trajectories and the other is a real-time algorithm to save energy when there is interaction between two consecutive trains. These algorithms were tested using a simulation-based metaheuristic optimization for the first case and a two-train tracking simulator for the second. The results showed that energy savings could be attained using the proposed algorithms maintaining the required safety and passenger comfort levels in the railway operation.

  • 139.
    Castel, Romain
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Connection of offshore wind farms to the grid in Europe and Brittany2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 140.
    Cazaux, Vincent
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Decision method for the investment in shunt capacitors based on a long-term voltage stability analysis2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the electric consumption increases and the constraints multiply, the grid becomes weaker and may not be able to face critical voltage stability problems. Indeed, in the past decades some blackouts occurred in Europe and America, due to voltage instabilities. At a 5-year horizon, new lines or new power plants cannot be built in time, it is therefore necessary to invest in capacitors to prevent voltage collapses. The core of this project is the best localization of these investments, to make the grid strong enough to bear a major fault in an already difficult situation.

    The first part of the master’s project is the development of a new method which permits to decide where to install new capacitors based on a dynamic approach.

    The second part consist on simulations performed on a specific part of the French grid. Each simulation was the subject of a variation of one of the different parameters or elements of the situation. These simulations have a double goal: to validate the method by examining the consistency of the different results, and to have a first idea of the impacting parameters, or their influence on the number of capacitor which should be installed, and their localizations.

  • 141.
    Chaigneau, Matthieu
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Forward Capacity Markets: Maintaining Grid Reliability in Europe2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The liberalization process of the electricity industry in many countries leads to new rules and new challenges for the grid management. System reliability is a major concern, mainly because of (a) the high level penetration of renewable energy sources and (b) the growing peak load and environmental regulations

    In most electricity markets, peak resources operate only during a short period, and at a high operating cost, jeopardizing their return on investment, while low-cost base resources make the most revenues on the market. Forward capacity markets, introduced by American operators such as PJM and ISO New England in 2007, aim at coping with this issue by providing the necessary financial incentives towards enough generation investments to meet future electricity needs. Since its first auction 4 years ago, the mechanism has proven to attract and retain competitive capacity on the market. The key characteristics are a single buyer structure, a fair pricing mechanism and a long term commitment from the TSO.

    But the development of such market is not meant to be constrained to American countries. In Europe, the so-called law NOME (New Organization of the Electricity Market) has been adopted in France in November 2010, representing a new step in establishing a fair, transparent and efficient energy market in France. It enforces market participants and operator to design a fair and transparent mechanism for long-term capacity procurement.

    This thesis introduces regulatory requirements from European countries which are in the process of designing forward capacity markets. These requirements are then compared to the mechanism brought in by PJM. Based on these specifications an adaptation of this mechanism to France is done, and a mathematical program simulating a forward capacity market is built using the software Aimms. Computational simulations are then led, based on a realistic dataset representing the French electricity market.

    The fairness, competitiveness and transparency of the proposed mechanism is afterwards demonstrated based on the analysis of simulations.

  • 142.
    Chaigneau, Matthieu
    et al.
    KTH, School of Electrical Engineering (EES).
    Lannez, S.
    Passelergue, J.
    Hesamzadeh, Mohammad R.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Forward Capacity Markets: Maintaining System Reliability in Europe2012In: 9th International Conference on the European Energy Market, EEM 12, IEEE , 2012, p. 6254643-Conference paper (Refereed)
    Abstract [en]

    Meeting peak demand is a major concern for grid operators, sometimes amplified by the liberalization of the electricity industry. Peak resources operate during a short period, at a high operating cost, and face difficulties to recover their investments. Sending the proper market signals to trigger long term generation investments in these types of generating units is a critical issue. Different incentivizing approaches have been adopted worldwide to cope with this issue, from a simple administratively-determined capacity payment, to complex but field-proven market designs complying with grid constraints. In France, the so-called law "NOME" (New Organization of the Electricity Market) represents a new step in establishing a fair, transparent and efficient energy market. It also enforces market participants and system operator to design a mechanism for long-term capacity procurement. This paper will introduce the motivation for developing capacity markets and describe an advanced mechanism that has been derived from the Alstom Grid clearing engine currently in operation in North America. An adaptation of this centralized market place to the situation in Europe will be discussed and simulated with realistic dataset representing the market structure of one particular European country.

  • 143.
    Chaillet, Maxime
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Assessment of remote controlled sectionalizers effects on power restoration processes of the distribution2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Distribution Network Operators (DNOs) have to ensure that electricity is supplied to customers according to voltage quality and power reliability requirements. The SAIDI (System Average Interruption Duration Index) is a performance index commonly used to measure reliability which expresses the average outage duration for each customer served. When an outage occurs on the distribution grid, remote controlled sectionalizers (RCS) are operated to enhance the restoration of power by sectionalizing the medium voltage (MV) grid before repairing the line. By analyzing data of outages, considering the frequency, the duration and the size of outages, statistical methods can be outlined to identify MV-lines where RCS investments may have significant improvements on reliability. To assess reliability improvements, RCS investment costs are compared to failure costs by setting an outage price through the cost of energy not served (ENS).

  • 144.
    Chamorro, Harold
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    The Impact of Non-synchronous Generation on Power Systems Dynamics2015Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Due to the increasing integration of Renewable Energy Sources (RES), and the installation of High Voltage Direct Current (HVDC) systems, more power is injected to the AC grid based on power electronic converters. This kind of power injection is called non-synchronous generation in this thesis.

    However, non-synchronous generation does not provide the inherent dynamical support to the system as a synchronous generator does. Thereby, the large inclusion of non-synchronous generation significantly affects the dynamics of the power system. This thesis analyses different aspects of the power system dynamics with the non-synchronous generation integration such as system frequency response, inertia and undamped oscillations.

    Initially, a theoretical frame is presented which deals with the basic concept of frequency response in power systems, the modal analysis, the Trajectory Sensitivity Analysis (TSA), Multi-Prony Analysis (MPA) and $Koopman$ Mode Analysis (KMA). The first dynamic aspect studied is the frequency response evaluating some indicators under the gradually increasing installation of non-synchronous generation. The second one, is the impact of non-synchronous generation on the Small Signal Stability (SSS). The analysis is emphasised in the dominant modes. Eigenvalues, mode shapes displacements and participation factors variations are analysed showing the changes during the gradually integration of non-synchronous generation.

    Furthermore, a second method for frequency mode estimation is applied which relies on on-line modified Prony method. The monitoring of the transient signals provides the observation of the frequency and damping modes from the simulation data measurements based on MPA. The impact on coherency is also shown through the application of KMA. To get the coherent groups it is used the so-called $Koopman$ operator, which is a based-measurements method. This method identifies and clusters the groups based on the spectral decomposition of Koopman modes. The groups obtained while the non-synchronous generation integration are shown. From the results it is shown that the non-synchronous generation inclusion effectively change the coherency in the test system. The test system, the Nordic32, is presented and the set-up scenarios are given. Finally, the TSA, which provides the sensitivity of power system trajectories with respect to the inertia is applied to another test system (IEEE 39) to show the impact of the inertia reduction on transient stability.

  • 145.
    Chamorro, Harold
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Influence of the Increasing Non-Synchronous Generation on Small Signal Stability2014In: 2014 IEEE PES General Meeting | Conference & Exposition, IEEE conference proceedings, 2014, p. 6938796-Conference paper (Refereed)
    Abstract [en]

    The increasing installation of aggregated renewable generation based Full Rated Converters (FRC) in current power systems is modifying their dynamic characteristics. This paper analyses the influence of large scale inclusion of non-synchronous generation through back-to-back Voltage Source Converters’(VSC) connection on power systems, by presenting the dynamic changes on inter-area oscillations in different penetration level cases. The aggregated model of VSC units is assumed. The Small Signal Stability Analysis (SSSA) is used to show thedynamic behaviour and presents the performance of the power systems related to the domain frequency modes in a test grid system. From the analysis, it is shown that the mode shapes and participation factors are displaced according to the penetration levels. Eigenvalue sensitivity analysis according to the inertia isalso applied, showing the impact of the large penetration of nonsynchronousgeneration.

  • 146.
    Chamorro, Harold
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Wind Power Impact on Power System Frequency Response2013In: 45th North American Power Symposium, NAPS 2013, IEEE , 2013, p. 6666880-Conference paper (Refereed)
    Abstract [en]

    The use of high power electronics in the large scale integration of wind power in the transmission and distribution systems can affect the system inertia response and the ability to recover frequency stability after large disturbances. Different approaches have been presented to show the system dynamic behaviour, and to quantify the wind power impact on the system inertial and frequency response. This paper gives a short overview of studies performed regarding the system inertia issues under high penetrations of wind power. Also, it presents the results of a case study to show how the system inertia can be affected by high penetrations of wind power.

  • 147.
    Chamorro, Harold R.
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Nazari, Mohammad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Babazadeh, Davood
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Malik, Naveed ur Rehman
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Consensus Control for Induction Motors Speed Regulation2014In: 2014 16TH European Conference on Power Electronics and Applications, 2014Conference paper (Refereed)
    Abstract [en]

    Cyber Physical Energy Systems (CPES) development requires the combination of distributed intelligence to fulfill the future complex tasks and reach the increase the energy demands. Electrical Industrial Systems (EIS) are in continuous evolving integrating new technologies allowing to a better performance and increase the efficiency. This paper applies the consensus protocol for Multi-Agent Systems (MAS) to control the speed of multiple induction motors. In this paper, the behaviour of the system under different disturbances and scenarios has been simulated, thus, confirming the suitability and simplicity of this method for coordinating the control actions.

  • 148.
    Chaves Avila, José Pablo
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    European Short-term Electricity Market Designs under High Penetration of Wind Power2014Doctoral thesis, monograph (Other academic)
  • 149.
    Chenine, Moustafa
    et al.
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Vanfretti, Luigi
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Bengtsson, Sebastian
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Implementation of an experimental wide-area monitoring platform for development of synchronized phasor measurement applications2011In: Power and Energy Society General Meeting, 2011 IEEE, IEEE , 2011, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Synchrophasor-based Wide-Area Monitoring and Control Systems (WAMC) are becoming a reality with increased international research and development. Several monitoring and control applications based on these systems have been proposed, and although with a relative small adoption, they are currently supporting the operations of some large transmission system operators. It is expected that the continued research and development of phasor data applications will enable the miracle of #x201C;Smart Grids #x201D; at the transmission level. The authors have realized that this can be achieved in timely fashion only if a research and development platform is developed to simultaneously address issues regarding information and communication infrastructures, and phasor data applications. This paper discusses the preliminary development, and deployment of an experimental wide-area monitoring and control platform in which several basic applications have been implemented, and that in the future will allow for the implementation and testing of envisioned applications. At its current stage, the platform allows both online monitoring and off-line analysis. In the future, it will be the cornerstone to a wider platform enabling research on phasor data applications that intrinsically account for ICT aspects.

  • 150.
    Chompoobutrgool, Yuwa
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Aspects of Wide-Area Damping Control Design using Dominant Path Synchrophasor Signals2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The presence of inter-area oscillations has long affected stability constraints, and therefore, limited the power transfer capacity of interconnected power systems. Adequate damping of these inter-area oscillations is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) are the most common devices used to enhance the damping of such oscillations. Many studies have demonstrated that PSSs using remote signals may perform better than using local signals.

    The advent of phasor measurement units (PMU) makes remote or wide-area signals become available, which enables various important applications. Of particular interest is wide-area damping control (WADC), which aims to utilize remote or wide-area measurements to damp the inter-area oscillations. However, two main challenges in WADC design are (1) feedback controller input signal selection (which PMU signal is best to use?), and (2) latency (which is inherent in the transmission of the measurements) considerations.

    In response to the first challenge, this thesis proposes a concept called dominant inter-area oscillation path, which serves to pinpoint a set of candidate signals that can be used as the feedback controller inputs by locating the interconnected corridors where the inter-area modal contents are the most observable. Derivation, identification, and use of the dominant inter-area oscillation paths are demonstrated throughout the thesis. Extensive analysis on the relationships between the proposed set of signals and system properties regarding stability and robustness is presented. To tackle the second challenge, the impacts of time delays on the system performance when using the dominant path signals are investigated.

    To date, several studies have proposed different control design methods using various oscillation dampers to design WADC. Nevertheless, neither a systematic method nor a concept that encompasses fundamental knowledge on power system dynamics has yet been offered. The objective of this thesis is, thus, to propose an analytical framework based on the dominant path concept which is built upon fundamental principles for feedback controller input signal selection in WADC. With this framework, a proper and systematic approach is developed. The proposed method allows to select appropriate signals and use them to effectively mitigate the inter-area oscillations that constrain power transfer capacity and affect system stability.

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