251 research outputs found
Fault estimation filter design with guaranteed stability using Markov parameters
No full textAccepted Author ManuscriptTeam Tamas KeviczkyTeam Raf Van de Pla
Distributed stochastic thermal energy management in smart thermal grids
No full textThis work presents a distributed stochastic energy management framework for a thermal grid with uncertainties in the consumer demand profiles. Using the model predictive control (MPC) paradigm, we formulate a finite-horizon chance-constrained mixed-integer linear optimization problem at each sampling time, which is in general non-convex and hard to solve. We then provide a unified framework to deal with production planning problems for uncertain systems, while providing a-priori probabilistic certificates for the robustness properties of the resulting solutions. Our methodology is based on solving a random convex program to compute the uncertainty bounds using the so-called scenario approach and then, solving a robust mixed-integer optimization problem with the computed randomized uncertainty bounds at each sampling time. Using a tractable approximation of uncertainty bounds, the proposed formulation retains the complexity of the problem without chance constraints. We also present two distributed approaches that are based on the alternating direction method of multipliers (ADMM) to solve the robust mixed-integer problem. The performance of the proposed methodology is illustrated using Monte Carlo simulations and employing two different problem formulations: optimization over input sequences (open-loop MPC) and optimization over affine feedback policies (closed-loop MPC)."Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public."Team Tamas Keviczk
Computationally tractable reserve scheduling for AC power systems with wind power generation
No full textThis work presents a solution method for a day-ahead stochastic reserve scheduling (RS) problem using an AC optimal power flow (OPF) formulation. Such a problem is known to be non-convex and in general hard to solve. Existing approaches follow either linearized (DC) power flow or iterative approximation of nonlinearities, which may lead to either infeasibility or computational intractability. In this work we present two new ideas to address this problem. We first develop an algorithm to determine the level of reserve requirements using vertex enumeration (VE) on the deviation of wind power scenarios from its forecasted value. We provide a theoretical result on the level of reliability of a solution obtained using VE. Such a solution is then incorporated in OPF-RS problem to determine up- and down-spinning reserves by distributing among generators, and relying on the structure of constraint functions with respect to the uncertain parameters. As a second contribution, we use the sparsity pattern of the power system to reduce computational time complexity. We then provide a novel recovery algorithm to find a feasible solution for the OPF-RS problem from the partial solution which is guaranteed to be rank-one. The IEEE 30 bus system is used to verify our theoretical developments together with a comparison with the DC counterpart using Monte Carlo simulations."Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public."Team Tamas Keviczk
Hungarian Roma and African American autobiographies in comparative perspective: Lakatos, Peline Nyari, Wright, and Hurston
No full textMy dissertation is a comparative study of the following Hungarian Roma and African American autobiographies: Menyhért Lakatos's Smoky Pictures, Hilda Péliné Nyári's My Little Life, Richard Wright's Black Boy, and Zora Neale Hurston's Dust Tracks on a Road. I use the rich critical literature on African American autobiographies to better understand Gypsy autobiographies, about which there is a paucity of literary scholarship. I make use of the latest developments in theoretical writings about the genre of
autobiography, particularly autoethnography. So, my study is a groundbreaking work on Hungarian Roma autobiographies, and my comparative method brings an original contribution to the fields of comparative literature and cross-cultural ethnic studies. My dissertation focuses, on the one hand, on how the Hungarian Roma and African American authors grapple with ways to understand their own cultures and present
their experiences and insights, and, on the other hand, on the equally complex presentations of contacts with the majority cultures. The authors search for ways to reveal the dynamics of their cultures and their special positions within them, using the language,
cultural productions, and ideologies of the majority culture, finding ways to express things that are often unthinkable in the majority culture's understanding of the world. A study of the narrators' relationships with their mothers and families opens up ways of
understanding the complexities of their own cultures and their complicated relationships to these cultures. While descriptions of the relationships with the mothers are readily accessible to most readers, these descriptions point beyond themselves to the complicated and emotionally charged relationships to the cultures. The presentation of intercultural encounters is equally unique and difficult in each
case, as the subject of the minority culture describes experiences of oppression and disadvantaged status. Experiences of poverty, isolation, disrespect, and lack of access to education can be difficult to transmit because these experiences penetrate the deepest levels of one's being. I study the presentations of violence because violent experiences are palpable and emotional ways of encountering oppression at the hands of the majority
culture. The understanding thus gained can explain the varying attitudes towards resistance among the four authors.Ph.D.Includes bibliographical referencesIncludes vitaby Tamas Demen
Distributed Stochastic Model Predictive Control Synthesis for Large-Scale Uncertain Linear Systems
No full textThis paper presents an approach to distributed stochastic model predictive control (SMPC) of large-scale uncertain linear systems with additive disturbances. Typical SMPC approaches for such problems involve formulating a large-scale finite-horizon chance-constrained optimization problem at each sampling time, which is in general non-convex and difficult to solve. Using an approximation, the so-called scenario approach, we formulate a large-scale scenario program and provide a theoretical guarantee to quantify the robustness of the obtained solution. However, such a reformulation leads to a computational tractability issue, due to the large number of required scenarios. To this end, we present two novel ideas in this paper to address this issue. We first provide a technique to decompose the large-scale scenario program into distributed scenario programs that exchange a certain number of scenarios with each other in order to compute local decisions. We show the exactness of the decomposition with a-priori probabilistic guarantees for the desired level of constraint fulfillment. As our second contribution, we develop an inter-agent soft communication scheme based on a set parametrization technique together with the notion of probabilistically reliable sets to reduce the required communication between each subproblem. We show how to incorporate the probabilistic reliability notion into existing results and provide new guarantees for the desired level of constraint violations. A simulation study is presented to illustrate the advantages of our proposed framework.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Tamas Keviczk
Foreword: The 15th IFAC Symposium on Large Scale Complex Systems (LSS 2019) was held at the Delft University of Technology (TU Delft), on May 26th-28th 2019.
No full textTeam Tamas Keviczk
Adaptive governance of aquifers with ATES: Use it or lose it (PPT)
No full textBetreft PPT-presentatie t.b.v. conferentieWater ResourcesPolicy AnalysisTeam Tamas Keviczk
Privatized distributed anomaly detection for large-scale nonlinear uncertain systems
Get PDFIn this article two limitations in current distributed model based approaches for anomaly detection in large-scale uncertain nonlinear systems are addressed. The first limitation regards the high conservativeness of deterministic detection thresholds, against which a novel family of set-based thresholds is proposed. Such set-based thresholds are defined in a way to guarantee robustness in a user-defined probabilistic sense, rather than a deterministic sense. They are obtained by solving a chance-constrained optimization problem, thanks to a randomization technique based on the Scenario Approach. The second limitation regards the requirement, in distributed anomaly detection architectures, for different parties to regularly communicate local measurements. In settings where these parties want to preserve their privacy, communication may be undesirable. In order to preserve privacy and still allow for distributed detection to be implemented, a novel privacy-preserving mechanism is proposed and a so-called privatized communication protocol is introduced. Theoretical guarantees on the achievable level of privacy, along with a characterization of the robustness properties of the proposed distributed threshold set design, taking into account the privatized communication scheme, are provided. Finally, simulation studies are included to illustrate our theoretical developments.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Jan-Willem van WingerdenTeam Tamas Keviczk
Fuel Cell Electric Vehicle-to-grid feasibility: A technical analysis of aggregated units offering frequency
No full textFuel Cell Electric Vehicles (FCEVs) in combination with green hydrogen (obtained from renewable sources), could make a significant contribution in decarbonizing the European transport sector, and thus help achieve the ambitious climate goals. However, most vehicles are parked for about 95% of their life time. This work proposes the more efficient use of these vehicles by providing vehicle-to-grid (V2G) services achieving the integration of the transport and energy systems. The aim of this work is to determine the technical and financial potential value that FCEVs could have by providing frequency reserves. Experiments were carried out with a Hyundai ix35 FCEV that was adapted with a power output socket so it can operate in V2G when parked, delivering maximum 10 kW direct current power. Results show that both power sources in the fuel cell electric vehicle, which are the fuel cell stack and the battery, can react in the order of milliseconds and thus are suitable to offer fast frequency reserves. The challenge lays in the communication between the car and the party that sends the signal for the activation of the frequency reserves. As one unit does not provide enough power to be able to participate in the electricity market, a car park acting as aggregator of FCEVs was designed taking into account current technology developments. A carpark with a direct current microgrid, a hydrogen local network and only occupied by FCEVs was designed. A financial model was developed to evaluate the economic potential of the car park to participate in the electricity market providing frequency reserves. Results show that by using the fuel cells in the FCEVs in V2G, monetary benefits could be obtained when providing automated frequency restoration reserves (aFRR) upwards. Key parameters are found to be the investment costs, amount of vehicles available, hydrogen price and price of aFRR. With a car park of approximately 400 cars all year long available, payback times of 11.8 and 3.5 years were obtained taking into account worst and best case scenarios for a 15 year period analysis, respectively.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Energy Technolog
Formal synthesis of analytic controllers for sampled-data systems via genetic programming
No full textThis paper presents an automatic formal controller synthesis method for nonlinear sampled-data systems with safety and reachability specifications. Fundamentally, the presented method is not restricted to polynomial systems and controllers. We consider a periodically switched controllers based on a Control Lyapunov Barrier-like function. The proposed method utilizes genetic programming to synthesize these function in analytic form, as well as the controller modes. Correctness of the controller are subsequently verified by means of a Satisfiability Modulo Theories solver. Effectiveness of the proposed methodology is demonstrated on multiple systems.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Tamas Keviczk
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