References of "Karangelos, Efthymios"
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See detailProbabilistic Reliability Management Approach and Criteria for Power System Short-term Operational Planning
Karangelos, Efthymios ULiege; Wehenkel, Louis ULiege

in Probabilistic Reliability Management Approach and Criteria for Power System Short-term Operational Planning (in press)

This paper develops a probabilistic decision making framework for reliability management in the short-term operational planning context. We build upon our recent work, which proposed a probabilistic ... [more ▼]

This paper develops a probabilistic decision making framework for reliability management in the short-term operational planning context. We build upon our recent work, which proposed a probabilistic reliability management approach and criterion (RMAC) for the latest decision making opportunity of real-time system operation. Here, we transpose the RMAC to the preceding problem instance of short-term operational planning, wherein i) risk is aggravated by the uncertainty on power injections and weather conditions, and, ii) the problem scope concerns choosing `strategic' actions (e.g., starting additional generating units, granting outage requests for maintenance, etc.) to facilitate decision making during the forthcoming real-time system operation. To anticipate on the latter, we formalize the notion of a real-time `proxy' as a simplified model of the real-time decision making context, adequately accurate for the purpose of operational planning decision making. Stating a first proposal for such a proxy, we mathematically formulate the RMAC for short-term operational planning as a multi-stage stochastic decision making problem and demonstrate its main features by case studies on a modified version of the single area IEEE RTS-96 system. [less ▲]

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See detailA computational model of mid-term outage scheduling for long-term system studies
Marin, Manuel ULiege; Karangelos, Efthymios ULiege; Wehenkel, Louis ULiege

in PowerTech Manchester 2017 Proceedings (2017)

This paper presents a computational model of the mid-term outage scheduling process of electric power transmis- sion assets, to be used in long-term studies such as mainte- nance policy assessments and ... [more ▼]

This paper presents a computational model of the mid-term outage scheduling process of electric power transmis- sion assets, to be used in long-term studies such as mainte- nance policy assessments and system development studies, while accounting for the impact of outage schedules on short-term system operation. We propose a greedy algorithm that schedules the outages one by one according to their impact on system operation estimated via Monte-Carlo simulations. The model is implemented in JULIA and applied to the IEEE RTS-96. [less ▲]

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See detailMachine Learning of Real-time Power Systems Reliability Management Response
Duchesne, Laurine ULiege; Karangelos, Efthymios ULiege; Wehenkel, Louis ULiege

in PowerTech Manchester 2017 Proceedings (2017)

In this paper we study how supervised machine learning could be applied to build simplified models of real-time (RT) reliability management response to the realization of uncertainties. The final ... [more ▼]

In this paper we study how supervised machine learning could be applied to build simplified models of real-time (RT) reliability management response to the realization of uncertainties. The final objective is to import these models into look-ahead operation planning under uncertainties. Our response models predict in particular the real-time reliability management costs and the resulting reliability level of the system. We tested our methodology on the IEEE-RTS96 benchmark. Among the supervised learning algorithms tested, extremely randomized trees, kernel ridge regression and neural networks appear to be the best methods for this application. Furthermore, by using feature “importances” computed by tree-based ensemble methods, we were able to extract the most relevant variables to predict the response of real-time reliability management, and thus obtain a better understanding of the system properties. [less ▲]

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See detailProbabilistic reliability management approach and criteria for power system real-time operation
Karangelos, Efthymios ULiege; Wehenkel, Louis ULiege

in Power Systems Computation Conference (2016, June)

This paper develops a probabilistic approach for power system reliability management in real-time operation where risk is a product of i) the potential occurrence of contingencies, ii) the possible ... [more ▼]

This paper develops a probabilistic approach for power system reliability management in real-time operation where risk is a product of i) the potential occurrence of contingencies, ii) the possible failure of corrective (i.e., post-contingency) control and, iii) the socio-economic impact of service interruptions to end-users. Stressing the spatiotemporal variability of these factors, we argue for reliability criteria assuring a high enough probability of avoiding service interruptions of severe socio-economic impact by dynamically identifying events of nonnegligible implied risk. We formalise the corresponding decision making problem as a chance-constrained two-stage stochastic programming problem, and study its main features on the single area IEEE RTS-96 system. We also discuss how to leverage this proposal for the construction of a globally coherent reliability management framework for long-term system development, midterm asset management, and short-term operation planning. [less ▲]

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See detailFramework for Threat Based Failure Rates in Transmission System Operation
Perkin, Samuel; Bjornsson, Gudjon; Baldursdottir, Iris et al

in Framework for Threat Based Failure Rates in Transmission System Operation (2016, February)

Reliability of electrical transmission systems isvpresently managed by applying the deterministic N-1 criterion, or some variant thereof. This means that transmission systems are designed with at least ... [more ▼]

Reliability of electrical transmission systems isvpresently managed by applying the deterministic N-1 criterion, or some variant thereof. This means that transmission systems are designed with at least one level of redundancy, regardless of the cost of doing so, or the severity of the risks they mitigate. In an operational context, the N-1 criterion provides a reliability target but it fails to accurately capture the dynamic nature of short-term threats to transmission systems. Ongoing research aims to overcome this shortcoming by proposing new probabilistic reliability criteria. Such new criteria are anticipated to rely heavily on component failure rate calculations. This paper provides a threat modelling framework, using the Icelandic transmission system as an example, highlighting the need for improved data collection and failure rate modelling. The feasibility of using threat credibility indicators to achieve spatio-temporal failure rates, given minimal data, is explored in a case study of the Icelandic transmission system. The paper closes with a discussion on the assumptions and simplifications that are implicitly made in the formulation, and the additional work required for such an approach to be included in existing practices. Specifically, this paper is concerned only with short term and real-time management of electrical transmission systems. [less ▲]

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See detailWhither probabilistic security management for real-time operation of power systems ?
Karangelos, Efthymios ULiege; Panciatici, Patrick; Wehenkel, Louis ULiege

in Bulk Power System Dynamics and Control - IX Optimization, Security and Control of the Emerging Power Grid (IREP), 2013 IREP Symposium (2013)

This paper investigates the stakes of introducing probabilistic approaches for the management of power system’s security. In real-time operation, the aim is to arbitrate in a rational way between ... [more ▼]

This paper investigates the stakes of introducing probabilistic approaches for the management of power system’s security. In real-time operation, the aim is to arbitrate in a rational way between preventive and corrective control, while taking into account i) the prior probabilities of contingencies, ii) the possible failure modes of corrective control actions, iii) the socio-economic consequences of service interruptions. This work is a first step towards the construction of a globally coherent decision making framework for security management from long-term system expansion, via mid-term asset management, towards short-term operation planning and real-time operation. [less ▲]

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See detailActive network management: planning under uncertainty for exploiting load modulation
Gemine, Quentin ULiege; Karangelos, Efthymios ULiege; Ernst, Damien ULiege et al

in Proceedings of the 2013 IREP Symposium - Bulk Power Systems Dynamics and Control - IX (2013)

This paper addresses the problem faced by a distribution system operator (DSO) when planning the operation of a network in the short-term. The problem is formulated in the context of high penetration of ... [more ▼]

This paper addresses the problem faced by a distribution system operator (DSO) when planning the operation of a network in the short-term. The problem is formulated in the context of high penetration of renewable energy sources (RES) and distributed generation (DG), and when flexible demand is available. The problem is expressed as a sequential decision-making problem under uncertainty, where, in the first stage, the DSO has to decide whether or not to reserve the availability of flexible demand, and, in the subsequent stages, can curtail the generation and modulate the available flexible loads. We analyze the relevance of this formulation on a small test system, discuss the assumptions made, compare our approach to related work, and indicate further research directions. [less ▲]

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See detailA computationally efficient algorithm for the provision of a day-ahead modulation service by a load aggregator
Mathieu, Sébastien ULiege; Karangelos, Efthymios ULiege; Louveaux, Quentin ULiege et al

Poster (2012, October 08)

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service ... [more ▼]

We study a decision making problem faced by an aggregator willing to offer a load modulation service to a Transmission System Operator (TSO). In particular, we concentrate on a day-ahead service consisting of a load modulation option, which can be called by the TSO once per day. The option specifies the maximum amplitude of a potential modification on the demand of the loads within a certain time interval. We consider the specific case where the loads can be modeled by a generic tank model whose inflow depends on the power consumed by the load and outflow is assumed to be known the day before for every market period. The level of the reservoir at the beginning of the market day is also assumed to be known. We show that, under these assumptions, the problem of maximizing the amplitude of the load modulation service can be formulated as a mixed integer linear programming problem (MILP). In order to solve this problem in a computationally efficient manner we introduce a novel heuristic-method. We test this method on a set of problems and demonstrate that our approach is orders of magnitude faster than CPLEX - a state-of-the-art software for solving MILP problems - without considerably compromising the solution accuracy. [less ▲]

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