References of "Capitanescu, Florin 40021446"
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See detailA Generic Approach for Solving Nonlinear-Discrete Security-Constrained Optimal Power Flow Problems in Large-Scale Systems
Platbrood, Ludovic; Capitanescu, Florin UL; Merckx, Christian et al

in IEEE Transactions on Power Systems (in press)

This paper proves the practicality of an iterative algorithm for solving realistic large-scale SCOPF problems. This algorithm is based on the combination of a contingency filtering scheme, used to ... [more ▼]

This paper proves the practicality of an iterative algorithm for solving realistic large-scale SCOPF problems. This algorithm is based on the combination of a contingency filtering scheme, used to identify the binding contingencies at the optimum, and a network compression method, used to reduce the complexity of the post-contingency models included in the SCOPF formulation. We show that by combining these two complementary ideas, it is possible to solve in a reasonable time SCOPF problems on large power system models with a large number of contingencies. Unlike most results reported for large-scale SCOPF problems, our algorithm uses a non-linear AC network model in both pre-contingency and post-contingency states, optimizes both active/reactive powers flows jointly, and treats the discrete variables. The proposed algorithm is implemented with state-of-the-art solvers and applied to two systems: a national grid with 2563 buses and 1297 contingencies, and a model of the European transmission network with 9241 buses and 12000 contingencies. [less ▲]

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See detailContributions to thermal constraints management in radial active distribution systems
Bilibin, Ilya UL; Capitanescu, Florin UL

in Electric Power Systems Research (2014), 111

This paper deals with centralized thermal overload management in active radial distribution systems that host a significant amount of distributed generation (DG). We investigate the benefits of using ... [more ▼]

This paper deals with centralized thermal overload management in active radial distribution systems that host a significant amount of distributed generation (DG). We investigate the benefits of using remotely controlled switches to reduce the amount of curtailed DG to remove overload. To this end we extend an existing optimization model to the problem of minimizing the non-firm DG curtailment to remove overload. We discuss the pros and cons of the various overload management goals given the particular features of radial distribution grids and propose, wherever possible, the use of a power flow tracing-based procedure to select the non-firm generators that should participate in overload removal. Although the approach focuses on overload removal it also inhibits violation of operational constraints such as voltage limits that may occur due to network reconfiguration. We prove the interest and feasibility of our approach in four distribution networks. [less ▲]

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See detailAssessing the Potential of Network Reconfiguration to Improve Distributed Generation Hosting Capacity in Active Distribution Systems
Capitanescu, Florin UL; Ochoa, Luis; Margossian, Harag UL et al

in IEEE Transactions on Power Systems (2014), 30(1), 346-356

As the amount of distributed generation (DG) is growing worldwide, the need to increase the hosting capacity of distribution systems without reinforcements is becoming nowadays a major concern. This paper ... [more ▼]

As the amount of distributed generation (DG) is growing worldwide, the need to increase the hosting capacity of distribution systems without reinforcements is becoming nowadays a major concern. This paper explores how the DG hosting capacity of active distribution systems can be increased by means of network reconfiguration, both static, i.e., grid reconfiguration at planning stage, and dynamic, i.e., grid reconfiguration using remotely controlled switches as an active network management (ANM) scheme. The problem is formulated as a mixed-integer, nonlinear, multi-period optimal power flow (MP-OPF) which aims to maximize the DG hosting capacity under thermal and voltage constraints. This work further proposes an algorithm to break-down the large problem size when many periods have to be considered. The effectiveness of the approach and the significant benefits obtained by static and dynamic reconfiguration options in terms of DG hosting capacity are demonstrated using a modified benchmark distribution system. [less ▲]

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See detailA Comprehensive Centralized Approach for Voltage Constraints Management in Active Distribution Grid
Capitanescu, Florin UL; Bilibin, Ilya UL; Romero Ramos, Esther

in IEEE Transactions on Power Systems (2014), 29(2), 933-942

This paper deals with the management of voltage constraints in active distribution systems that host a significant amount of distributed generation (DG) units. To this end we propose a centralized ... [more ▼]

This paper deals with the management of voltage constraints in active distribution systems that host a significant amount of distributed generation (DG) units. To this end we propose a centralized optimization approach which aims at minimizing the amount of MW curtailment of non-firm DG to remove voltage constraints. The salient feature of this approach is that it comprehensively and properly models the full variety of possible control means (i.e. DG active/reactive power including DG shut-down, on load tap changing transformer ratio, shunt capacitor, and remotely controlled switches or breakers), most of which having a discrete behavior. We develop and compare the performances of two optimization models on a snapshot basis for various distribution systems up to 1089 buses. In particular we show that the use of remotely controlled switches so as to transfer DG between feeders in case of voltage constraints may lead to significant reduction of the DG curtailment. [less ▲]

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See detailContingency ranking with respect to overloads in very large power systems taking into account uncertainty, preventive and corrective actions
Fliscounakis, Stephane; Panciatici, Patrick; Capitanescu, Florin UL et al

in IEEE Transactions on Power Systems (2013), 28(4), 4909-4017

This paper deals with day-ahead security management with respect to a postulated set of contingencies while taking into account uncertainties about the next day generation/load scenario. In order to help ... [more ▼]

This paper deals with day-ahead security management with respect to a postulated set of contingencies while taking into account uncertainties about the next day generation/load scenario. In order to help the system operator in decision making under uncertainty we aim at ranking these contingencies into four clusters according to the type of control actions needed to cover the worst uncertainty pattern of each contingency with respect to branch overload. To this end we use a fixed point algorithm that loops over two main modules: a discrete bi-level program (BLV) that computes the worst-case scenario, and a special kind of security constrained optimal power flow (SCOPF) which computes optimal preventive/corrective actions to cover the worst-case. We rely on a DC grid model, as the large number of binary variables, the large size of the problem, and the stringent computational requirements preclude the use of existing mixed integer nonlinear programming (MINLP) solvers. Consequently we solve the SCOPF using a mixed integer linear programming (MILP) solver while the BLV is decomposed into a series of MILPs. We provide numerical results with our approach on a very large European system model with 9241 buses and 5126 contingencies. [less ▲]

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See detailFeeder Protection Challenges with High Penetration of Inverter Based Distributed Generation
Margossian, Harag UL; Capitanescu, Florin UL; Sachau, Jürgen UL

in Proceedings of the EUROCON 2013 conference (2013, July)

The increasing proportion of inverter based distributed generation (DG) in the power system may limit the short circuit power available at distribution substations and consequently cause significant ... [more ▼]

The increasing proportion of inverter based distributed generation (DG) in the power system may limit the short circuit power available at distribution substations and consequently cause significant troubles for the protection of distribution feeders where DG are connected. In this paper, the current practices of distribution network operators in dealing with higher penetration levels of DG are investigated and evaluated using a realistic 31-node distribution network model with limited short circuit supply. The paper discusses the challenges for the protection system related to the integration of increasingly significant amounts of DG and highlights the need for more sophisticated protection systems. [less ▲]

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See detailOverloads Management in Active Radial Distribution Systems: an Optimization Approach Including Network Switching
Bilibin, Ilya UL; Capitanescu, Florin UL; Sachau, Jürgen UL

in 2013 IEEE PES PowerTech (2013, June)

This paper focuses on the real-time overloads management in active radial distribution systems that host a significant amount of distributed generators (DGs). In order to possibly reduce the amount of ... [more ▼]

This paper focuses on the real-time overloads management in active radial distribution systems that host a significant amount of distributed generators (DGs). In order to possibly reduce the amount of generation curtailed to remove congestion, and hence harvest as much renewable energy as possible, we propose a centralized optimization approach that includes the option to use remotely controlled grid switches and breakers so as to transfer distributed generation between feeders. To mitigate the computational burden posed by modeling the switching actions as binary variables we build upon a very convenient existing optimization framework that, for a radial distribution grid, transforms precisely the original mixed integer nonlinear programming (MINLP) problem into a much simpler mixed integer quadratically constrained (MIQC) one. Although the approach focuses on overload removal in course of optimization it also pays attention not worsening other operational constraints such as voltage limits. We prove the interest and feasibility of our approach using a 33-bus benchmark distribution system as well as a 61-bus real-life distribution system model. [less ▲]

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See detailDistributed Generator Status Estimation for Adaptive Feeder Protection in Active Distribution Grids
Margossian, Harag UL; Capitanescu, Florin UL; Sachau, Jürgen UL

in Proceedings of the CIRED2013 conference (2013, June)

This paper proposes a framework for adaptive feeder protection in distribution grids with a high amount of distributed generators (DGs) installed. The scheme adapts the feeder protection relay settings ... [more ▼]

This paper proposes a framework for adaptive feeder protection in distribution grids with a high amount of distributed generators (DGs) installed. The scheme adapts the feeder protection relay settings according to the changes in the connection status of those DGs that have a significant impact on the fault current. The core of the method consists in the identification of the connection status of the DGs using an iterative modified state estimation (SE) program. The approach is illustrated using a realistic 31-node distribution network model. [less ▲]

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See detailTowards optimal post-fault self-healing in future smart distribution grids
Capitanescu, Florin UL; Bilibin, Ilya UL; Sachau, Jürgen UL

in Renewable Energy & Power Quality Journal (2013)

This paper deals with a key functionality of the future distribution smart grids namely the automatic post-fault network self-healing. To this end we propose an optimization approach that aims finding the ... [more ▼]

This paper deals with a key functionality of the future distribution smart grids namely the automatic post-fault network self-healing. To this end we propose an optimization approach that aims finding the post-fault grid topology that minimizes the amount of unsupplied energy to consumers. The approach extends existing optimization models, developed in the context of losses minimization, for our particular application and proposes ways to overcome their limitations. We prove the interest of the approach on a 33-bus benchmark distribution system as well as on a 61-bus real-life distribution grid. [less ▲]

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See detailComputation of worst operation scenarios under uncertainty for static security management
Capitanescu, Florin UL; Wehenkel, Louis

in IEEE Transactions on Power Systems (2013), 28(2), 1697-1705

This paper deals with day-ahead static security assessment with respect to a postulated set of contingencies while taking into account uncertainties about the next day system conditions. We propose a ... [more ▼]

This paper deals with day-ahead static security assessment with respect to a postulated set of contingencies while taking into account uncertainties about the next day system conditions. We propose a heuristic approach to compute the worst-case under operation uncertainty for a contingency with respect to overloads. We formulate this problem as a non-convex nonlinear bilevel program that we solve approximately by a heuristic approach which relies on the solution of successive optimal power flow (OPF) and security-constrained optimal power flow (SCOPF) problems of a special type. The method aims at revealing those combinations of uncertainties and contingencies for which the best combination of preventive and corrective actions would not suffice to ensure security. Extensive numerical results on a small, a medium, and a very large system prove the interest of the approach. [less ▲]

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See detailExperiments with the interior-point method for solving large scale optimal power flow problems
Capitanescu, Florin UL; Wehenkel, Louis

in Electric Power Systems Research (2013), 95(2), 276-283

This paper reports extensive results obtained with the Interior-Point Method (IPM) for nonlinear programms (NLPs) stemming from large-scale and severly constrained classical Optimal Power Flow (OPF) and ... [more ▼]

This paper reports extensive results obtained with the Interior-Point Method (IPM) for nonlinear programms (NLPs) stemming from large-scale and severly constrained classical Optimal Power Flow (OPF) and Security-Constrained Optimal Power Flow (SCOPF) problems. The paper discusses transparently the problems encountered such as convergence reliability and speed issues of the method. [less ▲]

Detailed reference viewed: 163 (16 UL)