References of "Van Cutsem, Thierry"
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See detailDetecting with PMUs the onset of voltage instability caused by a large disturbance
Glavic, Mevludin; Van Cutsem, Thierry ULg

(2008, July)

This paper deals with long-term voltage instability triggered by the outage of transmission or generation equipments. It is shown how the onset of voltage instability could be detected in real-time from ... [more ▼]

This paper deals with long-term voltage instability triggered by the outage of transmission or generation equipments. It is shown how the onset of voltage instability could be detected in real-time from post-disturbance bus voltages provided by Phasor Measurement Units (PMUs), assuming observability of the whole region prone to voltage instability. An extended set of equilibrium equations is fitted to the measurements and the change in sign of sensitivities is onitored. The latter are easily computed even for a large system. The important effects of overexcitation limiters and load tap changers are taken into account. The approach is illustrated on a 52-bus 20-machine system, where PMU outputs are simulated from detailed time simulation. [less ▲]

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See detailINVESTIGATION OF A LOCAL INDICATOR OF VOLTAGE EMERGENCY IN THE HELLENIC INTERCONNECTED SYSTEM
Vournas, Costas; Sakellaridis, N.; Christoforidis, George et al

(2008, July)

In this paper we evaluate the performance of a proposed local indicator of voltage emergency for a simulated unstable contingency of the Hellenic Intercon-nected System identified through the on-line VSA ... [more ▼]

In this paper we evaluate the performance of a proposed local indicator of voltage emergency for a simulated unstable contingency of the Hellenic Intercon-nected System identified through the on-line VSA applica-tion for the summer peak of 2007. The effect of deadbands and tap range limits in delaying the emergency alarm issued is examined. The area mostly affected by the insta-bility is identified through the proposed algorithm and a simple load-shedding scheme sufficient to avert the collapse is suggested. [less ▲]

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See detailVoltage Instability
Van Cutsem, Thierry ULg

in Crappe, Michel (Ed.) Electric Power Systems (2008)

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See detailUndervoltage load shedding using distributed controllers
Otomega, Bogdan; Van Cutsem, Thierry ULg

in IEEE Transactions on Power Systems (2007), 22(4), 1898-1907

A new load shedding scheme against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring transmission voltages in a zone and controlling a group of related ... [more ▼]

A new load shedding scheme against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring transmission voltages in a zone and controlling a group of related loads. Each controller acts in closed-loop, shedding amounts that vary in magnitude and time according to the evolution of its monitored voltage. The whole system can operate without information exchange between controllers, the latter being implicitly coordinated through network voltages. The operation, design and robustness features are illustrated through simulations of a real system. [less ▲]

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See detailDistributed undervoltage load shedding
Otomega, Bogdan; Glavic, Mevludin; Van Cutsem, Thierry ULg

in IEEE Transactions on Power Systems (2007), 22(4), 2283-2284

A new design of load shedding against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring a transmission voltage, controlling a group of loads, acting in ... [more ▼]

A new design of load shedding against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring a transmission voltage, controlling a group of loads, acting in closed-loop, and adjusting its action to the voltage evolution. The whole system operates without information exchange between controllers. [less ▲]

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See detailIdentifying plausible cascading events in system stability assessment
Otomega, Bogdan; Van Cutsem, Thierry ULg

(2007, November)

An implementation of the event tree approach is proposed to determine possible sequences of cascading failures with severe impact on a given power system. The algorithm takes into account protection ... [more ▼]

An implementation of the event tree approach is proposed to determine possible sequences of cascading failures with severe impact on a given power system. The algorithm takes into account protection systems hidden failures and transmission system equipments overload. At each level of the event tree development, the sequence probability order is computed and a filtering tool is used to identify possible harmful sequence. These are furthermore analysed with a time domain simulation tool in order to assess their impact on the power system. This paper contains the description of the event tree algorithm as well as examples of its practical application on the Nordic32 test system. [less ▲]

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See detailModel predictive control to alleviate thermal overloads
Otomega, Bogdan; Marinakis, Adamantios ULg; Glavic, Mevludin et al

in IEEE Transactions on Power Systems (2007), 22(3), 1384-1385

An approach inspired by model predictive control is proposed to determine a sequence of control actions aimed at alleviating thermal overloads. The algorithm brings the line currents below their limits in ... [more ▼]

An approach inspired by model predictive control is proposed to determine a sequence of control actions aimed at alleviating thermal overloads. The algorithm brings the line currents below their limits in the time interval left by protections while accounting for constraints on control changes at each step. Its closed-loop nature allows to compensate for model inaccuracies. [less ▲]

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See detailA unified management of congestions due to voltage instability and thermal overload
Capitanescu, Florin ULg; Van Cutsem, Thierry ULg

in Electric Power Systems Research (2007), 77(10), 1274-1283

This paper proposes two approaches for a unified management of congestions due to voltage instability and thermal overload in a deregulated environment. Both techniques aim to remove, in some optimal ... [more ▼]

This paper proposes two approaches for a unified management of congestions due to voltage instability and thermal overload in a deregulated environment. Both techniques aim to remove, in some optimal manner, voltage and thermal congestions stemming from base case or post-contingency states, by a simultaneous handling of operating and security constraints with respect to several contingencies. The objective of the first approach is to adjust the market-based power injections (generator output and possibly load consumption) at the least cost while the second one aims at curtailing power transactions in a transparent and non-discriminatory way. These techniques rely on sensitivities which pinpoint the best remedial actions against congestions owing to voltage instability and thermal overload. Numerical results with both approaches are provided on a realistic 80-bus system model. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailEmergency alleviation of thermal overloads using model predictive control
Otomega, Bogdan; Marinakis, Adamantios ULg; Glavic, Mevludin et al

(2007, July)

An approach inspired of Model Predictive Control is proposed to determine a sequence of control actions aimed at alleviating thermal overloads in emergency conditions. The algorithm brings the line ... [more ▼]

An approach inspired of Model Predictive Control is proposed to determine a sequence of control actions aimed at alleviating thermal overloads in emergency conditions. The algorithm brings the line currents below their limits in the time interval left by protections, while accounting for constraints on control changes at each step. Its closed-loop nature allows to compensate for measurement noise and model uncertainties. [less ▲]

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See detailControl of phase shifting transformers by multiple transmission system operators
Marinakis, Adamantios ULg; Glavic, Mevludin; Van Cutsem, Thierry ULg

(2007, July)

A general framework is proposed for the control of phase shifting transformers owned by several TSOs, taking into account their interactions. The proposed solution is the Nash equilibrium of a sequence of ... [more ▼]

A general framework is proposed for the control of phase shifting transformers owned by several TSOs, taking into account their interactions. The proposed solution is the Nash equilibrium of a sequence of optimizations performed by the various TSOs, each of them taking into account the other TSOs’ control settings as well as operating constraints relative to the whole system. The method is applied to a linearized network model and illustrated on the IEEE 118-bus system. [less ▲]

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See detailEmergency Voltage Stability Controls: an Overview
Van Cutsem, Thierry ULg; Vournas, Costas

(2007, July)

This paper provides an overview of emergency voltage stability controls in power systems. First, a brief review is made of voltage instability mechanisms, countermeasures, and system protection schemes ... [more ▼]

This paper provides an overview of emergency voltage stability controls in power systems. First, a brief review is made of voltage instability mechanisms, countermeasures, and system protection schemes. Next, the paper discusses various aspects of emergency controls, including generator voltage control, load tap changer modified control and load shedding, pointing out some important features and addressing research aspects. Load shedding is considered in some more detail, and applications to two real systems of, respectively, a response-based and an event-based load shedding scheme, are described. [less ▲]

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See detailA purely distributed implementation of undervoltage load shedding
Otomega, Bogdan; Glavic, Mevludin; Van Cutsem, Thierry ULg

(2007, June)

A new design of load shedding against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring a transmission voltage and controlling a group of loads. Each ... [more ▼]

A new design of load shedding against long-term voltage instability is proposed. It uses a set of distributed controllers, each monitoring a transmission voltage and controlling a group of loads. Each controller acts in closed-loop, shedding amounts that vary in magnitude and time according to the evolution of its monitored voltage. The whole system operates without information exchange between controllers, the latter being implicitly coordinated through network voltages. The operation, design and robustness of the proposed scheme are illustrated through a small but realistic example. [less ▲]

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See detailModelling the short-term and long-term aggregate response of multiple loads fed through a sub-transmission network
Van Cutsem, Thierry ULg; Renoy, Quentin; Lefebvre, Daniel

(2006, November)

This paper addresses the problem of representing the aggregate response to voltage changes of a set of loads fed through distribution transformers connected by a subtransmission network. A simple, while ... [more ▼]

This paper addresses the problem of representing the aggregate response to voltage changes of a set of loads fed through distribution transformers connected by a subtransmission network. A simple, while accurate equivalent is proposed. The latter involves standard network components and includes a single internal bus. This equivalent matches both the short-term and the long-term response of the original system, the long-term dynamics coming from the load tap changers that control the distribution voltages. A procedure to identify its parameters from step responses of the unreduced system is detailed. The method is illustrated and validated on a large subtransmission-distribution system of Hydro-Québec. [less ▲]

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See detailCombined detailed and quasi steady-state time simulations for large-disturbance analysis
Van Cutsem, Thierry ULg; Grenier, Marie-Eve; Lefebvre, Daniel

in International Journal of Electrical Power & Energy Systems (2006), 28(9), 634-642

This paper deals with the simulation of long-term responses of power systems to large disturbances in the presence of discrete events. After outlining the power system model under the quasi steady-state ... [more ▼]

This paper deals with the simulation of long-term responses of power systems to large disturbances in the presence of discrete events. After outlining the power system model under the quasi steady-state (QSS) approximation, a method combining detailed and QSS time simulations is presented, the former being used for accuracy and the latter for efficiency reasons. Detailed time simulation is used to analyze the short-term period following a large disturbance and identify the discrete controls triggered. Next, QSS simulation is used to simulate the same time interval with the discrete controls imposed as external events, before letting the system evolve as usual in the long-term. This simple method has been successfully tested on the Hydro-Quebec system. (C) 2006 Elsevier Ltd. All rights reserved. [less ▲]

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See detailSome Reflections on Model Predictive Control of Transmission Voltages
Glavic, Mevludin; Van Cutsem, Thierry ULg

(2006, September)

This paper deals with the application of algorithms inspired by Model Predictive Control to solve voltage-related power system control problems in both normal and emergency operating conditions. In the ... [more ▼]

This paper deals with the application of algorithms inspired by Model Predictive Control to solve voltage-related power system control problems in both normal and emergency operating conditions. In the first part of the paper, we identify critical issues for a practical implementation of this methodology, and analyze how far these requirements have been met so far. In the second part, we outline a voltage control scheme that hopefully addresses the above issues. The central idea of this scheme is a static optimization to determine target control values, followed by a dynamic optimization to produce a feasible transition, both carried out in the closed-loop mode of Model Predictive Control. [less ▲]

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See detailEXPERIENCE GAINED BY THE APPLICATION OF A REAL-TIME VOLTAGE SECURITY ASSESSMENT METHOD AT THE HELLENIC TRANSMISSION SYSTEM OPERATOR
Christoforidis, George; Kabouris, John; Vournas, Costas et al

(2006, August)

Voltage instability is widely recognized as a significant threat of power system blackout. As far as real-time operation is concerned, there is a need for appropriate tools to identify dangerous ... [more ▼]

Voltage instability is widely recognized as a significant threat of power system blackout. As far as real-time operation is concerned, there is a need for appropriate tools to identify dangerous contingencies and assess security margins. The Hellenic Interconnected System presents a structural geographical imbalance between the main generation site and the main load center. This imbalance leads to bulk power transfers over long distances leading to voltage stability problems in areas of the southern system during heavy load conditions. In order to improve the operational practices, a realtime Voltage Security Assessment (VSA) tool has been installed at the National Control Center of the Hellenic Transmission System Operator (HTSO). The scope of VSA is the analysis of the impact of significant contingencies and the determination of security margins in terms of power transfers or power consumption in load areas. The computations performed within the VSA tool are based on a Quasi-Steady-State simulation, a fast time-domain method well suited to the analysis of long-term voltage stability phenomena. VSA is performed on the current system state, provided by the Energy Management System (EMS) state estimator. The VSA application incorporates functions for filtering the contingencies, determining secure operation limits, and deriving post-contingency PV curves for the identified dangerous contingencies. This paper is a description of the experience and the added value gained by the application of the real-time VSA, in parallel with the existing EMS, at the control center of HTSO. [less ▲]

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See detailQuasi steady-state simulation diagnosis using Newton method with optimal multiplier
Rousseaux, Patricia ULg; Van Cutsem, Thierry ULg

in IEEE PES General Meeting (Montreal) (2006)

This paper deals with the quasi steady-state approximation of the long-term dynamics. This fast time simulation method assumes that the short-term dynamics are stable and can be replaced by their ... [more ▼]

This paper deals with the quasi steady-state approximation of the long-term dynamics. This fast time simulation method assumes that the short-term dynamics are stable and can be replaced by their equilibrium equations. When the latter stop having a solution, the simulation undergoes a singularity. This paper proposes a method to identify which component(s) are responsible for the loss of equilibrium. The corresponding equations are identified using the Newton method with optimal multiplier. The method has been validated with respect to full time simulation. Very good results are shown on the Nordic-32 system, in cases where long-term voltage instability triggers loss of synchronism. The proposed method enhances time simulation at very low computational cost and can also help correcting model and/or operating point errors. [less ▲]

Detailed reference viewed: 73 (10 ULg)
See detailEmergency monitoring and corrective control of voltage instability
Van Cutsem, Thierry ULg; Vournas, Costas

in Savulescu, Savu (Ed.) Real-Time Stability in Power Systems: Techniques for Early Detection of the Risk of Blackout (2006)

After reviewing the basic voltage instability mechanisms, this chapter de-scribes emergency measures that can be used in order to contain voltage insta-bility and prevent a voltage collapse leading to a ... [more ▼]

After reviewing the basic voltage instability mechanisms, this chapter de-scribes emergency measures that can be used in order to contain voltage insta-bility and prevent a voltage collapse leading to a blackout. A real case of such a voltage collapse in the Hellenic system is presented and analyzed. Emer-gency measures presented include existing or projected controls acting on bulk power delivery transformer load tap changers, as well as direct load shedding. An actual design and application of a load shedding controller in the Hydro-Québec system is presented. [less ▲]

Detailed reference viewed: 53 (2 ULg)
See detailOn-line voltage security assessment
Vournas, Costas; Van Cutsem, Thierry ULg

in Savulescu, Savu (Ed.) Real-time stability in power systems: Techniques for the early detection of the risk of blackout (2006)

This chapter deals with voltage security assessment and its on-line application. Methods for contingency analysis are briefly reviewed. The associated con-cepts of transfer capability, loadability limit ... [more ▼]

This chapter deals with voltage security assessment and its on-line application. Methods for contingency analysis are briefly reviewed. The associated con-cepts of transfer capability, loadability limit, and secure operation margin are explored in some detail. Methods for preventive security control are outlined. An application of on-line VSA in the control center of a real system is then de-scribed and typical results available to operators are presented. [less ▲]

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See detailINVESTIGATION OF PARAMETERS AFFECTING VOLTAGE SECURITY OF THE HELLENIC INTERCONNECTED SYSTEM
Christoforidis, George; Kabouris, John; Vournas, Costas et al

(2005, August)

The Hellenic Interconnected System pre-sents a structural geographical imbalance between generation sites and load centers. This imbalance leads to bulk power transfers on long electrical distances ... [more ▼]

The Hellenic Interconnected System pre-sents a structural geographical imbalance between generation sites and load centers. This imbalance leads to bulk power transfers on long electrical distances leading to voltage stability problems. In order to improve the opera-tional practices aiming at improving the voltage security, an on-line Voltage Security Assessment tool has been installed at the National Control Center of the Hellenic Transmission System Operator that operates and controls the interconnected power system of Greece. This paper presents some indicative results obtained by the use of this tool. The analysis includes the investigation of the main parameters that affect the voltage stability of the system, such as the position of non-automatic taps of autotrans-formers, the network topology, and the spatial distribution of generation. [less ▲]

Detailed reference viewed: 57 (2 ULg)