References of "Van Cutsem, Thierry"
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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 ▲]

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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 ▲]

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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 ▲]

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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

(2005, August)

This paper deals with the simulation of long-term power system responses to large disturbances in the presence of discrete events. A method combining detailed and quasi steady-state time simulations is ... [more ▼]

This paper deals with the simulation of long-term power system responses to large disturbances in the presence of discrete events. A method combining detailed and quasi steady-state time simulations is presented, the former being used for accuracy and the latter for ef ciency reasons. Detailed time simulation is used to analyze the short-term period following a large disturbance and identify the discrete controls triggered. Next, quasi steady-state 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-Québec system. [less ▲]

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See detailQuasi steady-state models for long-term voltage and frequency dynamics simulation
Grenier, Marie-Eve; Lefebvre, Daniel; Van Cutsem, Thierry ULg

(2005, June)

The Quasi Steady-State (QSS) approximation of long-term dynamics relies on time-scale decomposition and consists of replacing faster phenomena by their equilibrium conditions, in order to reduce the ... [more ▼]

The Quasi Steady-State (QSS) approximation of long-term dynamics relies on time-scale decomposition and consists of replacing faster phenomena by their equilibrium conditions, in order to reduce the complexity of the whole model and increase the computation efficiency of time simulations. This paper describes the extension of a QSS model extensively used in long-term voltage stability studies, to readily incorporate the frequency dynamics that takes place over the same time scale. This extended QSS model relies on a common-frequency assumption. Its advantages, limitations and possible improvements are discussed through simulation results on the Hydro-Québec system, where it has been compared to full time scale simulations. Disturbances with an impact on either frequency or voltages are considered and the coupling between these two aspects of long-term dynamics is briefly discussed. [less ▲]

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See detailFast contingency filtering based on linear voltage drop estimates
Otomega, Bogdan; Van Cutsem, Thierry ULg

(2005, June)

This paper deals with the filtering of harmless contingencies in voltage stability and security analyses. In many systems, a post-contingency load flow allows to identify the contingencies with severe ... [more ▼]

This paper deals with the filtering of harmless contingencies in voltage stability and security analyses. In many systems, a post-contingency load flow allows to identify the contingencies with severe impact on voltage stability, as causing either divergence or large voltage drops. However, for filtering purposes, accurate voltage drops need not be computed; linear estimates obtained from sensitivity formulas are appropriate. For a given contingency, the method used in this paper solves a sparse linear system to update the phase angles, assuming constant voltage magnitudes. Then, assuming constant active power flows in the branches, a second sparse system is solved to update the voltage magnitudes. This yields better accuracy than one full load flow iteration while retaining the sparse structure of a decoupled formulation. For contingency analysis, the incidents are filtered by comparing the voltage drops to a threshold. For secure power margin computations, the same procedure is used after stressing the system in the specified direction. The method has been tested on a real system where it has been found to combine simplicity of implementation, quality of filtering and computational efficiency. [less ▲]

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See detailUnified sensitivity analysis of unstable or low voltages caused by load increases or contingencies
Capitanescu, Florin ULg; Van Cutsem, Thierry ULg

in IEEE Transactions on Power Systems (2005), 20(1), 321-329

This paper deals with the analysis of situations where load increases and/or contingencies cause transmission voltages to become unstable or unacceptably low. Simple sensitivities are proposed to ... [more ▼]

This paper deals with the analysis of situations where load increases and/or contingencies cause transmission voltages to become unstable or unacceptably low. Simple sensitivities are proposed to determine the relative efficiency of candidate remedial actions, which are parameter changes likely to strengthen the system. To this purpose, the sensitivities of the bus voltage magnitude experiencing the largest drop are considered. In the neighborhood of a loadability limit or a critical point, it is shown that these sensitivities and those based on eigenvalue and eigenvector computation are essentially the same. However, the proposed analysis can also deal with low but stable situations. The accuracy of the proposed sensitivities is demonstrated on the models of two real systems, in which the parameters of concern are bus power injections. [less ▲]

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See detailApplication of real-time voltage security assessment to the Hellenic Interconnected System
Van Cutsem, Thierry ULg; Kabouris, John; Christoforidis, George et al

in IEE Proceedings-Generation Transmission and Distribution (2005), 152(1), 123-131

The online voltage security assessment methods implemented at the national control centre of the Hellenic Interconnected System, within the framework of the OMASES project funded by the European Union are ... [more ▼]

The online voltage security assessment methods implemented at the national control centre of the Hellenic Interconnected System, within the framework of the OMASES project funded by the European Union are described. The heart of all computations is a fast time-domain method. Security is analysed with respect to power transfers in critical corridors or power consumption in load areas. Results take on the form of either precontingency secure operation limits, or postcontingency loadability limits, together with various diagnosis tips. Contingency filtering is performed to meet the real-time requirement. Typical results obtained during the test phase of the project are reported. [less ▲]

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See detailA new training simulator for improved voltage control of the Hydro-Québec system
Van Cutsem, Thierry ULg; Hassé, Gaëtan; Moors, Cédric et al

(2004, October)

This paper reports on the development of a training simulator focusing on voltage control and stability. It has been derived from a quasi steady-state simulation software already used and validated in ... [more ▼]

This paper reports on the development of a training simulator focusing on voltage control and stability. It has been derived from a quasi steady-state simulation software already used and validated in planning and operational planning studies. The computational engine has been provided with a user interface built on the client-server architecture, allowing the simulator to run on a network of PCs in a very flexible way. New displays can be set up easily and quickly. This tool is presently used by Hydro-Québec to improve the operator’s ability to control transmission voltages. Other features, uses and benefits are reported. [less ▲]

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See detailUndervoltage load shedding scheme for the Hydro-Québec system
Lefebvre, Daniel; Bernard, Serge; Van Cutsem, Thierry ULg

(2004, June)

In recent years, Hydro-Québec has undertaken a major program to upgrade the reliability of its transmission system. Much effort has been focused on increasing the system's ability to withstand extreme ... [more ▼]

In recent years, Hydro-Québec has undertaken a major program to upgrade the reliability of its transmission system. Much effort has been focused on increasing the system's ability to withstand extreme contingencies, usually caused by multiple incidents or the successive tripping of transmission lines. This paper deals with the conception and the control logic of an undervoltage load shedding scheme aimed at protecting the Hydro-Québec system against long-term voltage instability. Various results showing the impact of the operation of these automatisms on the system stability are provided in this paper. [less ▲]

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See detailDefinition and Classification of Power System Stability
Kundur, Prabha; Paserba, John; Ajjarapu, Venkat et al

in IEEE Transactions on Power Systems (2004), 19(2), 1387-1401

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current ... [more ▼]

The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security. [less ▲]

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See detailAn educational simulation tool for power system control and stability
Vournas, Costas; Potamianakis, Emmanuel G.; Moors, Cédric et al

in IEEE Transactions on Power Systems (2004), 19(1), 48-55

This paper presents a Simulink-based educational tool developed for the purpose of illustrating power system control and stability notions as well as introducing students to realistic, though tractable in ... [more ▼]

This paper presents a Simulink-based educational tool developed for the purpose of illustrating power system control and stability notions as well as introducing students to realistic, though tractable in size, design problems. Relevant courses are taught to last-year undergraduate as well as graduate students at the University of, Liege, Belgium, and the National Technical University of Athens, Greece.. After a brief description of the corresponding curricula, the paper describes the simulation tool and gives examples of problems and assignments given to the students. [less ▲]

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See detailDesign of an undervoltage load shedding scheme for the Hydro-Québec system
Lefebvre, Daniel; Moors, Cédric; Van Cutsem, Thierry ULg

(2003, July)

This paper deals with the control logic of an undervoltage, closed-loop load shedding scheme aimed at protecting the Hydro-Quebec system against long-term voltage instability. This scheme relies on a set ... [more ▼]

This paper deals with the control logic of an undervoltage, closed-loop load shedding scheme aimed at protecting the Hydro-Quebec system against long-term voltage instability. This scheme relies on a set of "if-then" rules whose parameters are determined through combinatorial optimisation, relying on the system dynamic response over a set of scenarios. Preliminary results of the above optimisation technique are given, besides a brief description of the foreseen implementation. [less ▲]

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See detailReverse-logic control of load tap changers in emergency voltage conditions
Otomega, Bogdan; Sermanson, Vincent; Van Cutsem, Thierry ULg

(2003, June 26)

This papers deals with the emergency control of Load Tap Changers (LTCs) to face low transmission voltages or voltage instability situations. The proposed simple control logic consists in reverting the ... [more ▼]

This papers deals with the emergency control of Load Tap Changers (LTCs) to face low transmission voltages or voltage instability situations. The proposed simple control logic consists in reverting the tap movements once the voltage at a monitored transmission bus falls below some threshold. A deadband on this voltage allows the system to settle down in between the normal and reverse logic modes. In order to control a large number of LTCs, the latter are divided into clusters, each with its own monitored voltage. The paper also considers the control of two levels of LTCs in cascade, where proper coordination is required between the two levels. The proposed scheme has been tested on a detailed EHV-HV-MV planning model of the Western region of the French transmission system operated by RTE. Long-term time responses to major disturbances are shown to illustrate the performance of the proposed scheme. [less ▲]

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See detailOMASES: A DYNAMIC SECURITY ASSESSMENT TOOL FOR THE NEW MARKET ENVIRONMENT
Bihain, André; Cirio, Diego; Fiorina, Mario et al

(2003, June 26)

The paper presents the efforts and results of a large consortium of European Industries, Research Centers and Universities involved in an EU research project named OMASES in the field of Power System ... [more ▼]

The paper presents the efforts and results of a large consortium of European Industries, Research Centers and Universities involved in an EU research project named OMASES in the field of Power System Dynamic Security Assessment (DSA). The overall structure of an on-line DSA tool including TSA – Transient Stability Assessment, VSA – Voltage Stability Assessment, TS – Training Simulator and MS – Market Simulator is reported. Some basic assumptions and methodological aspects of the tool are presented considering its possible use within actual or future Energy Management Systems under the new electric market environment. Scenarios set up for the validation phase and results are reported with reference to the Italian test facility. [less ▲]

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See detailOn-Line Voltage Security Assessment of the Hellenic Interconnected System
Vournas, Costas; Manos, George; Kabouris, John et al

(2003, June 26)

This paper describes the on-line Voltage Security Assessment environment developed within the framework of the EU-sponsored OMASES project, as well as its application to the Greek Interconnected Power ... [more ▼]

This paper describes the on-line Voltage Security Assessment environment developed within the framework of the EU-sponsored OMASES project, as well as its application to the Greek Interconnected Power System. The heart of all computations is a fast time-domain method. Security is analyzed with respect to power transfers in critical corridors or power consumption in load areas. Results take on the form of either precontingency secure operation limits, or post-contingency loadability limits, together with various diagnosis tips. Typical results obtained during the test phase of the project are reported. [less ▲]

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See detailL'instabilité de tension
Van Cutsem, Thierry ULg

in Crappe, Michel (Ed.) Stabilité et sauvegarde des réseaux électriques (2003)

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See detailComputation of simultaneous available transfer capability under thermal and voltage security constraints
Capitanescu, Florin ULg; Van Cutsem, Thierry ULg

(2002, September)

This paper proposes a method to compute the Available Transfer Capability (ATC) of a power system under both thermal and voltage security constraints. The objective is to determine, in some optimal manner ... [more ▼]

This paper proposes a method to compute the Available Transfer Capability (ATC) of a power system under both thermal and voltage security constraints. The objective is to determine, in some optimal manner, the ATC of several simultaneous transactions, such that any postulated contingency does not cause voltage instability nor thermal overloads. Thermal constraints are derived for every branch likely to be overloaded in post-contingency states. Voltage security constraints are derived from voltage unstable post-contingency scenario, obtained by Quasi Steady- State simulation, a fast time-domain method. The paper also addresses the discrimination problem, i.e. the fact that the computed ATC might favor some trades to the detriment of others. Variants will be discussed to deal with such situations. The method is illustrated on an 80-bus test system. [less ▲]

Detailed reference viewed: 42 (6 ULg)