References of "Otomega, Bogdan"
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See detailA two-level emergency control scheme against power system voltage instability
Otomega, Bogdan; Glavic, Mevludin ULg; Van Cutsem, Thierry ULg

in Control Engineering Practice (2014), 30

A two-level adaptive control scheme against power system voltage instability is proposed, to deal with emergency conditions by acting on distribution transformers and/or by curtailing some loads. The ... [more ▼]

A two-level adaptive control scheme against power system voltage instability is proposed, to deal with emergency conditions by acting on distribution transformers and/or by curtailing some loads. The lower level includes distributed controllers, each acting once the voltage at a monitored transmission bus settles below a threshold value. The upper level benefits from wide-area monitoring and adjusts in real-time the voltage thresholds of the local controllers. Emergency detection is based on the sign of sensitivities. The proposed scheme is robust with respect to communication failures. Its performance is illustrated through detailed simulations of a small but realistic 74-bus test system. [less ▲]

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See detailDistributed load interruption and shedding against voltage delayed recovery or instability
Otomega, Bogdan; Van Cutsem, Thierry ULg

in Proc. IEEE PES 2013 PowerTech Conference (2013, June)

This paper deals with a two-part system integrity protection scheme to be installed in distribution networks, to counteract fault-induced delayed voltage recovery or even short-term voltage instability ... [more ▼]

This paper deals with a two-part system integrity protection scheme to be installed in distribution networks, to counteract fault-induced delayed voltage recovery or even short-term voltage instability due to induction motors. The first part consists of a fast triggered but temporary reduction of some loads to facilitate motor re-acceleration after fault clearing. The second part resorts to load shedding, as a back-up. The scheme relies on purely distributed controllers; each of them measures a bus voltage and interrupts/disconnects load at the same bus. Tests have been performed on a generic MV/LV system. They illustrate the benefit of load interruption and the selectivity of the proposed scheme. [less ▲]

Detailed reference viewed: 81 (9 ULg)
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See detailWide-Area Adaptive Load Shedding Control to Counteract Voltage Instability
Otomega, Bogdan; Glavic, Mevludin; Van Cutsem, Thierry ULg

in Proceedings of the Power Plant and Power System Control Conference (PPPSC 2012) (2012, September)

A two-level adaptive load shedding scheme against voltage instability is proposed, adjusting its actions to the severity of the situation. The lower level includes a set of distributed controllers which ... [more ▼]

A two-level adaptive load shedding scheme against voltage instability is proposed, adjusting its actions to the severity of the situation. The lower level includes a set of distributed controllers which curtail loads once the voltages at monitored transmission buses fall and stay for some time below threshold values. The adaptive nature of the proposed scheme comes from the upper level adjusting those thresholds in real-time. At the time instant the upper level detects that the system enters an emergency condition, it sends a signal to the lower-level controllers requesting them to take their currently measured voltages as threshold values. The upper-level emergency detection can be based on various criteria, the key-point being that it takes advantage of a wide-area monitoring of the system. In particular, the paper illustrates the use of a voltage instability detection scheme based on sensitivity computation. In case the upper level fails sending its signal, the lower-level controllers act in purely distributed mode, each using its preset threshold voltage. The capabilities of the proposed scheme are illustrated on a small but realistic test system. [less ▲]

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See detailA load shedding scheme against both short- and long-term voltage instabilities in the presence of induction motors
Otomega, Bogdan; Van Cutsem, Thierry ULg

in Proceedings of the IEEE Trondheim Power Tech 2011 conference (2011, June)

In the presence of induction motors in loads, long-term voltage instability may result in sharp voltage decreases, once the generators supporting transmission voltages have their field currents limited ... [more ▼]

In the presence of induction motors in loads, long-term voltage instability may result in sharp voltage decreases, once the generators supporting transmission voltages have their field currents limited. Furthermore, after a fault, induction motors may fail re-accelerating and their stalling leads to short-term voltage instability. This paper investigates the ability of the load shedding scheme, previously proposed by the authors, to deal with both short and long-term voltage instabilities. The scheme is distributed with minimal amount of information exchange. It is also shown that the selectivity of this protection scheme can be increased by prioritizing in time the various controllers. Detailed time simulations of a test system are reported. [less ▲]

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See detailDecentralized tap changer blocking and load shedding against voltage instability: prospective tests on the RTE system
Capitanescu, Florin ULg; Otomega, Bogdan; Lefebvre, Hervé et al

in International Journal of Electrical Power & Energy Systems (2009), 31(9), 570-576

This paper reports on prospective tests of a system protection scheme against long-term voltage instability relying on a set of distributed controllers, each monitoring a transmission voltage, blocking ... [more ▼]

This paper reports on prospective tests of a system protection scheme against long-term voltage instability relying on a set of distributed controllers, each monitoring a transmission voltage, blocking tap changers and shedding loads in a zone. The emergency actions adjust in magnitude and location to the disturbance. Each controller acts in closed-loop, which guarantees robustness. The method is illustrated on a real-life model of the Western region of the RTE system. The choice of the controller settings is discussed in some detail and examples of performance are given, combining the above remedial action with capacitor switching and secondary voltage control. [less ▲]

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See detailLocal vs. wide-area undervoltage load shedding in the presence of induction motor loads
Otomega, Bogdan; Van Cutsem, Thierry ULg

in Proceedings of the IEEE PES PowerTech 2009 conference (2009, July)

In the presence of induction motor loads, long-term voltage instability may end up in a sharp voltage decrease, which makes the tuning of undervoltage load shedding more delicate. This paper first ... [more ▼]

In the presence of induction motor loads, long-term voltage instability may end up in a sharp voltage decrease, which makes the tuning of undervoltage load shedding more delicate. This paper first investigates the ability of a purely distributed load shedding scheme, previously proposed by the authors, to cope with these situations. Owing to difficulties to reconcile dependability and security, an alternative wide-area protection is considered. The latter consists of generators sending overexcitation signals to the load shedding controllers in order to allow the latter to act faster. Detailed time simulations of a test system are reported. [less ▲]

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See detailPROSPECTS OF AN IMPROVED SYSTEM PROTECTION SCHEME AGAINST VOLTAGE INSTABILITY IN THE RTE SYSTEM
Capitanescu, Florin ULg; Otomega, Bogdan; Lefebvre, Hervé et al

(2008, July)

This paper reports on prospective tests of a system protection scheme against long-term voltage instability relying on a set of distributed controllers, each monitoring a transmission voltage, blocking ... [more ▼]

This paper reports on prospective tests of a system protection scheme against long-term voltage instability relying on a set of distributed controllers, each monitoring a transmission voltage, blocking tap changers and shedding loads in a zone. The emergency actions adjust in magnitude and location to the disturbance. Each controller acts in closed loop, which guarantees robustness. The method is illustrated on a real-life model of the Western region of the RTE system. The choice of the controller settings is discussed in some detail and examples of performance are given, combining the above remedial action with capacitor switching and secondary voltage control. [less ▲]

Detailed reference viewed: 81 (7 ULg)
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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 ▲]

Detailed reference viewed: 71 (2 ULg)
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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 ▲]

Detailed reference viewed: 52 (4 ULg)
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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 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 ▲]

Detailed reference viewed: 57 (15 ULg)
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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 ▲]

Detailed reference viewed: 55 (7 ULg)
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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 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 ▲]

Detailed reference viewed: 51 (5 ULg)