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Reconstructing and Tracking Network State from a Limited Number of Synchrophasor Measurements ; Van Cutsem, Thierry in IEEE Transactions on Power Systems (2013), 28 A method is proposed to reconstruct and track network state from a limited number of Phasor Measurement Unit (PMU) data. To deal with the resulting unobservability, the state with bus powers and generator ... [more ▼] A method is proposed to reconstruct and track network state from a limited number of Phasor Measurement Unit (PMU) data. To deal with the resulting unobservability, the state with bus powers and generator voltages closest to previously estimated values is computed. Those values, treated as pseudomeasurements, are obtained from the last reconstructed state, in a recursive manner. The method involves solving an optimization problem with linear constraints. It is scalable insofar as it accommodates from a few PMUs up to configurations ensuring full network observability. Reconstruction of only a region is possible. These and other features are demonstrated on the Nordic32 test system, with synchronized phasors obtained from detailed time simulation of a situation evolving towards instability. Suitable choices of PMU location and pseudo-measurements are also discussed. [less ▲] Detailed reference viewed: 246 (32 ULg)Power system dynamic simulation: an iterative multirate approach Plumier, Frédéric ; Geuzaine, Christophe ; Van Cutsem, Thierry Poster (2013, April) Detailed reference viewed: 131 (14 ULg)Power System Simulation Challenges Aristidou, Petros ; Plumier, Frédéric ; Van Cutsem, Thierry et al Scientific conference (2013, March 05) Detailed reference viewed: 142 (12 ULg)Linearized Power Flow Equations Based Predictive Control of Transmission Voltages ; ; et al in Proceedings of the 46th Hawaii International Conference on System Sciences (HICSS-46) (2013, January) In this paper, an approach based on the concept of Model Predictive Control (MPC) is used to control transmission voltages and prevent long-term voltage instability. The MPC model is based on a linearized ... [more ▼] In this paper, an approach based on the concept of Model Predictive Control (MPC) is used to control transmission voltages and prevent long-term voltage instability. The MPC model is based on a linearized steady-state system model derived from power flow equations. Simulation results are presented for the case of Nordic32 test system. [less ▲] Detailed reference viewed: 199 (4 ULg)Wide-Area Adaptive Load Shedding Control to Counteract Voltage Instability ; ; Van Cutsem, Thierry 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 ▲] Detailed reference viewed: 128 (7 ULg)State Reconstruction from a Limited Number of Synchronized Phasor Measurements: Application to Voltage Instability Detection ; Van Cutsem, Thierry in Proceedings of the IEEE PES General Meeting (2012, July) This paper deals with the performance of the wide-area monitoring previously proposed by the authors in [1], [2] for early detection of voltage instability, when a limited number of synchronized phasor ... [more ▼] This paper deals with the performance of the wide-area monitoring previously proposed by the authors in [1], [2] for early detection of voltage instability, when a limited number of synchronized phasor measurements is available. This sensitivity-based scheme assumed that phasor measurements are sufficient in number and location for a state estimator to determine the voltages at all buses of the region prone to voltage instability. This paper demonstrates that the method still performs well when relying on bus voltages obtained from a state reconstruction procedure exploiting a limited number of synchronized phasor measurements which do not make the region of concern observable. The state reconstruction is formulated as the minimization, under constraints, of a weighted least square objective involving the available phasor measurements together with bus power pseudo-measurements relative to a reference state. The presented results relate to a 52-bus system with phasor measurements obtained from detailed time simulation of a long-term voltage unstable evolution triggered by a large disturbance. [1] M. Glavic, T. Van Cutsem, “Wide-Area Detection of Voltage Instability From Synchronized Phasor Measurements. Part I: Principle,” IEEE Trans. Power Syst., Vol. 24, No. 3, pp. 1408-1416, Aug. 2009 [2] M. Glavic, T. Van Cutsem, “Wide-Area Detection of Voltage Instability From Synchronized Phasor Measurements. Part II: Simulation Results,” IEEE Trans. Power Syst., Vol. 24, No. 3, pp. 1417-1425, Aug. 2009 [less ▲] Detailed reference viewed: 67 (7 ULg)A Schur Complement Method for DAE Systems in Power System Simulations Aristidou, Petros ; Fabozzi, Davide ; Van Cutsem, Thierry Scientific conference (2012, June 28) The power system networks in North America and Europe are the largest man-made interconnected systems in the world. Many power system applications rely on time consuming dynamic simulations of large-scale ... [more ▼] The power system networks in North America and Europe are the largest man-made interconnected systems in the world. Many power system applications rely on time consuming dynamic simulations of large-scale power systems in order to optimize the operation and ensure the reliability of the electricity network. Dynamic simulations of power systems involve the solution of a series of initial value, stiff, hybrid DAE systems over a time window. To achieve this, the time window is discretized and a new DAE system is formed and solved at each time step, with initial values taken from the previous time step solution. At each new time step, the DAE system to be solved can be different because of the discrete variables involved in the formulation (e.g. a differential equation can become algebraic and vice versa). A non-overlapping domain decomposition is proposed to speed up the solution of the DAE system using the Schur Complement Method. The special structure of the physical system helps define the domain partitioning scheme and eliminates the need for a partitioning algorithm. It allows the formulation and solution of the reduced system using sparse, direct solvers to obtain the interface variables. Afterward, the parallel evaluation of the internal subdomain variables is possible and efficient load balancing is achieved. Numerically, the method shows no convergence degradation when compared to the integrated method, which is traditionally used for solving power system DAEs. The aspects of decomposition, solution and optimization of the algorithm for the specific problem are discussed and results from the application of the DDM on realistic power system models are presented. [less ▲] Detailed reference viewed: 156 (34 ULg)Combining Full Transients and Phasor Approximation Models in Power System Time Simulation Plumier, Frédéric ; Fabozzi, Davide ; Geuzaine, Christophe et al in Proceedings of the 21th International Conference on Domain Decomposition Methods (DD21) (2012, June) Detailed reference viewed: 164 (33 ULg)A two-time scale simulation for dynamic analysis of power systems ; ; Van Cutsem, Thierry in Electric Power Systems Research (2012), 83 This paper proposes a two-time scale simulation approach of both short-term and long-term dynamics in power systems. The short-term transient period is analyzed by a full-time scale simulation while a ... [more ▼] This paper proposes a two-time scale simulation approach of both short-term and long-term dynamics in power systems. The short-term transient period is analyzed by a full-time scale simulation while a quasi-steady state model of the power system is used to simulate long-term dynamics. The proposed method is inspired of Singular Perturbation theory to model the interaction between the short-term and long-term dynamics. Based on this interaction, a suitable criterion to determine when the quasi-steady state model of a power system can be considered as a uniform approximation of the full-time scale model is proposed, which also determines the appropriate switching time between models. The proposed method is demonstrated on the 10-machine, 39-bus New England system and a 46-machine, 190-bus equivalent Mexican system. [less ▲] Detailed reference viewed: 238 (7 ULg)Simplified dynamic simulation Van Cutsem, Thierry ; Fabozzi, Davide Conference (2011, December 06) These are the slides of an invited presentation at the panel session "Pan European Grid Advanced Simulation and State Estimation (PEGASE)", aimed at disseminating the results of the PEGASE project funded ... [more ▼] These are the slides of an invited presentation at the panel session "Pan European Grid Advanced Simulation and State Estimation (PEGASE)", aimed at disseminating the results of the PEGASE project funded by European Community’s 7th Framework Programme (grant agreement No. 211407) [less ▲] Detailed reference viewed: 156 (11 ULg)Assessing the Proximity of Time Evolutions through Dynamic Time Warping Fabozzi, Davide ; Van Cutsem, Thierry in IET Generation, Transmission & Distribution (2011), 5(12), 1268-1276 Comparing time-series is a frequent task in many scientific fields. In power systems, in particular, it may be of interest to compare the outputs of a simplified and a detailed model, or to validate the ... [more ▼] Comparing time-series is a frequent task in many scientific fields. In power systems, in particular, it may be of interest to compare the outputs of a simplified and a detailed model, or to validate the output of a model with respect to a measured time response. The classical Euclidean distance, involving pairs of points of the two data series aligned in time, is not suited to the practical time evolutions met in power systems, which often involve variable time delays and jumps at discrete times. In this paper, an alternative measure of proximity, stemming from other scientific fields, is proposed for power system applications. It consists in warping the time axis to guarantee the best match between the two time-series, i.e. it maps points on two curves that are not aligned in time so as to minimize the sum of squared differences of their ordinates. Modifications and adaptations of the classical algorithm to better fit power system problems are discussed. The method is illustrated through three representative curve comparison problems. A multi-dimensional extension allowing system-wide measures of similarity is also proposed. [less ▲] Detailed reference viewed: 139 (15 ULg)State Reconstruction from Synchronized Phasor Measurements ; Van Cutsem, Thierry in Proceedings of the IEEE PES Innovative Smart Grid Technologies Europe 2011 (2011, December) The traditional state estimator relies on measurements affected by time skew and, while the whole system can be made observable, it cannot track the post-disturbance dynamics. Synchronized phasor ... [more ▼] The traditional state estimator relies on measurements affected by time skew and, while the whole system can be made observable, it cannot track the post-disturbance dynamics. Synchronized phasor measurements, on the other hand, can track those dynamics but, in a foreseeable future, they will be available in scarce configurations that do not allow estimating the whole system state. State reconstruction precisely aims at using the available phasor measurements to track the evolution of the power system - at least in a region of interest - in between two runs of a traditional state estimator. It minimizes under constraints a weighted least square objective involving both the phasor measurements and bus power pseudo-measurements relative to a reference state. The placement of phasor measurement units at the generator buses is recommended for accuracy. Tests are reported with phasor measurements obtained from time simulation of post-disturbance system evolution. The results deal with the effect on accuracy of the relative weights assigned to phasor and pseudo-measurements, the benefit of taking the reference bus powers from the last reconstructed instead of the pre-disturbance state, and the rate of the state reconstructions. [less ▲] Detailed reference viewed: 61 (5 ULg)Receding-horizon multi-step optimization to correct nonviable or unstable transmission voltages ; ; et al in IEEE Transactions on Power Systems (2011), 26(3), 1641-1650 In this paper, a receding-horizon multi-step optimization is proposed to correct non viable transmission voltages and prevent long-term voltage instability. The proposed control scheme is based on real ... [more ▼] In this paper, a receding-horizon multi-step optimization is proposed to correct non viable transmission voltages and prevent long-term voltage instability. The proposed control scheme is based on real-time control, inspired by model predictive control, and steady state power-flow-based equations. In order to anticipate load behavior and avoid using dynamic equations in the control scheme, explicit formulations are used to model evolution of load with time. The simulation results of the proposed technique are presented on the Nordic32 test system. [less ▲] Detailed reference viewed: 131 (25 ULg)On simplified handling of state events in time-domain simulation Fabozzi, Davide ; ; et al in Proceedings of the 17th PSCC (2011, August) The power system models typically used in dynamic simulations involve discrete events in addition to the standard differential-algebraic equations. Those events cause the system to jump from one ... [more ▼] The power system models typically used in dynamic simulations involve discrete events in addition to the standard differential-algebraic equations. Those events cause the system to jump from one continuous behavior to another. Solvers have to handle those jumps. This paper focuses on simplified time simulation where large steps are used in conjunction with stiff-decay integration methods to obtain approximate solutions in short computing times. In the proposed simulation scheme, the simulation time steps are not synchronized with the system jumps, which are treated a posteriori in a corrective step. In this context, the paper analyzes several simple nonlinear models involving limiters, switches, minimum gates, etc. from which some precautions to be taken at the modelling and solving stages are stressed. The paper also reports on results obtained with a representative power system model. [less ▲] Detailed reference viewed: 135 (39 ULg)A short Survey of Methods for Voltage Instability Detection ; Van Cutsem, Thierry in Proceedings of the IEEE PES General Meeting (2011, July) This paper shortly surveys existing and proposed methods for voltage instability detection. The emphasis is on methods relying on real-time measurements as well as on long-term voltage instability ... [more ▼] This paper shortly surveys existing and proposed methods for voltage instability detection. The emphasis is on methods relying on real-time measurements as well as on long-term voltage instability. Methods are classified according to the required measurement configuration: local vs. wide-area, standard SCADA-type vs. synchronized phasor measurements, etc. In the various categories, some of the features are summarized, and what appears to the authors as advantages or limitations is shortly discussed. An important feature is the ability to anticipate instability. Some tracks for further work on the subject are also outlined. [less ▲] Detailed reference viewed: 188 (7 ULg)Investigating State Reconstruction from Scarce Synchronized Phasor Measurements ; Van Cutsem, Thierry in Proceedings of the IEEE Trondheim Power Tech 2011 conference (2011, June) Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those ... [more ▼] Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those measurements are too scarce for the whole system state to be estimated. Therefore, we investigate the possibility to reconstruct coherent, time-synchronized system states from the available PMU data. State reconstruction is formulated as an optimization problem. The objective is to minimize, in the space of bus powers, the distance between the reconstructed state and the last state estimate provided by a standard state estimator. PMU data are imposed as equality constraints. Furthermore, the placement of PMUs near generators is advocated for higher accuracy of state reconstruction. The performance and potential benefits of the approach are illustrated by processing snapshots obtained from detailed time simulation of a test system subject to a disturbance and corrective actions. [less ▲] Detailed reference viewed: 57 (5 ULg)A load shedding scheme against both short- and long-term voltage instabilities in the presence of induction motors ; Van Cutsem, Thierry 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 ▲] Detailed reference viewed: 87 (2 ULg)On angle references in long-term time-domain simulations Fabozzi, Davide ; Van Cutsem, Thierry in IEEE Transactions on Power Systems (2011), 26(1), 483-484 Abstract—In power system dynamic models the complex network equations and the various phasors are projected onto reference axes. After a short critical review of commonly chosen reference axes, this ... [more ▼] Abstract—In power system dynamic models the complex network equations and the various phasors are projected onto reference axes. After a short critical review of commonly chosen reference axes, this letter proposes to use the center-of-inertia at the previous integration time step. This approach is shown to combine the advantages of the center-of-inertia with a sparser Jacobian structure and an easier handling of network splits. [less ▲] Detailed reference viewed: 259 (50 ULg)A Taxonomy of Multi-Area State Estimation Methods ; ; et al in Electric Power Systems Research (2011), 81(4), 1060-1069 This paper presents a critical review of the state of the art in Multi-Area State Estimation (MASE) methods, which are currently gaining renewed interest due to their capability of properly tracking multi ... [more ▼] This paper presents a critical review of the state of the art in Multi-Area State Estimation (MASE) methods, which are currently gaining renewed interest due to their capability of properly tracking multi-TSO transactions and accommodating highly redundant information systems. Based on several classification criteria, a taxonomy of MASE methods is first proposed. Two main categories, namely two-step or hierarchical versus decentralized, are identified. Then, for each class of methods, the resulting model structure and area interactions are discussed and a brief presentation is made of a selected subset of references. [less ▲] Detailed reference viewed: 268 (18 ULg)Wind integration and AGC frequency dynamics simulations using Quasi Steady-State approximation ; ; Van Cutsem, Thierry in Proc. of 9th international workshop on large-scale integration of wind power in powers systems (2010, October) Frequency dynamics studies are important at Hydro-Québec (HQ). Wind integration raises questions about HQ ability to maintain frequency regulation in normal operation and during contingencies. Quasi ... [more ▼] Frequency dynamics studies are important at Hydro-Québec (HQ). Wind integration raises questions about HQ ability to maintain frequency regulation in normal operation and during contingencies. Quasi Steady-State (QSS) approximation is the best alternative to simulate long-term voltage and frequency dynamics without compromising the exactness of simulation results. Collaboration between HQ and University of Liège allowed the development of numerous models. Frequency dynamics is represented by machines inertia, speed governors and a complete AGC controlling 13 hydro power plants including transmission delays. For voltage dynamics, static var compensators, synchronous condensers and tap changer transformers are also represented. Wind farms are modeled as generation patterns (Pwind = f(t)) including a Wind Farm Management System (WFMS). This paper addresses wind farm integration and AGC frequency regulation. Based on HQ field measurements and observations, the most pessimistic cases were simulated. Two scenarios are detailed: the 3500 MW of wind farms currently planned for 2015 and a hypothetical 10 000 MW of wind integration. The results show that actual AGC settings are accurate for the planned wind farms, but might need some changes for a 10 000 MW scenario. [less ▲] Detailed reference viewed: 162 (3 ULg) |
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