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Gustavo Valverde

Bio: Gustavo Valverde is an academic researcher from University of Costa Rica. The author has contributed to research in topics: AC power & Distributed generation. The author has an hindex of 15, co-authored 49 publications receiving 1973 citations. Previous affiliations of Gustavo Valverde include University of Manchester & ETH Zurich.


Papers
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Journal ArticleDOI
01 Jan 2011
TL;DR: It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties.
Abstract: Wide-area monitoring, protection, and control (WAMPAC) involves the use of system-wide information and the communication of selected local information to a remote location to counteract the propagation of large disturbances. Synchronized measurement technology (SMT) is an important element and enabler of WAMPAC. It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties. In this paper, the technological and application issues are addressed. Several key monitoring, protection, and control applications are described and discussed. A strategy for developing a WAMPAC system in the United Kingdom is given as well.

682 citations

Journal ArticleDOI
TL;DR: In this article, the unscented Kalman filter (UKF) is proposed for power system dynamic state estimation, which is based on the application of the Unscented Transformation (UT) combined with the Kalman Filter theory.
Abstract: A new estimation method for power system dynamic state estimation, the unscented Kalman filter (UKF), is presented. It is based on the application of the unscented transformation (UT) combined with the Kalman filter theory. One of the challenges in the process of power system estimation is coping with a highly non-linear mathematical model of network equations, which is usually approximated through a linearisation. The new derivative free estimation method overcomes this limitation using the UT and achieves better accuracy with simpler implementation. The UKF is derived and demonstrated using three different test power systems under typical network and measurement conditions. Its performance is compared with the classical extended Kalman filter. The simplicity of the new estimator and its low computational demand make it a better option to be applied in the next generation of dynamic system estimators.

325 citations

Journal ArticleDOI
TL;DR: A centralized control scheme to regulate distribution network voltages in the presence of high penetration of distributed generation using a linear model to predict the behavior of the system and the optimization is solved using quadratic programming.
Abstract: This paper presents a centralized control scheme to regulate distribution network voltages in the presence of high penetration of distributed generation. The approach is inspired of Model Predictive Control in order to compensate for modeling inaccuracies and measurement noise. The control actions, calculated from a multi-step optimization, are updated and corrected by real-time measurements. The proposed controller uses a linear model to predict the behavior of the system and the optimization is solved using quadratic programming. The proposed corrective control has been tested in a 11-kV distribution network including 75 nodes and hosting 22 distributed generating units.

265 citations

Journal ArticleDOI
TL;DR: The motivation, state-of-the-art, and future directions of the coordination of transmission system operators (TSO) and distribution system operator (DSO) are thoroughly discussed.
Abstract: In this paper, we review the emerging challenges and research opportunities for voltage control in smart grids. For transmission grids, the voltage control for accommodating wind and solar power, fault-induced delayed voltage recovery, and measurement-based Thevenin equivalent for voltage stability analysis are reviewed. For distribution grids, the impact of high penetration of distributed energy resources is analyzed, typical control strategies are reviewed, and the challenges for local inverter Volt–Var control is discussed. In addition, the motivation, state-of-the-art, and future directions of the coordination of transmission system operators (TSO) and distribution system operators (DSO) are also thoroughly discussed.

246 citations

Journal ArticleDOI
TL;DR: In this article, the conventional and synchrophasor measurements are simultaneously incorporated in the estimation problem without using any transformation of measurements, which makes it possible to take advantage of information from phasor measurement unit (PMU) branch current and voltage measurements.
Abstract: This paper presents a new hybrid constrained power system state estimator. The conventional and synchrophasor measurements are simultaneously incorporated in the estimation problem without using any transformation of measurements. This constrained formulation makes it possible to take advantage of information from phasor measurement unit (PMU) branch current and voltage measurements, improving the accuracy of the existing estimators. The methodology is applied on the IEEE 14-, 57-, and 118-bus test systems, and its performance is compared with other hybrid estimators.

131 citations


Cited by
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Journal Article
TL;DR: In this paper, a documento: "Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita" voteato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamentsi Climatici (Intergovernmental Panel on Climate Change).
Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.

3,979 citations

Journal ArticleDOI
TL;DR: In this paper, the authors study how to optimally manage the freshness of information updates sent from a source node to a destination via a channel and develop efficient algorithms to find the optimal update policy among all causal policies and establish sufficient and necessary conditions for the optimality of the zero-wait policy.
Abstract: In this paper, we study how to optimally manage the freshness of information updates sent from a source node to a destination via a channel. A proper metric for data freshness at the destination is the age-of-information , or simply age , which is defined as how old the freshest received update is, since the moment that this update was generated at the source node (e.g., a sensor). A reasonable update policy is the zero-wait policy, i.e., the source node submits a fresh update once the previous update is delivered, which achieves the maximum throughput and the minimum delay. Surprisingly, this zero-wait policy does not always minimize the age. This counter-intuitive phenomenon motivates us to study how to optimally control information updates to keep the data fresh and to understand when the zero-wait policy is optimal. We introduce a general age penalty function to characterize the level of dissatisfaction on data staleness and formulate the average age penalty minimization problem as a constrained semi-Markov decision problem with an uncountable state space. We develop efficient algorithms to find the optimal update policy among all causal policies and establish sufficient and necessary conditions for the optimality of the zero-wait policy. Our investigation shows that the zero-wait policy is far from the optimum if: 1) the age penalty function grows quickly with respect to the age; 2) the packet transmission times over the channel are positively correlated over time; or 3) the packet transmission times are highly random (e.g., following a heavy-tail distribution).

857 citations

Journal ArticleDOI
01 Jan 2011
TL;DR: It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties.
Abstract: Wide-area monitoring, protection, and control (WAMPAC) involves the use of system-wide information and the communication of selected local information to a remote location to counteract the propagation of large disturbances. Synchronized measurement technology (SMT) is an important element and enabler of WAMPAC. It is expected that WAMPAC systems will in the future reduce the number of catastrophic blackouts and generally improve the reliability and security of energy production, transmission, and distribution, particularly in power networks with a high level of operational uncertainties. In this paper, the technological and application issues are addressed. Several key monitoring, protection, and control applications are described and discussed. A strategy for developing a WAMPAC system in the United Kingdom is given as well.

682 citations

Journal ArticleDOI
TL;DR: This paper compiles information about different communication network requirements for different smart grid applications, ranging from those used in a Home Area Network, Neighborhood Area Network and Wide-Area Network, to serve as a comprehensive database of technology requirements and best practices for use by communication engineers when designing a smart grid network.

490 citations