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J. Y. Leost

Bio: J. Y. Leost is an academic researcher from Électricité de France. The author has contributed to research in topics: Voltage regulator & Automatic control. The author has an hindex of 2, co-authored 3 publications receiving 589 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors present studies conducted to reach an automatic determination of zones and pilot nodes based on the examination of the structure of the network and the concept of electrical distance has been developed.
Abstract: The voltage control of the French EHV power system is organized in three levels (primary, secondary, and tertiary) which concern distinct geographical areas and time constants. The authors present studies conducted to reach an automatic determination of zones and pilot nodes based on the examination of the structure of the network. The concept of electrical distance has been developed, and its close relationship with the theory of information is underlined. This concept allows the concept of structural controllability and observability of proximity to be extended to the power system. The combined use of this electrical distance and typological analysis algorithms has proven an effective method for the identification of the secondary voltage control zones of the French grid. >

313 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a review of the present regional secondary voltage control, and the prospects for the evolution towards a co-ordinated system, based on a sensitivity matrix model, closed-loop pole assignment and adaptive techniques.
Abstract: The voltage control of the french power system is organized in three hierarchical levels, which concern distinct geographical areas and time constants. The rapid and random variations are compensated by local primary and automatic actions on the generators A.V.Rs, then the slow variations are regulated by the secondary (at regional level) and tertiary (at national level) actions. The paper gives a review of the present regional secondary voltage control, and the prospects for the evolution towards a co-ordinated system, based on a sensitivity matrix model, closed-loop pole assignment and adaptive techniques. Analog and digital simulations are presented.

285 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the placement of a minimal set of phasor measurement units (PMUs) so as to make the system measurement model observable, and thereby linear, is investigated.
Abstract: The placement of a minimal set of phasor measurement units (PMUs) so as to make the system measurement model observable, and thereby linear, is investigated. A PMU placed at a bus measures the voltage as well as all the current phasors at that bus, requiring the extension of the topological observability theory. In particular, the concept of spanning tree is extended to that of spanning measurement subgraph with an actual or a pseudomeasurement assigned to each of its branches. The minimal PMU set is found through a dual search algorithm which uses both a modified bisecting search and a simulated-annealing-based method. The former fixes the number of PMUs while the latter looks for a placement set that leads to an observable network for a fixed number of PMUs. In order to accelerate the procedure, an initial PMU placement is provided by a graph-theoretic procedure which builds a spanning measurement subgraph according to a depth-first search. From computer simulation results for various test systems it appears that only one fourth to one third of the system buses need to be provided with PMUs in order to make the system observable. >

728 citations

Journal ArticleDOI
09 May 2005
TL;DR: The thesis of this paper is that the changing environment requires a new look at the operation of the power grid and a complete redesign of the control, communication and computation infrastructure.
Abstract: The power grid is not only a network interconnecting generators and loads through a transmission and distribution system, but is overlaid with a communication and control system that enables economic and secure operation. This multilayered infrastructure has evolved over many decades utilizing new technologies as they have appeared. This evolution has been slow and incremental, as the operation of the power system consisting of vertically integrated utilities has, until recently, changed very little. The monitoring of the grid is still done by a hierarchical design with polling for data at scanning rates in seconds that reflects the conceptual design of the 1960s. This design was adequate for vertically integrated utilities with limited feedback and wide-area controls; however, the thesis of this paper is that the changing environment, in both policy and technology, requires a new look at the operation of the power grid and a complete redesign of the control, communication and computation infrastructure. We provide several example novel control and communication regimes for such a new infrastructure.

337 citations

Journal ArticleDOI
01 Feb 2000
TL;DR: In this paper, the authors describe voltage instability phenomena, enumerate preventive and curative countermeasures, and present in a unified and coherent way various computer analysis methods used or proposed.
Abstract: A power system may be subject to (rotor) angle, frequency or voltage instability. Voltage instability takes on the form of a dramatic drop of transmission system voltages, which may lead to system disruption. During the past two decades it has become a major threat for the operation of many systems and, in the prevailing open access environment, it is a factor leading to limit power transfer. The objective of this paper is to describe voltage instability phenomena, to enumerate preventive and curative countermeasures, and to present in a unified and coherent way various computer analysis methods used or proposed.

318 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present studies conducted to reach an automatic determination of zones and pilot nodes based on the examination of the structure of the network and the concept of electrical distance has been developed.
Abstract: The voltage control of the French EHV power system is organized in three levels (primary, secondary, and tertiary) which concern distinct geographical areas and time constants. The authors present studies conducted to reach an automatic determination of zones and pilot nodes based on the examination of the structure of the network. The concept of electrical distance has been developed, and its close relationship with the theory of information is underlined. This concept allows the concept of structural controllability and observability of proximity to be extended to the power system. The combined use of this electrical distance and typological analysis algorithms has proven an effective method for the identification of the secondary voltage control zones of the French grid. >

313 citations

Journal ArticleDOI
TL;DR: In this paper, a new algorithm is developed to find the best line and bus-bar switching action for relieving overloads and voltage violations caused by system contingencies based on a sparse inverse technique and fast decoupled power flow with limited iteration count.
Abstract: It is widely known that corrective switching, including transmission line switching, bus-bar switching, and shunt element switching, may change the states of the power systems, and consequently, affect the distribution of power flows, transmission losses, short circuit currents, voltage profiles as well as transient stability of power systems. In this paper, a new algorithm is developed to find the best line and bus-bar switching action for relieving overloads and voltage violations caused by system contingencies based on a sparse inverse technique and fast decoupled power flow with limited iteration count. A general model of bus-bar switching action is also presented such that the new algorithm can simulate any kind of complicated bus-bar switching action. Furthermore, on the basis of a newly proposed voltage distribution factor by multiple iterations in power flow calculation, a novel algorithm for corrective voltage control by shunt switching is developed. These two algorithms are then integrated into a corrective switching algorithm. Simulation results on the WECC 179-bus system indicate that the new corrective switching algorithm proposed in this paper can effectively solve certain problems of line overloads and voltage violations. The computation time required is also satisfactory.

262 citations