Detection and identification of topology errors in electric power systems
TL;DR: In this paper, a method for detecting topology errors in electric power networks is developed by providing a geometric interpretation of the measurement residuals caused by such errors, and an equation is developed for a matrix whose column linear dependencies determine topology error detectability and identifiability.
Abstract: A method for detecting topology errors in electric power networks is developed by providing a geometric interpretation of the measurement residuals caused by such errors. A test for single topology errors is presented that is similar to the normalized residuals test for measurement errors. This test is generalized to multiple topology errors. The concept of critical network branches (where their removal renders the network unobservable) is introduced and extended to critical-branch k-tuples. It is shown that topology errors on critical branches cannot be detected from measurement residuals. An equation is developed for a matrix whose column linear dependencies determine topology error detectability and identifiability. An example for an IEEE 14 bus network is provided. >
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TL;DR: It is shown that undetectable attacks do not exist if a set of meters satisfying a certain branch covering property are protected, and their effect on real-time locational marginal pricing is examined.
Abstract: Covert data attacks on the network topology of a smart grid is considered. In a so-called man-in-the-middle attack, an adversary alters data from certain meters and network switches to mislead the control center with an incorrect network topology while avoiding detections by the control center. A necessary and sufficient condition for the existence of an undetectable attack is obtained for strong adversaries who can observe all meter and network data. For weak adversaries with only local information, a heuristic method of undetectable attack is proposed. Countermeasures to prevent undetectable attacks are also considered. It is shown that undetectable attacks do not exist if a set of meters satisfying a certain branch covering property are protected. The proposed attacks are tested with IEEE 14-bus and IEEE 118-bus system, and their effect on real-time locational marginal pricing is examined.
273 citations
Cites background from "Detection and identification of top..."
...The problem of detecting topology error from meter data is in fact a classical problem, casted as part of the bad data detection problem [12]–[14]....
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TL;DR: In this paper, an algorithm for solving LMS (least median of squares) in nonlinear systems has been proposed, where solutions are found through resampling methods based on linear approximations.
Abstract: An algorithm for solving LMS (least median of squares) in nonlinear systems has been proposed. The solutions are found through resampling methods based on linear approximations. These methods are suitable for parallel processing. The robustness of the LMS estimator has been verified on several test systems and illustrated on the IEEE 14-bus system. The concept of leverage points shed new light on the meter placement issue as well as the concepts of local redundancy and local breakdown point. A preliminary conclusion is that shorter lines have to be provided with enough measurements in order to increase their local redundancy. Indeed, they tend to be isolated in the factor space and weakly coupled with the surrounding measurements. >
158 citations
TL;DR: In this paper, a method for topology error identification based on the use of normalized Lagrange multipliers is proposed, which models circuit breakers as network switching branches whose statuses are treated as operational constraints in the state estimation problem.
Abstract: This paper introduces a method for topology error identification based on the use of normalized Lagrange multipliers. The proposed methodology models circuit breakers as network switching branches whose statuses are treated as operational constraints in the state estimation problem. The corresponding Lagrange multipliers are then normalized and used as a tool for topology error identification, in the same fashion as measurement normalized residuals are conventionally employed for analog bad data processing. Results of tests performed with the proposed algorithm for different types of topology errors are reported.
140 citations
TL;DR: In this paper, a linearized incremental small-signal power system model is used in conjunction with high-speed synchronized voltage phase angle measurements obtained from phasor measurement units.
Abstract: A method is proposed to detect and identify power system transmission line outages in near real-time. The method exploits the statistical properties of the small random fluctuations in electricity generation and demand that a power system is subject to as time evolves. To detect and identify transmission line outages, a linearized incremental small-signal power system model is used in conjunction with high-speed synchronized voltage phase angle measurements obtained from phasor measurement units. By monitoring the statistical properties of voltage phase angle time-series, line outages are detected and identified using techniques borrowed from the theory of quickest change detection. As illustrated through case studies, the proposed method is effective in detecting and identifying single- and double-line outages in an accurate and timely fashion.
133 citations
Cites background from "Detection and identification of top..."
...Numerous approaches have been proposed to detect and identify topology errors in the context of state estimation [8]–[10]....
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TL;DR: A practical algorithm that uses real-time measurements to estimate parameter errors and a sensitivity based error identification approach and a weighted least square (WLS) estimation is proposed that can be easily incorporated into any state estimation package.
Abstract: Network parameter errors can severely impact the quality of state estimation solutions and degrade the usefulness of advanced applications in an energy management system (EMS). An efficient and effective algorithm is needed to estimate the network parameters. In this paper, a practical algorithm that uses real-time measurements to estimate parameter errors is proposed. The algorithm consists of a sensitivity based error identification approach and a weighted least square (WLS) estimation. It can be easily incorporated into any state estimation package. The algorithm has been implemented In the PG&E EMS and tested using the real-time data. Test results are very promising. >
125 citations
References
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TL;DR: An approximate mathematical model related to the dc load-flow model yields noniterative-state estimation equations, simplified prediction of effects of network and generation-load pattern changes on network flow, and simplified detection and identification of modeling errors.
Abstract: The static state of an electric power system is defined as the vector of the voltage magnitudes and angles at all network buses. The static-state estimator is a data-processing algorithm for converting redundant meter readings and other available information into an estimate of the static-state vector. Discussions center on an approximate mathematical model (related to the dc load-flow model). This model yields noniterative-state estimation equations, simplified prediction of effects of network and generation-load pattern changes on network flow, and simplified detection and identification of modeling errors. Results of some initial computer studies on the real power-voltage angle portion of the approximate model are discussed.
439 citations
TL;DR: In this paper, a power system is observable if the measurements made on it allow determination of bus voltage magnitude and angle at every bus of the network, and the theoretical basis for an algorithm for determining observability is presented.
Abstract: A power system is observable if the measurements made on it allow determination of bus voltage magnitude and angle at every bus of the network. This paper outlines the theoretical basis for an algorithm for determining observability. Based on this theory, an algorithm for networks containing both bus injection and line flow measurements is presented.
414 citations
TL;DR: The efficiency of the sparse vector methods is verified by tests on a 156-bus, a 1598-bus and a 2265-bus system and the new methods are significantly faster than the established sparse matrix techniques.
Abstract: Sparse vector methods enhance the efficiency of matrix solution algorithms by exploiting the sparsity of the independent vector and/or the desire to know only a subset of the unknown vector. This paper shows how these methods can be efficiently implemented for sparse matrices. The efficiency of the sparse vector methods is verified by tests on a 156-bus, a 1598-bus and a 2265-bus system. In all cases tested, the new methods are significantly faster than the established sparse matrix techniques.
338 citations
01 Dec 1987
TL;DR: The various steps in constructing the model from the real-time measurements are described, including the determination of the network topology, the estimation of thenetwork state, and the approximate modeling of the unobservable (external) network.
Abstract: The use of large digital computers in control centers has made it possible to track the changing conditions in the power system with a mathematical model in the computer. This real-time model can be used to assess the security of the present system as well as to check out possible control strategies. In this paper the various steps in constructing the model from the real-time measurements are described. These steps include the determination of the network topology, the estimation of the network state, and the approximate modeling of the unobservable (external) network. This paper also discusses the checks for observability and bad measurements, and the calculation of bus load forecast factors and generator penalty factors.
183 citations
TL;DR: In this paper, the authors developed the theoretical basis for determining the bad measurement detectability properties of the state estimator from the topology of the 1-line diagram and the locations of the measurements.
Abstract: A power system static-state estimator has the ability to detect and purge some measurement errors. This paper develops the theoretical basis for determining the bad measurement detectability properties of the state estimator from the topology of the 1-line diagram and the locations of the measurements. Based on this theory, an algorithm is described that: 1) identifies those measurements that have detectable error residuals; and 2) determines the regions of measurement error residual spread.
159 citations