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Journal ArticleDOI

Bound Estimates of the Severity of Line Outages in Power System Contingency Analysis and Ranking

F. D. Galiana1
01 Sep 1984-IEEE Power & Energy Magazine (IEEE)-Vol. 103, Iss: 9, pp 2612-2624
TL;DR: In this paper, the effect of line outages on the real power flows of a system is analyzed using the DC load flow model and it is shown that the impact of the out4ge of line jk on the power flow of an arbitrary line lm can be bounded above and below by a series of progressively tighter values which in the limit correspond to the exact load flow solution.
Abstract: The effect of line outages on the real power flows of a system is analyzed using the DC load flow model. It is shown that the effect of the out4ge of line jk on the power flow of an arbitrary line lm can be bounded above and below by a series of progressively tighter values which in the limit correspond to the exact DC load flow solution. The calculation of these bound estimates on the contingency line flows is progressively more computationally demanding as the limits tighten, however, the simple to compute bounds, although more conservative, still serve to filter out a large portion of the non-critical contingencies. The remaining few potentially critical outages can then be ranked and analyzed through the full DC load flow.
Citations
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Journal ArticleDOI
01 Dec 1987
TL;DR: This paper reviews present formulations and methods, and tries to point out areas of difficulty that constitute the main challenges for successful practical on-line implementations over the coming years.
Abstract: An operationally "secure" power system is one with low probability of blackout or equipment damage. The power system control processes needed to maintain a designated security level at minimum operating cost are extremely complicated. They increasingly depend upon on-line computer security analysis and optimization. This on-line technology is still relatively new, with enormous further potential. Since security and optimality are normally conflicting requirements of power system control, it is inappropriate to treat them separately. Therefore, they are slowly becoming coalesced into a unified hierarchical mathematical problem formulation: one that is, however, far too complex to afford anything but an approximate, near-optimal solution. The practical validity of this unifying trend relies on being able to incorporate all significant security constraints within the process. The main two current computational tools in this field are contingency analysis and special operations-oriented versions of optimal power flow (OPF). Contingency analysis identifies potential emergencies through extensive "what if?." simulations on the power system network. OPF is a major extension to the conventional dispatch calculation. It can respect system static security limits, and can schedule reactive as well as active power. Moreover, the advanced versions of OPF include or interface with contingency analysis. This paper reviews present formulations and methods, and tries to point out areas of difficulty that constitute the main challenges for successful practical on-line implementations over the coming years.

533 citations

Journal ArticleDOI
01 Feb 1992
TL;DR: A broad overview of on-line power system security analysis is provided in this paper, with the intent of identifying areas needing additional research and development, such as external system modeling and external system analysis.
Abstract: A broad overview of on-line power system security analysis is provided, with the intent of identifying areas needing additional research and development. Current approaches to state estimation are reviewed and areas needing improvement, such as external system modeling, are discussed. On-line contingency selection has become practical, particularly for static security. Additional work is necessary to identify better indices of power system stress to be used in on-line screening filters for both static and dynamic security analysis. Use of optimal power flow schemes to recommend optimal preventive and corrective strategies is presented on a conceptual level. Techniques must be further developed to provide more practical contingency action plans, which include real-world operating considerations and use a reasonably small number of control actions. Techniques must be developed for costing operating variables which are not easily quantified in dollars. Soft or flexible constraints and time variables must be included in the preventive and corrective strategy formulation. Finally, the area of on-line transient and dynamic security analysis is presented. >

229 citations

Journal ArticleDOI
TL;DR: This paper generalizes the "terrorist threat problem" first defined by Salmero/spl acute/n, Wood, and Baldick by formulating it as a bilevel programming problem, and converts it into an equivalent single-level mixed-integer linear program by replacing the inner optimization by its Karush-Kuhn-Tucker optimality conditions.
Abstract: This paper generalizes the "terrorist threat problem" first defined by Salmero/spl acute/n, Wood, and Baldick by formulating it as a bilevel programming problem. Specifically, the bilevel model allows one to define different objective functions for the terrorist and the system operator as well as permitting the imposition of constraints on the outer optimization that are functions of both the inner and outer variables. This degree of flexibility is not possible through existing max-min models. The bilevel formulation is investigated through a problem in which the goal of the destructive agent is to minimize the number of power system components that must be destroyed in order to cause a loss of load greater than or equal to a specified level. This goal is tempered by the logical assumption that, following a deliberate outage, the system operator will implement all feasible corrective actions to minimize the level of system load shed. The resulting nonlinear mixed-integer bilevel programming formulation is transformed into an equivalent single-level mixed-integer linear program by replacing the inner optimization by its Karush-Kuhn-Tucker optimality conditions and converting a number of nonlinearities to linear equivalents using some well-known integer algebra results. The equivalent formulation has been tested on two case studies, including the 24-bus IEEE Reliability Test System, through the use of commercially available software.

220 citations


Cites background from "Bound Estimates of the Severity of ..."

  • ...The identification of the most critical deliberate outage could be carried out using traditional approaches in which a prespecified set of contingencies is simulated, one at a time [6]–[10]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors present an analytic, closed-form expression for and the computationally efficient evaluation of LODFs under multiple-line outages under a cascading outage scenario.
Abstract: Distribution factors play a key role in many system security analysis and market applications. The injection shift factors (ISFs) are the basic factors that serve as building blocks of the other distribution factors. The line outage distribution factors (LODFs) may be computed using the ISFs and, in fact, may be iteratively evaluated when more than one line outage is considered. The prominent role of cascading outages in recent blackouts has created a need in security applications for evaluating LODFs under multiple-line outages. In this letter, we present an analytic, closed-form expression for and the computationally efficient evaluation of LODFs under multiple-line outages

155 citations

Journal ArticleDOI
17 Oct 2005
TL;DR: The paper highlights issues and challenges for implementing security options in electricity markets and concludes that global analyses of security options could provide additional opportunities for seeking optimal and feasible schedules in various time scales.
Abstract: This paper reviews the status of security analyses in vertically integrated utilities and discusses the impact of system security on the operation and the planning of restructured power systems. The paper is focused on the static security rather than the dynamic security of power systems. The paper also discusses assumptions, functions, and calculation tools that are considered for satisfying power systems security requirements. In addition, the security coordination among time-based scheduling models is presented. In particular, real-time security analysis, short-term operation,midterm operation planning, and long-term planning are analyzed. The paper highlights issues and challenges for implementing security options in electricity markets and concludes that global analyses of security options could provide additional opportunities for seeking optimal and feasible schedules in various time scales.

141 citations

References
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Journal ArticleDOI
TL;DR: In this article, a load model, generation system, and transmission network which can be used to test or compare methods for reliability analysis of power systems is described. But the authors focus on the reliability of the power system and do not consider the transmission system.
Abstract: This report describes a load model, generation system, and transmission network which can be used to test or compare methods for reliability analysis of power systems. The objective is to define a system sufficiently broad to provide a basis for reporting on analysis methods for combined generation/transmission (composite) reliability.

2,289 citations

Journal ArticleDOI
TL;DR: This paper describes a simple, very reliable and extremely fast load-flow solution method that is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities.
Abstract: This paper describes a simple, very reliable and extremely fast load-flow solution method with a wide range of practical application. It is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities. The method is a development on other recent work employing the MW-?/ MVAR-V decoupling principle, and its precise algorithmic form has been determined by extensive numerical studies. The paper gives details of the method's performance on a series of practical problems of up to 1080 buses. A solution to within 0.01 MW/MVAR maximum bus mismatches is normally obtained in 4 to 7 iterations, each iteration being equal in speed to 1? Gauss-Seidel iterations or 1/5th of a Newton iteration. Correlations of general interest between the power-mismatch convergence criterion and actual solution accuracy are obtained.

1,447 citations

Journal ArticleDOI
TL;DR: In this article, the authors present an advanced contingency selection algorithm, which is essentially equivalent to a ranking based on the results of a DC load flow of each case, only at a fraction of the calculation time.
Abstract: This paper reports on the development of an advanced contingency selection algorithm giving superior results compared to earlier techniques. Problems inherent in the earlier algorithm resulted in occasional misranked contingency cases. The new algorithm gives results which are essentially equivalent to a ranking based on the results of a DC load flow of each case, only at a fraction of the calculation time. A complete derivation, test results and applications are given in the paper.

186 citations

Journal ArticleDOI
TL;DR: The compensation theorem is applied in conjunction with ordered triangular factorization of the nodal admittance matrix to simulate the effect of changes in the passive elements of the network on the solution of a problem without changing the factorization.
Abstract: The compensation theorem is applied in conjunction with ordered triangular factorization of the nodal admittance matrix to simulate the effect of changes in the passive elements of the network on the solution of a problem without changing the factorization. The scheme includes network elements with mutual impedances. Compared with impedance matrix methods which are ordinarily used for power system applications, this method, which permits exploitation of matrix sparsity, always requires less computer storage and, with few exceptions, is much faster.

133 citations

Journal ArticleDOI
TL;DR: A fast approximate method is presented for solving the ac power flow problem for line and generator outages, significantly more accurate than any linear approximation and significantly faster than the Newton-Raphson method for an approximate solution.
Abstract: A fast approximate method is presented for solving the ac power flow problem for line and generator outages. The method is significantly more accurate than any linear approximation and significantly faster than the Newton-Raphson method for an approximate solution. The method has applications in system planning and operations where approximate ac power flow solutions are acceptable. The method is applicable to system planning for rapid location of design criteria violations and it is particularly well adapted for system operation use as an on-line security monitor. Efficiency is achieved through decoupling of real and reactive power equations, sparse matrix methods, an experimentally determined iteration scheme and the use of the matrix inversion lemma to simulate the effect of branch outages.

118 citations


"Bound Estimates of the Severity of ..." refers background or methods in this paper

  • ...The analysis of contingencies, particularly line outages, is important to utilities in both operation and planning [1,2,3,4,5]....

    [...]

  • ...To speed up this process which has to be executed for possibly hundreds of contingencies, and repeated every time the system load or structure changes significantly, methods based on the compensation theorem (1] or on the matrix inversion lemma [2,3,4] have been developed....

    [...]