Automatic Contingency Selection Algorithm Research Articles

Experiences of automatic contingency selection algorithms on the NGC system

An essential aspect of modern power system security assessment is the consideration of any contingencies which may arise due, for example, to planned or unplanned outages of lines, and which may cause system overloads or abnormal system voltages. Several methods have been developed during the last few years to address this problem and within the National Grid Company, the /spl Delta/P/sup 2/X outage ranking process has been used in the past. However, this /spl Delta/P/sup 2/X outage ranking method may not identify those critical outages associated with relatively low /spl Delta/P/sup 2/X changes. The paper reports on investigations carried out to determine which simplified methods would ensure that all voltage-based severe outages were identified.

95/03692 A unified model and automatic contingency selection algorithm for the P and Q subproblems

95/03692 A unified model and automatic contingency selection algorithm for the P and Q subproblems

A unified model and automatic contingency selection algorithm for the P and Q subproblems

Abstract A new approach to automatic contingency selection (ACS) and ranking is presented in this paper. ACS for the P and Q subproblems is solved by a unified network flow model and algorithm. It is based on the existence of weak coupling between real and reactive quantities in power systems. The performance indices to assess the severity of contingencies are defined as the total real and reactive load to be curtailed. The proposed model and its algorithm are examined numerically with IEEE 5-bus, 14-bus, 30-bus, 57-bus and 118-bus test systems on an M-340 computer.

Comparative analysis of the convergence characteristics of second-order loadflow methods

The second-order loadflow technique defined in rectangular coordinates has become attractive because of the large amount of computation required in the evaluation of polar trigonometric functions in conventional loadflow methods. Seven versions of the second-order loadflow technique are developed and their convergence characteristics and computing times determined with tests carried out on the IEEE 14 and 30 bus networks. It is suggested that the version based on the CRIC approach warrants further developments into optimal power flows and automatic contingency selection algorithms for real-time control.

A Fast Loop-Based Algorithm for Automatic Contingency Selection

In order to speed up on-line security assessment, a fast loop-based automatic contingency selection algorithm is presented in this paper. A linearized active power flow model is built up and loop analysis method with introduction of series potential compensation is used to compute the distribution of the flows after occurance of outages, thereby the change of active power performance index due to outage is calculated, and from which an outage list is constructed. Instead of using detailed AC (or DC) load flow calculation for each outage case, only one m-dimensiona1 forward/backward substitution solution is required to construct the outage list, where m is the number of loops which is much less than the number of buses. Therefore, this method is very fast in speed in contrast with the node-based method. Several digital examples are carried out and the calculated results show that the proposed method is more accurate than that by using a single P-Q iteration of FDLF, at the same time, the calculation speed is hundreds of times faster than the latter. Simultaneous multi-outages can also be simulated and their formulas for calculation are also given.

A Fast Automatic Contingency Selection Algorithm with Bus Voltage Criteria

Automatic contingency selection, which is used in power transmission system reliability evaluation is discussed. The paper presents a new method in which the post-contingency volt age is analytically evaluated in terms of the pre-contingency voltage and the parameters of an outage line or transformer. The new method is compared with the linear method, the local method and the curtailment method. The results of computation done on three test systems demonstrated that the new method gives almost the same precision as the results of the other three methods, but with significant superiority in computing time.

Analysis of Automatic Contingency Selection Algorithms

This paper presents a method for evaluating the effectiveness of the presently used Automatic Contingency Selection (ACS) algorithms in capturing contingencies which give out-of-limit conditions. The evaluation is given in terms of both capture and false- alarms rates, which are computed a priori together with a stopping criterion. Furthermore a method is given for enhancing the ACS algorithm's effectiveness in terms of maximizing the capture rate and minimizing the false-alarm rate. The theory is given for selecting the set of weights in the scalar performance index (PI) for both real power and voltage problems in order to circumvent some of the misranking problems, and more importantly, how to select the threshold value of the PI in order to capture all the critical contingencies while minimizing the capture of the non- critical ones. Since the PI used in the paper is similar to that used in the present ACS algorithms, the results give a systematic method for tuning these algorithms in order to maximize their effectiveness for the particular power system under study.

Analysis of Automatic Contingency Selection Algorithms

Analysis of Automatic Contingency Selection Algorithms

On-Line Automatic Contingency Selection Algorithms

This paper presents a unified approach to calculate the sensitivity of performance index for single branch outages, generation/load outages or a combination of them. For real-time implementation relative merits of several existing contingency selection algorithms are investigated. New updating algorithms are proposed to enhance the implementation of sensitivity method for on-line applications. Secondary outages are analyzed and shown that it is feasible to include them in an overall automatic contingency selection algorithm.

On-Line Automatic Contingency Selection Algorithms

This paper presents a unified approach to calculate the sensitivity of performance index for single branch outages, generation/load outages or a combination of them. For real-time implementation relative merits of several existing contingency selection algorithms are investigated. New updating algorithms are proposed to enhance the sensitivity method for on-line applications. Secondary outages are analyzed and show that it is feasible to include them in an overall automatic contingency selection algorithm.

Automatic Contingency Selection for On-Line Security Analysis - Real-Time Tests

Results of various real-time tests performed on the AEP- EHV System with the automatic contingency selection algorithm proposed in [1] are reported.