Critical Contingency Cases Research Articles

Placement of SVC for Multi-objective Function using RCGA

This paper addresses the optimal placement of static var compensators (SVCs) in a power system network in such a manner that power loss, voltage deviation and installation cost is minimized. Voltage deviation is minimized by improving voltage profile. The aim of this study is to minimizing the power loss, voltage deviation and installation cost under critical contingency and increasing load condition in power system network. The multi-objective function is carried out in this study. RCGA is used to solve the optimization problem in this paper which is one of the heuristic methods. Real Coded Genetic Algorithm optimization helps in determining the location of the SVC. The proposed approach has been tested on IEEE-30 Bus test system with different objectives. It has also been observed, we can apply this algorithm to larger systems with computational difficulties. The obtained results show that the suggested method of SVC placement is effective in reducing the real power loss, voltage deviation and installation cost during normal as well as critical contingency cases. General Terms Power Loss, SVC, Critical Contingency, Real Coded Genetic Algorithms.

Optimal Placement of Unified Power Flow Controller Based on System Loading Distribution Factors

This article has proposed new sensitivity factors, called system loading distribution factors, to determine the optimal location of unified power flow controllers in the power systems. The proposed sensitivity factors have been computed for each line, as the change in the line real power flow with respect to the change of system loading, for the system intact, and for a few critical line outage contingency cases under different loading scenarios. The effectiveness of the proposed method has been demonstrated on an IEEE 30-bus system and a practical 75-bus Indian system in terms of reducing the system congestion, real and reactive power spot prices, generation cost, system real power loss, and total wheeling charges during normal, as well as a few critical contingency cases and at different loading conditions. The results of the proposed approach have been compared with two existing methods.

Optimal Location of Static Var Compensator Device for Damping Oscillations

Problem statement: Static Var Compensators (SVC) devices are used to improve voltage and reactive power conditions in AC systems. An additional task of SVC is to increase transmission capacity as result of power oscillation damping. The effectiveness of this controller depends on its optimal location and proper signal selection in the power system network. A residue factor had been proposed to find the optimal location of the SVC controllers to damp out the inter-area mode of oscillations. Approach: The proposed residue factor was based on the relative participation of the parameters of SVC controller to the critical mode. A simple approach of computing the residue factor had been proposed, which combined the linearized differential algebraic equation model of the power system and the SVC output equations. Input-output controllability analyses were used to assess the most appropriate input signals (stabilizing signal) for SVC device. Results: The placements of SVC controller had been obtained for the base case as well as for the critical contingency cases. Conclusion: The effectiveness of the proposed method was demonstrated on 25 bus of south Malaysian power system.

An Approach for Optimal Placement of Static VAr Compensators Based on Reactive Power Spot Price

In this paper, a new reactive power spot price index (QSPI) has been suggested to determine the optimal location of static VAr compensator (SVC) in the power system. The proposed index has been computed at each bus based on the reactive power spot price under different loading conditions for the system intact and critical line outage contingency cases. The effectiveness of the proposed method has been tested on two practical Indian systems. The results show that the suggested method of SVC placement is effective in reducing the real and reactive power spot prices, generation cost, system real power loss, total wheeling charges, and enhancing the system loading margin during normal as well as critical contingency cases.

Placement of FACTS controllers using modal controllability indices to damp out power system oscillations

Flexible ac transmission systems (FACTS) controllers are being used to damp out the power system oscillations. The effectiveness of these controllers depends on their optimal location in the power system network. A controllability index has been proposed to find the optimal location of the FACTS controllers to damp out the inter-area mode of oscillations. Three types of FACTS controllers have been considered, which include static var compensator, thyristor-controlled series compensator and unified power flow controller. The proposed controllability index is based on the relative participation of the parameters of FACTS controllers to the critical mode. A simple approach of computing the controllability indices has been proposed, which combines the linearised differential algebraic equation model of the power system and the FACTS output equations. The placements of FACTS controllers have been obtained for the base case as well as for the critical contingency cases. The effectiveness of the proposed method is demonstrated on New England 39-bus system and 16-machine, 68-bus system.

Optimal Placement of SVC for Static and Dynamic Voltage Security Enhancement

This paper presents a sensitivity based approach to determine optimal location of Static VAR Compensator (SVC) for voltage security enhancement. The proposed approach of SVC placement computes sensitivity of system loading factor with respect to reactive power generation, derived from reactive power balance equation. This sensitivity factor has been termed as Bus Static Participation Factor (BSPF). The sensitivity of the most critical eigen value with respect to bus voltage magnitude has been considered as Bus Dynamic Participation Factor (BDPF). BSPF and BDPF have been combined to obtain Bus Hybrid Participation Factor (BHPF), which have been computed for the system intact case and critical contingency cases and used for selecting the optimal site for the SVC installation. The effectiveness of the proposed approach of SVC placement has been validated on a practical 75-bus Indian system with respect to enhancement of the static as well as dynamic voltage stability margins.

Direct Ranking for Voltage Contingency Selection

It is now commonly accepted that for security assessment of a power system, the most efficient and practical strategy is to deal with the problem in two stages. First in contingency selection, those potentially critical contingency cases are ranked by the severity of their impacts on a system. Then in contingency analysis, detailed AC power flows are applied only to the most dangerous cases appearing on top of the ranked list. In the past decade, the problem of ranking outage cases in the order of decreasing severity has attracted a lot of intensive studies, and many efficient and reliable algorithms were developed. But most of these techniques can only be applied to MW limit security problems. On the other hand, voltage problems were also found to be a very important aspect of security assessment. It has become the target of many research projects. Because the MVAR-voltage problem involves a much more complicated model than the MW-angle problem, significant obstacles were experienced in developing ranking algorithms for voltage security monitoring, making it an area where further study is still required. Almost all contingency ranking algorithms employ a scalar performance index to represent a global severity of voltage disturbance after a contingency event. The scalar performance index can be viewed as a weighted distance in voltage space measuring the post contingency voltage profile against specified voltage limits.