Power system simulation and contingency ranking using load bus voltage index (original) (raw)
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Contingency evaluation for voltage security assessment of power systems
2009
The demand for electricity is expected to continue to increase given the recent world population projection of about 30% increase in the next three decades. Consequently power systems are equally expected to be more heavily loaded than before. Unfortunately the environmental and economic constraints restrict the expansion of the existing power system facilities. This scenario requires a constant attention since it could result to voltage collapse which could in turn lead to a total blackout. This paper presents the procedure required to carry out a contingency assessment and ranking of the load buses and lines of power systems for voltage security. This would ensure that power systems are operated above a desired voltage stability margin to forestall voltage collapse. The impact of single line outage contingency on the static voltage stability margin, as well as the available transfer capability across the areas of the test system, are examined in the paper.
SUPERIORITY OF CONTINGENCY RANKING METHOD USING CAPTURE RATIO IN POWER SYSTEM SECURITY ANALYSIS
IAEME PUBLICATION, 2020
Contingency analysis is best method to predict the power system condition, if any unwanted event like failure of single or multi transmission lines, generator outage etc., has occurred in the system. The process of identifying most critical contingency is determined with the help of contingency selection and this can be achieved by calculating performance indices such as power performance index (PIp) and Voltage performance index (PIv). Contingency selection method basically has two approaches, direct and indirect. In direct approach, the contingency ranking is done with the help of load flow program and in indirect approach, the contingency ranking is done with the help of some approximate method like distribution factor method etc. Ranking of most severe contingency can be determined on the basis of their performance index value. Prediction of best ranking method can be judged on the basis of their capture ratio and the CPU time or time taken in analysis. Here, in this paper, a new method based on Analytic Hierarchy Process (AHP) is proposed and analysis is carried out in detail for the impact of N-1 (single line outage) on interconnected power system. A new Capture ratio (NCr) is also proposed in this paper, which provides most promising results as compared to existing capture ratio calculation method. The effectiveness of the method has been tested on IEEE-118 bus test system. The proposed method is best suitable method of contingency ranking for implementation in online power system security checks.
POWER SYSTEM SECURITY ASSESSMENT AND CONTINGENCY ANALYSIS USING SUPERVISED LEARNING APPROACH
The most important requirement and need for proper operation of power system is maintenance of the system security. The security assessment analysis is done to determine until what period the power system remains in the safe operable mode. Contingency screening is done to identify critical contingencies in order to take preventive actions at the right time. The severity of a contingency is determined by two scalar performance indices: Voltage-reactive power performance index(í µí±í µí°¼í µí±£í µí±) and line MVA performance index(í µí±í µí°¼í µí±í µí±£í µí±). Performance indices are calculated based on the conventional method known as Newton Raphson load flow program. Contingency ranking is done based on the severity of the contingencies. In this proposed work, contingency analysis is done with IEEE 14 bus. Since the system parameters are dynamic in nature and keeps on changing, there is need of so ft computing technologies. Supervised learning approach that uses Feed-Forward Artificial Neural Network(FFNN) is employed using pattern recognition methodology for security assessment and contingency analysis. A feature selection technique based on the correlation coefficient has been employed to identify the inputs for thee FFNN. With these soft computing techniques, greater accuracy is achieved.
Power System Contingency Analysis to detect Network Weaknesses
Steady state power system insecurity such as transmission lines being overloaded causes transmission elements cascade outages which may lead to complete blackout. The power system operator must know the system state at any instant. The contingency analysis is used to predict which contingencies make system violations and rank the contingencies according to their relative severity. Contingency Analysis is useful both in the network design stages and for programmed maintenance or network expansion works to detect network weaknesses. The weaknesses can be strengthened by transmission capacity increase, transformers rating increase besides circuit breakers ratings increase. This work outlines mathematical models for the simulation of generator outages and transmission line and transformer outages so as to carry out a full AC load flow based contingency analysis and ranking. The method has been applied to Sudan National Grid (NG) and gives good results in determining the network weaknesses and suggesting the new transmission lines and transformers capacities which ensures better power system security.