Line Resistance Effects on Transient Stability and Critical Clearing Time Prediction by Using Statistical Techniques.

The subject of stability is of great concern in the planning and operating stages of electric power systems. A power system is stable if after some kind of disturbance it returns to the steady state or normal operation. The power system after any type of disturbance adjusts itself to the new conditions. The reaction of the system is different for various conditions such as load changes, type of the fault and different location of the fault. There has been continuous development of new methods and techniques for increasing the transient stability limit, and determination of the critical clearing time in an electric power system. The purpose of this dissertation is to determine the increase in the transient stability limit by resistance insertion on the most effective transmission line of the electric power system. Also, the critical clearing time has been predicted and compared with the actual critical clearing time. The most suitable, simple and efficient statistical techniques are used for the dissertation objective. In this investigation, load magnitudes are treated as random variables with the assumption that active and reactive load magnitudes are normally distributed with a standard deviation about ten percent of the mean. For the model development, the initial data is found by a simulation method. A response surface model is used to find the most effective line to insert a reasonable amount of resistance for increasing the transient stability limit. In predicting power flow on line (5-1), several variables are candidates for predictor variables. The forward selection technique of model building was used to select the five most influential predictors. A multiple linear regression model gives a logical and efficient result for critical clearing time prediction. The results of the power flow on line (5-1) and the critical clearing times are found and are compared with the actual values.