GOLKAR - K N. TOOSI UNIVERSITY OF TECHNOLOGY
ABADIAN - BIRJAND UNIVERSITY BIRJAND

Many large power systems are increasingly experiencing voltage collapse. It is common to associate voltage collapse with the instability to provide reactive power at the necessary locations within the system.To predict the proximity of voltage collapse , a direct method based on the eigen values of the Jacobian matrix is suggested in this paper . Indices gives the values of load at critical point of the P-V curve .. On-line application to practical size power system is expected to be possible.For the last decate, voltage collapse phenomena has received increasing attention and are now pointed' as a major cause of insecurity in large number of power systems. Although the collapse mechanism still suffers from the lack of widely accepted descriptions and modelling, it is believed to be associated with inadequite reactive power support at any key buses.The topic on the prediction of voltage collapse or voltage instability has been appeared frequently in recent literatures. The static voltage, collapse phenomenon can be subdivided into iterative load flow methods and direct methods.In this paper a d irect method for estimating the voltage collapse proximity is presented. The method is fast and accurate enough and has priority to iterative methods regarding speed ,and accuracy.The method has been applied on some networks and the results shows the priority of that on other ones.