STEADY-STATE VOLTAGE INSTABILITY ASSESSMENT IN A POWER-SYSTEM

With the increase of loading and exploitation of power transmission sy stem and also due to the improved optimized operation, the problem of voltage stability and voltage collapse attracts more and more attentio n. The phenomenon of possible steady state voltage instability is crea ting serious concern among operators of large interconnected power sys tems. Maintaining adequate system voltage has become a major problem, as utilities are being forced to operate the system close to the therm al capability or steady state voltage stability limit. A voltage colla pse can take place in power systems or subsystems quite abruptly, whic h requires improved continuous monitoring of the system state. There a re different methods used to study the voltage collapse phenomenon, su ch as the Jacobian method, the simplified Jacobian method, the multipl e load flow method and the voltage collapse proximity indicator method . It is proposed to modify the method of multiple load flow to obtain the weakest buses and the maximum injected powers for each bus. The me thod of voltage collapse proximity indicators is also simplified. Thes e different methods are applied on a simple power system to study the problem of voltage-collapse, and a comparison is made between them wit h indicating the merits and demerits of each. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.