Study of Voltage Stability

Abstract: Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the system under normal operating conditions and after being subjected to a disturbance. A system inters a state of voltage instability when a disturbance such as increase in load demand, or change in system condition causes a progressive and uncontrolled drop in voltage. The management of power systems has become more difficult than earlier because power systems are operating closer to security limits. One of the serious problems in power systems that can threaten the concept of power systems reliability and security is voltage instability. Therefore in recently the analysis of voltage stability is very important. This paper discusses study of voltage stability, and the eastern section of national Grid of Sudan (NGS) is selected as case study. Load flow analysis for the eastern part of NGS in the base case is done, and the results show that the voltage values are within rang. The results present a high voltage drop after fault occurrence in Halfa bus, and the all voltage buses are about 0.5 pu, which may lead to voltage instability. Simulation is done usin ETAP software.

Keywords: voltage stability, voltage collapse, Fault, voltage drop, ETAP