Abstract:
Maintaining power system security is one of the challenging tasks for the power system engineers. The security assessment is an essential task as it gives the knowledge about the system state in the event of a contingency; where power system becomes more severe under contingency conditions. In general, the contingencies may be outage of transmission lines or generators. To identify the effect of outages on system security, the contingency analysis is one of the analytical tools. This dissertation discusses the security of the power system for the purpose of maintaining the continuity of the power flow from the station to the consumers within rated values whatever the circumstances of the generation stations. The main objective of this dissertation is to study the security assessment of the power system in general, and then the study is extended to investigate the system security assessment of Yemen National grid (YNG) as a case study, presenting contingency analysis to predict the line outage (n-1), and to study the states of keeping the system secure and reliable by using load-flow method. DigSILENT power-factory version15 program is used to carry out the simulation of Yemen national grid (YNG), to fulfill these contingency studies. The obtained results are analyzed and discussed using analytical tables and figures and system security is evaluated. According the results of the dissertation the system “Yemen National Grid” is not secure.
