الملخص الإنجليزي
Voltage stability analysis of power system is a major requirement, particularly in the planning phase of the development or expansion of a power network. Micro-grid is normally composed of relatively small-distributed generators supplying islanded distribution network. Although a micro-grid may not be a complex interconnected power system similar to a transmission network, but it has some characteristics that makes it undergo stability problems when it is exposed to disturbances. In this research, a study is being done to expand the power network of the area of Musandam in the Sultanate of Oman. Since, this area is not connected to the main interconnected system of Oman, it operates as a microgrid. The ultimate goal of this study is to investigate the voltage stability of Musandam micro-grid during the expansion of the network. In order to perform the voltage stability analysis, modal analysis as well as PV and QV curves were evaluated based on load flow for selected scenarios. A MATLAB m-file has been developed to carry out the static voltage stability analysis along with ETAP software. It was found that MOD bus is the weakest bus in Khasab micro-grid that is participating in the voltage instability more than others.
The dynamic voltage stability analysis has been performed by using time domain simulation with PSAT software. In addition, since normally the micro-grid consists of more than one type of source, then, Doubly Fed Induction Generator (DFIG) wind turbine was added to Musandam micro grid for the purpose of testing its effect in the voltage stability. It was shown that DFIG wind turbine generator improves the voltage profile and the voltage stability as well as the frequency of the micro-grid under most types of disturbances. Under three phase short circuit, it was found that the system was more stable in the lagging power factor case of the DFIG. When the fault occurred at the terminals of the DFIG, it was found that the system stability was more effected compare to the situation when the fault occurred at synchronous generators bus.
