Stability Investigations in Power Systems With The National Grid of the Sudan as A Special Case

Abstract

The stability and control of electrical power systems represent the most serious problems, which may face the expansion of power systems. The National Grid of the Sudan (N.G.), which supplies electricity to the Capital Khartoum and most of the center towns, has faced many problems of stability during its continuous expantion in size and complexity by adding new power stations or new loads. These problems have been complicated by lack of real understanding of the system’s behavior. The National Electricity Corporation of Sudan has carried out many studies to estimate load forecasts for short and long term planning, and has suggested reinforcements for the weak points of the system. But still the problems of small signal stability of the N.G. remain especially as the demand increases continuously. In this study the problem of small signal stability is presented and discussed in details. Also, the study presents new techniques for the evaluation and interpretation of eigen value sensitivity in the context of analysis and control of oscillatory stability in multi-machine power system. These techniques combine the numeric power of modal analysis of state-space models that can be obtained from system transfer functions. Certain models and equations for power system elements in the area of steady state, transient and dynamic stability were presented and many computer programs were written to analyse and improve small signal stability for any power system. These studies were then applied to the N.G. of the Sudan. These programs were efficient with straightforward formulation and less computation requirements and can easily be implemented on any suitable personal computer. The study, also, gives many suggestions to improve the stability of the N.G. covering the existing and forecasting loads and generations up to 2006.