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Satellites are complicated systems designed to accomplish different missions in space. Simulating satellite motion using digital computers gives the ability to visualize dynamically its motion in space, as well as the areas of the earth's surface covered by its service. In this paper fundamentals of astrodynamics were applied to implement a software system that simulates satellite motion in 3D space. In addition, it interactively computes and visualizes the satellite's ground trace and footprint coverage on the rectangular map of the earth.

This paper introduces the mathematical modeling of an advanced member of flexible ac transmission systems (FACTS) controller which is a unified power flow controller (UPFC). This model submitted the implementation of the device in conventional Newton-Raphson (NR) power flow algorithm; it is derived from two-voltage source represented and analyzed in detail. The model takes operational losses of UPFC into account so it represents a more robust and feasible alternative than other methods. Based on the proposed model a program in Matlab language has been written to extend conventional NR algorithm. A computer simulation study performed on IEEE 14-bus test system and IEEE 30-bus test system are presented to test the approach by locating the UPFC anywhere in a power system. The effect of UPFC allocation on power system operation has been investigated in detail and the power losses minimization of the power system with UPFC has been achieved using the proposed method by adjusting the location of UPFC with a proper adjustment of UPFC parameters.