| In recent years, computers were widely used in the area of electric power system. The drawing of the electric power networks is the basis of electric power system analysis, and a lot of work has been done on this subject. Single-phase analysis method and three-phase analysis method are discussed, and single-phase models and three-phase models of a. c. power system main elements are presented in this paper by introducing the principle of penetration. Topology graphic is applied to electric power networks, and a new method to form the three-phase nodal admittance matrices with three-phase branches is proposed. On the basis of former research, drawing software Neharpal.0 is developed to analyze the negative phase sequence and harmonic of electric traction loads. Neharpal. 0 has a popular GUI, and has the characters of class' s hierarchy and opening, which makes it easy to expand, maintain and replant. When the parameters of electric power networks changed, the parameters of elements of the drawing system also changed, which enhances the intelligence of the drawing software. Using Neharpal. 0, an actual electric power system with electric traction loads is studied, and the voltage of negative phase sequence and harmonic on point of common coupling (PCC) in electric power system caused by electric traction loads are obtained. Compared with the actual results, it indicates that the models and the arithmetic in this paper are right and the drawing software Neharpal. 0 is useful. |
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