| With the power systems in China have entered an era of large power grid, extra high voltage, large unit size, large power plant and long distance power transmission. The systematic structure and operation mode has been increasingly complex. It makes the power system stability more striking, the regulation of the voltage more difficult. Voltage stability is the essential requirement of the secure and stable operation of power system. Therefore, how to prevent the occurrence of voltage collapse accident, improve system security, as all current grid is one important issue of concern.This thesis focuses on static voltage stability analysis of power system considering composite load model. The algorithm of continuous power flow improved and composite load model of system voltage stability influences are systemically analyzed and studied in theory. The main content as follows:First of all, the paper proposes an improved continuous power flow, using the geometric parameters of the full use of the increase in one-dimensional convergence correction equation has changed direction avoid singular of Jacobin matrix to improve the existing tide convergence. Through the analysis of the example, confirmed the effectiveness of the algorithm. Secondly, based on composite load model (ZIP load and induction motor load combination) and their impact on voltage stability carried out in-depth study. In the construction of composite load model based on the analysis of the static load of the composite load characteristics, and apply it directly to power system PV curve calculations. By analyzing the composite load models on system voltage stability, and research the relationship between the induction motor load stability and power system voltage stability relationship.In addition, the impact of load models on V-Q curves and reactive power margin are studied in this thesis. Apply a variable reactive power at the critical bus. The V-Q curve can be obtained resulting in reactive power margin. The relatively critical bus can be identified by sensitivity and reactive power method, and analyze the different load models on the V-Q curve and the impact of reactive power margin.Finally, the singular value decomposition method based on voltage stability analysis in this thesis. The singular value decomposition method based on Jacobin matrix is proposed to determine the relevant indicators of the critical node, and to judge critical regional and system stability margin. Through practical examples, confirming the validity of the method, also analyzed the load model the impact of weak nodes. |
