Voltage Stability Assessment Of Power System With SSSC Devices

Blackouts and failures were incurred by the damaged devices and voltage collapse,For meeting the demands of power quality and maintaining the power system stability, it is very important to keep the voltage in the range of specification. Blackouts and failures were incurred by the damaged devices and voltage collapse,which were the results of severe voltage abnormity in the power system. For meeting the demands of power quality and maintaining the power system stability, it is very important to keep the voltage in the range of specification.As the frequent occuring of the voltage collapse, the voltage instability problem has become a serious problem in modern power systems and has been paid much attention to since the late 1970's.Great progress has been made in this area during the last decades,especially in the static voltage stabillity. As an important part of electric power system stabilization, voltage stabilization and its content aggrandize the connotation of power system stabilization.The voltage abnormity and its control attract high attention recently. With the development of Flexible AC Transmission System (FACTS), more control and application measures can be used for voltage control, var compensation and the power system voltage stabilizationBased on a hybrid power injection model of SSSC, this paper introduces singular value decomposition method and eigenvalue structure analysis method, bese on which,two analytic indexes, LC_j,Df_i are given to assess the weatest bus in voltage and to predict the loadding mode in dangerous way.This paper also introduces the history and actuality of voltage stability, also particularly introduce the analysis method. Mathematics theory of singular value decomposition method as well as eigenvalue structure analysis method in the fourth and fifth chapter. This paper also introduces the concept of Flexible AC transmission systems (FACTS) and the Synchronous Series Compensator (SSSC). The effects, of which power flow of electric network is also expatiated.This paper also presents a hybrid power injection model of SSSC for power flow and voltage stability analysis. Two analytic indexes, LC_j and Df_i, are given to assess the weatest bus in voltage and to predict the loadding mode in dangerous way. Based on singular value decomposition method, The effect of SSSC and its model on power system voltage stability is studied under some conditions, such as proportionally loading at all nodes, or loading only at the most sensitive node to the voltage. This paper also proposes a method for analyzing the weakest voltage nodes and greatly loading nodes using the proposed voltage analytic indexes, LC_j and Df_i. This paper taking IEEE-14 bus system for example, the influence of load variation on minimum singular value as well as the influence on LC_j and Df_i value is analyzed while the loads are increased in average, then the weak region and the weakest bus in the power system are determined. Calculation example shows that it will be effectively for the improvement of system voltage level and voltage stability as well as the improvement of the weakest bus while the SSSC is located at the determined weakest bus.