Saddle Node Bifurcation Applied To Analyse Voltage Stability In Wind Power System Including TCSC And SVC

At present, the power system of China has been entered into a period of the EHV, new energy, and long-distance transmission. Limited transmission capacity and instability-especially the voltage instability are week in state grid which the main power grid structure is lagging behind in order that systems often run close to the limit state of transmission capacity for some reasons. But reactive power compensation technology can effectively improve the level of stability and transmission capacity of the system. Especially the TCSC and SVC have been used to analyze and control the voltage in the regular system. In this paper, bifurcation theory which is used to analyze the nonlinear differential equation plays an important role in the data analysis of impact of TCSC and SVC wind power system which elaborated the voltage instability and control mechanism. Its main contents are as follows:(1) Select the TCSC as a voltage regulator device to make the voltage stability research of the saddle-node bifurcation in the typical wind power system. Firstly, establish the model of wind power system which select the Pinject and the equivalent impedance XTCSC of TCSC as SNB control parameters; secondly, calculate the nonlinear differential equations by the application of bifurcation theory and prove effectiveness of the TCSC voltage stability control which can improve the ability of the system voltage stability and transmission capacity in order to keep the safe operation of the power system.(2) Owing to the relationship between the reactive power and voltage, establish a typical wind power system model including TCSC and SVC, Firstly, comparative analyze the impact between the TCSC and SVC separately which illustrates that they can change the line transmission power and improve the line voltage stability, at the same time we can see SVC is better than TCSC in improving the transmission power and TCSC can more effectively improve the voltage stability. Secondly, they are installed in the same wind power system which select Pinject, Bsvc and XTCSC as the saddle-node bifurcation parameters for the study of voltage stability, then get the multidimensional SNB boundary and the dates describe the adjustment of voltage stability among Pinject, Bsvc,XTCSC, this paper reveals TCSC and SVC have a positive role in improving the capacity of wind farm and enlarging the margin of the voltage stability.