Thevenin Dynamic Equivalence And Voltage Stability Analysis Of Power System With FACTS Device

With the constant development of the electric power load and power electronics technology,FACTS device based on IGBT has become a hot research.This devices applied to the field of power system analysis have the advantage of flexibility and rapid control,improving transmission capacity,improving the system performance,which also bring new challenges.Besides,modem power system has the tendency to long distance transmission,large capability,high voltage grid,the pressure of voltage stability is more and more high,the voltage stability of large area power outages have occurred from time to time,it becomes more and more difficult to maintain a safe and stable grid.Promoting the understanding of relation between new technologies and voltage stability is the foundation of facing these challenges.This paper firstly focus on the basic principle and steady-state model of FACTS devices,giving the equivalent power model and control parameters,and studying the Thevenin equivalence application in voltage stability analysis.Applying maximum principle,it analyzes the nonlinear power system limit condition of power transmission with FACTS devices.The necessary condition of maximum power of load node that load static equivalent impedance modulus is equal to comprehensive dynamic equivalent impedance modulus.Basing on the dynamic Thevenin equivalence principle,this paper gives the calculation expressions of Thevenin dynamic equivalent impedance.The method applied synchronous detection of node voltage increment and load current injection,which can track dynamic Thevenin dynamic equivalent impedance in real time and accuracy.IEEE nodes testing system verified the correctness of the above theory.Next,expression for calculating the sensitivity parameters based on dynamic Thevenin equivalence principle was presented.This expression demonstrated the grid operating status and voltage stability quickly and simply through the analysis of relationship between Thevenin dynamic equivalent impedance and FACTS device variables.The simulation conbined impedance modulus margin index indicated that we can determine voltage stability with sensitivity analysis in power system with FACTS devices.