Research On The Improvement Of Transmission Section Limit With FACTS

Since the large-scale power grid interconnection,the capacity of power exchanging between the areas have a huge impact on the security and stability of the grid.Therefore,how to determine the transient stability constraints limit of power between areas,and how to control the transmission sections running within transient stability limit,accurately and quickly,has become an important issue needed to solve for the current power system.Flexible AC transmission system(FACTS)is based on power electronics or other static controllers,can improve the controllability and increases the power transmission capacity,FACTS manufactures controllable power grid active power and reactive power and other primary equipment in use of thyristor?GTO?MOSFET and other elements,in order to achieve the real-time control of voltage,impedance,phase angle,power flow and so on,has the ability to achieve transmission power control and maximum capability of flexible transmission.In this paper,the software PSD-BPA's transient calculation module is used to simulate a variety of FACTS devices connected to the grid,multi-angle analysis of the effect of FACTS devices access on the transient characteristics of the system is presented,also the improvement of large-scale power grid section flow limit with FACTS devices connected is presented from the qualitative and quantitative perspectives.First,this thesis analyzes and compares a variety of different types of FACTS devices,basic principle and composition structure of FACTS devices and their impact on power system steady-state and transient characteristics is also introduced.At the same time,the steady-state or transient mathematical model of STATCOM,TCSC,TCPST,UPFC and other typical FACTS devices is established.Secondly,the concept of the transmission section limit is described in detail.The time domain simulation method is introduced to solve the problem of transient calculation of power system which contains both algebraic equations and differential equations.At the same time,the paper also introduces the calculation method of transmission section limit and the principle and method of generator and load shedding.Finally,using software PSD-BPA realize the transient simulation with FACTS devices access to large-scale power grid,and by improving the section power flow,gradually approaching the system transient stability boundary,and according to a certain criterion.obtained transmission section limit.Designing a variety of FACTS devices combined access program,and the simulation results are compared and analyzed.The results show that a variety of FACTS devices access to system has varying degrees of increase on transient stability and the transmission section limit,at the same time,they can improve the transient stability limit of the system,more effective to prevent the system oscillation.The analytical results obtained and the solution method have important reference value for the selection and installation of FACTS devices in power grid.