Research On Analysis And Control Of Chain Coupled Network Dynamic Stability

With the expansion of power grid interconnection scale,dynamic stability problems caused by the weak interconnection between systems are emerging.Especially,due to the unknown coupling relationship between sections,the relevant stability study on the chain sending network is quite complicated.However,the existing research involving the multi-sections interaction was dominated by qualitative analysis,and research on the coupling mechanism is not sufficient.Therefore,the paper makes a further study on the multi-section chain network dynamic stability problem.In the paper,a calculation method about relative sensitivity and coupling degree between sections of chain network dynamic stability was proposed,to provide the basis for dynamic stability analysis and control of chain network.Firstly,the stability problem in chain network was introduced,and research present situation about system dynamic performance and chain grid stability under interaction between multi-sections are summarized,from the three aspects including analysis methods,affecting factors and improvement measures.Then,the basic principle of the dynamic stability in single-machine infinite-bus system was analyzed theoretically.After introduction on the common dynamic stability analysis methods,a simple chain system model was built,at the same time,for several factors relating to system dynamic stability level,re levant simulation calculation and Prony analysis were conducted.Thus,influence rule of various factors on the system damping was summarized,to lay the foundation for the subsequent chapters.Secondly,the relationship between interconnected system dynam ic stability and the relative angle between two systems had been analyzed,and as a result,the relative angle between the two sides of the contact section was used as second characterization of dynamic stability.Then the relationship between power flow a nd equivalent power angle of two clusters on both sides of certain section had been deduced.And based on eigenvalue sensitivity analysis theory,affect differences of different sections on the system dynamic performance was analyzed,according to the relative angle changes caused by power flow perturbation.Furthermore,a calculation method had been proposed of relative sensitivity and mutual coupling degree between transmission sections in chain grid.Finally,the proposed method was used to study the dynamic stability of the simple system model and the actual chain network.In simple system,comparison between theoretical calculation and simulation results under different conditions,shows that the method can calculate section sensitivity on dynamic stab ility and cross coupling degree,according to the chain system parameters and initial operation information.In Mengxi chain grid,it was equivalent analysed for its complex topology.And then section dynamic stability sensitivity and cross coupling computation was calculated,based on the relevant parameters and initial operation information of multi-sections chain equivalent system.Meanwhile,based on the actual data,the effection and feasiblility of proposed method had been proved by simulation.As a result,in the light of above calculation result,dynamic stability improvement measures of power system had been taken,from two aspects of primary system and secondary system;meanwhile,faced with load demand changes,the optimal control between multi-sections power flow was conducted,in order to ensure the system dynamic stability level,which the above application has shown that the method has a certain practical value.At the end of this paper,the research results were summarized,and some suggestions were put forward for the main problems and the development direction of this subject.