Research On Optimization Of Hierarchical Protection And Control System For Smart Substation

With the grid structure of power system becoming more and more complex,the requirements of power system for relay protection and stability control are also increasing.Therefore,Studying the theoretical methods and technical principles of power system protection and control has important theoretical significance and application value.At present,most of the researches are focused on the first line of defense-fast and reliable relay protection,but less on the third line of defense-Safety and stability control.The hierarchical protection and control system can provide a hierarchical protection and control system at the local level,station domain level and wide area level.The ground level protection meets the requirements of fast and reliable fault removal,the station level protection control improves the performance of public protection control,and the wide area level protection control realizes the coordinated control at the regional grid level.In this paper,the problem of low-frequency and low-voltage load shedding in the third line of defense is studied when the power system is damaged by multiple serious accidents.By analyzing the existing problems of hierarchical protection and low-frequency and lowvoltage load shedding methods,a dynamic parameter setting optimization algorithm is proposed,and the optimal design scheme for hierarchical protection and control system of substation is given.Compared with the original protection and control system,the optimized hierarchical low-frequency and low-voltage load shedding can track and measure the changes of various parameters in the process of frequency and voltage losing stable oscillation in real time through the station area and wide area communication network,shorten the recovery time of frequency voltage and improve the steady-state frequency voltage value.This paper focuses on the protection and control functions of the hierarchical protection and control system of intelligent substation.The specific contents are as follows:First,this article explains the background,significance and purpose of hierarchical protection control research,and analyzes the research status at home and abroad.On this basis,the structure of hierarchical protection control system is described.According to the characteristics of hierarchical distribution,the protection scope and functions of different levels are divided.Secondly,combined with the dynamic characteristics of the frequency and voltage of the power grid under the hierarchical protection control framework,the influence of the frequency and voltage regulation and control on the security and stability of the power system is analyzed.This paper studies the current low-frequency and low-voltage load shedding configuration scheme and the problem of constant load shedding parameters.Combined with the characteristics of hierarchical protection control,an improved hierarchical low-frequency and low-voltage load shedding scheme based on the optimization and setting algorithm of low-frequency and low-voltage load shedding is proposed.Thirdly,considering the new requirements of power grid development for relay protection and automatic control,the hierarchical protection and control system is designed by embedding the optimized low-frequency and low-voltage load shedding scheme.Taking 220 kV substation and 110 kV substation as examples,combined with the hierarchical low-frequency and low-voltage load shedding to optimize the configuration of the intelligent substation protection control system.Finally,Summarize the research content of this article.The optimized low-frequency and low-voltage load shedding can reduce the frequency and voltage oscillation amplitude,and the system recovery process is more stable and the frequency and voltage are closer to the rated value.At the end of the article,the limitations of this research topic are pointed out,and the prospect of hierarchical protection and control is put forward.