Frequency-dependent Parameter Identification for Improved Dynamic State Estimation Based Protection Based on Characteristic Signal Injection of Half-bridge MMC in Flexible DC Grids  

作　　者：Ming Nie Jinghan He Meng Li Huiyuan Zhang Keao Chen 

机构地区：[1]School of Electrical Engineering,Beijing Jiaotong University,Beijing 100044,China [2]China Electric Power Research Institute,State Grid Corporation of China,Beijing 100192,China

出　　处：《Journal of Modern Power Systems and Clean Energy》2024年第6期1823-1836,共14页现代电力系统与清洁能源学报(英文)

基　　金：This work was supported by National Natural Science Foundation of China-State Grid Corporation Joint Fund for Smart Grid(No.U2066210).

摘　　要：In flexible DC grids, the rapid rise of fault current requires that the line protection must complete the fault identification within a few milliseconds. Dynamic state estimation based protection(DSEBP) provides a new idea for flexible DC line protection with good performance. However, the operating frequency in the DC grid is 0 Hz. When the DC grid is operating normally, it is difficult to identify the line parameters online to improve the performance of the protection method. This paper proposes a method to identify the frequency-dependent parameters of flexible DC grids based on the characteristic signal injection of half-bridge modular multilevel converter(HB-MMC). The characteristic signal is extracted by the Prony algorithm to calculate the line parameter under different frequencies. Afterwards, the number and position of residues and poles of frequency-dependent parameters are determined using the vector fitting method. Finally, an improved DSEBP is proposed. The simulation shows that the frequency-dependent parameters obtained by the proposed parameter identification method can be used in the improved DSEBP normally, and the identified parameters have better precision.

关 键 词：Parameter identification modular multilevel converter(MMC) state estimation PROTECTION flexible DC grid 

分 类 号：TM721.1[电气工程—电力系统及自动化]