School of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China
This work is supported by National Natural Science Foundation of China (No. 51677023) and National Key R&D Program of China (No. 2016YFB0900903).
The three-wire bipolar structure based high voltage direct current (TWBS-HVDC) transmission system can greatly enhance the transmission capacity of the DC lines, which has become an effective method for converting AC line into DC line and improving line capacity. Aiming at the difference between TWBS-HVDC and bipolar DC system in connection ways, a current calculation method of short-circuit fault at DC side for two-terminal TWBS-HVDC system is proposed. Firstly, the transient equivalent model of TWBS-HVDC system is established based on modular multilevel converter (MMC) based transient equivalent circuit in the stage from different faults at DC side to the operation of DC breakers of lines. The number of independent circuits and the order of dynamic components in the transient equivalent circuit are taken as the standard, all DC faults are classified into three categories, and the state equations of each kind of fault are analyzed and deduced. The analytical expression of fault current is obtained by solving the eigenvalue and eigenvector of coefficient matrix in the state equation. Finally, a two-terminal TWBS-HVDC system simulation model is established in the MATLAB/Simulink digital simulation platform, and the simulation results validate the effectiveness and accuracy of the state equation solution method of short-circuit fault at the DC side of the proposed TWBS-HVDC system, which can provide a scientific basis for the selection of DC breakers and parameter setting of current limiting reactors.
LI Guoqing,LIU Xianchao,ZHANG Song,et al.Current Calculation Method of Short-circuit Fault at DC Side for MMC Based Two-terminal TWBS-HVDC[J].Automation of Electric Power Systems,2020,44(5):91-100.DOI:10.7500/AEPS20190601001Copy