串补线路瞬时性故障的判别研究-电力系统及其自动化专业论文.docx

Subject : Identification of Transient Fault on Series Compensated Line Specialty : Electric Power System and Automation Name : Zhang Yan (Signature) Instructor : Shang Liqun (Signature) ABSTRACT Single-phase grounding fault of EHV transmission line is mainly divided into two states: permanent fault and transient fault. Transient fault is usually occurs in these two kinds of faults, and the reclosing technique can improve the stability and reliability of power system. But if it reclosed in permanent fault, it will impact the system again and damage the work condition of breaker. Therefore, judging the single-phase grounding fault before reclosing to realize adaptive reclosure is particularly important. The series compensation transmission line is given more attention because it can improve the transmission power, reduce network losses and it also has certain economic. Therefore, it is necessary to judge the nature of fault in series compensated EHV transmission line. This paper first researches the shunt reactor and series capacitor, and then establishes the simulation model of EHV series compensated line. As the amplitude of arc current is the important factor to determine the ability of arc extinguish, so arc current of steady and transient state in series compensated transmission line is simulated. Through the simulation it can obtain that the low frequency component existed in the transient process of the arc current will increase the transient value of arc current and affect the extinction of arc. Therefore some measures must be found out to inhibition of the arc current in order to ensure the arc can self-extinguish smoothly. The frequency components of recovery voltage are calculated after the laplace transform of EHV series compensated transmission line model. Through MATLAB/SIMULINK simulation to observe the frequency difference between the series compensation and without series compensation line to determine the nature of single-phase ground fault. Th