Research On Theory Of Traveling Wave Protection Of HVDC Lines

HVDC (High Voltage Direct Current) transmission takes an increasingly important position in the long distance and high-power transmission project, for its large power of transmission, low cost and good performance advantages of control. It is regarded as the principal means of high-capacity, long-distance transmission and asynchronous networking in developed countries. In China, HVDC becomes hotter and hotter as the result of"Western Power to the East, North and South to Share Power, National-link Network"especially in the vigorous development of the state UHV in recent years. However, according to the operation of"GZB-SNQ and TSQ-GBJ HVDC project", reliability of Circuit Protection Device of domestic and international HVDC lines is not high, within easily disoperation and other issues. So how to improve reliability of HVDC transmission lines is urgently needed to solve in our country's development of HVDC.In this paper, we introduced the principle of the HVDC transmission system as well as the composition of DC systems and characteristics of DC lines. Then we raised the concept of traveling wave, and discuss on the protection of the traveling wave theory in the process of occurrence of the DC line fault. More, we built a traveling wave protecting model for HVDC transmission lines based on the GZB-SNQ HVDC project which could be run on the simulation software"PSCAD/ EMTDC". The protection principle and criterion of the actual operation of TSQ-GBJ HVDC project have been correspondingly simulated and analyzed. We also took the comparative analysis about traveling wave protection of ABB and that of SIEMENS. The results show that these two protection scheme have a degree of lack of vulnerability to noise interference.To that end, this paper introduces and applies the wavelet transform mathematical tool to the HVDC lines protection, which forms the distance protection and direction protection of current polarity comparative based on wavelet transform for HVDC lines. Having been taken full simulation analysis in detail, these two kinds of protection principle performance feasibility in practice. Finally, this will provide a theoretical basis and technical support for the protection of HVDC transmission line.