Distance protection scheme with travelling wave for UHVDC transmission line based on wavelet transform

The ultra high voltage direct current(UHVDC) is the important technical means for the solution of high voltage, large capacity, and long distance power transmission. +/- 800KV UHVDC transmission technology will be used in the projects which transfer hydroelectric power in Yunnan Province and Jingshajiang river to Guangdong Province and Shanghai and other places in China. Along with the rapid development of UHVDC in China, how to improve the security and reliability of the running of UHVDC system has become an urgent thing. Travelling wave protection is the main protection for HVDC link. So it is necessary for us to study Travelling wave protection for UHVDC link. In this paper, the circuit of UHVDC transmission is given out. The parameters for different electric equipments, such as converter transformer, converter, electric line, reactor, filter are given out. The travelling wave protection theory is discussed in this paper,too. The PSCAD program is used to simulate the UHVDC transmission system. We have the simulation result and draw the conclusion in this paper.