Renewable energy line protection based on voltage traveling wave polarity

Abstract

Renewable energy has weak feedforward and controlled characteristics, so the traditional industrial frequency protection does not work when renewable energy is sent out through AC transmission line. On the contrary, the traveling wave protection methods can judge the fault before the control system responds, which are one of the effective ways to solve the problem encountered in renewable power system. However, the existing traveling wave protection schemes are limited by the sampling rate, which makes it difficult to accurately identify the internal near-end fault and the internal remote-end fault. To solve this problem, the grid diagram of traveling wave in case of internal and external faults is analyzed at first. Then, the time difference between zero-mode and line-mode is used to judge the fault location. For the near-end fault and remote-end fault which are difficult to be accurately identified based on the time difference, the first reverse polarity traveling wave is used to identify the near-end fault and the polarity of the first two line-mode traveling waves is used to identify the remote-end fault. Simulation results show that the proposed scheme can quickly identify internal and external faults. At the same time, the proposed scheme has good ability to withstand transient resistance.

Keywords

• renewable energy line
• traveling wave protection
• voltage traveling wave
• wavelet transform
• polarity comparison
• single-ended protection