BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@booklet{EasyChair:1378,
author = {Chur Hee Lee and Seung Wan Kim and Jong Su Yun},
title = {Analysis on Fault Location of TCSC Lines with Travelling Wave},
howpublished = {EasyChair Preprint 1378},
year = {EasyChair, 2019}}