Evaluation of travelling wave protection performance in converter-dominated networks

Abstract

This paper presents a comprehensive study to investigate the travelling wave protection performance in networks with high penetration of Converter-Based Resources (CBRs). Representative network models are developed in the sub-step environment of the Real-Time Digital Simulator (RTDS) and realistic Hardware-in-the-Loop (HiL) tests are conducted on a pair of travelling wave relays (TWRs) to emulate realistic system and fault scenarios. The studies have been conducted in two stages: firstly, systematic tests with a total number of 300 cases have been conducted to have a high-level assessment of TWRs' performance under different fault conditions, e.g. varied fault types, fault positions, Fault Inception Angles (FIAs), and fault resistances; and secondly, detailed investigation has been conducted on selected and representative cases to understand the impact of various factors, e.g. the line-end transformer, system fault levels, converter controls and external faults, on the protection performance. Based on the test results and analysis, it was found that the performance of the TWR is largely unaffected by the variation of system fault levels and converter control strategies, but the connection of the line-end transformer and the low FIAs present challenges for the healthy operation of TWRs in some conditions. Although the tests were conducted for a pair of specific commercially available TWRs, the results have been analysed in a generic manner, so the findings will not only facilitate understanding the benefits/limitations of travelling wave protection in the network with high amounts of CBRs, but also provide a valuable reference for system operators to select the protection solutions in the future.