Research on application of active current differential protection method on AC transmission lines in UHV AC–DC interconnected system

摘要

The rapid development of ultra-high voltage (UHV) AC–DC interconnected system has brought with it some new features, such as characteristics of distributed parameters becoming more distinct, internal parameters changing faster, and harmonic becoming more unstable, which pose new challenges for the correct operation of relay protection and automation devices. The aim here is to study the application of active current differential protection method in UHV AC–DC interconnected system. Firstly, the negative influence of UHVDC connection on the effectiveness of traditional current protection method is analysed. Next, the principle of active current differential protection method is introduced, which shows that this method is less susceptible to the variation of system parameters and unstable harmonics. On this basis, simulations have been conducted on PSCAD platform to explore the application of this method on AC transmission lines in case of various fault types. The simulation results show that the active current differential protection can increase the sensitivity of protection of UHV AC–DC interconnected system.