Performance evaluation of power differential protection applied to half-wavelength transmission lines

Abstract

The half-wavelength transmission line is considered a feasible alternative to interconnect very distant electrical subsystems, in the range of thousands of kilometers. Despite presenting good economic advantages, this alternative still has some challenges. This kind of line has unique characteristics, which makes it difficult to apply protection methods as practised today. This paper presents an analysis of power differential protection developed for half-wavelength transmission lines. Here, the performance of complex power is analysed. The method uses apparent power in the sequence domain to develop efficient protection. During an external fault, there is a balance between the measured power in both line terminals. However, when an internal fault occurs, this balance is broken. MATLAB simulations show that the method achieved good results, mainly in detecting faults in the central region of the line and external faults. Additionally, the tests considered the spark-gap apparatus to remove severe resonant fault conditions.