Analysis of zero sequence power directional unit for multi-circuit transmission lines with different voltage levels

This paper discusses the zero sequence power directional unit performance of multi-circuit transmission lines on the same tower with different voltage levels in different type faults. The analysis results show that the zero-sequence mutual induction between transmission lines will impact the performance of zero sequence power directional unit and in some conditions, the zero sequence power directional unit will mal operate. The analysis results was proven using RTDS (Real-time Digital Simulator) in 1000kV/500kV quadruple circuit transmission line considering different fault cases.