EMT-Based RDR and DWT Protection Techniques Simulation of Three-Winding Power Transformer

Recently, as inverter-based VREs are connected to the power grid, fault phenomena different from those of conventional synchronous generator-based power grids are appearing. This paper was conducted as a preliminary step in the development of an improved protective relaying algorithm that can prevent malfunctions in transformer systems. First, we describe the RDR based on the second harmonic using FFT, and the transformer protection technique based on DWT. We model a 345/161/23kV, 600MVA three-winding power transformer system using real system data. After reviewing the accuracy of the result of the steady-state simulation, we analyze the transients of magnetizing inrush, winding ground fault, and winding short-circuit fault. Finally, we simulate and implement the RDR protection technique with second-harmonic restraint using FFT of PSCAD library in EMT tools, and the protection of power transformer using DWT of EMT library and verify its performance.