Current-based Newton-Raphson power flow calculation for AT-fed railway power supply systems

Abstract

This paper proposes a current-based Newton-Raphson power flow method for an autotransformer (AT)-fed railway power supply system. The power flow formulation based on the NR method for such a multi-conductor system is revised. The train’s position variation and load variation cases were studied on the impacts of a dynamically moving train to the performance of the proposed power flow method. The Nakhon Ratchasima – Nong Khai railway line was used to study the convergence characteristics of the proposed method when implementing in a practical situation. The results of the proposed NR method were compared with those of the Gauss-Seidel (GS) and sequential linear power flow (SLPF) method for the same power system. The analysis and comparison of convergence behaviour of all three methods have been done in details. By varying train’s position, the GS method showed the great drop in the number of iterations and execution time at the AT’s positions but it appeared to be the maximum execution time for the SLPF method, while the proposed NR did not show substantial changes. For the case of load variation, GS and SLPF method showed an increase in the number of iterations and execution time with the load while the proposed NR was almost unchanging with the load. Regardless of memory usage, the proposed NR showed better convergence for both train position and load variation cases.