A scaled-down prototype of transmission line for six-phase conversio n under transient overvoltage

Abstract

Six-phase transmission line (SPTL) system can be an alternative method to increase the existing transmission line power transfer capability to meet the increasing electrical energy demand of the future. In Malaysia, understanding and the knowledge of high phase conversion can be considered very shallow to contribute toward the realization of the six-phase transmission line. Tests on actual line settings and configuration which are needed during a study are the main challenges to researchers who have limited access to the lines. This is due to the fact that any changes to the actual line settings and configurations while the systems is running normally will not be appreciated by the power utilities who are committed to minimizing any cause of interruption to their supply system. To overcome this problem, this research project came out with broadly two programs. The first part is to carried out simulation studies of the SPTL, and the second part of this project focuses on construction a scaled down model of SPTL. The strategy is to compare the result of the study from the experimental point of view with the results obtained from simulation. Thus, the research could come out with the full understanding of SPTL system in term of its steady state and switching transient phenomena. In order to realize the SPTL system, the simulation study uses the ATP/EMTP incorporates two sets of three-phase transformer with other apparatus of the high voltage transmission system to come out with SPTL system model. In the experimental setup, the Tenaga Nasional Berhad (TNB) 132kV transmission line running from Kuala Krai to Gua Musang was used as the basis for the development of the scaled down power transmission line model (SDPTLM) of the SPTL system. From the research studies, it was found that the magnitude of phase-to-ground and phase-tophase switching surges of the converted system is much higher compared to the allowable crest voltage value of parent system. It was approximately 2.02 – 8.20 pu for both switching energization and switching de-energization. The percentage difference between the experimental and simulation was in the range 1.42 to 2.22. The switching energization and de-energization as well as steady state studies carried out in this work can be used by utility companies such as TNB as feasibility studies when converting their existing three-phase transmission lines to SPTL in future.