An efficient method of automatic distance relay settings for transmission line protection

This paper presents a method for automatic distance relay setting to overcome the overlapping problem of the protection zones. The proposed method is developed as a program aimed at enhancing the calculation of the setting values of the digital distance relay for each protection zone more effectively. The program is developed by using the DPL script (DIgSILENT Programming Language) that is a tool for the analysis of industrial, utility and commercial electrical power systems. In order to validate the performance, the developed program is used for the protection design of closed-loop and radial power system of the Provincial Electricity Authority (PEA), Thailand. From the validation results, it is found that the developed program can ensure that the distance relay operates correctly in its protection zone, leading to higher reliability of the primary protection system of PEA and the shorter of the time spent on the protection design.