Autoreclosing of 110–500 kV mixed transmission lines using a distance method to determine the damaged section

To identify damage on a cable section of mixed 110–500 kV power transmission lines, a number of methods are currently being used. Their effectiveness is achieved due to the use of additional equipment and the organization of communication channels. There are methods that make it possible to identify damage of the cable without using additional devices. However, they have a significant disadvantage due to the inability to determine short circuit near the transition point from the overhead section to the cable section. Thus, the important task is to develop an effective method to determine the damaged section of a mixed transmission line without the use of additional equipment. Methods of mathematical modeling of electrical circuits have been used. The implementation of the distance method to determine the damaged section and evaluate the effectiveness of its application has been carried out in the PSCAD. The results of the research have been processed by the MathCAD computer-aided design system and the MATLAB software package. A distance method is proposed to determine the damaged section of a mixed transmission line based on the emergency mode parameters when the cable is located at any of its sections. The authors have analyzed the influence of the grounding location of the cable shield on the effectiveness of the autoreclosing of a mixed power transmission line. The authors have studied the effect of the mutual angle between the electromotive forces of the systems on the sides of the mixed transmission line on the effectiveness of the distance method to determine the damaged section. The developed method to determine the damaged section makes it possible to increase the efficiency of autoreclosing of mixed transmission lines. The limitations of the applicability of the method are related to the use of short cables located at a distance from the beginning and end of the power transmission line. To increase the efficiency of the developed method for lines with short cable section, the use of special high-precision algorithms to determine signal parameters is required.