Abstract:
Transmission lines are a key factor of the transmission network of a country which connects Grid Substations and the Power stations. Performance of transmission lines has a great impact on reliability aspects of a particular power supply system of a country. Unreliable transmission lines can lead to partial or even total power failures resulting with great financial losses. Radially connected power stations can be isolated from the transmission network by tripping the connected lines to the transmission system. The lightning back flashover effects are recognized as one of the major causes of transmission line outages.
Several types of solutions are presently available to address the issue of lightning back flashovers. Installing of Transmission Line Arresters (TLA) is of great popularity due to its good performance, with low cost compared to the other traditional solutions. However, latest technology called “Multi Chamber System (MCS)” are now being widely used worldwide to protect transmission lines as well as distribution lines from lightning surges including direct and indirect lightning surges. A novel technology, extension of MCS, Multi Chamber Insulator Arresters (MCIA) are the latest arrester technology which has great advantages over all the traditional surge mitigation techniques including installation of TLAs.
This report describes a case study which was carried out on one of a critical 132kV transmission line of the Sri Lankan transmission network, having several past records of lightning back flashover related outages resulting with partial system failures.
The study described in this report is mainly focuses on the way of analyzing the back flashover events by transient modeling and subsequent simulation of the selected transmission line in an electromagnetic transient computer program. The study uses the Power System CAD (PSCAD) software program as the software tool for the purpose of modeling and simulation of selected 132kV, Mathugama-Kukle transmission line.
Simulation of the created transmission line model is carried out with and without MCIA model to evaluate the improvements in lightning back flashover performance after installation of MCIAs in the selected transmission line.
The result of the simulations shows that the installation of 06 Nos. of MCIAs on all phases of a selected tower improves the back flashover mitigation performance on the same tower as well as the towers on the either sides of the selected tower. Thus, lightning performance of the selected transmission line is improved.
