ANALYSIS AND ENHANCEMENT OF HIGH VOLTAGE TRANSMISSION NETWORK PROTECTION DESIGN WITH A DIRECTIONAL ISOLATED GROUNDING SYSTEM

• Main Author: Izhar Tarigan, Fadlin
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82036
• Institution: Institut Teknologi Bandung

The electrical power transmission system plays a vital role in delivering electrical energy from the power plant to the users. This system is vulnerable to disruptions caused by lightning strikes because it is exposed to the atmosphere at heights exceeding other objects over distances ranging from tens to hundreds of kilometers. Protection of high-voltage transmission networks, particularly High Voltage Overhead Transmission Lines (HVOTL), against lightning strikes has been developed using various technologies such as arresters, direct grounding, counterpoises, unbalanced insulators, free-standing masts, and extended mast terminals. Nevertheless, failures in lightning protection on transmission networks that result in outages still occur. Therefore, technological innovation is needed for the protection of transmission networks. One such innovation is the patented method titled “Method and Equipment for Protecting High Voltage Transmission Networks from Lightning Strikes by Separating the Protective Ground Wire and Grounding from the Transmission Tower,” referred to in this thesis as the “Directional Separate Grounding System” (SPTT). SPTT is designed to enhance the reliability of transmission network protection by separating the connecting path between lightning strikes and the tower using an isolator pin. SPTT comprises finials, isolator pins, down conductors, and Lorentz grounding, each playing a role in protecting the transmission network from lightning strikes. The finial functions to capture and divert the lightning current away from the tower, while the isolator pin separates the ground wire from the tower to provide a capacitive effect that protects against impulse currents. The down conductor acts as the primary medium for channeling the lightning impulse current, and the Lorentz grounding ensures the effective distribution of the current into the ground. Various studies on SPTT technology have yet to provide a detailed explanation of the working principles of this method. Simulations conducted on SPTT have been limited to power systems with different voltage levels than PLN’s system and lightning current characteristics differing from standard lightning current characteristics. Although SPTT has been implemented in parts of PLN’s transmission network from 2017 to 2023, no analysis has been conducted regarding the protection failures that have occurred. Therefore, an analysis of transmission network protection using SPTT is carried out in this thesis. The analysis includes a theoretical review of SPTT’s working principles, simulations using ATP Draw, and testing the implementation of SPTT on several sections of PLN’s transmission network. The simulation results show that SPTT can withstand lightning strikes up to 20.9 kA with an impulse voltage of 125 kV. Field tests indicate an effectiveness of SPTT ranging from 91-98% in preventing transmission network outages due to lightning strikes. The damage to some finials and outages is likely caused by lightning strikes with currents exceeding 20.9 kA. Enhancing SPTT performance can be achieved by placing SPTT isolator pins with a BIL value of 300-650 kV, using down conductors with insulated conductors having an impedance of less than 50 ?, and using Lorentz grounding electrode materials with lower impedance values.