Optimization of location and number of lightning arresters in 420 kV substations in Turkish high voltage electricity system

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2014
Tulaz, Mert Ozan
Insulation coordination is defined as the selection of the dielectric strength of equipment in relation to the voltages which can appear on the system for which the equipment is intended and taking into account the service environment and the characteristics of the available protective devices. In an insulation coordination study, the voltage levels of power system equipment are determined in order to ensure the protection of equipment against overvoltages. This proper design in terms of the insulation coordination provides the reliability of the system by decreasing insulation failures and reduces the cost of the system by preventing oversizing of the equipment. Hence, insulation coordination is an important study for power systems in order to prevent failures and overinvestment. In this thesis, an insulation coordination study is performed for lightning overvoltages in 420 kV substations in Turkish High Voltage Electricity System. The lightning impulse withstand voltage levels of the equipment are analyzed and evaluated as compared to current values in the system. In order to obtain optimum lightning arrester locations and numbers in the substation, different cases are defined and analyzed through computer simulations on Alternative Transient Program (ATP). In this context, this thesis study proposes additional lightning arrester application at the line entrance to existing lightning arresters located at the front of power transformer in 420 kV substations of Turkish High Voltage Electricity System. With this additional application, it is concluded that lightning impulse withstand voltage levels of equipment can be reduced to voltages that are the standard values recommended in IEC for 420 kV systems, 1300 kV for power transformer and 1425 kV for other equipment.
Citation Formats
M. O. Tulaz, “Optimization of location and number of lightning arresters in 420 kV substations in Turkish high voltage electricity system,” M.S. - Master of Science, Middle East Technical University, 2014.