Distance Protection of Power System in presence of FACTS elements

Abstract

With the development and implementation of various compensation devices, i.e. Flexible AC Transmission Systems (FACTS), protection relays are inevitably impacted in negative ways causing loss of protection accuracy. In this Thesis, firstly, detailed study of power system in presence of different faults is performed. Secondly, the compensation elements are added to the power system and impact of these elements on the faults and distance protection are completely studied. The faults are considered as symmetrical and unsymmetrical. The objective of this Thesis is to verify the effect of different compensation elements to the fault currents and on the zone settings to adjust protection devices. The compensation elements in this study are chosen to simulate the purpose of FACTS devices. Capacitors are connected in parallel and in series. In addition, inductors are connected in parallel to the transmission line. Shunt capacitors are required to adjust the power system voltage, while the purpose of series capacitance, is to increase power transfer capacity. Shunt reactors are used for voltage control in cases of light loads or capacitive loads. The results of this Thesis show impact of compensation techniques in different fault currents and consequently on the protection devices. Furthermore, the settings of the protection devices should be readjusted to correctly cover intended zone.