PROJECT TITLE :

Ground distance relay compensation in the presence of delta-hexagonal phase shifting transformer

ABSTRACT:

In this study, the effects of the delta-hexagonal part shifting transformers (PSTs) on the operation of distance relays and their trip boundaries are investigated under totally different fault resistances and locations. Existence of fault resistance in part-to-ground faults creates an unreliable operation of distance relays. Trip boundaries are used to determine the fault resistance effects on the impedance calculated by the relay. Moreover, PSTs are used to control the facility flow in transmission lines. Finally, a feasible methodology for eliminating the PSTs detrimental effects on the operation of the space relays is presented. This method, that uses the voltage distinction between the PST terminals, is getting prevalent in modifying the operation of the distance relays even below the high resistance faults. Phasor measurement units (PMUs) are used to calculate this voltage as PMU signals and a foreign signal system is employed to transmit them to the system protection centre. All the simulations are conducted with Electro-Magnetic Transient Program.