Abstract
High impedance faults, changing network structure and line series compensation can lead to overreaching or underreacting of the conventional distance relays which can imperial security, stability, and sustainability of power systems. To overcome these challenging issues, this paper presents a new adaptive primary protection scheme for transmission lines based on pilot superimposed impedance (PSI). In the proposed scheme, PSI is defined as the ratio of the superimposed component of voltage phasor obtained from the local end to the sum of superimposed component current phasors obtained from both ends of the protected transmission line. Since the proposed PSI shows the different responses for internal and external faults, it is compared with the developed threshold based on Thevenin impedance for detecting the faulted phases inside and outside the protected line. In the case of internal faults, the PSI is less than the network Thevenin impedance which is seen from the bus adjacent to the relay. Due to establishing the proposed threshold based on the Thevenin impedance seen from the bus behind the corresponding relay, it can be adaptively updated when the network structure is changed. This feature helps to yield robust protection not only in different contingencies of the network but also in the case of weak source networks. The proposed method is also tested in the case of high fault resistance, load encroachment (LE) condition and series capacitive compensation in the long-distance transmission line. The obtained results confirm the security and dependability of the proposed protection scheme.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call