Improvement of Overcurrent Protection Reliability Using Phasor Study

Capability of the power system protection scheme to introduce a reliable and secure relay response has become a critical matter. Digital relays use special algorithms to filter unwanted components of the input signal and extract the fundamental component. Meanwhile, proper techniques must be used to prevent mal-trip of such relays, due to transient and harmonic currents in the network. This paper, presents using the real and imaginary part of current phasor in order to discriminate between fault and non-fault events. Some typical transient currents due to transformer energizing, capacitor switching and induction motor starting are simulated in Power Factory software and results of using the method are discussed and illustrated.

Improvement of Overcurrent Protection Reliability Using Phasor Study Keywords:

Digital Relay , Phasor Components , Transient Current , Power Factory DIgSILENT