Design And Performance Analysis Of A Computer Model Of An Incremental Quantity Distance Element In Protective Relays

Toby Russell, Louisiana Tech University


This thesis presents the procedure of designing and implementing an incremental quantity distance element in protective relays using the Electromagnetic Transients Program (EMTP). This impedance-based element is derived from a new approach to traditional phasor-based protection schemes and has many advantages in its protection applications. The principal advantage is that the incremental quantity distance element can operate very rapidly, thereby reducing the strains associated with a fault on a power system. The details of the element’s design, including equation derivation, filter design, and EMTP block logic implementation, are included. The EMTP distance element was verified using a variety of simulations on a simple system as well as a detailed 69 kV system under study. The operation of the computer-based distance element was compared to the operation of SEL-T400L Time-Domain Line Protection Relays (SEL-T400L Relays). These commercially available relays have an internal protection scheme called the time-domain incremental quantity distance element (TD21) that is similar in nature to the incremental quantity distance element designed in this thesis using EMTP. This comparison was made possible by utilizing the playback testing procedure that is outlined in this thesis. The comparisons of the EMTP model and the TD21 elements are presented along with other results from the computer model verification process.