Dl. Waikar et Psm. Chin, FAST AND ACCURATE PARAMETER-ESTIMATION ALGORITHM FOR DIGITAL DISTANCERELAYING, Electric power systems research, 44(1), 1998, pp. 53-60
Response of digital distance relaying depends on the fast and accurate
calculation of parameters such as voltage and current phasors and fau
lt impedance. This paper describes a new apparent impedance estimation
algorithm that is based on modal components theory. It is shown in th
e paper that the proposed algorithm has several advantageous features
in terms of speed and accuracy over previously suggested symmetrical a
nd modal components based algorithms. The paper discusses a procedure
for deriving a fault impedance estimation algorithm that can be used f
or protecting power transmission lines. The proposed algorithm was eva
luated using an alternative transient program (ATP). The program model
s a power system, simulates many fault conditions on a selected transm
ission line and generates fault data. The relay software then obtains
filtered, scaled and sampled data and calculates fault impedance using
the proposed algorithm. The relay characteristic makes trip decisions
based on the fault impedance estimates. The paper shows the feasibili
ty of the proposed algorithm for first zone distance protection. Some
results of these studies are presented and discussed in the paper. (C)
1998 Elsevier Science S.A.