Predicting the optimum routine test interval for protective relays

Abstract

This paper discusses die goals of routine maintenance testing for protective relays. The paper advances a Markov Probability model diat predicts die optimum test interval for protective relays widi and widiout self-testing capabilities. The model uses known system transition rates and relay failure rates. The probability model shows diat die optimum test interval for a relay widi self-tests is quite long.Digital relay failures can also cause relay misoperations and prevent operation for faults. However, relay characteristics are typically not affected by failures. Failures tend to be significant enough to eidler generate a self-test failure indication or cause dIe user to recognize dIe problem during nonnal operation of dIe relay.

A novel kind of monitoring and analyzing system for digital substation functional loop

“…According to standard IEC-61850, the logical level of a certain digital substation should be as process level, bay level, and substation level [5]. As shown in Fig.…”

Short Term Reliability Analysis for Protection System with Average Unavailability

“…Eliminating P n+1 (t) (11), the ISP for remaining n states is described by (12), and its solution given by (13), where C and D are dependent on the transition rates to the (n+1) th state, and C is reversible. The IU is then solved by (14).…”

“…ISP at the start and the end of the evaluation period τ from t 0 to t 1 may overestimate or underestimates the risk level. Therefore average state probability(ASP) P[t 0 , t 1 ] is defined by (15), and solved as (16) when combined with (12).…”

“…Based on the assumption of exponential duration for the up and the down states with fixed transition rate, the steady-state unavailability is quantified from the Markov transitions [6][7][8], and the optimal maintenance interval and redundancy setting are studied [9][10][11][12][13]. For power systems, the risk level is related to the time-dependent unit outputs, load demands, and network topology, therefore the short-term reliability evaluation with the period of hours/minutes attracts wide attention.…”

Inconsistent Decision System: Rough Set Data Mining Strategy to Extract Decision Algorithm of a Numerical Distance Relay - Tutorial

“…With regular and rigorous analyses the performance reliability of the digital protective relays can be ascertained, their availability maximized and subsequently their misoperation risks minimized [2]. The precise relay operation analyses would normally be assessing the relay characteristics, evaluating the relay performance and identifying the relay-power system interactions so as to ensure that the protective relays operate in correspond to their predetermined settings [3,4].…”