Enhanced real time coordination of distance and user defined over current relays

Novel stepwise and combined stepwise–piece‐wise linear tripping characteristics for coordinating numerical overcurrent relays

“…The next relay (R 3 ) is to mainly protect the line section between the buses B3 and B4 (L34) and to provide a backup protection for Table 1 Pros and cons of different NSCs introduced in various references Reference Advantage Disadvantage [7] Preserving constant CTI between the main/backup relay pairs for entire fault current range Unnecessary increase of time delay by moving the fault location along the main and backup protection zones of the relay Stabilising against the cold load/hot load pickup currents without increasing relay time delay against the higher fault currents Limited number of ahead relays Directly applicable with the existing industrial OCRs [9] Reducing overall operating times of the relays compared to SCs Coordination problem during dynamic change of the fault current Less flexibility [10][11][12][13] Reducing overall operating times of the relays compared to SCs Needing to measure the fault voltage in addition to the fault current Needing to set an extra set point Inapplicable with the exiting OCRs [14] Reducing overall operating times of the relays compared to SCs Inapplicable with the exiting OCRs Removing the drawback of general increase of operating time by moving the relay location towards the source Increasing number of parameters to set in large-scale power systems [15][16][17][18][19][20][21][22][23] Offering more desirable and flexible characteristic Increasing computation burden for coordination Reducing overall operating times of the relays Inapplicable with the exiting OCRs Needing to set some extra set point [24] Offering more desirable and flexible characteristic Increasing time interval between the main/backup relay pairs by decrease of the fault current Reducing overall operating times of the relays Inapplicable with the exiting OCRs [25] Preserving constant CTI between the main/backup relay pairs for entire fault current range Difficulty to apply to the large-scale meshed grids…”

“…The other way of forming a NSC is to consider the constant parameters of the SCs as variable set points. This approach was employed in [15][16][17][18][19][20][21][22][23] by considering the constants A, B and C of the IEEE standard characteristics [4] as variable set points. This way, more desirable and flexible TCCs with reduced operating times were achieved for the relays.…”

Voltage–current–time inverse‐based protection coordination of photovoltaic power systems

“…The performance of the VCTI relay is validated through hardware in simulation using real-time digital simulator (RTDS) in the laboratory as well as through Omicron relay testing kit [21]. The TDS, I p , k, and A are sequentially varied over the range mentioned in Section 3 above for modified 8 bus relay R1.…”

Power system protection with digital overcurrent relays: A review of non-standard characteristics

“…In addition, the study pointed out that increasing the limits of constants decreases the solution quality. The constants A and B in the IEC standard characteristic were considered as variables in [69,70,71,72,73,74,75,76,77]. The studies achieved a decrease in OTs of the relays while addressing the effect of DG.…”