Optimal Protection Coordination for Microgrid under Different Operating Modes

Table 7

Operating times and CTIs for bolted single line-to-ground faults in utility-only mode and in grid-connected mode.

Primary relay	Back-up relay	Operating time (sec)
		Utility-only mode			Grid-connected mode
		Primary	Backup	CTI	Primary	Backup	CTI
FCB2	Main CB1	0.261 (0.379)*	0.636 (0.636)	0.375 (0.257)	0.256 (0.370)	0.637 (0.636)	0.381 (0.266)
FCB3	Main CB1	0.261 (0.377)	0.636 (0.636)	0.375 (0.259)	0.253 (0.364)	0.637 (0.636)	0.384 (0.272)
LCB4	FCB2	0.100 (0.144)	0.300 (0.379)	0.2 (0.235)	0.099 (0.140)	0.299 (0.370)	0.2 (0.23)
LCB5	FCB2	0.101 (0.133)	0.365 (0.379)	0.264 (0.246)	0.099 (0.126)	0.372 (0.384)	0.273 (0.258)
LCB6	FCB2	0.016 (0.019)	0.458 (0.461)	0.442 (0.442)	0.017 (0.019)	0.463 (0.467)	0.446 (0.448)
LCB7	FCB3	0.100 (0.144)	0.300 (0.379)	0.2 (0.235)	0.099 (0.140)	0.299 (0.358)	0.2 (0.218)
LCB8	FCB3	0.101 (0.133)	0.365 (0.379)	0.264 (0.246)	0.099 (0.122)	0.380 (0.381)	0.281 (0.259)
LCB9	FCB3	0.016 (0.019)	0.458 (0.461)	0.442 (0.442)	0.018 (0.019)	0.496 (0.505)	0.478 (0.486)

∗The corrected values are shown in parentheses.