Coordination of dual setting overcurrent relays in microgrid with optimally determined relay characteristics for dual operating modes

Protection and Control of Modern Power Systems

Table 3 Current through relay coils in grid-connected and islanded operating modes for 7-bus microgrid system

Faulty line	Relay pair	Primary relay	Backup relay (dual)	Fault current through relay coils
				Grid-connected (A)		Islanded mode (A)
				Primary	Backup	Primary	Backup
L1	RP1	R1	R3	12.075	3.19	9.03	0.64
	RP2	R1	R5	12.075	2.53	9.03	1.76
	RP3	R2	R7	17.175	4.13	11.52	1.45
L2	RP4	R3	R1	9.561	4.10	8.07	2.39
	RP5	R3	R5	9.561	2.16	8.07	1.04
	RP6	R4	R14	16.075	2.64	5.35	1.59
	RP7	R4	R15	16.075	1.69	5.35	3.30
L3	RP8	R5	R1	17.196	3.27	12.4	2.32
	RP9	R5	R3	17.196	2.67	12.4	0.538
	RP10	R6	R16	16.785	6.18	11.72	2.60
L4	RP11	R7	R2	7.038	9.94	6.174	7.34
	RP12	R8	R9	16.793	2.34	6.134	2.80
L5	RP13	R9	R8	16.038	6.08	5.356	6.52
	RP14	R10	R11	11.634	10.86	8.65	7.85
L6	RP15	R11	R10	19.90	19.37	9.154	8.36
	RP16	R12	R13	7.18	22.15	4.94	15.11
L7	RP17	R13	R12	18.28	5.75	9.675	2.97
	RP18	R14	R4	11.04	5.51	6.43	6.37
	RP19	R14	R15	11.04	3.012	6.43	3.66
L8	RP20	R15	R4	17.728	3.047	9.52	5.22
	RP21	R15	R14	17.728	2.075	9.52	1.435
	RP22	R16	R6	9.734	9.145	8.14	6.165