IEEE Test System	No. of Optimal PMUs		% of Additional PMUs compared with original placement	Additional PMU Placement Location considering critical buses
IEEE Test System	Normal Operating Condition	More weight age to critical PMUs	% of Additional PMUs compared with original placement
14	4	6	50%	1 4
30	10	14	40%	5 8 12 16 22
57	17	26	53%	4 7 11 21 23 30 33 34 42
118	32	51	59%	4 6 8 18 32 46 54 57 58 78 83 88 96 100 106 108 111 112 117