“…To achieve the complete observability of the given system, total 42 PMUs are required. The optimal locations for these PMUs are 6,8,11,12,14,16,17,19,20,22,23,25,26,29,31,32,34,36,37,41,42,44,45,46,47,48,49,51,52,56,57,58,59, 60, 61, 62, 63, 64, 65, 66, 67, and 68. Placing PMUs on these locations will make the system completely observable at least by two PMUs, even when single-transmission line or PMU is lost.…”