“…The test case systems are assumed to be partially observable through PMUs. From the existing studies, for complete system observability based on PMUs only, an optimal number of 4, 10, and 17 PMUs are required for IEEE 14 bus, IEEE 30 bus, and IEEE 57 bus, respectively [39] , [40] , [41] , [42] . Therefore, each test case considers a random number of PMUs for partial observability (less than the optimal number).…”