Joint placement of phasor and conventional power flow measurements for fault observability of power systems

The authors consider the problem of joint optimal placement of phasor measurement units (PMUs) and conventional power flow measurements to ensure observability under faulted conditions in power systems. The formulation is initially posed as a non-linear integer programming problem and then transformed into an equivalent integer linear programming (ILP) problem through boolean implications. The resulting ILP problem is solved for the optimal solution on IEEE 14, 30, 57 and 118 bus systems and a large 2383 bus Polish system. The placement results obtained with the proposed formulation require fewer PMUs for fault observability compared with systems with fixed locations of conventional measurements. The results thus potentially provide a more economical solution to observability under faults compared with those obtained solely with PMU placement.