Day by day, electrical energy demand increases in developing countries Due to that increment, complexity of the transmission and distribution grids gets scaled up. Alternating the components of conventional grid with smart grid devices is required owing to the fact that monitoring more complex grids by conventional methods is hard. The purpose of this study is to monitor datas synchronously. Phasor measurement units (PMU) and GPS enable to measure current, voltage and phasor angle simultaneously. Since PMUs are expensive, PMUs should be reasonably located to keep number of them low. In this study, optimum number of PMUs place at 9 and 14-bus IEEE test system.