Both the growing number of dispersed generation plants and storage systems

and the new roles and functions on the demand side (e.g. demand side management) are

making the operation (monitoring and control) of electrical grids more complex, especially

in distribution. This paper demonstrates how to integrate phasor measurements so that

state estimation in a distribution grid profits optimally from the high accuracy of PMUs.

Different measurement configurations consisting of conventional and synchronous mea-

surement units, each with different fault tolerances for the quality of the calculated system

state achieved, are analyzed and compared. Weighted least squares (WLS) algorithms for

conventional, linear and hybrid state estimation provide the mathematical method used in

this paper. A case study of an 18-bus test grid with real measured PMU data from a 110 kV

distribution grid demonstrates the improving of the system’s state variable’s quality by

using synchrophasors. The increased requirements, which are the prerequisite for the use

of PMUs in the distribution grid, are identified by extensively analyzing the inaccuracy of

measurement and subsequently employed to weight the measured quantities.