  This paper presents novel methods for parameter identification in electrical
grids with small numbers of spatially distributed measuring devices, which is
an issue for distribution system operators managing aged and not properly
mapped underground Low Voltage (LV) grids, especially in Germany. For this
purpose, the total impedance of individual branches of the overall system is
estimated by measuring currents and voltages at a subset of all system nodes
over time. It is shown that, under common assumptions for electrical
distsribution systems, an estimate of the total impedance can be made using
readily computable proxies. Different regression methods are then used and
compared to estimate the total impedance of the respective branches, with
varying weights of the input data. The results on realistic LV feeders with
different branch lengths and number of unmeasured segments are discussed and
multiple influencing factors are investigated through simulations. It is shown
that estimates of the total impedances can be obtained with acceptable quality
under realistic assumptions.
