  Distribution grid topology and admittance information are essential for
system planning, operation, and protection. In many distribution grids, missing
or inaccurate topology and admittance data call for efficient estimation
methods. However, measurement data may be insufficient or contaminated with
large noise, which will introduce fundamental limits to the estimation
accuracy. This work explores the theoretical precision limits of the topology
and admittance estimation (TAE) problem, with different measurement devices,
noise levels, and the number of measurements. On this basis, we propose a
conservative progressive self-adaptive (CPS) algorithm to estimate the topology
and admittance. Results on IEEE 33 and 141-bus systems validate that the
proposed CPS method can approach the theoretical precision limits under various
measurement settings.
