Line Impedance Estimation

Line impedance estimation provides crucial information for power-line communication (PLC), power quality estimation, and grid-connected power electronics applications. Online techniques are particularly useful as the line impedance is time-dependent. This work uses a phase-controlled switch to generate a turn-on transient, which provides information about the line. Previous switching-based approaches focus on fitting line characteristics to a model. This article extends previous work by using a common electrical load in place of previously used capacitors, inductors, and short circuits. Nonparametric line impedance estimation is also demonstrated. An inrush transient generates a current with a wide-bandwidth spectral content to replace a sinusoidal injection sweep. Good estimation performance is demonstrated from dc up to 200 kHz.