Method and apparatus for grid impedance detection

摘要

A method and apparatus for monitoring an AC line for impedance change. In one embodiment, the method, comprises superimposing a tone on an AC current coupled to the AC line, wherein the tone is a higher frequency than an AC voltage waveform on the AC line; applying a correlation over a sampled AC voltage waveform, obtained by sampling the AC voltage waveform, to generate a correlated signal; and determining whether at least one change in characteristic of the correlated signal occurs.

主权项

1. A method for monitoring an AC power grid, comprising one or more distributed generation systems, for impedance changes, comprising:
superimposing a tone on an AC current flowing in an AC line of a distributed generation system connected to the AC power grid, wherein the tone has a higher frequency than a frequency of an AC voltage waveform of the power grid; applying a correlation between a sampled AC voltage waveform and a copy of the superimposed tone to generate a correlated signal, wherein the sampled AC voltage waveform is obtained by sampling the AC voltage waveform subsequent to superimposing the tone on the AC current determining whether at least one change in a characteristic of the correlated signal occurs, thereby detecting a change in the grid impedance.