Single-Phase Distribution Transformer Modeling for Narrowband Power Line Communications

This paper proposes three different black-box models for a 10-kVA 7.967 kV-120/240 V distribution transformer that is suitable to narrowband power line communication studies. One is valid in the 3-500 kHz range, while the remaining two are simpler models valid for the CENELEC band (3-148.5 kHz). The models are represented as equivalent circuits derived from the rational approximation of the transformer admittance matrix using either phase- or modal-domain theory. All parameters needed for their implementation in electrical circuit solvers are given. Validation is performed not only in frequency domain, but also in time domain, with the application of voltage signals that excite the 3-500 kHz and 3-148.5 kHz frequency bands uniformly. The models are shown to accurately predict the attenuation and distortion of signals transferred through the transformer for a wide range of load conditions for both downstream and upstream signal transmission. Signal attenuation is shown to be load dependent, frequency dependent, and sensitive to the considered transmission path (downstream or upstream).