M. D'Amore

Digital Signal Transmission on Power Line Carrier Channels: An Introduction

The possibility of transmitting digital signals on power line carrier channels is investigated. An accurate model of the multiconductor transmission line and a rigorous propagation algorithm are used. A computer aided procedure is presented to evaluate transient response to any input digital signal code. The discrete convolution method uses the inverse Fourier transform of the channel frequency response in amplitude and phase. The eye diagram approach permits evaluation of channel performance. The results obtained in an application on a 3-phase long line confirm the feasibility of the proposed method.

Telecommunication systems on power distribution networks: high frequency performances of carrier channels

In the framework of a project aimed at the design and installation of a new extensive distribution automation system in the ENEL SpA (Italian National Electricity Company) distribution network, this paper presents the investigations carried out to check the feasibility of a line carrier system on the primary (medium voltage 10-30 kV) network. In particular, this paper reports the experimental investigations conducted in the laboratory on various network components, to assess their behavior in the 20-100 kHz frequency range, and some signal transmission tests on real networks. Analytical procedures to predict the high frequency signal propagation in the network, set up for this purpose, are also described. The results of their applications to various network configurations are used as a guide for the optimal design of the power carrier communication system. >

Digital generator of corona noise on power line carrier channels

A procedure is presented for the design of a digital simulator which generates a random time sequence having the statistical characteristics of the corona noise that occurs on transmission line carrier channels. The method involves the synthesis of an autoregressive filter excited by a white-noise generator is a part of the overall digital transmission system, which includes the generating and receiving sections, and the PLC (power line carrier) channel. The proposed procedure is applied to simulate corona noise on practical HVAC transmission lines. >

Electromagnetic interference from digital signal transmission on power line carrier channels

A procedure is presented to evaluate the electromagnetic field generated by a digital transmission system on multiconductor power-line carrier channels. The vertical component of the electric field and the horizontal component of the magnetic field are defined by approximate formulaes of varying accuracy, depending on the frequency and the distance from phase conductors. Field sources are the currents traveling along the line, which are evaluated by means of an accurate simulation model of the transmission system and a rigorous wave propagation algorithm. Frequency spectra and lateral profiles of the field components are computed for single-phase and two-phase couplings on a horizontal power line. Digital channel capacity is shown to increase as the pulse repetition interval T decreases. However, if T increases, the harmonic content of the input signal code increases and, consequently, electromagnetic pollution rises for a given carrier channel. It is concluded that the EMI (electromagnetic interference) level is an important constraint which must be taken into account when choosing T and, more generally, in the design of the digital transmission system. >

Analytical Method for Calculating Corona Noise on HVAC Power Line Carrier Communication Channels

A method is presented for computing corona noise level on coupling arrangements of HVAC power line carriers. Corona noise is generated by the corona current, which is injected into the bundle conductors by the corona sources randomly distributed along the line. Corona current is computed by adding the excitation function and the propagation factor. The excitation function is eval uated by using a formula already definied for predicting radio noise level. The propagation factor is computed by using a very accurate line simulation-model and a rigorous propagation algorithm, valid also for a non-uniform transmission system of any length or geometrical configuration or terminal impedances. Corrective terms are introduced, which allow evaluation of corona noise in the carrier frequency range, with any given bandwidth, in terms of quasi-peak or rms or average value.

Effect of Reflection Waves on Poliphase Non-Uniform Power Line Carrier Channels: A New Propagation Matrix Model

A new matrix model is presented for the study of the voltage and current waves propagation on lossy, non-uniform, polyphase transmission lines. The transmission system is composed of sub-systems in which there are present discontinuities due to junctions of different line sections, phase transpositions, terminal loads. At every discontinuity the reflected (backward) and transmitted waves are computed as functions of the incident (forward) ones by means of matrix operators. An overall transmission matrix relating the input-output voltages and currents is defined, taking into account the multiple reflections caused by two or more discontinuities. The proposed mathematical model is used to compute the voltage attenuation coefficient of practical coupling connections on non-uniform lines, in a wide range of frequencies. The results obtained offer useful indications for the evaluation of the effects on voltage attenuation produced by the reflected waves, and for the optimal choice of terminal impedances.

A New Efficient Method to Evaluate Carrier Channel Performances on Long EHV Power Lines With Transpositions

A new mathematical model to evaluating the carrier channel performances on lossy, non-uniform multiconductor transmission lines is presented. Travelling wave the ory is used to define the current and voltage propagation equations on transmission systems which present discontinuity points due to phase transpositions, terminal impedances, shunt-faults. The proposed algorithm makes it possible to compute the voltage attenuation at the generic progressive along the line and in abnormal conditions caused by the presence of a shunt-fault. Practical applications are presented for two long EHV transmission lines with phase transpositions. The results obtained show the effects on voltage attenuation produced by the presence of transpositions and line faults and offer useful indications for the optimal choice of coupling arrangements.