Abstract
M.Ing. (Electrical Engineering Science)
In today's rapidly changing technological environment, more and more importance is being
attached to producing products as small as possible to save space as well as materials.
Systems today use a wide range of signals, from those used to transmit energy, to small
signal electronic signals used for control purposes. As these signals are not very
compatible, they must each have their own cable harness to prevent unwanted interference
between the signals. As a first step to reducing system size, the control signals (or any
signal containing information) may be transmitted on the power transmission line, using
techniques investigated in this dissertation.
Systems using the same conductors for simultaneous energy and data transmission have
many applications ranging from high tech systems to low cost rural communication.
Examples of systems where this technology can be applied include:
(a) distributed high frequency power systems, where switching of remote equipment
can be done from a central point;
(b) communication and control in harsh environments such as mining complexes,
where switching of fans and motors for example can be done from a central point, while a
communication network can be established by placing the information signals on the
power cables; and
(c) flexible manufacturing cells, where robots can be controlled via the power
transmission harness.
On the other hand, rural communication systems can be realised over the 50 Hz utility
transmission network in remote areas. Such a system has the advantage of offering a low
cost solution to providing access to communication to a large number of people spread
over a large area.
The work described In this dissertation covers two systems, firstly information
transmission over the 50 Hz utility network and secondly, the design of a high frequency
distributed power system utilising simultaneous information transmission on the
transmission line.The first three chapters give an introduction to the technology and
discuss the theory which must be applied to make simultaneous energy and information
transmission over one conductor viable.
Chapter 4 discusses the 50 Hz utility network as an information distribution network. The
advantages and disadvantages are discussed, while some solutions are proposed how the
disadvantages can be overcome.
Chapter 5 discusses a high frequency distributed power system using simultaneous
information transmission. The converter design is discussed, while some special design
considerations are given which are essential to successful simultaneous information
transmission in such a distributed system. To help with the design of the converter used, a
simulation was carried out to predict the voltage and current waveforms in such a
converter, the results of which can be seen in Appendix B..
The aim of simultaneously transmitting energy and information on the same transmission
line was realised in both cases. In the 50 Hz system it was shown that adding external
networks to guide the information carrier around obstacles such as 50 Hz power
transformers improved the information transmission. A distributed power system however
does not need external elements as long as the design of transformers follows the special
considerations as described in chapter 5.