G4 Doctoral dissertation (monograph)

Assessing the Applicability of Low Voltage Direct Current in Electricity Distribution — Key Factors and Design Aspects


Open Access publication

Publication Details
Authors: Karppanen Janne
Publishing place: Lappeenranta
Publication year: 2020
Language: English
Related Journal or Series Information: Acta Universitatis Lappeenrantaensis
ISBN: 978-952-335-576-7
eISBN: 978-952-335-577-4
ISSN: 1456-4491
JUFO-Level of this publication:
Permanent website address: http://urn.fi/URN:ISBN:978-952-335-577-4
Open Access: Open Access publication

Abstract

In many countries, the electricity distribution companies are facing the challenge of how to develop
the networks effectively and respond to the future needs of societies. Changes in the electricity
end use, aging network assets, integration of distributed energy resources, and renewable
energy together with the increasing dependence on electricity supply are topical issues. From
societies’ point of view, an important question is: What are the socio-economically feasible approaches
and solutions that enable the transformation towards a more flexible energy system?
One recognized technological alternative for the latter part of the electricity distribution is the
application of power electronics and direct current. In this work, the main emphasis is on the
public electricity distribution, especially in rural areas.

Low voltage direct current (LVDC) distribution can be used in various application targets having
different properties. Its feasibility is highly dependent on the operating environment and
its special characteristics including regulation, business environment, energy policy, technical
and safety perspectives, existing installations, cost structures, and national and even regional
development needs. Concurrently, there are many properties within the LVDC distribution that
can be selected and designed in multiple ways. Such are for instance voltage levels, earthing
system, converter characteristics, network structures and topologies, and location of converters.
The overall feasibility of LVDC is dependent on the selection of suitable system properties for
a particular operating environment. For now, as LVDC is a novel solution in public electricity
distribution, it is challenging for the distribution system operators to estimate the potential and
feasibility of the LVDC as there are no practices of how the LVDC networks and systems could
and should be designed.

In this work, a process was developed to support the strategic decision-making and assessment
of the role of LVDC in the long-term network development. The work provides answers to
the two principal questions of how to determine the potential LVDC targets and which kinds
of technical solutions are suitable and advantageous, depending on the characteristics of the
operating environment. To be able to answer these questions, the value and impact of various
factors have to be understood. These include aspects ranging from the operating environment
to the LVDC network itself and technical specifications in the system design. In the work,
theoretical analyses, practical experiences, and case examples of different explanatory environments
were used. The contributions can be used in assessing the viability of LVDC in different
environments.


LUT Focus Areas

Last updated on 2020-03-12 at 10:25