Innovation in Global Power - Parsons Brinckerhoff

Distributing Power to Users
A Survey of Power System Packages for
Distribution Network Analysis
http://www.pbworld.com/news_events/publications/network/
By Arthur Ekwue, Godalming, UK, 44 (0)148352 8609, ekwueA@pbworld.com; Nicola Roscoe, Manchester, UK, 44 (0)161200 5193,
roscoeN@pbworld.com; and Charles Lynch, Northwich, UK, 44 (0)16064 7889, calynch@PowerAnalysis.co.uk
The authors present the
results of a survey undertaken
amongst distribution
network operators around
the world to identify tools
that would be suitable for
the distribution networks of
the future. Their objectives
are to share this technical
information with other
power engineers within
PB and to improve the
awareness within our firm
of future trends and how
we are contributing to
them.
The global trend to reduce greenhouse emissions is leading to increasing levels of new
electricity generation from renewable sources and the embedding of this new power
within electricity distribution networks. These changes will have some implications for
the electricity distribution networks and their operators (DNOs). For example:
• The connection of renewable generation could raise the fault levels on existing transmission
lines to values beyond the capacity of existing switchgear because of the fault contributions
from the renewable generators themselves.
• The new generation sources could displace existing conventional methods of generation that,
historically, have provided the response characteristics needed to maintain the overall
integrity of the transmission system. This could result in instability problems when the
intermittent generators supply a significant proportion of system demand, especially at light loads.
• Voltage control and power quality problems can arise when generators embedded within
the distribution networks start or stop generating power. If not properly regulated, this
could cause other network users to suffer voltage fluctuations outside the acceptable
statutory limits and inject unwanted harmonics into the voltage waveform.
Such changes, and increasing power loads, are putting new demands on DNOs and on the
software packages they use to perform the critical analyses of their networks’ performance.
One of our clients, a DNO facing these issues, wanted to upgrade its network analysis system
accordingly, and hired PB to identify:
• Power system analytical software that will be suitable for distribution networks of the future
• Strengths and weaknesses of such software packages as seen by users, including ease of use.
We approached this task by conducting an extensive survey of DNOs around the world.
Some did not want to share this information, but those who did were equally interested
in learning of our findings. While PB uses or has used many of the commercially available
packages mentioned in this article, it was not our task to provide our judgment of them,
but to report on the experiences that DNOs had with them. It should be noted that
several of the packages are used for transmission network analysis also, but investigating
that application was not within the scope of this project.
The Survey
Arthur Ekwue and Nicola Roscoe
are principal power system
engineers and professional
associates. Arthur is based in
Godalming and Nicola is in
Manchester.
Charles Lynch is the principal
engineer/director of Power Analysis
Limited, which is based in
Northwich, UK.
1 L A Jorge et al, “DPlan: Through
R&D into a World Class Product”,
Proceedings of EPRI Latin American
Conference and Exhibition, Rio de
Janeiro, Brazil, 2001.
The main questions of the survey centred on the availability of power system analysis tools
to assist in the connection of embedded generation on the 33 kV, 11 kV and LV (low voltage)
networks. This included software packages used for:
• Load flow, fault level, transient stability, reliability (customer interruptions and customer
minutes lost calculations), contingency studies and protection coordination
• Power quality studies, including voltage unbalance, flicker, motor starting and harmonics.
The survey included some open ended questions aimed at learning:
• Whether the DNOs had geographic information systems (GISs) and, if so, whether there
were links between the GIS and the planning software
• How DNOs rated the software packages they used in terms of usability, manufacturer
support (e.g. technical support, user groups etc) and cost
• Whether the DNOs had any plans to change or upgrade the software they used currently
and, if so, what alternatives were being considered.
75 PB Network #68 / August 2008