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|Title: ||Dynamic equivalencing of distribution network with embedded generation|
|Authors: ||Feng, Xiaodan Selina|
|Supervisor(s): ||Bialek, Janusz|
|Issue Date: ||25-Jun-2012|
|Publisher: ||The University of Edinburgh|
|Abstract: ||Renewable energy generation will play an important role in solving the
climate change problem. With renewable electricity generation increasing,
there will be some significant changes in electric power systems, notably
through smaller generators embedded in the distribution network.
Historically insignificant volumes of Embedded Generation (EG) mean that
traditionally it has been treated by the transmission system operator as
negative load, with its impact on the dynamic behaviour of power systems
neglected. However, with the penetration level increasing, EG would start
to influence the dynamics and stability of the transmission network. Hence
the dynamic behaviour of distribution network cannot be neglected any
In most cases, a detailed distribution network model is not always available
or necessary for the study of transmission network dynamics and stability.
Thus a dynamic equivalent model of the distribution network that keeps its
essential dynamic behavior, is required.
Most existing dynamic equivalencing methods are based on the assumption
that the detailed information of the complete power system is known.
Dynamic equivalencing methods based on coherency of the machines have
been applied to transmission networks but cannot be applied to distribution
networks due to their radial structure. Hence an alternative methodology
has been developed in this project to derive the dynamic equivalent model
of the distribution network using system identification, without the detailed
information of the distribution network necessarily known.
Case studies have been accomplished in PSS/E on a model of the Scottish
transmission network with the distribution network in Dumfries and
Galloway. Embedded generation with a certain penetration level in either
conventional generation or DFIG wind generation has been added to the
model of the distribution network. The dynamic equivalent models of the
distribution network are compared with the original distribution network
model using a series of indicators. A constant power model has also been
involved in the comparison to illustrate the advantage of using the dynamic
equivalent to represent the distribution network.
The results suggest that a proper dynamic equivalent model derived using
this methodology may have better agreement to the original power system
dynamic response than constant power equivalent. A discussion on factors that influence the performance of the dynamic equivalent model, is given to
indicate the proper way to use this methodology.
The major advantage of the dynamic equivalencing methodology developed
in this project is that it can potentially use the time series obtained from
measurements to derive the dynamic equivalent models without knowing
detailed information on the distribution network. The derived dynamic
equivalent, in a simple spate-space form, can be implemented in commercial
simulation tools, such as PSS/E.|
|Keywords: ||dynamic equivalent|
|Appears in Collections:||Engineering thesis and dissertation collection|
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