15 research outputs found
Topological analysis of the power grid and mitigation strategies against cascading failures
This paper presents a complex systems overview of a power grid network. In
recent years, concerns about the robustness of the power grid have grown
because of several cascading outages in different parts of the world. In this
paper, cascading effect has been simulated on three different networks, the
IEEE 300 bus test system, the IEEE 118 bus test system, and the WSCC 179 bus
equivalent model, using the DC Power Flow Model. Power Degradation has been
discussed as a measure to estimate the damage to the network, in terms of load
loss and node loss. A network generator has been developed to generate graphs
with characteristics similar to the IEEE standard networks and the generated
graphs are then compared with the standard networks to show the effect of
topology in determining the robustness of a power grid. Three mitigation
strategies, Homogeneous Load Reduction, Targeted Range-Based Load Reduction,
and Use of Distributed Renewable Sources in combination with Islanding, have
been suggested. The Homogeneous Load Reduction is the simplest to implement but
the Targeted Range-Based Load Reduction is the most effective strategy.Comment: 5 pages, 8 figures, 1 table. This is a limited version of the work
due to space limitations of the conference paper. A detailed version is
submitted to the IEEE Systems Journal and is currently under revie
Distributed Generation and Resilience in Power Grids
We study the effects of the allocation of distributed generation on the
resilience of power grids. We find that an unconstrained allocation and growth
of the distributed generation can drive a power grid beyond its design
parameters. In order to overcome such a problem, we propose a topological
algorithm derived from the field of Complex Networks to allocate distributed
generation sources in an existing power grid.Comment: proceedings of Critis 2012 http://critis12.hig.no
Epidemic and Cascading Survivability of Complex Networks
Our society nowadays is governed by complex networks, examples being the
power grids, telecommunication networks, biological networks, and social
networks. It has become of paramount importance to understand and characterize
the dynamic events (e.g. failures) that might happen in these complex networks.
For this reason, in this paper, we propose two measures to evaluate the
vulnerability of complex networks in two different dynamic multiple failure
scenarios: epidemic-like and cascading failures. Firstly, we present
\emph{epidemic survivability} (), a new network measure that describes the
vulnerability of each node of a network under a specific epidemic intensity.
Secondly, we propose \emph{cascading survivability} (), which characterizes
how potentially injurious a node is according to a cascading failure scenario.
Then, we show that by using the distribution of values obtained from and
it is possible to describe the vulnerability of a given network. We
consider a set of 17 different complex networks to illustrate the suitability
of our proposals. Lastly, results reveal that distinct types of complex
networks might react differently under the same multiple failure scenario
Optimizing the robustness of electrical power systems against cascading failures
Electrical power systems are one of the most important infrastructures that
support our society. However, their vulnerabilities have raised great concern
recently due to several large-scale blackouts around the world. In this paper,
we investigate the robustness of power systems against cascading failures
initiated by a random attack. This is done under a simple yet useful model
based on global and equal redistribution of load upon failures. We provide a
complete understanding of system robustness by i) deriving an expression for
the final system size as a function of the size of initial attacks; ii)
deriving the critical attack size after which system breaks down completely;
iii) showing that complete system breakdown takes place through a first-order
(i.e., discontinuous) transition in terms of the attack size; and iv)
establishing the optimal load-capacity distribution that maximizes robustness.
In particular, we show that robustness is maximized when the difference between
the capacity and initial load is the same for all lines; i.e., when all lines
have the same redundant space regardless of their initial load. This is in
contrast with the intuitive and commonly used setting where capacity of a line
is a fixed factor of its initial load.Comment: 18 pages including 2 pages of supplementary file, 5 figure
Context-Independent Centrality Measures Underestimate the Vulnerability of Power Grids
Power grids vulnerability is a key issue in society. A component failure may
trigger cascades of failures across the grid and lead to a large blackout.
Complex network approaches have shown a direction to study some of the problems
faced by power grids. Within Complex Network Analysis structural
vulnerabilities of power grids have been studied mostly using purely
topological approaches, which assumes that flow of power is dictated by
shortest paths. However, this fails to capture the real flow characteristics of
power grids. We have proposed a flow redistribution mechanism that closely
mimics the flow in power grids using the PTDF. With this mechanism we enhance
existing cascading failure models to study the vulnerability of power grids.
We apply the model to the European high-voltage grid to carry out a
comparative study for a number of centrality measures. `Centrality' gives an
indication of the criticality of network components. Our model offers a way to
find those centrality measures that give the best indication of node
vulnerability in the context of power grids, by considering not only the
network topology but also the power flowing through the network. In addition,
we use the model to determine the spare capacity that is needed to make the
grid robust to targeted attacks. We also show a brief comparison of the end
results with other power grid systems to generalise the result.Comment: Pre-Proceedings of CRITIS '1
Effects Comparison of Different Resilience Enhancing Strategies for Municipal Water Distribution Network: A Multidimensional Approach
Water distribution network (WDN) is critical to the city service, economic rehabilitation, public health, and safety. Reconstructing the WDN to improve its resilience in seismic disaster is an important and ongoing issue. Although a considerable body of research has examined the effects of different reconstruction strategies on seismic resistance, it is still hard for decision-makers to choose optimal resilience enhancing strategy. Taking the pipeline ductile retrofitting and network meshed expansion as demonstration, we proposed a feasible framework to contrast the resilience enhancing effects of two reconstruction strategies—units retrofitting strategy and network optimization strategy—in technical and organizational dimension. We also developed a new performance response function (PRF) which is based on network equilibrium theory to conduct the effects comparison in integrated technical and organizational dimension. Through the case study of municipal WDN in Lianyungang, China, the comparison results were thoroughly shown and the holistic decision-making support was provided