12,425 research outputs found
MATCASC: A tool to analyse cascading line outages in power grids
Blackouts in power grids typically result from cascading failures. The key
importance of the electric power grid to society encourages further research
into sustaining power system reliability and developing new methods to manage
the risks of cascading blackouts. Adequate software tools are required to
better analyze, understand, and assess the consequences of the cascading
failures. This paper presents MATCASC, an open source MATLAB based tool to
analyse cascading failures in power grids. Cascading effects due to line
overload outages are considered. The applicability of the MATCASC tool is
demonstrated by assessing the robustness of IEEE test systems and real-world
power grids with respect to cascading failures
Dynamic Effects Increasing Network Vulnerability to Cascading Failures
We study cascading failures in networks using a dynamical flow model based on
simple conservation and distribution laws to investigate the impact of
transient dynamics caused by the rebalancing of loads after an initial network
failure (triggering event). It is found that considering the flow dynamics may
imply reduced network robustness compared to previous static overload failure
models. This is due to the transient oscillations or overshooting in the loads,
when the flow dynamics adjusts to the new (remaining) network structure. We
obtain {\em upper} and {\em lower} limits to network robustness, and it is
shown that {\it two} time scales and , defined by the network
dynamics, are important to consider prior to accurately addressing network
robustness or vulnerability. The robustness of networks showing cascading
failures is generally determined by a complex interplay between the network
topology and flow dynamics, where the ratio determines the
relative role of the two of them.Comment: 4 pages Latex, 4 figure
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
Failure Localization in Power Systems via Tree Partitions
Cascading failures in power systems propagate non-locally, making the control
and mitigation of outages extremely hard. In this work, we use the emerging
concept of the tree partition of transmission networks to provide an analytical
characterization of line failure localizability in transmission systems. Our
results rigorously establish the well perceived intuition in power community
that failures cannot cross bridges, and reveal a finer-grained concept that
encodes more precise information on failure propagations within tree-partition
regions. Specifically, when a non-bridge line is tripped, the impact of this
failure only propagates within well-defined components, which we refer to as
cells, of the tree partition defined by the bridges. In contrast, when a bridge
line is tripped, the impact of this failure propagates globally across the
network, affecting the power flow on all remaining transmission lines. This
characterization suggests that it is possible to improve the system robustness
by temporarily switching off certain transmission lines, so as to create more,
smaller components in the tree partition; thus spatially localizing line
failures and making the grid less vulnerable to large-scale outages. We
illustrate this approach using the IEEE 118-bus test system and demonstrate
that switching off a negligible portion of transmission lines allows the impact
of line failures to be significantly more localized without substantial changes
in line congestion
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