306 research outputs found
Changes in Cascading Failure Risk with Generator Dispatch Method and System Load Level
Industry reliability rules increasingly require utilities to study and
mitigate cascading failure risk in their system. Motivated by this, this paper
describes how cascading failure risk, in terms of expected blackout size,
varies with power system load level and pre-contingency dispatch. We used Monte
Carlo sampling of random branch outages to generate contingencies, and a model
of cascading failure to estimate blackout sizes. The risk associated with
different blackout sizes was separately estimated in order to separate small,
medium, and large blackout risk. Results from secure models of the IEEE
RTS case and a 2383 bus case indicate that blackout risk does not always
increase with load level monotonically, particularly for large blackout risk.
The results also show that risk is highly dependent on the method used for
generator dispatch. Minimum cost methods of dispatch can result in larger long
distance power transfers, which can increase cascading failure risk.Comment: Submitted to Transmission and Distribution Conference and Exposition
(T&D), 2014 IEEE PE
Quantifying the Influence of Component Failure Probability on Cascading Blackout Risk
The risk of cascading blackouts greatly relies on failure probabilities of
individual components in power grids. To quantify how component failure
probabilities (CFP) influences blackout risk (BR), this paper proposes a
sample-induced semi-analytic approach to characterize the relationship between
CFP and BR. To this end, we first give a generic component failure probability
function (CoFPF) to describe CFP with varying parameters or forms. Then the
exact relationship between BR and CoFPFs is built on the abstract
Markov-sequence model of cascading outages. Leveraging a set of samples
generated by blackout simulations, we further establish a sample-induced
semi-analytic mapping between the unbiased estimation of BR and CoFPFs.
Finally, we derive an efficient algorithm that can directly calculate the
unbiased estimation of BR when the CoFPFs change. Since no additional
simulations are required, the algorithm is computationally scalable and
efficient. Numerical experiments well confirm the theory and the algorithm
Cascading Power Outages Propagate Locally in an Influence Graph that is not the Actual Grid Topology
In a cascading power transmission outage, component outages propagate
non-locally, after one component outages, the next failure may be very distant,
both topologically and geographically. As a result, simple models of
topological contagion do not accurately represent the propagation of cascades
in power systems. However, cascading power outages do follow patterns, some of
which are useful in understanding and reducing blackout risk. This paper
describes a method by which the data from many cascading failure simulations
can be transformed into a graph-based model of influences that provides
actionable information about the many ways that cascades propagate in a
particular system. The resulting "influence graph" model is Markovian, in that
component outage probabilities depend only on the outages that occurred in the
prior generation. To validate the model we compare the distribution of cascade
sizes resulting from contingencies in a branch test case to
cascade sizes in the influence graph. The two distributions are remarkably
similar. In addition, we derive an equation with which one can quickly identify
modifications to the proposed system that will substantially reduce cascade
propagation. With this equation one can quickly identify critical components
that can be improved to substantially reduce the risk of large cascading
blackouts.Comment: Accepted for publication at the IEEE Transactions on Power System
Can the Markovian influence graph simulate cascading resilience from historical outage data?
It is challenging to simulate the cascading line outages that can follow initial damage to the electric power transmission system from extreme events. Instead of model-based simulation, we propose using a Markovian influence graph driven by historical utility data to sample the cascades. The sampling method encompasses the rare, large cascades that contribute greatly to the blackout risk. This suggested new approach contributes a high-level simulation of cascading line outages that is driven by standard utility data
Analysis of the blackout risk reduction when segmenting large power systems using lines with controllable power flow
Large electrical transmission networks are susceptible to undergo very large blackouts due to cascading failures, with a very large associated economical cost. In this work we propose segmenting large power grids using controllable lines, such as high-voltage direct-current lines, to reduce the risk of blackouts. The method consists in modifying the power flowing through the lines interconnecting different zones during cascading failures in order to minimize the load shed. As a result, the segmented grids have a substantially lower risk of blackouts than the original network, with reductions up to 60% in some cases. The control method is shown to be specially efficient in reducing blackouts affecting more than one zone.DG and PC acknowledge funding from project PACSS RTI2018-093732-B-C22 and APASOS PID2021-122256NB-C22 of the MCIN/AEI/10.13039/501100011033/ and by EU through FEDER funds (A way to make Europe), from the Maria de Maeztu program MDM-2017-0711 of the MCIN/AEI/10.13039/501100011033/, and also from the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 957852, VPP4Islands). B.A.C. and J.M.R.-B. acknowledge access to Uranus, a supercomputer cluster located at Universidad Carlos III de Madrid (Spain) funded jointly by EU FEDER funds and by the Spanish Government via the National Research Project Nos. UNC313-4E-2361, ENE2009-12213-C03-03, ENE2012-33219, and ENE2012-31753. OGB was supported in part by FEDER/Ministerio de Ciencia, Innovacion y Universidades - Agencia Estatal de Investigación, Project RTI2018-095429-B-I00 and in part by FI-AGAUR Research Fellowship Program, Generalitat de Catalunya. The work of OGB is supported by the ICREA Academia program
Stochastic Model for Power Grid Dynamics
We introduce a stochastic model that describes the quasi-static dynamics of
an electric transmission network under perturbations introduced by random load
fluctuations, random removing of system components from service, random repair
times for the failed components, and random response times to implement optimal
system corrections for removing line overloads in a damaged or stressed
transmission network. We use a linear approximation to the network flow
equations and apply linear programming techniques that optimize the dispatching
of generators and loads in order to eliminate the network overloads associated
with a damaged system. We also provide a simple model for the operator's
response to various contingency events that is not always optimal due to either
failure of the state estimation system or due to the incorrect subjective
assessment of the severity associated with these events. This further allows us
to use a game theoretic framework for casting the optimization of the
operator's response into the choice of the optimal strategy which minimizes the
operating cost. We use a simple strategy space which is the degree of tolerance
to line overloads and which is an automatic control (optimization) parameter
that can be adjusted to trade off automatic load shed without propagating
cascades versus reduced load shed and an increased risk of propagating
cascades. The tolerance parameter is chosen to describes a smooth transition
from a risk averse to a risk taken strategy...Comment: framework for a system-level analysis of the power grid from the
viewpoint of complex network
- …