Estimating the Propagation of Interdependent Cascading Outages with Multi-Type Branching Processes

In this paper, the multi-type branching process is applied to describe the statistics and interdependencies of line outages, the load shed, and isolated buses. The offspring mean matrix of the multi-type branching process is estimated by the Expectation Maximization (EM) algorithm and can quantify the extent of outage propagation. The joint distribution of two types of outages is estimated by the multi-type branching process via the Lagrange-Good inversion. The proposed model is tested with data generated by the AC OPA cascading simulations on the IEEE 118-bus system. The largest eigenvalues of the offspring mean matrix indicate that the system is closer to criticality when considering the interdependence of different types of outages. Compared with empirically estimating the joint distribution of the total outages, good estimate is obtained by using the multitype branching process with a much smaller number of cascades, thus greatly improving the efficiency. It is shown that the multitype branching process can effectively predict the distribution of the load shed and isolated buses and their conditional largest possible total outages even when there are no data of them.Comment: Accepted by IEEE Transactions on Power System

Comparison between different electrical configurations of emergency diesel generators for redundancy and reliability improving

The failure of an emergency diesel generator could cause a blackout with economic or human losses, especially if it occurs in a hospital. The authors performed an up to date statistic on diesel generators fails has been investigated in a hundred of hospitals. Although standard maintenance operation has been correctly performed, it has been found a 6 % of failures for the genset per year. MTBF of generators and main components have been investigated and updated values are reported in this paper. Components reliability is proved to be at its maximum technological value, consequently an innovative solution is here proposed. Often neighboring buildings or different electrical systems have separated emergency generators. Nowadays, in case of genset failure, most of the electrical installations are not designed to be fed from other generators. Several electrical configurations for diesel generators interconnections have been studied, in order to guarantee the mutual succor between them and therefore improving reliability. Two innovative schemes for emergency generators connection are here proposed for a more reliable electrical design

Predicting cascading failures in power systems using graph convolutional networks

Worldwide targets are set for the increase of renewable power generation in electricity networks on the way to combat climate change. Consequently, a secure power system that can handle the complexities resulted from the increased renewable power integration is crucial. One particular complexity is the possibility of cascading failures — a quick succession of multiple component failures that takes down the system and might also lead to a blackout. Viewing the prediction of cascading failures as a binary classification task, we explore the efficacy of Graph Convolution Networks (GCNs), to detect the early onset of a cascading failure. We perform experiments based on simulated data from a benchmark IEEE test system. Our preliminary findings show that GCNs achieve higher accuracy scores than other baselines which bodes well for detecting cascading failures. It also motivates a more comprehensive study of graph-based deep learning techniques for the current problem

The Impact of Transitory Income on Birth Weights: Evidence from a Blackout in Zanzibar

Do transitory income shocks affect infant health? I find evidence that birth weights fell following a temporary income reduction caused by an unexpected, month-long blackout in Zanzibar. Relying on 350 household surveys collected during field work, I show that the 2008 blackout reduced labor supply of workers in electricity-dependent jobs by an average of 25%, with no effect on workers in other sectors. The income shock was temporary. Using over 20,000 birth records from a maternity ward, I document a reduction in the average birth weight of children exposed to the blackout while in utero, and an increase in the probability of low birth weight. Supporting a causal interpretation of these results, the reduction in weights is correlated with measures of maternal exposure to the blackout. In particular, reductions in birth weights were largest among children from wards with intermediate levels of employment in electrified sectors. The two causes that are most consistent with these results are a blackout-induced decline in maternal nutrition, and maternal stress. Alternative explanations are examined, including the possible effects of a temporary fertility shift. It is shown that the blackout increased births, but that selection into pregnancy cannot explain the drop in birth weights.Neonatal health, Birthweights, Nutrition, Fertility, Transitory income, Blackouts, Africa

Part 3: Systemic risk in ecology and engineering

The Federal Reserve Bank of New York released a report -- New Directions for Understanding Systemic Risk -- that presents key findings from a cross-disciplinary conference that it cosponsored in May 2006 with the National Academy of Sciences' Board on Mathematical Sciences and Their Applications. ; The pace of financial innovation over the past decade has increased the complexity and interconnectedness of the financial system. This development is important to central banks, such as the Federal Reserve, because of their traditional role in addressing systemic risks to the financial system. ; To encourage innovative thinking about systemic issues, the New York Fed partnered with the National Academy of Sciences to bring together more than 100 experts on systemic risk from 22 countries to compare cross-disciplinary perspectives on monitoring, addressing and preventing this type of risk. ; This report, released as part of the Bank's Economic Policy Review series, outlines some of the key points concerning systemic risk made by the various disciplines represented - including economic research, ecology, physics and engineering - as well as presentations on market-oriented models of financial crises, and systemic risk in the payments system and the interbank funds market. The report concludes with observations gathered from the sessions and a discussion of potential applications to policy. ; The three papers presented in this conference session highlighted the positive feedback effects that produce herdlike behavior in markets, and the subsequent discussion focused in part on means of encouraging heterogeneous investment strategies to counter such behavior. Participants in the session also discussed the types of models used to study systemic risk and commented on the challenges and trade-offs researchers face in developing their models.Financial risk management ; Financial markets ; Financial stability ; Financial crises

Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems

The first-ever Ukraine cyberattack on power grid has proven its devastation by hacking into their critical cyber assets. With administrative privileges accessing substation networks/local control centers, one intelligent way of coordinated cyberattacks is to execute a series of disruptive switching executions on multiple substations using compromised supervisory control and data acquisition (SCADA) systems. These actions can cause significant impacts to an interconnected power grid. Unlike the previous power blackouts, such high-impact initiating events can aggravate operating conditions, initiating instability that may lead to system-wide cascading failure. A systemic evaluation of "nightmare" scenarios is highly desirable for asset owners to manage and prioritize the maintenance and investment in protecting their cyberinfrastructure. This survey paper is a conceptual expansion of real-time monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework that emphasizes on the resulting impacts, both on steady-state and dynamic aspects of power system stability. Hypothetically, we associate the combinatorial analyses of steady state on substations/components outages and dynamics of the sequential switching orders as part of the permutation. The expanded framework includes (1) critical/noncritical combination verification, (2) cascade confirmation, and (3) combination re-evaluation. This paper ends with a discussion of the open issues for metrics and future design pertaining the impact quantification of cyber-related contingencies