CHALLENGES OF CASCADING FAILURE failures are dependent as cascade propagates

1. CHALLENGES OF CASCADING FAILURE • failures are dependent as cascade propagates • huge number of unlikely interactions of different types • rare, extreme events of high cost to society (heavy tails in pdf) • cascading both in and between infrastructures Ian Dobson: risk of cascading failure, blackouts, complex systems; background in electric power systems, nonlinear dynamics dobson@engr.wisc.edu

2. ISSUES FOR MONITORING CASCADING FAILURE RISK • science of cascading failure requires: • data (real and simulated) • theory and simulation models at different levels of detail • statistical estimation of model parameters • a new risk analysis • need to efficiently estimate risk of events of all sizes probability Probabilistic branching process model of cascading failure can reproduce power system simulation of cascading line overloads number of line failures

3. FAILURE OF COMPLEX ENGINEERED SYSTEMS • Large infrastructure networks are not arbitrary; they upgrade and evolve dynamically in response toconsumer demand, economics, and recent failures(think of biologists studying evolving species). • Evolving networks could have universal features such as power laws in event size pdfs. We can study these complex system steady states! probability Simulated power grids can self-organize towards blackout size pdfs consistent with observed North American blackout data. red dots = data; lines = simulation. Joint work with Carreras & Newman blackout size

4. For more information: google “ian dobson papers” or email dobson@engr.wisc.edu