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This paper presents a novel approach to managing cascading failures in power grids using distributed autonomous agents. It emphasizes the importance of local control and cooperation among agents, which can enhance system resilience without the need for global knowledge. By implementing a spatial decomposition strategy and model predictive control, the network can address violations effectively. Simulations reveal that collaboration among agents significantly improves solution quality while minimizing communication overhead. The findings advocate for investment in distributed solutions that align with the distributed nature of power network authority.
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Controlling Cascading Failures with Cooperative Autonomous Agents Paul Hines Sarosh Talukdar Dong Jia Huaiwei Liao TPP Graduate Consortium, 27 July 2005 Work supported by ABB Corporate Research & the Carnegie Mellon Electricity Industry Center Photo: Marc O. Rieger http://www.math.cmu.edu/~ana/Pictures/pic7.html
Some cascading failures Hines, 18-Apr-05
Blackout size CDF Source: Talukdar & NERC/DOE data Hines, 18-Apr-05
What is a cascading failure? Hidden failure(s) Disturbance Violation(s) Relay operation(s) Blackout Network state transitions Hines, 18-Apr-05
Reducing cascading failure risk • Prevention method • Reduce the risk through conservative operations • “N-1” security • Imposes additional dispatch costs • Control method • Reduce the risk through improved control systems • Give the grid “good reflexes” Hines, 18-Apr-05
One approach… Hidden failure(s) Disturbance Interrupt the CF sequence here from a central location Violation(s) Relay operation(s) Blackout Network state transitions Hines, 18-Apr-05
Another approach… Hidden failure(s) Disturbance Interrupt the CF sequence here froma central location Violation(s) Relay operation(s) Blackout Network state transitions Hines, 18-Apr-05
A new approach… Hidden failure(s) Disturbance Interrupt the CF sequence here using distributedautonomous agents Violation(s) Relay operation(s) Blackout Network state transitions Hines, 18-Apr-05
Rationale for using distributed agents • Information • No need for global knowledge • Reduced “seams” problems • Speed • Computation & action co-located • Robustness • Distributed solutions tend to be more resistant to failures Hines, 18-Apr-05
Problem statement • Improve the grid control system by • eliminating power system network violations at minimum social cost before a cascading failure results • using only distributed autonomous agents capable of shedding local load and generation. Hines, 18-Apr-05
Solution method – Spatial decomposition Autonomous Hines, 18-Apr-05
Solution method – Incremental work • Allow each agent to work iteratively to remove the violations that it is aware of • Model Predictive Control: • Calculate a plan • implement a portion of the plan • update the plan • implement a portion of the plan • … • Allow for cooperation among agents Hines, 18-Apr-05
Operators u x Power Network Bus 1 Measurement hardware 1 Load/gen controller 1 Bus n Load/gen controller n Measurement hardware n Hines, 18-Apr-05
Operators x u u1 Power Network δ1 Measurement hardware 1 Load/gen controller 1 agent 1 + un δn Measurement hardware n Load/gen controller n agent n + Communication Network Hines, 18-Apr-05
Solution method -- Cooperation • Definition: • The sharing of useful information. • Many methods exist, we use the following: • When agents calculate a solution: • Compare that solution with those neighbors who appear to require control actions • If a discrepancy exists: • exchange important measurements • recalculate • repeat no more than 3x Hines, 18-Apr-05
Verification method • Perform repeated simulations using IEEE networks and random double contingencies • Adjust the amount of communication (the size of the internal neighborhood) Hines, 18-Apr-05
Typical result Branch outages 8,40rl=2, re=10 Hines, 18-Apr-05
Control error Control error Hines, 18-Apr-05
Control error vs. communication Local neighborhood radius Hines, 18-Apr-05
Conclusions • It is possible to control cascading failures using a flat network of distributed autonomous agents • Cooperation can vastly improve solution quality and/or reduce the amount of communication required • Improving the grid control system should allow operators to make better tradeoffs among conflicting objectives • (Dispatch costs, reliability, protection, network investment) Hines, 18-Apr-05
Related policy issues • Where network authority is inherently distributed (>100 independent control areas in US eastern interconnect) a distributed solution has many advantages over centralized solutions. • While it is technically possible to control cascading failures, incentives for investment in such technologies are not always aligned with the costs. Hines, 18-Apr-05