), in 2014.
Self-organized criticality It has been argued on the basis of
historical data and computer modeling that
power grids are
self-organized critical systems. These systems exhibit unavoidable disturbances of all sizes, up to the size of the entire system. This phenomenon has been attributed to steadily increasing demand/load, the economics of running a power company, and the limits of modern engineering. While blackout frequency has been shown to be reduced by operating it further from its critical point, it generally is not economically feasible, causing providers to increase the average load over time or upgrade less often resulting in the grid moving itself closer to its critical point. Conversely, a system past the critical point will experience too many blackouts leading to system-wide upgrades moving it back below the critical point. The term critical point of the system is used here in the sense of statistical physics and nonlinear dynamics, representing the point where a system undergoes a
phase transition; in this case the transition from a steady reliable grid with few cascading failures to a very sporadic unreliable grid with common cascading failures. Near the critical point the relationship between blackout frequency and size follows a
power-law distribution. Others advocate greater use of electronically controlled
high-voltage direct current (HVDC) firebreaks to prevent disturbances from cascading across AC lines in a
wide area grid.
OPA model In 2002, researchers at
Oak Ridge National Laboratory (ORNL), Power System Engineering Research Center of the
University of Wisconsin (PSerc), and the
University of Alaska Fairbanks proposed a mathematical model for the behavior of electrical distribution systems. This model has become known as the OPA model, a reference to the names of the authors' institutions. OPA is a cascading failure model. Other cascading failure models include Manchester, Hidden failure, CASCADE, and Branching. The OPA model was quantitatively compared with a
complex networks model of a
cascading failure – Crucitti–Latora–Marchiori (CLM) model, showing that both models exhibit similar phase transitions in the average network damage (load shed/demand in OPA, path damage in CLM), with respect to transmission capacity.
Mitigation of power outage frequency The effects of trying to mitigate cascading failures near the critical point in an economically feasible fashion are often shown to not be beneficial and often even detrimental. Four mitigation methods have been tested using the
OPA blackout model: • Increase critical number of failures causing cascading blackouts – Shown to decrease the frequency of smaller blackouts but increase that of larger blackouts. • Increase individual power line max load – Shown to increase the frequency of smaller blackouts and decrease that of larger blackouts. • Combination of increasing critical number and max load of lines – Shown to have no significant effect on either size of blackout. The resulting minor reduction in the frequency of blackouts is projected to not be worth the cost of the implementation. • Increase the excess power available to the grid – Shown to decrease the frequency of smaller blackouts but increase that of larger blackouts. In addition to the finding of each mitigation strategy having a cost-benefit relationship with regards to frequency of small and large blackouts, the total number of blackout events was not significantly reduced by any of the above-mentioned mitigation measures. In 2015, one of the solutions proposed to reduce the impact of power outage was introduced by M. S. Saleh. ==Major power outages==