Based on the essence of self-organized criticality and optimal power flow (OPF)

a model is developed to capture the cascading failures and blackouts in power systems

after analysis on the limitations of the existing blackout models. The proposed model contains two dynamics

one is the fast dynamics which simulates the serial blackouts in power system

the other is the slow dynamics which reflects the growth of the power system. Simulations in an IEEE 30-bus system with the proposed model show that the process of the cascading and blackout can be captured by the fast dynamics

together with the self-organized criticality of fast dynamics with respect to the micro-scale. In addition

the macro-scale of self-organized criticality of the power system can be revealed from the viewpoint of the total load demand vs. the total network transfer capability. Furthermore

improving the transmission ability of the network can effectively prevent large-scale disastrous blackout and reduce the risk of power failure.