Simulation of cascade contingencies in power systems

This paper proposes a probabilistic model based on Monte Carlo simulations in order to study the cascade phenomena. Firstly, the probabilistic model takes into account the operation of protection system, such as hidden failures and unnecessary operations, which are simulated. Once the sequence of protections is randomly generated, the state of the power system is evaluated by means of the load flow, in order to simulate sympathetic cascades, i.e. to simulate overloads and line´s openings. The overload branches analysis involves a deterministic step and a probabilistic model of the action of the operator. The severity of contingencies due to cascades is measured with three indicators: number of involved branches, expected energy non-supplied (EENS), and loading of the system. The EENS is computed as function of the load shedding, while the system loading is computed for post-contingency condition using the continuation power flow. The proposed method has been tested on the IEEE 118 bus system.