Online inference of the dynamic security level of power systems using fuzzy techniques

Dynamic security assessment (DSA) is the evaluation of the ability of the power system to withstand sudden disturbances and to survive the transition to an acceptable steady state condition. During system operation, the online determination of the dynamic security level is fundamental in order to take appropriate countermeasures, with the goal of bringing the system, if necessary, to a more secure operation condition. The most important drawbacks are the lack of "easy to use" and "comprehensive" DSA tools for system operators and the speed of computation that make online DSA to be still not fully operational, particularly when complex models are required for analyzing large interconnected systems. To overcome this, a new approach for power system online DSA is presented in this paper. The proposal is based on a three-stage fuzzy inference system, which composes a fuzzy index making use of seven performance indexes herein defined. The calculation of the performance indexes is based on results obtained through full simulations of the system behavior in front of each one of the credible contingencies in a given operation state. The full simulation, the calculation of the performance indexes and the composing of the fuzzy index are made using distributed processing. The performance of the methodology herein proposed is evaluated using 115-node electric grid, and the results obtained are shown and discussed.