A fuzzy logic approach to security-based bulk power system reliability evaluation

The most significant parameter in a bulk power adequacy assessment are the load point and overall system "load curtailment indices." Many utilities have difficulty in interpreting the calculated load curtailment indices, as the existing models do not always consider realistic and practical operating conditions. Simple linear programming formulations are found to be inadequate in satisfying realistic system objectives and constraints. The present paper models uncertainties in loads and generations as fuzzy numbers. The load curtailment indices (while load and generation being uncertain) are calculated using fuzzy linear programming. The proposed method is applied to the RBTS 6-bus and IEEE 14-bus test system. The results of the computation are optimistic in terms of minimization of the objective function compared to probabilistic approach, and these are more realistic. In the above application, contingency analysis has been carried out up to 2nd level, and contingencies that cause the system to go to extreme emergency state have been accounted for