Sensitivity Evaluation of Sensitive Equipment Based on Fuzzy Theory Due to Voltage Sags

A new sensitivity evaluation method for sensitive equipment based on fuzzy theory due to voltage sags is proposed in this paper. The transitional process is considered as a fuzzy limit state, which is from safety to fault during voltage sags. The degree of membership which belongs to safety state is used to describe this transitional process. Energy function is used as the membership function. Normal distribution is used to describe the random process of system disturbance and tolerant capacity of equipment. The parameters of probability density function of system disturbance is calculated from the simulation data of IEEE -30, while that of tolerant capacity of equipment is calculated from the test data. Simulation results show that the method proposed is available and accurate.