Insulation Coordination Model Based on Breakdown Characteristics of Air-Gap Subjected to Damped Alternating Overvoltages

This article examines and calculates the probability of failure probability of a rod-plane air gap (RPAG) under a damped alternating overvoltage (DAOV) based on a large amount of experimental data and the probability density distribution of measured overvoltages in a power system. By changing the length of the RPAG, the authors propose a prediction model for the breakdown characteristics of any length of RPAG, with the variable of DAOV parameters (including the damping factor and frequency). The results show that the model can adequately predict the breakdown characteristics of any RPAG under the action of the DAOV. Based on color channel representation, we show the results of 4-D prediction in the form of a 2-D graph. The authors combine this with a system economic model to develop a model for dynamic insulation coordination (DIC). With changes in the length of the RPAG, this model can dynamically characterize the safety factor of the system to efficiently and accurately determine whether the insulation for the air gap meets the relevant safety requirements. The proposed DIC model helps improve the accuracy of insulation design and can be used in industrial applications as a statistical method for coordinating insulations in power systems.