Papers by Keyword: Energy Gradient

Abstract: Converter is the core of a HVDC transmission system. In order to recognize the converter fault, the state of electric parameters is measured by real-time online monitoring method. It has great significance for making condition-based maintenance strategy. In the paper, the basic structure and fault type of the converter are discussed. Based on the ETSDAC of ADPSS simulation package, a HVDC transmission system is established, and the essential characteristics of each electrical quantity in main circuit when fault occurs are analyzed. Under different fault conditions, energy gradient is used to characterize changes of electric parameters. Finally, according to the energy variation, the online monitoring electrical quantities of each fault state are determined. Simulation results show that this method can be used to choose electric quantities for online monitoring.

Abstract: A virtual crack vector model is proposed in this paper to simulate the branched crack propagation and simplify its calculation of energy release rate. An energy gradient fracture criterion is constructed based on this model. It can take account of the effects of biaxial loads or T-stress on brittle mixed mode fracture and agrees well with the test data of biaxial tensile fracture and the specially conducted experiment of the influences of ox on the mixed mode fracture of plexiglas. Considering its advantage of predicting initial propagation angle and critical fracture stress independently without the determination of the core region radius, it can be used as a practical fracture criterion for brittle mixed mode fracture under biaxial tension.