Distribution of Ground Fault Currents Along Transmission Lines -- An Improved Algorithm
The calculation of fault current distribution between ground wires and ground is important for the operation of modern power systems. A new method is presented based on an approach whereby the current distribution is solved through the computation of driving-point impedances. The method is applied to three phase systems with mutual couplings between conductors (phase and ground, respectively) included. Currents computed by this method and methods published in recent literature are compared and are found in good agreement. Results show that the method is more efficient in terms of CPU time and memory space.
Minimum Shield Wire Size???Fault Current Considerations
This paper presents results showing the effect of various system parameters on shield wire fault current requirements. The effect of tower footing resistances, generator excitation systems, dc offsets and fault location are shown. Current splitting between shield wires in one span is examined, and shield wire capabilities are presented.
Centrifuge modelling of effects of shield tunnels on existing tunnels in soft clay
With the rapid development of the subway network,the phenomena of shield tunnels going across the adjacent tunnels are becoming more and more common.The interaction between shield tunneling and nearby tunnels is more complicated than the ordinary shield tunneling in intact soil strata.Based on the project of Shanghai Bund Passage crossing Metro Line 2,the method of centrifuge modeling together with the field measurement is employed to study the effects shield tunneling on nearby strata and existing tunnels.In centrifugal model tests,the effects simulation techniques considering the unloading of excavation,ground loss and grouting are developed to analyze the longitudinal settlement of the shield tunnel and the existing tunnel induced by the shield tunneling.Besides,the deformation distribution and settlement curves of the existing tunnels during shield construction are studied by using the monitoring data.