In order to improve the operation safety and stability of power cables, it is necessary to conduct targeted research on different grounding modes. Firstly, the appropriate cable parameters are selected according to the specific use, and the model is established in ATP-EMTP according to the selected cable parameters. Then, the availability of three grounding modes models of grounding at one end, grounding at both ends and cross-connection grounding (cable core grounding, shielding layer grounding and armor layer grounding) are compared and verified by simulation. Finally, by setting the shielding layers of different thicknesses as a comparison, the impedance and current characteristics of the cables under three different grounding methods are analyzed. The results show that the impedance values of the three grounding methods are basically the same. However, according to the current characteristics, when the shielding layer and the armored layer are cross-connected and grounded, the current of them is much smaller than that which is grounded by other grounding methods. Therefore, under the comprehensive consideration of economic benefits, this grounding is the best choice. This study provides guidance for the grounding mode of cable early laying, and provides reference for other cable related research.

Due to the complex and diverse seabed environment, the coupling effect of high depth and temperature will seriously affect the operation stability of submarine cables. Therefore, the thermal-mechanical coupling model and inherent characteristics of submarine armored cables in soil environment are simulated and analyzed. Firstly, the influence of different buried depth and surrounding seawater temperature on cable temperature in soil environment is studied. Then the natural frequency of the cable is obtained by modal analysis. Since the low frequency vibration mainly occurs in the operation process, the high frequency vibration is not easy to excite and decay quickly, only the first eight order vibration is considered. The results show that it is beneficial to avoid the vibration near the resonance frequency, to lay in the relatively shallow position and to reduce the buried depth appropriately.

This paper proposes the data mining method of voltage sag severity based on DHP algorithm and replaceable coefficient to assess the risk of voltage sag. The DHP (Direct Hashing and Pruning) is served to mine the relationship between voltage sag characteristic attribute (VSCA) in the fault scenario and the voltage sag severity (VSS) of node. Using direct hash pruning technology, frequent item sets can be found quickly and mining efficiency can be improved. The association rules are matched with the actual fault scenarios through replaceable coefficients to get the VSS of actual fault scenarios. Finally, the effectiveness and accuracy of this method are verified by simulation and examples.