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![Figure 1. A cross-sectional view of an XLPE cable. Courtesy [1].](publication/338193157/figure/fig1/AS:840719962996738@1577454667152/A-cross-sectional-view-of-an-XLPE-cable-Courtesy-1_Q320.jpg)
![Figure 3. Microstructural view of water tree [11].](publication/338193157/figure/fig3/AS:840719963000838@1577454667204/Microstructural-view-of-water-tree-11_Q320.jpg)
Contexts in source publication
Context 1
... are three main types of water trees, as illustrated in Figure 2(a). The first is the bow-tie water trees, which are so named because of its resemblance to a bow-tie. ...
Context 2
... is the main culprit in most insulation breakdown occurrences, mainly when formed at the outer (insulation-screen) interface [3]. Figure 2(b) illustrates how a vented water tree can result in insulation breakdown. Bush trees, which is an aggregation of many vented water trees, is the third class. ...
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Citations
... Offshore energy is one of the most prominent renewable energy resources which is currently under development, globally. This energy generation relies on some critical structures, among which are wind-blades and Hi-Voltage electrical transport cables that connect offshore farms to onshore [1][2][3][4][5][6]. A lot of research is carried out to suggest the best ways to maintain the reliability of offshore structures. ...
Submarine power cables are expected to last 20 years without maintenance to be considered technologically reliable enough and economically beneficial. One of the main issues facing this target is the development of what is called commonly water-trees (nanometer-sized flaws filled with residual humidity), that form within XLPE (cross-linked Polyethylene) insulators and then migrate towards copper, thus leading to its corrosion and further to possible shut-down. Water trees are resulting from the coalescence of nanovoids filled with residual humidity that migrate towards copper under the combined effects of electrical forces and plastic deformation. The nanovoids are originated during manufacturing, shipping, handling and embedding in deep seas. The formation of these nanovoids leads to the degradation of the service lifetime of submarine power cables. Current research is intended to come up with a way to go a little further towards the generalization of coalescence of n nanovoids. In the perspective of multi-physics modeling, a preliminary 3D finite element model was built. Although water voids are distributed randomly inside XLPE, in this study, two extreme cases where the voids are present parallel and perpendicular to the copper surface, were considered for simplification. This will enable checking the electric field effect on neighbouring voids, in both cases as well as the influence of the proximity of the conductor on the plasticity of voids, that further leads to their coalescence. It is worthwhile to note that assessing water-trees formation and propagation through an experimental campaign of ageing tests may extend over decades. It would therefore be an exceptional opportunity to be able to get insight into this mechanism through numerical modeling that needs a much shorter time. The premilinary model suggested is expected to be extended in the future so that to include more variables (distribution and shapes of nano-voids, water pressure, molecular modeling, electric discharge.
... However, the models he uses are static, because they focus on the changes of cable insulation characteristics in a certain period of time. erefore, a new electromagnetic field modeling method is needed, focusing on the parabolic form changes of model values [6]. Hadi believes that economic constraints and lack of sufficient space will require cables with higher current carrying capacity. ...
The transmission and radiation of underground variable frequency electromagnetic waves will seriously interfere with the operation of the power cable and its surrounding environment. At present, the test methods for power cables basically require the impedance of the test system to match the characteristic impedance of the cable. The defect is that the process of designing and making the impedance matching impedance network is relatively complex and requires high manufacturing accuracy. In order to solve these problems, this paper puts forward the electromagnetic field fast detection formula and electromagnetic field shielding method of underground variable frequency power cable. The research method of this paper is the principle of shielding electromagnetic field materials and the suppression principle of shielding layer for electromagnetic coupling. The function of the two principles is to study the reflection, absorption, and multiple reflection of electromagnetic waves and to study the cut-off frequency of the nonmagnetic shielding layer. These two principles guide the experiment. In this paper, the measurement formula of the shielding performance of mismatched cables is derived through experiments. The results show that the error of the measurement formula is no more than 8 dB. Then, through the experiment of restraining the interference of magnetic materials on the electromagnetic field, it is concluded that the magnetic field shielding performance can reach 20 dB. Then, through the performance test of electromagnetic field shielding materials, the shielding efficiency of metal fiber antiradiation materials is the largest, and the average efficiency reaches 76.4 dB.
