Loss Allocation in Submarine Armored Three-Core HVAC Power Cables

Abstract

Loss allocation of the three different components (conductor, sheaths and armor) of solidly bonded three-core separated lead-sheathed armored cables, frequently employed in offshore wind farms, is challenging due to the lack of accurate enough analytical expressions in the IEC standard. Also, loss allocation through experimental tests leads to inaccurate results since it is based on questionable assumptions. This paper improves both the IEC formulae and experimental methods by means of different analytical corrections in the conductor and sheath loss expressions. To this aim, an ad hoc application interface (Virtual Lab) based on 3D numerical simulations (finite element method) has been developed. This tool virtualizes and automates different test setups to emulate, in few seconds, the most employed experimental procedures in this type of cable. The analytical corrections have been derived from an in-depth analysis of a first set of 368 cables, ranging from 30 to 275 kV. The new loss expressions were successfully applied to a second set of 645 armored cables of quite diverse features (voltages from 10 to 275 kV, sections and dimensional parameters), hence bringing a general framework for any kind of three-core armored cable.

Evaluation of the power frequency magnetic field generated by three-core armored cables through 3D finite element simulations

“…This USM (implemented in COMSOL Multiphysics [28]) can be solved in less than 1 min [22] in most of the cases, limiting the computational burden when simulating other complex geometries never analyzed before through 3D-FEM simulations, such as those combining steel wires and PE separators or double-layered armored cables. All these cases, together with new features that extensively evaluate the environmental impact of TCACs in terms of MF emissions, are now included in the graphical user interface (GUI) developed recently in [29] (called Virtual Lab). This tool, which is capable of reproducing typical experimental setups usually employed for testing TCACs (with a consequent reduction of cost), serves as a perfect platform for the analysis and optimization of the cable design in terms of power losses, electrical parameters and MF emissions.…”

Experimental validation of ultra-shortened 3D finite element electromagnetic modeling of three-core armored cables at power frequency

“…As described in [33,34], the USM makes use of rotated periodicity for reducing the length of the 3D geometry to be simulated up to…”

“…Having all this in mind, this paper develops the experimental validation of the USM presented in [32][33][34][35]. To this aim, a faithful replication of previously published experimental studies on a set 10 actual TCACs, representing a wide variety of voltages, cross sections and conductor materials, has been performed.…”

“…In this sense, the use of rotated periodicity as an additional boundary condition was proposed in [29] for reducing the length of the 3D geometry to be simulated, being shorter than 2 m in most situations. Subsequent studies [30,31] proposed further improvements, reducing the length of the 3D-FEM model to the maximum in [32][33][34][35], with values as short as 2-3 cm. This ultra-shortened 3D-FEM model (USM) reduces simulation time below 1 minute without loss in accuracy compared to larger 3D-FEM models [34].…”

Experimental Validation of Ultra-Shortened 3D Finite Element Models for Frequency-Domain Analyses of Three-Core Armored Cables

“…The USM presented in [24]- [26] is based on the symmetries found in the geometry and the electromagnetic field distribution in TCACs, so that rotated periodicity can be applied in just a small slice of the cable (Figure 1) with a length (L) equal to…”