Dynamic Rating of Three-Core XLPE Submarine Cables Considering the Impact of Renewable Power Generation

Abstract

This paper discusses how to determine the most suitable high voltage alternating current (HVAC) submarine cable in the design phase of new projects. A thermal ladder network method (LNM) is used to analyse the thermal behaviour in the centre of the conductor as the hottest spot of the cable. Based on an approved static cable rating method and thermal cable analysis of transient conditions, applied by a step function with transient time duration greater than one hour, this paper proposes a method for a dynamic rating of submarine cables. The dynamic rating accomplished through an iterative process. The method is tested with MATLAB simulation and validated in comparison to a finite element method (FEM) based approach with high accuracy.

Opportunities to Improve Marine Power Cable Ratings with Ocean Bottom Temperature Models

“…The scale of these variations are such that cables can experience both significant seasonal and, as cable lengths increase ((e.g., >80 km AC [24], >300 km DC) [25]), spatial variations. Despite these potential changes, standard cable design practice routinely considers 10 • C, 12 • C, or, most commonly, 15 • C to be a representative estimate of ambient temperature at cable depth, irrespective of the location of the cable or how it will be operated over a year [26,27]. A rare example of considering proximal ocean bottom temperature measurements [14] demonstrated that the standard assumption was 10 • C lower than that of the summer OBTs, resulting in potentially dangerous cable-operating temperatures.…”

A Thermal Model for Three-Core Armored Submarine Cables Based on Distributed Temperature Sensing

“…However, in most of these applications, the actual temperature of the conductor (or at the cable surface) is required, so it must be adequately derived from the DTS measurements. Since the location of the OF is not standardized [16,17], this involves the use of analytical or numerical adjustment methods, becoming a standard equivalent thermal network-based method (ETN) [10,11,13,[18][19][20][21], where the spatially distributed DTS temperature and the cable current are employed as real-time inputs for obtaining the temperatures of the different cable components (conductor, screen/sheath, jacket, etc.). Due to the thermal resistances and capacitances involved, better static and dynamic results are obtained when the OF is installed closer to one of the already existing ETN nodes (screen/sheath, jacket, etc.).…”

“…However, it is well-known that the IEC 60287 standard [18] overestimates the power losses in this type of cables. In this sense, 2D simulations based on the finite element method (FEM) were extensively employed for validating the performance of the ETN [20]. Nevertheless, both [18] and 2D-FEM models lead to important errors due to the simplifying assumptions considered, where relevant aspects regarding TCAC design are not taken into account, such as the twisting of armor wires and conductors.…”