CIGRE - Symposium Aalborg , Denmark

Our CTO Etienne Rochat give the following symposium during the CIGRE conference in Denmark (4-7th June 2019 ).

The Symposium subject was "Combining Distributed Temperature Sensing (DTS) and Dynamic Cable Rating (DCR) as an efficient means of managing submarine cable load"

​SUMMARY
Distributed Temperature Sensing (DTS) provides real time information of submarine cable
temperature, as a function of the cable load and surrounding conditions. Longer than 100km
cable are now instrumented using stimulated Brillouin based interrogators (Brillouin Optical
Time Domain Analysers, BOTDA) that are compatible with optical amplification. When
combined with Real Time thermal Rating (RTTR)/Dynamic Cable Rating (DCR), dynamic load
management becomes possible, ensuring safe delivery of current peaks when necessary
without risking any damage to the cable due to overload or local hot spots. The combination
of DTS and RTTR/DCR also provides some evaluation of the Depth of Burial (DoB) associated
with the potential risk of being snagged by anchoring and fishing activities, or from sagging in
cases of severe exposure

RTTR/DCR computations requires electrical data as well as seabed thermal characteristics as
measured during survey. Thermal characteristics may vary between surveyed points as well
as over time due to seabed changes such as seabed migration through sand waves, and tidal
currents that all constantly affect the cable surrounding conditions. These events will ultimately
impact the cable temperature, which is measured by the DTS. Thus, continuous DTS
measurements over the full cable length can be understood as a means of adjusting
RTTR/DCR input parameters to match the varying field conditions, guaranteeing that the cable
rating is always as accurate as possible

DTS systems are now defined by a set of parameters within an IEC standard. Those
parameters are inter-dependent. Historically, temperature resolution was prioritised as the key
parameter, resulting in long spatial resolution, and long data acquisition time lt is now obvious
that this choice resulted in potential defaults such as hot spots, which are usually very short,
to be averaged out by the DTS. Today, field experiments show that one should prioritise a
short spatial resolution in order to identify and localise critical hot spots at the earliest possible
time
Thus, DTS with short spatial resolution, when combined with DCR, becomes a powerful tool
for load management as well as for asset integrity

Contact us to have the complete symposium document in case of interest.