Submarine Root Survey of Powered Cables
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Submarine Root Survey of Powered Cables Supplying former ‘Power Isolated Island’ Field test provides blueprint for future de facto survey method INTRODUCTION Located in the South China Sea, Hainan Island is the smallest province of China and is the nation’s southernmost point. It is renowned for tropical climates, beach fronts and its wild mountainous inlands. In the city of Sanya, a tourist hot-spot, sits an array of luxury hotels alongside the attractive Yanoda Rainforest hiking trails, suspension bridges and waterfalls. Geographically, Hainan Island is separated from Guangdong’s mainland Leizhou Peninsula by the Qiongzhou (Hainan) Strait, a body of water and the main terminal of travel from island-to-mainland. Hainan Island was once known locally as the ‘Power Isolated Island’ as all power was controlled and delivered from the island itself. However, the Fukang Line (power cables) were laid in June 2009 from mainland across the Qiongzhou Strait, to the island in order to back up the entire Hainan island power supply. The role of this four-cable line was fundamental to ending the ‘Power Isolated Island’ tag as it is now responsible for the whole island’s power as a backup should there be a grid collapse in the on-island power supply network. The Fukang Line requires an annual root survey to assess the condition, location and depth of burial of the cables in order to continuously support Hainan Island. This survey is an unprecedented challenge each year as the power supply needs to be turned off in order successfully survey, as well as being influenced by a number of pressures and factors. Traditionally, this survey work has been undertaken using tone injection systems alongside sub-bottom profilers so a seafloor map could be produced. The operation of this set equipment means that the cables could not be surveyed whilst powered but in turning the power off, the island is at great risk should any faults occur in the main power supply. Product Case Study Teledyne TSS Instruments Product: HydroPACT 350 cable tracking system Application: Submarine cable root survey Project: Nanling Terminal Station field test for Hainan Island back up power supply cables annual survey Organisations: China ORE, Qingdao Ocean Research Equipment Services Limited, EHV Power Transmission Company of China Southern Power Grid Contacts: James Shaw, Teledyne TSS Jerry Li Mingbo, China ORE Date: October 2017 Location: Qiongzhou (Hainan) Strait, Hainan Island, South China Qiongzhou Strait; Leizhou Peninsula and Hainan Island (The Fukang Line of subsea cables runs from mainland China across the Qiongzhou Strait to Hainan

Submarine Root Survey of Powered Cables Supplying Former ‘Power Isolated Island’ CONTINUED The HydroPACT 350 cable tracker is designed to track cable and umbilical location, skew angle and depth of burial. Using two coil triads (Port and Starboard), the system is usually mounted onboard an ROV in a triangular formation. PROCESS In order for the end-user to adopt this new survey approach, and to be able to survey the cables whilst live, a trial was necessary to test the equipment so that it could be verified for performance and so that a blueprint could be established. China ORE, Qingdao...

Product Case Study SOLUTION The main advantage in ultising the 350 system is that the cable survey can now be undertaken with the cables still powered eliminating the need to organise a poweroff operation. Any window of power-off needs to coincide with appropriate survey weather that requires in-depth scheduling (and a bit of weather luck!) which all equates to one huge logistical undertake. As well as the weather, a survey vessel, a survey team, the power company, Hainan Island and its inhabitants, businesses, hospitals and homes have to be considered and aligned in order to even set a...

Submarine Root Survey of Powered Cables Supplying Former ‘Power Isolated Island’ CONTINUED SUMMARY Through China ORE, who supplied the HydroPACT 350 for the trial and then onto EHV Power Transmission Company, the need to survey the Fukang Line power cables whilst still powered has been met. Surveyors can now survey the line without having to organise the complex power-off operation, simplifying the process ten-fold. ‘This new cable tracking system brings us so many benefits and it will be integrated onto our new SMD ROV system’, said Mr Zhoujing, Chief Engineer of Operation and Maintenance...