Basslink CEO Malcolm Eccles has refuted recent claims by Hydro Tasmania that the cause of the cable’s failure was operational stress at the hands of Basslink.
“Such claim is not supported by Hydro Tasmania’s own expert reports which merely posit one possible cause of the December 2015 outage, without providing conclusive and definitive proof,” Mr Eccles said.
“Having conducted an initial review of the reports – which are yet to be made public – there are a number of key points that we would like to highlight.
“Firstly, Hydro Tasmania’s experts did no actual testing on the Basslink cable or any similar HVDC cables. They used a theoretical model based on certain assumptions to come to a set of conclusions. These assumptions make the experts’ conclusions speculative and not based on actual facts,” he said.
“As Hydro Tasmania’s own experts recognise, their reports do not conclude their answer is a proven cause of the cable failure. The reports offer an opinion based on certain assumptions, that overheating was caused by excessive transmission of electricity from Tasmania to the mainland.
“The reports have not solved any ‘mystery’ as alleged by Mr Stephen Davy the CEO of Hydro Tasmania,” Mr Eccles said.
“Basslink has operated and maintained the Basslink facilities in accordance with the instructions from the manufacturers, Siemens and Prysmian, and in accordance with good electricity industry practice. The manufacturers have in place a control system and Cable Load Prediction System to protect the Basslink facilities from overheating. As reported in December 2016, when the Basslink interconnector fault investigation was completed, Cable Consulting International’s (CCI), one of the world’s leading submarine power cable experts, report noted that the other section of the cable it sampled was in sound condition.
“The Basslink facilities are designed to be operated at the continuous rating of 500MW or at 630MW for limited periods. In the circumstances which Basslink has received these reports, and while not accepting the conclusions and recommendations in the reports, Basslink will operate the interconnector at the continuous rating of 500MW in line with good electricity industry practice. This will be an interim measure and this position coincides with Hydro Tasmania’s request.
“As a prudent and responsible operator, Basslink will consult its manufacturers, Siemens and Prysmian, on the matters raised in the Hydro Tasmania reports.
“Another point to highlight is neither Basslink, nor its cable system manufacturers, Siemens and Prysmian, were consulted during the drafting of Hydro Tasmania’s reports, which makes the reports one-sided,” added Mr Eccles.
Mr Eccles said Basslink stood by the independent investigation that was undertaken by CCI, who described the exact cause of the subsea cable fault as “cause unknown”.
“Based on the findings of CCI, Basslink maintains the cable fault was a force majeure event,” he said.