A fleet of seismic survey vessels owned by Petroleum Geophysical Services (PGS) of Norway has had its analogue load commutated inverter (LCI) drive systems upgraded to a digital control platform by Dynamotive.

The upgrade has delivered active dynamic load reduction to the vessels propulsion systems and improved the efficiency and utilisation of the generators and the ships power management system. It has also provided the added reassurance of optional remote support engineering from Dynamotive from anywhere in the world, via a secure internet connection.

According to the company, the project upgrade delivers a high performance, robust and reliable propulsion drive system with extended life cycle. Components from the original LCI drive system – such as power thyristors and Brush-manufactured synchronous machines – were re-used, ensuring minimum intrusion on the ship’s infrastructure.

The upgrade features ABB’s high speed AC 800PEC controller which forms the heart of the digital front end (DFE) design. The DFE brings a faster and more dynamic response to the propulsion systems relative to available ship power.

The AC 800PEC is a high performance process control system that provides the control and management of the thyristor power devices. It combines high-speed control capability for dynamic load management, with low-speed process control and information tasks usually carried out by separate PLC units.

Dynamotive overcame the challenges faced by retrofitting by supplying a mix of new control cabinets and technologies deployed on chassis plates, enabling all components to be integrated seamlessly into the retained elements of the vessel’s control system. An important aspect of the retrofit design is the smaller, more compact modular hardware which assists the ease of the on-board system integration, installation, commissioning and any subsequent maintenance by on-board personnel. ­Dynamotive continues to manage and maintain the fleet’s original analogue drive system along with the new digital drive system, in partnership with Wilhelmsen Ship Management, which acts on behalf of the vessel owners, PGS.


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