Assessment of the Temporary Generation options for late-life operation of the offshore platform

Arc Flash Safety has been contracted to carry out a full power systems assessment of Temporary Generation at multiple stages of late-life offshore platform operation. The purpose of the assessment is to ensure the modified configuration, without the main GTGs, can be operated safely with no risk to equipment or personnel.
 

The system
The generator package consisted of several small rental Diesel generators, connected to the main HV switchboard via step-up transformers. 

The challenge
Decreasing loads at later stages of decommissioning required a reduced amount of generators online - this varying load and generator configuration required several system configurations to be considered. 

Issues highlighted
During the studies some potential issues with system voltages and equipment overload were discovered, and recommendations were made to mitigate these problems. 

Earthing requirement
Another area that required attention was platform earthing - removal of main generators caused the HV switchboard to operate unearthed which was not acceptable.  An alternative earthing method was proposed via a step-up transformer to enable the operation of the Temporary Generation package. 

Motor starting study
The studies also included motor starting to determine feasibility of starting the largest motors at different phases. This involved modelling the locked rotor current and resulting reactive and active power demand which was compared with the temporary generation capacity.

Protection discrimination and Arc Flash Studies.

Lastly, protection discrimination and arc flash studies were completed - these studies determined protection settings required for the new equipment to discriminate with existing platform protection under all scenarios and assessed the arc flash levels at all stages of decommissioning.

Revised protection settings were proposed to reduce the arc flash energies at certain switchboards.

The result
By applying our recommendations the client was able to safely operate temporary generation during the decommissioning phase with piece of mind that all operating challenges have been considered.

Explore Decomissioning options with Arc Flash Safety
At Arc Flash Safety we are always happy to help customers to complete their projects and achieve targets. Our engineers are experienced in all study types commonly required during late-life platform operations and Decommissioning stages.  Explore our full service capabilities here and contact us to discuss your requirements.