In this article, the Shoreline simulation logic is explained. Each type of maintenance task's flow from failure/creation to finished is mapped and how every agent (vessels, assets, techs) works is described, with a focus on assumptions that have been made during our modelling.

Status and processes related to O&M Design are defined as followed:

Assets and maintenance tasks

The first statechart illustrates the status of the wind turbine, it represents the two different operational status. The second statechart shows the way a work order requires action. 

The operational statechart represents when the wind turbine is working and generating energy, and also shows a stopped status where the turbine is down due to weather conditions or failures.

When an action triggers, it means that some maintenance or repair work needs to be done in the wind turbine. The diagram shows the process of how it is carried out, from the creation of the order until it is finished.

Scheduled Maintenance and Components

  • Maintenance 
  • Repair 
  • Replacement 

Fixable represents all failing assets included in a case. The process diagram shows how maintenance, repair, and replacement tasks are carried out from and to a 'stable' state where non-orders are performed.

Logistics (CTV, SOV, Heli, Tug)

The vessel process diagram shows the behaviour of different logistics. It represents a common pattern along the whole operational period of the wind farm.

Work orders for vessels

  • Standard order 
  • Component replacement order 
  • Component replacement order using a towing vessel 

The process diagram below explains the different states when an order is generated. The next two diagrams are more specific for  HLV and tug vessel.

When a component replacement order is assigned to an HLV, the vessel will follow the process as shown.

Other component replacements can be assigned to a towing vessel, and the different states will be the ones shown below.

HLVs

HLV vessel process with work order capacity

  • Vessel chartered - waiting until the charter lead time is completed
  • Check if it is time to schedule the vessel
    1. Is it above the minimum used capacity for going out?
    2. Is it past the longest waiting time for one of the work orders assigned?
  • Schedule the vessel mobilizing, preparing transit, transit to the first asset, and jacking up
  • Schedule work on the asset, jacking down, and the next transit
    1. The next transit is either to the next assigned work order, and then jacking up
    2. Or the transit is back to port and then demobilizing
    3. This is repeated until there is no more assigned work orders and the vessel is back at port
  • Charter ends, and the vessel is free to be chartered when the next failure happens

 

Work orders

  • HLV required work order is created
  • Assign work order to a HLV
    1. Check if there is already a vessel chartered, which has not been scheduled for going offshore yet, which has capacity left for the new work order
    2. Otherwise charter a new vessel
  • Work is performed once the assigned HLV gets to that location of that work order
  • Work order closed


Towing

The state chart below shows the component, crane and towing vessel involvement in the component replacement order with a tug. A towing vessel is required to replace the component and meanwhile the vessel on the way to the wind farm, the crane starts mobilising towards the port, and the component lead time starts counting. Once the component reached the shore, it is fixed on the port by the crane and taken back to the offshore wind turbine by the tug.

Crane

The crane is used to fix components that are taken to the port. Below, the process diagram showed presents all states a crane goes through when operating.

HLV vessel process
  • Vessel chartered - waiting until the charter lead time is completed
  • Check if it is time to schedule the vessel
  • Is it above the minimum used capacity for going out?
  • Is it past the longest waiting time for one of the work orders assigned?
  • Schedule the vessel mobilizing, preparing transit, transit to the first asset, and jacking up
  • Schedule work on the asset, jacking down, and the next transit
  • The next transit is either to the next assigned work order, and then jacking up
  • Or the transit is back to port and then demobilizing
  • This is repeated until there is no more assigned work orders and the vessel is back at port
  • Charter ends, and the vessel is free to be chartered when the next failure happens
 
Workorders
  • HLV required work order is created
  • Assign work order to a HLV
  • Check if there is already a vessel chartered, which has not been scheduled for going offshore yeat, which has capacity left for the new work order
  • Otherwise charter a new vessel
  • Work is performed once the assigned HLV gets to that location of that work order
  • Work order closed