ORBIT

ORBIT is a tool developed by the National Renewable Energy Lab (NREL) for performing process-based bottom up installation and cost modeling for the offshore wind balance of system process. It is intended to be used for tradeoff studies, installation logistics research, and for modeling overall balance of system costs. Each module captures the main drivers of installation time and cost in a highly customizable framework, allowing the user to override any default values if they wish.

The primary structure of ORBIT relies on the Project Manager to intrepret the user specified configuration. Refer to the library/project/config <https://github.com/WISDEM/ORBIT/tree/master/library/project/config>. The ProjectManager calls DesignPhase to include all the wind farm components that comprise the balance of system, then it calls InstallationPhase to schedule all the installation processes for each component. Available design phases can be found here and installation phases can be found here. Details about the design and installation phases are presented throughout this documents page.

Design Phase

ORBIT is very modular by design to allow a user to define an offshore wind plant in many different configurations and simulate its design and installation. Modules in ORBIT represent the design of different components for an offshore wind plant (eg. substructures, array cabling system, etc.) as well as the installation of these components (eg. monopile installation, turbine installation, etc.). The modularity will allow for novel technologies or installation strategies to be easily introduced and compared with baseline methodologies as the industry develops.

Installation Phases

In ORBIT, each installation phase of an offshore wind project development is defined by a series of discrete processes that represent the installation of a component. Durations and respective costs of each of these processes are then calculated based on fundamental parameters of the project and defined vessels, such as determining the length of time a specific offshore lift will require depending on crane specifications and component mass.

These processes are then modeled using a Discrete Event Simulation (DES) framework, where each process must satisfy operational constraints (weather or vessel interactions) before it proceeds. In this way, weather delays can be accounted for in the installation process, and the associated impact on project risk and construction phase sequencing can be determined. The DES framework of ORBIT is built using the python package SimPy.

Library

A library directory includes data/specifications on cables, vessels, ports, turbines, and example projects in the form of yaml files. Users can copy and modify or create entirely new yaml files to customize their project. By sticking to the same file structure, users simply have to update the name or reference to the data in their configuration file.