About the Assembly

The Assembly property in the Turbine section defines the physical structure of the turbine as a tree structure. The ComponentsLibrary details a list of parameterised components which can be used in the Assembly, and the Assembly tree defines their position and connectivity. A component in the ComponentsLibrary can appear many times in the Assembly tree.

Assembly Tree Format

The Assembly tree is formed out of nested JSON objects. Each component in the tree has a name, and then an object definition (enclosed in curly brackets) that must include the ComponentDefinition (referencing a parameterised definition of a component in ComponentDefinitions) and any number of named children.

Both the name of the child in the Assembly tree and the name within ComponentsLibrary can be any valid JSON string, so long as it is unique within its siblings (so the hub can cannot have two children named "PitchSystem", but each of those can have a child named "Blade").

"Assembly": {
  "Tower": {
    "ComponentReference": "#/ComponentDefinitions/TowerX100m",
    "YawSystem": {
      "ComponentReference": "#/ComponentDefinitions/YawSystemR568",
      "DrivetrainAndNacelle": {
        "ComponentReference": "#/ComponentDefinitions/DrivetrainAndNacelleCC83X",
        "Generator": {
          "ComponentReference": "#/ComponentDefinitions/VariableSpeedGenerator8MW-12" },
        "Hub": {
          "ComponentReference": "#/ComponentDefinitions/IndependentPitchHubStd3Bld",
          "PitchSystem_1": {
            "ComponentReference": "#/ComponentDefinitions/PitchSystemR322T6",
            "Blade": {
            "ComponentReference": "#/ComponentDefinitions/Blade50M2D" }},
          "PitchSystem_2": {
            "ComponentReference": "#/ComponentDefinitions/PitchSystemR322T6",
            "Blade": {
              "ComponentReference": "#/ComponentDefinitions/Blade50M2D" }},
          "PitchSystem_3": {
            "ComponentReference": "#/ComponentDefinitions/PitchSystemR322T6",
            "Blade": {
              "ComponentReference": "#/ComponentDefinitions/Blade50M2D" }}}}}}}

Definition of Components within the Assembly

The order of connection of components in the Assembly is important for defining how the turbine structure behaves. This gives rise to the concept of parent and child components. Consider an example of two components that connect together within the Assembly. One is referred to as a parent component the other is a child component. The parent is closest to the root of the tree while the child is furthest from the root of the tree. This example is illustrated in Figure 1. A parent can connect to multiple child component(s) or siblings. Components that have no children form the leaves of the tree.

Each component has two node types (proximal and distal) that act as connection points to other components. A component has a single proximal and one or more distal nodes. From a components perspective: the proximal node is closest to the root of the tree and the distal node is closest to the leaves of the tree. Consequently the proximal node of a component is the connection point to it's parent component. Unless the component is the first in the assembly tree. Finally, a distal node of a component is the connection point to one of it's children components.

The proximal node forms the origin of the body-fixed frame. The components properties are generally defined in the body-fixed frame. The distal node is the origin of the distal frame. The body-fixed frame of a child component will match the distal frame of it's parent component.

Figure 1: Anatomy of a component. The parent component body-fixed frame is denoted \((x_{b,p},y_{b,p},z_{b,p})\) and the distal frame is denoted \((x_{d,p},y_{d,p},z_{d,p})\). The child component body-fixed frame is denoted \((x_{b,c},y_{b,c},z_{b,c})\) and the distal frame is denoted \((x_{d,c},y_{d,c},z_{d,c})\).

Components

The following components are available for use within the Assembly:

Component	Description
Blades	Represents a wind turbine blade with both structural and aerodynamic properties.
Drivetrain and Nacelle	Represents the drivetrain of a turbine, along with its supporting mainframe and cover.
Generator	Represents a the electrical generator.
Pitch System	Represents a pitch bearing along with its actuation.
Tower	Represents an axisymmetric tower of circular cross-section. This has structural, hydrodynamic, and aerodynamic (including tower shadow) properties.
Yaw System	Represents a yaw bearing along with its actuation.
Translation	A utility component which allows an offset to be inserted into the assembly tree. This can be used to represent the original offset to where the first component is located (eg to embed the tower below the ground level), or to model a small offset like an imbalance.
Rotation	A utility component that allows for the change in orientation between two components. This can be used to represent a non-parameterised design feature such as a sweep inboard of the pitch system, or an imbalance or manufacturing/assembly defect.