System
The System is the main container of components and the time series data references. PowerSystems.jl uses a hybrid approach to data storage, where the component data and time series references are stored in volatile memory while the actual time series data is stored in an HDF5 file. This design loads into memory the portions of the data that are relevant at time of the query, and so avoids overwhelming the memory resources.
Accessing components stored in the System
PowerSystems.jl implements a wide variety of methods to search for components to aid in data manipulation. Most of these use the Type Structure to retrieve all components of a certain Type.
For example, the most common search function is get_components, which takes a desired device Type (concrete or abstract) and retrieves all components in that category from the System. It also accepts filter functions for a more refined search.
Given the potential size of the return, PowerSystems.jl returns Julia iterators in order to avoid unnecessary memory allocations. The container is optimized for iteration over abstract or concrete component types as described by the Type Structure.
Accessing data stored in a component
Using the "dot" access to get a parameter value from a component is actively discouraged, use "getter" functions instead
Using code autogeneration, PowerSystems.jl implements accessor (or "getter") functions to enable the retrieval of parameters defined in the component struct fields. Julia syntax enables access to this data using the "dot" access (e.g. component.field), however this is actively discouraged for two reasons:
- We make no guarantees on the stability of component structure definitions. We will maintain version stability on the accessor methods.
- Per-unit conversions are made in the return of data from the accessor functions. (see the per-unit section for more details)