External Grid

Create Function

For creating a single external grid:

For creating multiple external grids at once:

Component Table Data

net.ext_grid

Parameter	Datatype	Value Range	Explanation
name	string		Name of the external grid
junction	integer		Index of connected junction
p_bar	float	\(>\) 0	Pressure set point [bar]
t_k	float	\(>\) 0	Temperature set point [K]
in_service	boolean	True / False	Specifies if the external grid is in service.
type	string	Naming conventions: “p” - for node with fixed pressure “t” - for node with fixed temperature “pt” - for node with fixed pressure and temperature	Type variable to classify external grids

Physical Model

An external grid is used to denote nodes with fixed values of pressure or temperature, that shall not be solved for anymore. In many cases, an external grid represents a connection to a higher-level grid (e.g. representing the medium pressure level in a low pressure grid). Please note the type naming convention, stating that “p” means that the pressure is fixed, “t” means that the temperature is fixed and “pt” means that both values are fixed at the connected junction. For nodes with fixed pressure, the mass flow into or out of the system is not known prior to calculation, but is a result of the pipeflow calculation.

Also note that there has to be at least one fixed value of pressure for hydraulic calculations and one fixed value for temperature in heat transfer calculations for each separate part of the grid. This is also checked for in the connectivity check.

Result Table Data

net.res_ext_grid

Parameter	Datatype	Explanation
mdot_kg_per_s	float	Mass flow at external grid node [kg/s] (negative if leaving the system)