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 higherlevel 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) 