Global constraint on generator dispatch

[Daniel Coles]

Dear all,

I am struggling to implement a Global Constraint on the dispatch of a generator with type="operational_limit, based on the documentation here: 

https://docs.pypsa.org/v1.0.0/user-guide/optimization/global-constraints/#primary-energy 

I have attached a very simple dispatch case to demonstrate the issue, where I am trying to get the model to cover half of the load using the Generator 'OCGT_CCS', even though it has a higher marginal price. 

The lines for implementing this global constraint are: 

ocgt_ccs_dispatch=1000 * 8760 * 0.5
network.add("GlobalConstraint","OCGT_CCS_dispatch",type="operational_limit",carrier_attribute="Carrier",carrier="CCGT",sense="=",constant=ocgt_ccs_dispatch)   # in MWh (52e6 for 52 TWh)  

For some reason this is not being implemented , and the dispatch optimisation simply chooses the cheaper CCGT generator to meet all of the load 

I am running PyPSA 1.0.7, which should overcome any version issues, given that I've seen that implementing global constraints in version s<ca. 0.22 was causing some problems.

Any help greatly appreciated.

Kind regards,

Danny