Constraint issues (node_state) used in Spine

[shuo1990]

Hi,

I have a model, as seen in the Figure.

There are two units (V2H charger and EV availability) and three nodes (Household, EV, EV usage).

I have already set node_state_min (10% SOC) in the node named 'EV'. It is adopted for the route of EV- EV availability - EV usage.

How can I separately set another minimum constraint (30% SOC) for the other route EV - V2H charger - Household?

Kind regards
Shuo

[soininen]

This looked more like SpineOpt issue than Spine Toolbox so I moved it here.

[DillonJ]

Hi @shuo1990. It's not clear to me what you are trying to do. The state of charge (or node_state in SpineOpt terms) is a variable associated with the node. Any flows into that node can increase the node_state and flows out of the node can reduce the node_state. The node_state variable represents the energy stored in the node at a point in time and specifying a node_state_min will create a lower bound constraint on that variable. The energy stored in the node (node_state) is specific only to the node and is not specific to the energy flows to any units connected to that node, however any flows between the node and units will impact that node_state. Perhaps you want to set a minimum flow to the EV availability and V2H Charger units using the min_unit_flow parameter on the unit__to_node / unit__from_node relationships?

[DillonJ]

@shuo1990 inferring from the duplicate issue #954, you want to prevent discharge from the EV node. Then, you want to constrain the flows from the node rather than the state of charge. I would use either min_unit_flow or unit_capacity to set lower/upper bounds on the discharge flow as appropriate - perhaps using time patterns or time series.

[clizbe]

@DillonJ Thanks for the quick response. I'm converting this to a Support Discussion, so please continue the convo there.