Off-grid CHP

[Bill-Becker]

This pull request introduces support for operating reserves in off-grid scenarios with Combined Heat and Power (CHP) systems. It enables modeling of CHP as either a provider or a consumer of operating reserves, depending on the scenario configuration. The changes also add a comprehensive test to verify correct behavior when CHP requires operating reserves and ElectricStorage provides them.

Key changes include:

Support for CHP Operating Reserve Logic:

• Added the operating_reserve_required_fraction field to the CHP struct, with logic to set and validate it based on the off_grid_flag. This allows CHP to either require or provide operating reserves in off-grid scenarios. [1] [2] [3] [4]
• Updated the Techs construction to classify CHP as requiring or providing operating reserves in off-grid mode, based on its operating_reserve_required_fraction.

Constraint and Expression Updates:

• Modified the operating reserve constraint logic to handle CHP appropriately: added expressions and constraints for CHP as a reserve-requiring or reserve-providing technology, and ensured correct upper bounds on reserve provision. [1] [2]
• Updated the setup of operating reserve fractions to include CHP.

Scenario and Input Handling:

• Allowed CHP as a permitted technology in off-grid scenarios and ensured the correct passing of the off_grid_flag to the CHP constructor. [1] [2]

Testing and Validation:

• Added a new test scenario (chp_offgrid.json) and a detailed test script (test_chp_offgrid.jl) that verifies: [1] [2]
  • CHP requires operating reserves and the battery is sized to provide them.
  • The load is met, no grid interaction occurs, and financial calculations are consistent.

These changes collectively enhance the model's flexibility for off-grid microgrid scenarios involving CHP and operating reserves.