Like all thermal method calculations, the method is called at the end of a simulation run. This method first calculates the original, unmodified load (as an energy) by adding the hourly system load and load adjustment slots for all hours within a time step.

The user selects the power sources that will be used to modify the load by setting values in the Modified Load Power Sources Used table. This table has one column and three rows: Conventional Hydro Power Evaluated, Pump Power Evaluated, and Allocated Energy Evaluated. Power sources that should be used to modify the load have a non-NaN value while unused sources have a NaN value. See Modified Load Power Sources Used for details.

The Modified Load initially equals the original load (System Load minus Load Adjustment). The net generation from the selected power sources are subtracted from this load. If any of the selected power sources have a value of NaN then the modified load is also NaN. For example, during a normal pre-optimization simulation, modified load will be NaN for all timesteps because hydropower generation is not yet known. In contrast, during a fully specified simulation or a post-optimization rulebased simulation, modified load will be calculated because all hydropower generations will be known. See Modified Load for details.

Allocated power is constrained by minimal and maximal power generation for each time period combined with periodic total energy requirements. The power is allocated to level the load in coordination with other power sources.

After calculating the individual economic components for each time period, the totals for all time periods are placed in the Linear Total Values table slot.

See Calculate Modified Load in Optimization for details on how the method is used in optimization.