openego / eDisGo / 42179982648

87%

push

github

Penalise the heat balance slacks in every OPF version (#853)

The heat pump balance of the OPF is cop·(php + phps2) == pd + phss − phs.
phps2 is electrical power that covers heat demand without being drawn from
the grid, and phss is surplus heat. Both are meant only for inconsistent heat
pump data. Only the objectives of opf_version 2 and 4 priced them. In
versions 1 (the default) and 3 they were free, so the OPF covered part of the
heat demand with phps2. The optimised heat pump time series were far too low
while the solve reported success. This also affected the presets
overlying_grid_opf and overlying_grid_opf_spatial.

All four objectives now add heat_slack_penalty (HEAT_SLACK_PENALTY = 1e4).
from_powermodels stores phps2 in grid_slacks_t.hp_operation_slack in every
version. It logs a warning with the affected heat pumps, time steps and
energy whenever a slack exceeds 1e-4 MW, and says what to check.

In versions 3 and 4, the quadratic penalty on the overlying-grid requirement
slacks scales with the branch costs. For a large deviation from the heat
pump requirement it can exceed the fixed penalty, so the slacks can still be
used. The warning names that requirement as a possible cause in these
versions, and the penalty docstring and FUNCTION_COVERAGE.md state the limit.

The methodology documentation adds both slacks to the heat pump balance.
New tests check the coefficients in all objectives and that the slacks stay
zero in all versions. They also run the OPF end to end for versions 1 and 3
and check that the warning names the heat pump when its heat demand cannot
be covered.

Fixes #695

21 of 21 new or added lines in 1 file covered. (100.0%)

10205 of 11754 relevant lines covered (86.82%)

0.87 hits per line