Update optimization.py

[michaelpiron]

Implemented changes:

• Inverted the objective formulas in the case of "grid cost" cost function
• Changed the cost calculation to be consistent with the objective formula, in case of "grid cost" cost function (the cost calculation didn't distinguish between set_total_pv_sell = TRUE vs FALSE, whereas the objective function did).

To resolve following issue:

While looking at the code in order to understand the functioning of EMHASS, I noticed an inconsistency in the objective formulas.
The profit cost function shows this:

emhass/src/emhass/optimization.py

Lines 196 to 204 in bec6f76

	if self.costfun == 'profit':
	if self.optim_conf['set_total_pv_sell']:
	objective = plp.lpSum(-0.001*self.timeStep*(unit_load_cost[i]*(P_load[i] + P_def_sum[i]) + \
	unit_prod_price[i]*P_grid_neg[i])
	for i in set_I)
	else:
	objective = plp.lpSum(-0.001*self.timeStep*(unit_load_cost[i]*P_grid_pos[i] + \
	unit_prod_price[i]*P_grid_neg[i])
	for i in set_I)

which looks correct, and is consistent with the EMHASS documentation:

• In the case of an energy contract where the totality of the PV produced energy is injected into the grid, the grid offtake volume equals = P_load + P_deferrable_sum
• Else (only the excess of PV produced energy is injected), the grid offtake equals = P_grid_pos

However, the "grid cost" cost function seems to have the formulas inverted, which is unexpected:

emhass/src/emhass/optimization.py

Lines 205 to 211 in bec6f76

	elif self.costfun == 'cost':
	if self.optim_conf['set_total_pv_sell']:
	objective = plp.lpSum(-0.001*self.timeStep*unit_load_cost[i]*P_grid_pos[i]
	for i in set_I)
	else:
	objective = plp.lpSum(-0.001*self.timeStep*unit_load_cost[i]*(P_load[i] + P_def_sum[i])
	for i in set_I)

Therefore, I wonder if the objective formulas in "Grid cost" cost function shouldn't be inverted.

[michaelpiron]

For the sake of clarity: I didn't test these changes, as I don't have my dev space/container set up yet.
I hope someone else can test this. On the other hand, the proposed changes are limited.

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (bec6f76) 88.16% compared to head (d77c4f6) 88.11%.

Files	Patch %	Lines
src/emhass/optimization.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
- Coverage   88.16%   88.11%   -0.06%     
==========================================
  Files           6        6              
  Lines        1420     1422       +2     
==========================================
+ Hits         1252     1253       +1     
- Misses        168      169       +1     

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