Bugfix load shedding scaling (#1908)

* Fix bugs by (i) removing sign argument and (ii) using isinstance

* Remove todo and color and nice_name assignment.

* Add release notes.

* Change p_nom_extendable=True to p_nom=np.inf

* Updated doctables for load_shedding

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Author: jonathan-peel

doc/configtables/solving.csv

@@ -1,7 +1,7 @@
 ,Unit,Values,Description
 options,,,
 -- clip_p_max_pu,p.u.,float,To avoid too small values in the renewables` per-unit availability time series values below this threshold are set to zero.
--- load_shedding,bool/float,"{'true','false', float}","Add generators with very high marginal cost to simulate load shedding and avoid problem infeasibilities. If load shedding is a float, it denotes the marginal cost in EUR/kWh."
+-- load_shedding,bool/float,"{'true','false', float}",Set to true to add generators with very high marginal cost to simulate load shedding and avoid problem infeasibilities. The default value is 1e5 €/MWh = 100 €/kWh (see http://journal.frontiersin.org/article/10.3389/fenrg.2015.00055/full). Override this value by setting a float denoting the new cost in MWh. Consider lowering the cost if you are struggling with long solve times.
 -- curtailment_mode,bool/float,"{'true','false'}",Fixes the dispatch profiles of generators with time-varying p_max_pu by setting ``p_min_pu = p_max_pu`` and adds an auxiliary curtailment generator (with negative sign to absorb excess power) at every AC bus. This can speed up the solving process as the curtailment decision is aggregated into a single generator per region. Defaults to ``false``.
 -- noisy_costs,bool,"{'true','false'}","Add random noise to marginal cost of generators by :math:`\mathcal{U}(0.009,0,011)` and capital cost of lines and links by :math:`\mathcal{U}(0.09,0,11)`."
 -- skip_iterations,bool,"{'true','false'}","Skip iterating, do not update impedances of branches. Defaults to true."

doc/release_notes.rst

@@ -9,6 +9,8 @@ Release Notes
 Upcoming Release
 ================
 
+* Fixed bugs with load shedding due to incorrect use of `sign` argument in `n.add` and `np.isscalar` (https://github.com/PyPSA/pypsa-eur/pull/1908).
+
 * chore: disable PTES dynamic capacity by default 
 
 * Add CO2 emission prices configurable per planning horizon for sector-coupled models.

scripts/solve_network.py

@@ -462,22 +462,19 @@ def prepare_network(
     if load_shedding := solve_opts.get("load_shedding"):
         # intersect between macroeconomic and surveybased willingness to pay
         # http://journal.frontiersin.org/article/10.3389/fenrg.2015.00055/full
-        # TODO: retrieve color and nice name from config
-        n.add("Carrier", "load", color="#dd2e23", nice_name="Load shedding")
+        n.add("Carrier", "load")
         buses_i = n.buses.index
-        if not np.isscalar(load_shedding):
-            # TODO: do not scale via sign attribute (use Eur/MWh instead of Eur/kWh)
-            load_shedding = 1e2  # Eur/kWh
+        if isinstance(load_shedding, bool):
+            load_shedding = 1e5  # Eur/MWh
 
         n.add(
             "Generator",
             buses_i,
             " load",
             bus=buses_i,
             carrier="load",
-            sign=1e-3,  # Adjust sign to measure p and p_nom in kW instead of MW
-            marginal_cost=load_shedding,  # Eur/kWh
-            p_nom=1e9,  # kW
+            marginal_cost=load_shedding,  # Eur/MWh
+            p_nom=np.inf,
         )
 
     if solve_opts.get("curtailment_mode"):