Nodal documentation

Overview

The zonal-to-nodal component of R2X is a process by which the results of a zonal capacity expansion model (CEM) can be applied to a nodal production cost model (PCM). This exists as four main steps:

1. Determine the zone-wise and technology-wise capacity that needs to be added to and removed from the PCM to match the CEM’s prescribed capacities.

2. Deactivate capacity from the PCM’s generators pursuant to the prescribed capacities.

3. Rank the PCM’s nodes by build favorability.

4. Add new capacity to the PCM’s nodes pursuant to the prescribed capacities.

The inputs required to run the workflow are the following:

• PCM – Either a Sienna model (.json file) or a Plexos model (.xml file)

• CEM results – ReEDS run folder

• Node metadata file – A .csv file giving information about the PCM’s nodes such as their locations, voltages, and load participation factors (required columns: node_id, latitude, longitude, reeds_ba, voltage, load_participation_factor)

Process

The following are the steps of the zonal-to-nodal workflow and their corresponding files:

1. Parse CEM results (parser/reeds.py)

2. Read node metadata (parser/nodes.py)

3. Parse PCM (parser/plexos.py or parser/sienna.py)

4. Apply CEM results to PCM (nodal/apply_cem_to_pcm.py)

   • Compute required capacity additions and reductions to reconcile PCM and CEM zone-wise and technology-wise capacities (nodal/compute_capacity_additions_and_reductions.py)

   • This requires a mapping between the PCM and CEM technologies and a mapping connecting the PCM nodes to their CEM zones (from the node metadata file)

   • Execute required capacity reductions by fully and partially deactivating capacity from PCM generators (nodal/execute_retirements.py)

     • Higher heat rates correspond to higher deactivation priority

   • Rank PCM nodes (within their zones) by build favorability (nodal/node_ranking.py)

     • Higher deactivated capacity, voltage, and load participation factor correspond to higher favorability

     • The available transmission capacity of each node is also computed at this step

   • Execute standard capacity additions by assigning (disaggregated) capacity to PCM nodes (nodal/execute_capacity_additions.py)

     • reV technologies and technologies included in enabled custom buildouts (see “user-configurable values”) are excluded

     • Capacity is disaggregated according to per-technology average generator sizes from WECC and/or according to median generator sizes of the PCM

     • Limits on per-node capacity injection can be enforced with respect to the computed available capacities or user-defined limits (see “user-configurable values”)

     • For nodes with deactivated capacity, the amount of deactivate capacity also serves as an upper bound for capacity injection

   • Execute reVX-based capacity additions (nodal/revx_aggregation.py)

     • The per-supply curve capacities are normalized according to the investment capacity determined in the first step

     • Only reV technologies (see “user-configurable values”) are included

     • Nodal injection limits cannot be enforced

   • Add timeseries data to non-reV VRE technologies (nodal/postprocessing.py)

     • Profiles are based on the recf.h5 input file from the ReEDS run

   • Execute custom capacity additions (nodal/ext/build_vre_based_bess.py)

     • This entails assigning new capacity to nodes in ways that deviate from the standard procedure of the fourth step

     • Custom buildouts and their corresponding technologies are defined in nodal_defaults.json (see “user-configurable values”)

     • For instance, the “vre_based_bess” custom buildout assigns new BESS capacity to PCM nodes with higher VRE capacity, load participation factor, and voltage corresponding to higher favorability and with a maximum of 50% of the node’s solar (if short-duration BESS) or wind (if long-duration BESS) instset guicursor=a:blinkon1alled capacity

   • Add auxiliary generator attributes to the new builds based on ReEDS and WECC data (nodal/postprocessing.py)

   • Create formatted generator and storage data (nodal/postprocessing.py)

   • Write system update report detailing initial, deactivated, new, and total per-zone and per-technology capacities (nodal/postprocessing.py)

• Export updated PCM (parser/sienna.py or parser/plexos.py)

User-configurable Values

• bess_lpf_threshold – Only nodes with load participation factor equal to or above this threshold will be considered for VRE-based BESS buildout. (default: 0.001)

• custom_nodal_buildout_tech_map – Mapping between available custom buildouts and their corresponding CEM technologies. (default: {vre_based_bess: [battery]})

• custom_nodal_buildouts – Enabled custom buildouts. (default: [vre_based_bess])

• disable_transmission_capacity_limits – Whether the capacity injection of nodes should be limited by their available transmission capacities in non-reVX buildouts. (default: True)

• distpv_capacity_threshold_MW – New distributed PV generators will only be assigned capacities equal to or above this value. (default: 100)

• new_build_prefix – String that gets attached to the beginning of new generators’ names. (default: ReEDS)

• nodal_build_capacity_limit_MW – Each node can only receive new capacity until its total capacity reaches this value. (default: infinity)

• nodal_build_unit_limit – Each node can only receive new capacity until its total number of units reaches this value. (default: 5)

• reV_capacity_threshold_MW – Minimum capacity of new generators created by reVX. (default: 100)

• reV_node_voltage_threshold_kV – Only nodes with voltages equal to or above this threshold will be considered for the buildout of reV technologies (rev_techs). (default: 100)

• rev_techs – CEM technologies that should be built by reVX PlexosAggregation. You must have reV supply curves and capacity factor files for each tech. (default: [upv, wind-ons, wind-ofs])