Change Log

0.9.5 (6 August 2024)

• Fixes a bug that causes delayed mobilizations. The underlying cause was the lack of resetting the index column of WombatEnvironment.weather after filtering out rows that exist prior to the starting year of the simulation.

• The Polars minimum version was bumped to avoid a deprecation error with the previous index column generation method.

0.9.4 (1 July 2024)

• Adds support for Python 3.11 and 3.12.

• Adds the following capability and servicing equipment codes:

  • MCN for medium cranes, which should enable greater options for land-based wind.

  • VSG for vessel support groups, or any representation of multiple vessels used for a single operation.

• Updates Polars API usage to account for a series of deprecation and future warnings.

• Changes the metrics demonstration to use the COREWIND Morro Bay in situ example, and adds the availability plotting to the demonstration example.

• RepairRequest.prior_operating_level has been added to allow 100% reduction factor failures to correctly and consistently restore the operating level of a subassembly following a repair.

• Replaces the valid_reduction attrs validator with validate_0_1_inclusive to reuse the logic in multiple places without duplicating checking methods.

• Adds a replacement flag for interruption methods, so that a failure or replacement comment can be added as a cause for simpy.process.interrupt. This update allows the failure and maintenance processes to check if an interruption should cause the process to exit completely. Additionally, the forced exit ensures that processes can't persist after a replacement event when a process is recreated, which was happening in isolated cases.

• Fixes a bug in RepairManager.purge_subassemble_requests() where the pending tows are cleared regardless of whether or not the focal subassembly is the cause of the tow, leading to a simulation failure.

• Fixes a bug in utilities/utilities.py:create_variable_from_string() to operate in a way that is expected. The original method was removing all numerics, but only leading punctuation and numerics should be replaced, with any punctuation being replaced with an underscore.

• Adds additional inline comments for clarification on internal methods.

• Update README.md to be inline with current conda and Python standards.

• Fully adopts functools.cache now that older Python versions where functools.lru_cache was the available caching method.

• Fixes a Pandas FutureWarning by removing a now unnecessary piece of code in wombat/core/post_processor.py:equipment_costs

v0.9.3 (15 February 2024)

• Reinstate the original time-based availability methodology, which is based on all turbines, not the wind farm total.

• Replace the black formatter with ruff.

• Adopt pyupgrade to ensure modern Python language usage.

• Add the NumPy 2.0 integration tool to Ruff.

v0.9.2 (13 November 2023)

General

• Adds the PowerPoint file used in the NAWEA/WindTech 2023 Workshop.

• Updates all coming soon links and typos.

Bug Fixes

• Fixes an edge-case introduced in v0.9.1 where traveling during a crew transfer process is able to occur after the end of the simulation period.

• The documentation has been completely converted to a Jupyter Book paradigm due to a build issue found in the GitHub Actions.

v0.9.1 (27 October 2023)

• Removes the pre-public release analysis data and results, located atlibrary/original-outdated, from the repository, but can be found in all releases prior to v0.9. This is being done to manage the package size and ensure it can be published to PyPI.

v0.9 (27 October 2023)

Bug Fixes

• Repairs that had a weather delay extended repairs past the end of the shift now properly extend the repair into future shifts instead of completing early. This has a small negative impact on availability because that means some repairs can take longer than they had originally.

• Traveling to a system for a repair where the timing extends beyond the end of the shift, but into the next shift, is now registered as a shift delay just like travel weather delays that extend beyond the end of the current shift but before the start of the next shift. This has a small positive impact on availability because a turbine or cable may not start being repaired until weather is more consistently clear, rather than starting it and extending it for many shifts.

• Windfarm.cable() now correctly identifies 2 and 3 length cable naming conventions to differentiate which version of the cable id is being retrieved.

• An edge case where events occurred just after the end of a simulation has been resolved by checking the datetime stamp of that event and not adding any action log to the simulation that is after the WombatEnvironment.end_datetime.

• A bug in how the total wind farm operating level was calculated is updated to account for substation downtime, rather than using a sum of all turbine values.

• Metrics.time_based_availability and Metrics.production_based_availability have been updated to use to take advantage of the above fix. Similarly, the time-based availability skews higher now, as is expected when taking into account all availability greater than 0, and the energy-based availability drops moderately as a result of accounting for the substation downtime.

General Updates

• Metrics.equipment_labor_cost_breakdowns now has a by_equipment boolean flag, so that the labor and equipment costs can be broken down by category and equipment. Additionally, total_hours has been added to the results, resulting in fewer computed metrics across the same set of breakdowns.

• "request canceled" and "complete" are now updated in the logging to directly state if it's a "repair" or "maintenance" task that was completed or canceled to ensure consistency across the logging messages. As a result, Metrics.task_completion_rate() can now correctly differentiate between the completed tasks effectively.

• The use of unique naming for the servicing equipment is now enforced to ensure that there is no overlap and potential confusion in the model.

• New, experimental plotting functionality has been added via wombat.utilities.plot.

  • plot_farm_layout plots the graph layout of the farm. Note that this will not work if realistic lat/lon pairs have not been provided in the layout CSV.

  • plot_farm_availability plots a line chart of the monthly overall windfarm availability. Additional toggles allow for the plotting of individual turbines in the background and/or a 95% confidence interval band around the farm's availability

  • plot_detailed_availability plots a heatmap of the hourly turbine and farm operational levels to help in debugging simulations where availability may be running suspiciously low (i.e., a turbine might have shut down or a cable failure didn't get repaired within a reasonable time frame).

• Simulation.service_equipment is now a dictionary to provide clear access to the servicing equipment details.

• Simulation.from_config() requires both a library input and a file name input for the configuration after deprecating the library field from the configuration requirements due to it being cumbersome

• Metrics.opex() provides the opex output by category if by_category is set to be True

Methodology Updates

• Subassemblies and cables are now able to resample their next times to failure for all maintenance and failure activities, so that replacement events reset the timing for failures across the board.

• Systems are no longer interrupted once the servicing equipment addressing a repair or maintenance task is dispatched, and instead are interrupted just before the crew is transferred to begin repair, maintenance, or unmooring. This has a small net positive increase in the availability for short travel distances, but can vary if the travel time is more than a few hours (i.e., large distance to port, slow travel due to weather, & etc.)

• When a tow to port repair is in the queue, no other repairs or maintenance activities will occur for that turbine until it's brought into port for repairs.

Deprecations

• The original library structure has been fully deprecated, please see the Reference/How To example for more details on converting data that has not yet been updated.

• All PySAM functionality has been deprecated as it's no longer relevant to this work.

• The Simulation.config no longer requires the library field to reduce conflicts with sharing data between users.

v0.8.1 (28 August 2023)

• Fixes a bug where servicing equipment waiting for the next operational period at the end of a simulation get stuck in an infinite loop because the timeout is set for just prior to the end of the simulation, and not just after the end of the simulation's maximum run time.

v0.8.0 (16 August 2023)

Bug Fixes

• Most of the # type: ignore comments have been removed, or the past errors have been resolved

• Failure and maintenance logic in the Cable and Subassembly models have been wrapped in if/else blocks to ensure previously unreachable code still can't be reached under limited conditions

• Fixes a bug in where the mobilization duration is logged. Previously, the mobilization duration was logged upon completion, but now is logged while during the actual mobilizing, with costs still being logged upon completion.

• Fixes an uncommon error where repairs are made twice causing the simulation to fail. This was caused by a control mismatch in the unscheduled repair process, and was fixed by better tracking and controlling when a repair moves from "pending" (submitted), to "processing" (handed off to the servicing equipment for repair or to the port for a tow-to-port repair cycle), to "completed" (the repair is registered as complete). Additionally, the servicing equipment no longer relies on receiving the first repair from the repair manager on dispatch, and follows the same get_next_request() logic that will occur following the initial dispatch and repair.

• Fixes an error where a repair has replacement=True and operation_reduction < 1 both resets the operating_level back to 1 and readjusts for the operation_reduction, which can cause operating_level > 100%

• ServiceEquipment.crew_transfer() uses a while loop in place of an if with recursion strategy to handle unsafe transfer conditions to continuously wait until the next shift's available window.

Features

• Adds a non_stop_shift attribute to ServiceEquipmentData, UnscheduledServiceEquipmentData, ScheduledServiceEquipmentData, and PortConfig that is set in the post-initialization hook or through DateLimitsMixin._set_environment_shift() to ensure it is updated appropriately. Additionally, all checks for a 24 hour shift now check for the non_stop_shift attribute.

• Metrics.emissions() has been added to the list of available metrics to calculate the emissions from idling at port or sea, tranisiting, and maneuvering. Co-authored by and inspired by analysis work from @hemezz.

• Simulation now accepts a random_seed or random_generator variable to seed the random number generators for Weibull failure timeouts and wait timing between event completions. Setting the random_seed to the same value from one simulation to the next will net the same results between different simulations, whereas the random_generator can be used to use the same generator for a batch of simulations.

General

• All assert statements are now only called when type checking is performed

• Replaces all .get(lamda x: x == request) with a 10x faster .get(lambda x: x is request) to more efficiently filter out the desired event to be removed from the repair manager and port repair management.

• WombatEnvironment.weather is now a Polars DataFrame to improve efficiency and indexing bottlenecks introduced in Pandas 2.0.

• All subassembly cable files are read in once, and stored in a dictionary to provide a modest speed up for the simulation initialization.

v0.7.1 (4 May 2023)

• Features

  • Metrics.process_times() now includes the time_to_start, representing the time between when a request is submitted, and when the repairs officially start.

  • Expand the acceptable date formats for the weather profiles to allow for year-first.

v0.7.0 (3 May 2023)

• Replace Flake8 and Pylint in the pre-commit workflow with ruff, and fix/ignore the resulting errors as appropriate

• Features:

  • Weather data now has the ability to contain more than just the required "windspeed" and "waveheight" columns. This will allow for easier expansion of the weather model in the future, and increase compatibility with other NREL techno economic modeling frameworks.

• Bug fixes:

  • Maintenance and failure simulation process interruptions were occuring prior to starting the process timing, and causing simulation failures.

  • Duplicated parameters were being processed in WombatEnvironment.log_action stemming from improper handling of varying parameters in some of the more complex control flow logic in in situ repairs.

  • Another edge case of negative delays during crew transfers where there is insufficient time remaining in the shift after account for weather, so the method was called recursively, but not exiting the original loop.

  • Port management of in situ and tow-to-port capable tugboats wasn't properly accounting for tugboats of varying capabilities, and assuming all tugboats could do both. The vessel management and repair processing were out of sync causing duplicated turbine servicing/towing.

  • RepairManager has consolidated the dispatching of servicing equipment to be the following categories instead of the previously complex logic:

    • If a request is a tow-to-port category, have the port initiate the process

    • If the dispatching thresholds are met, then have the port initiate a repair for port-based servicing equipment, otherwise the repair manager will dispatch the appropriate servicing equipment.

  • ServiceEquipment.weather_delay() no longer silently processes a second weather delay.

  • Intra-site travel is now correctly logging the distance and duration of traveling between systems at the site by moving the location setting logic out of crew_transfer method and being entirely maintained within, or next to, the travel method of ServiceEquipment.

  • RepairManager now properly waits to dispatch servicing equipment until they are no longer under service from another servicing equipment unit.

  • Servicing equipment are no longer simultaneously dispatched from both the Port and RepairManager causing simulations to potentially error out when the System.servicing or Cable.servicing statuses are overridden by the second-in-line servicing equipment. This was resolved by the port waiting for the turbine, a tugboat, and a spot at port to become available, then immediately halting the turbine, and starting the tow-in logic.

  • Missing ServiceEquipment.dispatched status updates have been amended, so no matter the operation, a piece of servicing equipment should be set to dispatched = True until the crew is back and repair is completed.

  • To avoid multiple dispatches to a single turbine, cable, or substation, or multiple dispatches of a single vessel/onsite equipment, a random timeout between 0 and 30 seconds (in simulation time) is processed, then a status double-checking occurs.

  • Metrics.process_times() now includes the "N" column to indicate the number of processes that fall into each category.

v0.6.2 (3 February 2023)

• Warnings from Pandas .groupby() calls have been silenced by shifting the column filtering to before the groupby method call.

• Fixed the towing to port logging message, and subsequent Metrics.number_of_tows() search criteria to correctly calculate the number of tows in each direction.

• Fixes a bug in the crew transfer logic where the travel time back to port is longer than the weather delay itself, and a negative time delay is incorrectly attempted to be processed.

v0.6.1 (31 January 2023)

• A hot fix for the code comparison data not being found when installing from PyPI, which was caused by missing __init__.py files in the reconfigured library structure.

v0.6.0 (10 January 2023)

In v0.6, due to a series of bug fixes, logic improvements, and feature additions (all described below), users can expect mild to significant shifts in their results. These shifts, while startling, move WOMBAT towards more accurate results now that servicing equipment can't be dispatched multiple times in a row, statuses can't be reset without failure. Additionally, in our validation cases this has led to an average speedup of 71%, or 3.5x faster run times.

New and Updated Features

• Environmental and logistics considerations via prohibited operations periods and speed reduction periods.

  • All periods can be set for each servicing equipment, or across the board when set at the environment level

  • For ports, the same logic applies where the environment can set the port variables and the port can set its associated tugboats' variables

  • When a setting is defined in multiple locations, the more conservative restriction is applied

  • Variables non_operational_start, non_operational_end create the annualized period where operations are prohibited, resulting in the creation of the array non_operational_dates and set non_operational_dates_set.

  • Variables reduced_speed_start, reduced_speed_end create the annualized period where the maximum speed, reduced_speed, for all operations is imposed, resulting in the creation of the array reduced_speed_dates and set reduced_speed_dates_set.

• Export Cables

  • Models the export cabling system as a single cable between the substation and the interconnection point or as a connection between multiple substations. For multiple connected substations, the model assumes they are independent systems.

  • Adds support for "type" in the wind farm layout CSV file, which should be filled with either "substation" or "turbine". This column supports multi-substation farms so that accurate plots and connections can be made. For instance, multiple connected substations, can now be accurately rendered and modeled in the farm.

  • Adds support for "upstream_cable_name" in the wind farm layout CSV file, to provide an individualized name to a cable in place of using the name field in the cable settings file for all similar cables.

• New library structure that mirrors ORBIT (see below diagram)! In v0.7, the original library structure will be officially deprecated in favor of the below, and during the v0.6 lifecycle a warning will be raised to instruct users where to place and structure folders going forward.

  <library>
    ├── project
      ├── config       <- Project-level configuration files
      ├── port         <- Port configuration files
      ├── plant        <- Wind farm layout files
    ├── cables         <- Export and Array cable configuration files
    ├── substructures  <- Substructure configuration files
    ├── turbines       <- Turbine configuration and power curve files
    ├── vessels        <- Land-based and offshore servicing equipment configuration files
    ├── weather        <- Weather profiles
    ├── results        <- The analysis log files and any saved output data
  

  • Adds create_library_structure to wombat.core.library so that users can create the appropriate folder structure for a new project without having to manually create each and every folder.

• Maintenance.operation_reduction has been enabled to better resemble the effect of unaddressed maintenance.

• Failure now has a boolean flag for replacement to indicate if a replacement is required, which allows for operational shutdowns without necessitating a full replacement of the subassembly. Additionally, this flag enables a replacement event for non-shutdown failures.

General Improvements

• Bump Python versioning requirements to 3.8+

• Add PyArrow dependency for fasting save/load processes for CSV reading and writing

• Convert boolean operational statuses for System, Subassembly, Cable, and ServiceEquipment to SimPy events for more efficient processing and accurate delays for restarting

• Fix numerous bugs in the repair logic introduced by the use of boolean checks and status switches, which also improve simulation performance. These issues were primarily caused by erroneously resetting the status, but with the new event setting and .succeed() logic to clear an operation, the previously incorrect resetting is much harder to do.

• Continue to improve the performance of low-level simulation operations to realize further improvements in memory usage and simulation performance

• Logging is now based on directly writing to CSV in place of the logging-based infrastructure

  • All underlying infrastructure withing the simulation have also been updated to accommodate the different file types, which allows for more direct interaction at the end of the simulation and enables PyArrow CSV read/write

  • This enables:

    • deprecation warnings to be passed directly to the terminal/notebook without interfering with the file handling

    • reasonable speedups to simulation times by not having additional overhead from the logging and buffering

• Metrics.process_times() has been converted to efficient pandas code for fast computation.

• The Metrics example usage documentation page has been rewritten and reformatted to provide more helpful information to users

• Metrics methods now accurately account for the effect of substation operating reductions on upstream turbines so that each substation's subgraph multiplies the turbine operating capacity by the substation operating capacity.

• Fixes a bug in the RepairManager.get_next_highest_severity_request() where requests aren't processed in first in, first out order with a severity level priority.

• Remove duplicated logic in the Subassembly and Cable maintenance and failure modeling ensuring that repetitive logic is identical between scenarios.

0.5.1 (22 July 2022)

• Updates to use the most recent pandas API/recommendations, which fixes numerous warnings in the Metrics class

• Fixes inconsistency in returning floats vs DataFrames in the Metrics class

• Updates the examples to work with the returned DataFrame values, and adds warnings about the change in usage

• Updates the documentation configuration to be compatible with the latest sphinx book theme API usage

• Adds a potential fix to an occasional issue where the logging files can't be deleted using WombatEnvironment.cleanup_log_files() because the file is still considered to be in use

0.5.0 (30 June 2022)

• Adds capabilities: "TOW" and "AHV" for tugboat/towing equipment and anchor-handling vessels

• Adds a tow-to-port strategy that is activated for repairs with the "TOW" capability in the servicing

• Adds a Port class to handle the tow-to-port class and tugboat-based service requests

• Allows for any name to define the subassemblies of a turbine or substation to enable users to use the naming conventions they are most familiar with or most meaningful for their own work

• Minor bug fixes in the Metrics class to improve stability, improve code reuse, and documentation\

• Adds nearly all documentation updates from PR #39 as a result of an internal code review, but makes the changes in the source files that generate the example notebooks, so is not a direct merge

• Adds an annual fee to PortConfig.annual_fee that gets applied monthly, though is not included in any metrics yet.

• Adds UnscheduledServiceEquipmentData.tow_speed to differentiate between towing speeds and traveling speeds required between port and site, and implements the towing speed application appropriately

• Adds a location flag to the events logging infrastructure and implements its usage across the simulation architecture

• Creates the metric Metrics.number_of_tows to track the number of tows and provides breakdowns as needed

• Creates the metric Metrics.vessel_crew_hours_at_sea to track the number of vessel or crew hours at sea

• Creates the metric Metrics.port_fees to calculate any port fees associated with a project

• Creates the metric Metrics.opex to calculate a project's operational expenditures

• Creates the metric Metrics.NPV to calculate a project's net present value

• Modifies Metrics.project_fixed_costs to have more time resolutions to align with the OpEx calculation options

• Fixes some results formatting inconsistencies in the Metrics class

0.4.1 (2022-March-8)

• Adds code diagrams to demonstrate how the various components connect

• Updates the documentation to be better in line with the current state of the software

• Fixes a bug that allowed the x_metrics_inputs.yaml file to persist after the cleanup method is called.

• Updates the provided library content structure to account for future updates

0.4.0 (2022-February-4)

• Testing now included!

• pathlib.Path is used in place of os throughout for easier to read file maneuvering.

• attrs.define and attrs.field have been adopted in place of attr.s and attr.ib, respectively.

• Typing style is updated for future python type annotations as, e.g., Union[List[str], str] -> list[str] | str.

• Unused imports have been further cleaned up.

• Better caching of commonly computed values for faster simulations

• Simulation metrics are now able to be saved for later reloading and use.

• Minor documentation updates, mostly in the examples section for changed API usage.

• Validation cases have been re-run for the most up-to-date version.

• wombat.windfarm.system.System no longer requires every subassembly model to be defined for increased flexibility and ease of definition of turbine simulations

• wombat.utilities.hours_until_future_hour() correctly moves to the expected hour in the future, regardless of the number of days that are added.

• The IEA Task 26 validation cabling vessel was renamed from "cabling.yaml" to "cabling_scheduled.yaml" for consistent naming conventions.

• Improved error messages throughout.

• wombat.core.simulation_api.Simulation no longer accepts name as an input, and reads it directly from the configuration.

• wombat.core.simulation_api.Simulation.run now has a create_metrics flag that defaults to True to indicate if the metrics suite should be created, so that False can be used if numerous analyses will be run and post-processed after the fact.

• wombat.core.simulation_api.Simulation.save_metrics_inputs added to allow for saving the elements required to recreate a Metrics object at a later point in time.

• wombat.core.environment.WombatEnvironment.workday_start and wombat.core.environment.WombatEnvironment.workday_end are better validated for edge cases.

• wombat.core.environment.WombatEnvironment._weather_setup validates the start and end points against the provided weather profile and against each other to ensure they are valid boundaries.

• wombat.core.environment.WombatEnvironment.cleanup_log_files will only try to delete files that actually exist to avoid unexpected simulation failures at the last step.

• wombat.core.environment.WombatEnvironment.date_ix accepts datetime.datetime and datetime.date inputs to avoid unnecesary errors or manipulations in a simulation.

• wombat.core.environment.WombatEnvironment.log_action now only accepts numeric inputs for system_ol and part_ol.

• wombat.core.environment.WombatEnvironment.weather_forecast now rounds the starting time down to include the current hour, which fixes a bug in some edge cases where a crew transfer at the end of the shift gets stuck and has to wait until the next shift despite ample time to transfer.

• wombat.core.environment.WombatEnvironment.is_workshift correctly accounts for around the clock shifts.

• wombat.core.data_classes.annual_date_range now uses numpy.hstack to construct 1-D multiple year date ranges to ensure there is no nesting of data.

• wombat.core.repair_management.RepairManager.submit_request will only attempt to deploy servicing equipment for strategies that have been initialized to reduce unnecessarily running code.

• wombat.core.repair_management.RepairManager.get_request_by_turbine was renamed to wombat.core.repair_management.RepairManager.get_request_by_system to explicitly include substations. to remove repeated calculations and checks.

• wombat.core.repair_management.RepairManager.get_request_by_severity request checking was optimized to remove repeated calculations and checks.

• wombat.core.repair_management.RepairManager.purge_subassembly_requests no longer prematurely exits the loop to purge unnecessary requests from the logs in case of a replacement being required. Additionally, an exclude parameter has been added for niche use cases where all but a couple of requests will need to be removed.

• wombat.core.service_equipment.ServiceEquipment has more attributes for tracking its location throughout a simulation.

• wombat.core.service_equipment.ServiceEquipment.find_uninterrupted_weather_window now rounds float inputs up to the nearest whole number to ensure the proper length window is retrieved.

• wombat.core.service_equipment.ServiceEquipment.find_interrupted_weather_window uses math.ceil in place of np.ceil().astype(int) for strictly python data types in computation.

• wombat.core.service_equipment.ServiceEquipment.travel consistently resets the location attributes when moving between site and port to fix bugs in the end location.

• wombat.core.service_equipment.ServiceEquipment.crew_transfer now indicates when the crew is actually being transferred, and updates the equipment's location post-transfer. Additionally, the travel time in delays is now accounted for, so the actually elapsed time is accounted for in processing weather delays. A bug in processing weather delays is fixed and uses the correct SimPy timeout call so that the simulation does not get stuck due to improper calling.

• wombat.core.service_equipment.ServiceEquipment.process_repair adds a safety window to account for the crew having enough time to safely transfer back to the equipment. This logic is likely not entirely fixed, but is sufficiently fixed for the time being.

• wombat.core.service_equipment.ServiceEquipment.process_repair:

  • fixes a bug in the hours to process calculation by reconfiguring the control flow for both simplicity and accuracy.

  • Additionally, the equipment will travel back to port if the work shift is over, so the equipment does not skip steps the repair logic.

  • Weather delays will also not be processed if the actual repair is finished, and will be moved to the crew transfer step.

  • The hours required vs hours available is reset for equipment that have around the clock shifts, so the timing is not arbitrarily capped, which also reduces the number of steps in the simulation.

  • The work shift indicator check now accounts for the equipment's specific work shift settings, and not the environment's to ensure the proper operating parameters are used.

  • The control flow for if there isn't enough time to perform the repair is updated to accurately account for when and where the equipment needs to travel

  • Cables are no longer retrieved through system and causing an error when processing their repairs.

• wombat.core.service_equipment.ServiceEquipment._calculate_intra_site_time now accounts for a speed of 0 km/hr so that function will not error out when there is a travel distance, but no speed.

• wombat.core.service_equipment.ServiceEquipment.run_scheduled now sets the onsite variable for equipment that are always on site for more consistent handling of the onsite attribute.

• wombat.core.service_equipment.ServiceEquipment.wait_until_next_operational_period now resets the equipment's location attributes so its location can't incorrectly persist from the last step.

• wombat.core.service_equipment.ServiceEquipment.register_repair_with_subassembly correctly retrieves the cable information for upstream cables to be reset.

• wombat.core.post_processor.Metrics.service_equipment_utilization has a new methodolgy that uses the actual number of days in operation instead of a backwards computation that consistently and accurately accounts for the days where the servicing equipment is in operation. Additionally, the filtering is updated to match the filter for total days, which also improves accuracy of results.

• wombat.core.post_processor.Metrics.from_simulation_outputs classmethod was added to easily load simulation data for after-the-fact analyses.

• wombat.windfarm.Windfarm operations logging message generation routines were optimized.

• wombat.windfarm.Windfarm.system was created in place of wombat.windfarm.Windfarm.node_system as a convenience method for grabbing the System object from the windfarm graph layout.

• wombat.windfarm.Windfarm.cable was created to replicate the system method for cable objects.

• wombat.windfarm.Windfarm, wombat.windfarm.system.cable.Cable, and wombat.windfarm.system.system.System all have an operating level property that is the current operating level and one that does not account for if a system is being serviced, and therefore registered as non-operational. This fixes a bug in the dispatching of unscheduled service equipment when a repair request is submitted while a repair is occurring that drops the operating level below the strategy threshold. In the dispatching check we now are able to consider the operating level before a system was shut down for repairs and avoid improper dispatching.

• wombat.windfarm.system.cable.Cable now takes end_node in place of upstream_nodes to simplify the initialization process and be more explicit about the starting and ending points on the cable.

• wombat.windfarm.system.cable.Cable.interrupt_subassembly_processes is now interrupt_processes and only interrupts the cable's own maintenance and failure simulation processes.

• wombat.windfarm.system.cable.Cable.interrupt_all_subassembly_processes wraps interrupt_processes to ensure similar functionality between system and subassembly methods for use in the simulations.

• wombat.windfarm.system.cable.Cable logging now properly records itself as the target of repairs and maintenance tasks instead of its starting node.

• wombat.windfarm.system.cable.Cable.upstream_nodes has been updated to be in the correct order the nodes sit on the string

• wombat.windfarm.system.subassembly.Subassembly.interrupt_subassembly_processes is now interrupt_processes and only interrupts the cable's own maintenance and failure simulation processes.

• wombat.windfarm.system.system.System.interrupt_all_subassembly_processes was added so that subassemblies are no longer directly interacting with each other, and the interruptions are caused by the system's themselves.

• wombat.windfarm.system.system.System.log_action no returns the Subassembly.id instead of the __repr__ for the object to create a legible log.

0.3.5 (2021-December-9)

• Downtime-based and requests-based unscheduled maintenance models have been added to servicing equipment.

• Windfarm.current_availability is able to account for multiple substations and is now an accurate calculation of the operating level across the windfarm.

• Simulation.from_inputs() is replaced by Simulation.from_config() to be more straightforward for users.

• ServiceCrew has been added for expansion to multiple crews.

• Servicing equipment now have separate travel and crew_transfer, weather_delay, and repair functions to more realistically simulate the separate processes involved.

• The windfarm now has a distance matrix to calculate the distance between any two systems onsite, for instance, substation to cable, cable to turbine, etc.

• Bug fix in the task completion rate metric.

• WombatEnvironment.log_action() enforces the use of keyword arguments with only 3 required inputs.

• WombatEnvironment.weather_forecast() outputs now include the datetime index.

• If no PySAM settings are provided, the financial_model will be set to None with a NotImplementedError being raised for any attempted usage of the PySAM powered functionality.

• Fix bugs in Maintenance and Failure initialization.

• Fix bugs in operating level accounting from recent updates.

• Update the Unicode typing in all docstrings.

• Update the documentation to account for all the recent changes, including adding a new demonstration notebook for the 3 new strategies.

0.3.1 (2021-March-2)

• Updated the simulation/ folder to be a single-level core/ directory.

• Updates the order of the keyword arguments for WombatEnvironment.log_action(), and makes all arguments keyword-only arguments.