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Table of Contents

Introduction

Nempy is a python package for modelling the dispatch procedure of the Australian National Electricity Market (NEM). The idea is that you can start simple, like in the example below, and grow the complexity of your model by adding features such as ramping constraints, interconnectors, FCAS markets and more.

A brief introduction to the NEM can be found at the link below:

https://aemo.com.au/-/media/Files/Electricity/NEM/National-Electricity-Market-Fact-Sheet.pdf

Documentation

A more detailed introduction to Nempy, examples, and reference documentation can be found on the readthedocs page.

Community

Nempy is open-source and we welcome all forms of community engagement, some more info is provided below.

Support

You can seek suport for using Nempy using the discussion tab on GitHub (https://github.com/UNSW-CEEM/nempy/discussions), checking the issues register (https://github.com/UNSW-CEEM/nempy/issues), or by contacting Nick directly n.gorman at unsw.edu.au.

Reporting issues

Issues with Nempy can be reported via the issues register (https://github.com/UNSW-CEEM/nempy/issues), issues submissions do not need to adhere to any particular format.

Contributing

Contributions via pull requests are welcome. Contributions should; follow the PEP8 style guide (with exception of line length up to 120 rather than 80), ensure that all existing automated tests continue to pass (unless you are explicitly changing intended behavour, please highlight this in your pull request description), implement automated tests for new features, and provided doc strings for public interfaces.

Get in touch

This project is being lead by Nick Gorman, a PhD candidate at the University for New South Wales and the Collaboration on Energy and Environmental Markets (CEEM). As part the project we hope to engage with and support prospective users of the software. Feel welcome to get in touch if you have any questions, want to provide feed back, have a feature request, are interested in collaborating or just want to discuss this project. You can contact Nick via n.gorman at unsw.edu.au.

Installation

Installing nempy to use in your project is easy.

pip install nempy

To install for development purposes, such as adding new features. Download the source code, unzip, cd into the directory, then install.

pip install e .[dev]

Then the test suite can be run using.

python -m pytest

A simple example

import pandas as pd
from nempy import markets

# Volume of each bid, number of bands must equal number of bands in price_bids.
volume_bids = pd.DataFrame({
    'unit': ['A', 'B'],
    '1': [20.0, 50.0],  # MW
    '2': [20.0, 30.0],  # MW
    '3': [5.0, 10.0]  # More bid bands could be added.
})

# Price of each bid, bids must be monotonically increasing.
price_bids = pd.DataFrame({
    'unit': ['A', 'B'],
    '1': [50.0, 50.0],  # $/MW
    '2': [60.0, 55.0],  # $/MW
    '3': [100.0, 80.0]  # . . .
})

# Other unit properties
unit_info = pd.DataFrame({
    'unit': ['A', 'B'],
    'region': ['NSW', 'NSW'],  # MW
})

# The demand in the region\s being dispatched
demand = pd.DataFrame({
    'region': ['NSW'],
    'demand': [120.0]  # MW
})

# Create the market model
market = markets.SpotMarket(unit_info=unit_info, 
                            market_regions=['NSW'])
market.set_unit_volume_bids(volume_bids)
market.set_unit_price_bids(price_bids)
market.set_demand_constraints(demand)

# Calculate dispatch and pricing
market.dispatch()

# Return the total dispatch of each unit in MW.
print(market.get_unit_dispatch())
#   unit service  dispatch
# 0    A  energy      40.0
# 1    B  energy      80.0

# Return the price of energy in each region.
print(market.get_energy_prices())
#   region  price
# 0    NSW   60.0

A detailed example

The example demonstrates the broad range of market features that can be implemented with nempy and the use of auxiliary modelling tools for accessing historical market data published by AEMO and preprocessing it for compatibility with nempy.

Warning: this example downloads approximately 8.5 GB of data from AEMO.

# Notice: this script downloads large volumes of historical market data from AEMO's nemweb portal.

import sqlite3
import pandas as pd
from nempy import markets
from nempy.historical_inputs import loaders, mms_db, \
    xml_cache, units, demand, interconnectors, \
    constraints

con = sqlite3.connect('market_management_system.db')
mms_db_manager = mms_db.DBManager(connection=con)

xml_cache_manager = xml_cache.XMLCacheManager('cache_directory')

# The second time this example is run on a machine this flag can
# be set to false to save downloading the data again.
download_inputs = True

if download_inputs:
    # This requires approximately 5 GB of storage.
    mms_db_manager.populate(start_year=2019, start_month=1,
                            end_year=2019, end_month=1)

    # This requires approximately 3.5 GB of storage.
    xml_cache_manager.populate_by_day(start_year=2019, start_month=1, start_day=1,
                                      end_year=2019, end_month=1, end_day=1)

raw_inputs_loader = loaders.RawInputsLoader(
    nemde_xml_cache_manager=xml_cache_manager,
    market_management_system_database=mms_db_manager)

# A list of intervals we want to recreate historical dispatch for.
dispatch_intervals = ['2019/01/01 12:00:00',
                      '2019/01/01 12:05:00',
                      '2019/01/01 12:10:00',
                      '2019/01/01 12:15:00',
                      '2019/01/01 12:20:00',
                      '2019/01/01 12:25:00',
                      '2019/01/01 12:30:00']

# List for saving outputs to.
outputs = []

# Create and dispatch the spot market for each dispatch interval.
for interval in dispatch_intervals:
    raw_inputs_loader.set_interval(interval)
    unit_inputs = units.UnitData(raw_inputs_loader)
    interconnector_inputs = interconnectors.InterconnectorData(raw_inputs_loader)
    constraint_inputs = constraints.ConstraintData(raw_inputs_loader)
    demand_inputs = demand.DemandData(raw_inputs_loader)

    unit_info = unit_inputs.get_unit_info()
    market = markets.SpotMarket(market_regions=['QLD1', 'NSW1', 'VIC1',
                                                'SA1', 'TAS1'],
                                unit_info=unit_info)

    # Set bids
    volume_bids, price_bids = unit_inputs.get_processed_bids()
    market.set_unit_volume_bids(volume_bids)
    market.set_unit_price_bids(price_bids)

    # Set bid in capacity limits
    unit_bid_limit = unit_inputs.get_unit_bid_availability()
    market.set_unit_bid_capacity_constraints(unit_bid_limit)
    cost = constraint_inputs.get_constraint_violation_prices()['unit_capacity']
    market.make_constraints_elastic('unit_bid_capacity', violation_cost=cost)

    # Set limits provided by the unconstrained intermittent generation
    # forecasts. Primarily for wind and solar.
    unit_uigf_limit = unit_inputs.get_unit_uigf_limits()
    market.set_unconstrained_intermitent_generation_forecast_constraint(
        unit_uigf_limit)
    cost = constraint_inputs.get_constraint_violation_prices()['uigf']
    market.make_constraints_elastic('uigf_capacity', violation_cost=cost)

    # Set unit ramp rates.
    ramp_rates = unit_inputs.get_ramp_rates_used_for_energy_dispatch()
    market.set_unit_ramp_up_constraints(
        ramp_rates.loc[:, ['unit', 'initial_output', 'ramp_up_rate']])
    market.set_unit_ramp_down_constraints(
        ramp_rates.loc[:, ['unit', 'initial_output', 'ramp_down_rate']])
    cost = constraint_inputs.get_constraint_violation_prices()['ramp_rate']
    market.make_constraints_elastic('ramp_up', violation_cost=cost)
    market.make_constraints_elastic('ramp_down', violation_cost=cost)

    # Set unit FCAS trapezium constraints.
    unit_inputs.add_fcas_trapezium_constraints()
    cost = constraint_inputs.get_constraint_violation_prices()['fcas_max_avail']
    fcas_availability = unit_inputs.get_fcas_max_availability()
    market.set_fcas_max_availability(fcas_availability)
    market.make_constraints_elastic('fcas_max_availability', cost)
    cost = constraint_inputs.get_constraint_violation_prices()['fcas_profile']
    regulation_trapeziums = unit_inputs.get_fcas_regulation_trapeziums()
    market.set_energy_and_regulation_capacity_constraints(regulation_trapeziums)
    market.make_constraints_elastic('energy_and_regulation_capacity', cost)
    scada_ramp_down_rates = unit_inputs.get_scada_ramp_down_rates_of_lower_reg_units()
    market.set_joint_ramping_constraints_lower_reg(scada_ramp_down_rates)
    market.make_constraints_elastic('joint_ramping_lower_reg', cost)
    scada_ramp_up_rates = unit_inputs.get_scada_ramp_up_rates_of_raise_reg_units()
    market.set_joint_ramping_constraints_raise_reg(scada_ramp_up_rates)
    market.make_constraints_elastic('joint_ramping_raise_reg', cost)
    contingency_trapeziums = unit_inputs.get_contingency_services()
    market.set_joint_capacity_constraints(contingency_trapeziums)
    market.make_constraints_elastic('joint_capacity', cost)

    # Set interconnector definitions, limits and loss models.
    interconnectors_definitions = \
        interconnector_inputs.get_interconnector_definitions()
    loss_functions, interpolation_break_points = \
        interconnector_inputs.get_interconnector_loss_model()
    market.set_interconnectors(interconnectors_definitions)
    market.set_interconnector_losses(loss_functions,
                                     interpolation_break_points)

    # Add generic constraints and FCAS market constraints.
    fcas_requirements = constraint_inputs.get_fcas_requirements()
    market.set_fcas_requirements_constraints(fcas_requirements)
    violation_costs = constraint_inputs.get_violation_costs()
    market.make_constraints_elastic('fcas', violation_cost=violation_costs)
    generic_rhs = constraint_inputs.get_rhs_and_type_excluding_regional_fcas_constraints()
    market.set_generic_constraints(generic_rhs)
    market.make_constraints_elastic('generic', violation_cost=violation_costs)
    unit_generic_lhs = constraint_inputs.get_unit_lhs()
    market.link_units_to_generic_constraints(unit_generic_lhs)
    interconnector_generic_lhs = constraint_inputs.get_interconnector_lhs()
    market.link_interconnectors_to_generic_constraints(
        interconnector_generic_lhs)

    # Set the operational demand to be met by dispatch.
    regional_demand = demand_inputs.get_operational_demand()
    market.set_demand_constraints(regional_demand)
    
    # Get unit dispatch without fast start constraints and use it to
    # make fast start unit commitment decisions.
    market.dispatch()
    dispatch = market.get_unit_dispatch()
    fast_start_profiles = unit_inputs.get_fast_start_profiles_for_dispatch(dispatch)
    market.set_fast_start_constraints(fast_start_profiles)
    if 'fast_start' in market.get_constraint_set_names():
        cost = constraint_inputs.get_constraint_violation_prices()['fast_start']
        market.make_constraints_elastic('fast_start', violation_cost=cost)

    # If AEMO historical used the over constrained dispatch rerun
    # process then allow it to be used in dispatch. This is needed
    # because sometimes the conditions for over constrained dispatch
    # are present but the rerun process isn't used.
    if constraint_inputs.is_over_constrained_dispatch_rerun():
        market.dispatch(allow_over_constrained_dispatch_re_run=True,
                        energy_market_floor_price=-1000.0,
                        energy_market_ceiling_price=14500.0,
                        fcas_market_ceiling_price=1000.0)
    else:
        # The market price ceiling and floor are not needed here
        # because they are only used for the over constrained
        # dispatch rerun process.
        market.dispatch(allow_over_constrained_dispatch_re_run=False)

    # Save prices from this interval
    prices = market.get_energy_prices()
    prices['time'] = interval
    outputs.append(prices.loc[:, ['time', 'region', 'price']])

con.close()
print(pd.concat(outputs))
#                   time region      price
# 0  2019/01/01 12:00:00   NSW1  91.870167
# 1  2019/01/01 12:00:00   QLD1  76.190796
# 2  2019/01/01 12:00:00    SA1  86.899534
# 3  2019/01/01 12:00:00   TAS1  89.805037
# 4  2019/01/01 12:00:00   VIC1  84.984255
# 0  2019/01/01 12:05:00   NSW1  91.870496
# 1  2019/01/01 12:05:00   QLD1  64.991736
# 2  2019/01/01 12:05:00    SA1  87.462599
# 3  2019/01/01 12:05:00   TAS1  90.178036
# 4  2019/01/01 12:05:00   VIC1  85.556009
# 0  2019/01/01 12:10:00   NSW1  91.870496
# 1  2019/01/01 12:10:00   QLD1  64.991736
# 2  2019/01/01 12:10:00    SA1  86.868556
# 3  2019/01/01 12:10:00   TAS1  89.983716
# 4  2019/01/01 12:10:00   VIC1  84.936150
# 0  2019/01/01 12:15:00   NSW1  91.870496
# 1  2019/01/01 12:15:00   QLD1  64.776456
# 2  2019/01/01 12:15:00    SA1  86.844540
# 3  2019/01/01 12:15:00   TAS1  89.582288
# 4  2019/01/01 12:15:00   VIC1  84.990796
# 0  2019/01/01 12:20:00   NSW1  91.870496
# 1  2019/01/01 12:20:00   QLD1  64.776456
# 2  2019/01/01 12:20:00    SA1  87.496112
# 3  2019/01/01 12:20:00   TAS1  90.291144
# 4  2019/01/01 12:20:00   VIC1  85.594840
# 0  2019/01/01 12:25:00   NSW1  91.870167
# 1  2019/01/01 12:25:00   QLD1  64.991736
# 2  2019/01/01 12:25:00    SA1  87.519993
# 3  2019/01/01 12:25:00   TAS1  90.488064
# 4  2019/01/01 12:25:00   VIC1  85.630617
# 0  2019/01/01 12:30:00   NSW1  91.870496
# 1  2019/01/01 12:30:00   QLD1  64.991736
# 2  2019/01/01 12:30:00    SA1  87.462000
# 3  2019/01/01 12:30:00   TAS1  90.196284
# 4  2019/01/01 12:30:00   VIC1  85.573321