This post introduces energy-py-linear - a Python library for optimizing energy assets using mixed integer linear programming (MILP).
Posts in this series:
MILP guarantees convergence to the global optimum of a cost function for linear systems. In energy battery storage and combined heat and power can be modelled and optimized using linear programming.
Optimizing battery dispatch into a wholesale market
energy-py-linear can be used to optimize a battery that uses price arbitrage in a wholesale market:
import energypylinear as epl model = epl.Battery(power=2, capacity=4) prices = [10, 50, 10, 50, 10] info = model.optimize(prices, timestep='30min') import pandas as pd pd.DataFrame().from_dict(info) Import [MW] Export [MW] Power [MW] Charge [MWh] 0 2.0 0.0 2.0 0.000000 1 0.0 2.0 -2.0 0.066667 2 2.0 0.0 2.0 0.000000 3 0.0 2.0 -2.0 0.066667 4 NaN NaN NaN 0.000000
The battery charges during the low price periods and discharges during the high price periods. The battery is fully discharged during the last period (a sign of optimal behaviour).
NaN row is given because the
Charge is the battery level at the start of each interval. This last row tells us what the
Charge level is for the battery after the optimization is finished.
The dispatch above is for perfectly forecast prices - the library can also be used to measure forecast quality by passing in a forecast along with true prices:
# a forecast that is the inverse of the prices we used above forecasts = [50, 10, 50, 10, 50] info = model.optimize(prices, forecasts=forecasts, timestep='30min')
Optimizing combined heat and power
energy-py-linear can be used to optimize CHP systems. First a list of the assets in the plant is made, then this plant configuration is optimized for given prices:
from energypylinear import chp assets = [ chp.GasTurbine(size=10, name='gt1'), chp.Boiler(size=100, name='blr1'), chp.Boiler(size=100, name='blr2', efficiency=0.9), chp.SteamTurbine(size=6, name='st1') ] info = chp.optimize( assets, gas_price=20, electricity_price=1000, site_steam_demand=100, site_power_demand=100, ) info total steam generated 130.0 t/h total steam consumed 30.0 t/h steam to site 100.0 t/h total power generated 16.0 MWe total power consumed 0.2 MWe net grid 84.2 MWe power to site 100.0 MWe
Thanks for reading!