OPF - unexpected results with 2 generators on the same bus

[MS132000]

Hi, I have read the documentation but I found this case where the OPF seems not to be working. I built a network with 2 generators, one being much cheaper than the other, connected to the same bus . I expected that the expensive generator does not generate anything but nevertheless, with the OPF I get that they generate exactly the same (I attached a summary with all the results evaluated at 05:00 a.m.). I appreciate any help to understand why I got these results.

OPF Example - two generators with different cost_RESULTS.pdf

Originally posted by @MS132000 in https://github.com/e2nIEE/pandapower/issues/1361#issuecomment-1461003083

[LukasKur]

Maybe it´s due to the negative prices (- 200 €/MW)? Did you try it out with e.g. 1 €/MW for the cheaper gen?

[MS132000]

@LukasKur thanks for the answer, I tried to simulate with all the prices positive but I still get the same results

[rbolgaryn]

Hi @MS132000 ,

what are the max/min constraints?

Can you please post the complete code snippet from your example?

[MS132000]

Hi @rbolgaryn , thanks for the reply.

the constraints are as follows:

• for busses| min_vm_pu=0.95, max_vm_pu=1.05
• for lines| max_loading_percent=100
• for trafo| max_loading_percent=100
• for external grid| min_p_mw=-200, max_p_mw=200,max_q_mvar=200, min_q_mvar=-200
• for gen1 and gen2| min_p_mw=0, max_p_mw=200, min_q_mvar=-200, max_q_mvar=200

I send attached a zip file with the Jupiter simplified code and an Excel file with the load profile(which is not controllable)

example_file.zip Load_Profile.xlsx

[jwiemer112]

The OPF only starts to optimize if any constraints are violated. Maybe that's the reason why the OPF doesn't change anything.

Greez Jan

[rbolgaryn]

Sorry I won't be looking at the Excel file. Is the resulting power 200 MW?

[MS132000]

The OPF only starts to optimize if any constraints are violated. Maybe that's the reason why the OPF doesn't change anything.

Greez Jan

but isn't it supposed that the pandapower OPF optimize regardless of the initial conditions of the generators?

On the other hand, I tried to make the constraints more flexible and the OPF gives me other results, but always generating the same thing with both generators (being the generation costs very different)

Also, I tried to start, as an initial condition of the OPF, with the results of the executed OPF, but both generators continue to provide the same power

[MS132000]

Sorry I won't be looking at the Excel file. Is the resulting power 200 MW?

no, both generators start with p=0MW. Just set pmax=200MW so that the limiting constraint would not be on the generators

[rbolgaryn]

please add a minimal example in the comment

[MS132000]

please add a minimal example in the comment

import pandapower as pp import numpy as np import os import pandas as pd import tempfile from pandapower.timeseries import DFData from pandapower.timeseries import OutputWriter from pandapower.timeseries.run_time_series import run_timeseries from pandapower.control import ConstControl import matplotlib.pyplot as plt import openpyxl.utils.cell import openpyxl from openpyxl.styles.alignment import Alignment %matplotlib inline

def simple_test_net(): net = pp.create_empty_network()

# LINES
b150 = pp.create_bus(net, 150, min_vm_pu=0.95, max_vm_pu=1.05, index=0)
b0 = pp.create_bus(net, 150, min_vm_pu=0.95, max_vm_pu=1.05, index=1)
b1 = pp.create_bus(net, 31.5, min_vm_pu=0.95, max_vm_pu=1.05, index=2)
b2 = pp.create_bus(net, 31.5, min_vm_pu=0.95, max_vm_pu=1.05, index=3)
b3 = pp.create_bus(net, 31.5, min_vm_pu=0.95, max_vm_pu=1.05, index=4) 

# TRAFO
trafo=pp.create_transformer_from_parameters(net, hv_bus=b0,
lv_bus=b1, sn_mva=63, vn_hv_kv=150, vn_lv_kv=31.5, vkr_percent=0, 

vk_percent=11.63, pfe_kw=26.108, i0_percent=0, shift_degree=0, tap_side="hv", tap_neutral=9, tap_max=17, tap_min=1, tap_step_percent=1.5, tap_step_degree=0, tap_pos=9, tap_phase_shifter=False, in_service=True, name="Trafo_TRA", vector_group=None, index=1, max_loading_percent=100, parallel=1, df=1.0, pt_percent=None, oltc=None, tap_dependent_impedance=None, vk_percent_characteristic=None, vkr_percent_characteristic=None, xn_ohm=None)

pp.create_line(net, b150, b0, 100, "149-AL1/24-ST1A 110.0", max_loading_percent=100,parallel=1)
pp.create_line(net, b1, b2, 10, "149-AL1/24-ST1A 110.0", max_loading_percent=100,parallel=1)
pp.create_line(net, b2, b3, 10, "149-AL1/24-ST1A 110.0", max_loading_percent=100,parallel=1)

# LOAD
pp.create_load(net, b2, p_mw=10., q_mvar=-5., name='load1', controllable=False)

# EXTERNAL GRID
e=pp.create_ext_grid(net, b150, min_p_mw=-200, max_p_mw=200,max_q_mvar=200, min_q_mvar=-200,controllable=True)
costeg = pp.create_poly_cost(net, e, 'ext_grid', cp1_eur_per_mw=500)#,cq1_eur_per_mvar=200)

# GENERATOR G1
g1=pp.create_sgen(net, b3, p_mw=0, q_mvar=0, min_p_mw=0, max_p_mw=200, min_q_mvar=-200, max_q_mvar=200, name='sgen1', controllable=True,index=0)
costo_g1=pp.create_poly_cost(net, g1, 'sgen1', cp1_eur_per_mw=200)#,cq1_eur_per_mvar=200)

# GENERATOR G2
g2=pp.create_sgen(net, b3, p_mw=0, q_mvar=0, min_p_mw=0, max_p_mw=200, min_q_mvar=-200, max_q_mvar=200, name='sgen2', controllable=True,index=1)
costo_g2=pp.create_poly_cost(net, g2, 'sgen2', cp1_eur_per_mw=1)#-200)#,cq1_eur_per_mvar=1)

return net

def create_output_writer(net, time_steps, output_dir): ow = OutputWriter(net, time_steps, output_path=output_dir, output_file_type=".xlsx", log_variables=list()) ow.log_variable('res_sgen', 'p_mw') ow.log_variable('res_sgen', 'q_mvar') ow.log_variable('res_bus', 'vm_pu') ow.log_variable('res_line', 'loading_percent') ow.log_variable('res_line', 'i_ka')

ow.log_variable('res_line', 'p_from_mw') 
ow.log_variable('res_line', 'q_from_mvar') 
ow.log_variable('res_line', 'p_to_mw') 
ow.log_variable('res_line', 'q_to_mvar') 

ow.log_variable('res_load', 'p_mw')
ow.log_variable('res_load', 'q_mvar')
ow.log_variable("res_ext_grid", "p_mw")
ow.log_variable("res_ext_grid", "q_mvar")
ow.log_variable("res_trafo", "pl_mw") 
ow.log_variable("res_trafo", "ql_mvar") 
ow.log_variable('res_trafo', 'loading_percent')
ow.log_variable("res_trafo", "p_lv_mw") 
ow.log_variable("res_trafo", "q_lv_mvar") 

return ow

output_dir = os.path.abspath('C:/Results')

print("Results can be found in the folder folder: {}".format(output_dir)) if not os.path.exists(output_dir): os.mkdir(output_dir)

net = simple_test_net()

n_timesteps = 24

profile_p_load = pd.DataFrame() profile_q_load = pd.DataFrame()

Load_Profile = os.path.abspath('C:/Load_Profile.xlsx'')

DF_load_p_mw = pd.read_excel(Load_Profile, index_col=0) DF_load_q_mvar = pd.read_excel(Load_Profile, index_col=1)

profile_p_load['load1_p'] = DF_load_p_mw[0].tolist()
profile_q_load['load1_q'] = DF_load_q_mvar[1].tolist()

ds_p_load = DFData(profile_p_load) ds_q_load = DFData(profile_q_load)

ConstControl(net, element='load', variable='p_mw', element_index=[0], data_source=ds_p_load, profile_name=["load1_p"]) ConstControl(net, element='load', variable='q_mvar', element_index=[0], data_source=ds_q_load, profile_name=["load1_q"])

time_steps = range(0, n_timesteps)

ow = create_output_writer(net, time_steps, output_dir=output_dir)

run_timeseries(net, time_steps, run=pp.runopp, delta=1e-16)

[MS132000]

Thank you very much @SteffenMeinecke !! (The question was answered in issue #1361 )