Power Flow algorithm #172

YaeSakura1 · 2021-09-15T07:15:39Z

YaeSakura1
Sep 15, 2021

Dr. Cui,
To solve the AC/DC power flow need sequential or unifified methods , how does ANDES do AC/DC power flow calculations?
Thanks!

Best regards

Answered by cuihantao

Sep 17, 2021

Hi,

ANDES uses the unified. AC and DC devices are solved simultaneously based on the power injection formulation.

View full answer

cuihantao · 2021-09-17T18:53:28Z

cuihantao
Sep 17, 2021
Maintainer

Hi,

ANDES uses the unified. AC and DC devices are solved simultaneously based on the power injection formulation.

1 reply

YaeSakura1 Sep 20, 2021
Author

Thank you Dr.Cui,
Thanks for your reply!

Best regards

YaeSakura1 · 2021-09-21T05:22:15Z

YaeSakura1
Sep 21, 2021
Author

Dr. Cui,
To solve the LCC-VSC AC/DC power flow, i modeled the LCC model.
I want to know is that right? please give me some advice.
Thanks!

Best regards

"""line commutated converter models"""

from andes.models.dcbase import ACDC2Term
from andes.core.param import NumParam
from andes.core.var import Algeb, State, ExtState, ExtAlgeb # NOQA
from andes.core.service import ConstService, ExtService # NOQA
from andes.core.discrete import HardLimiter, Switcher, AntiWindup # NOQA
from andes.core.block import PIController #NOQA

class LCC(ACDC2Term):
"""Data for LCC in power flow"""
def init(self, system, config):
ACDC2Term.init(self, system, config)
self.rsh = NumParam(default=0.0025, info="AC interface resistance", unit="ohm", z=True,
tex_name='r_{sh}')
self.xsh = NumParam(default=0.06, info="AC interface reactance", unit="ohm", z=True,
tex_name='x_{sh}')

    self.p0 = NumParam(default=0.0, info="AC active power setting", unit="pu")
    self.q0 = NumParam(default=0.0, info="AC reactive power setting", unit="pu")
    self.vdc0 = NumParam(default=1.0, info="DC voltage setting", unit="pu", tex_name='v_{dc0}')

    self.k0 = NumParam(default=0.0, info="Loss coefficient - constant")
    self.k1 = NumParam(default=0.0, info="Loss coefficient - linear")
    self.k2 = NumParam(default=0.0, info="Loss coefficient - quadratic")

    self.droop = NumParam(default=0.0, info="Enable dc voltage droop control", unit="boolean")
    self.K = NumParam(default=0.0, info="Droop coefficient")
    self.vhigh = NumParam(default=9999, info="Upper voltage threshold in droop control", unit="pu")
    self.vlow = NumParam(default=0.0, info="Lower voltage threshold in droop control", unit="pu")

    self.vshmax = NumParam(default=1.1, info="Maximum ac interface voltage", unit="pu")
    self.vshmin = NumParam(default=0.9, info="Minimum ac interface voltage", unit="pu")
    self.Ishmax = NumParam(default=2, info="Maximum ac current", unit="pu")

    self.KR = NumParam(default=1, info="Rectifier-side transformer tap ratio", unit="pu/pu")
    self.KI = NumParam(default=1, info="Inverter-side transformer tap ratio", unit="pu/pu")

    self.amax = NumParam(default=100, info="Maximum firing angle", unit="rad")
    self.amin = NumParam(default=5, info="Minimum firing angle", unit="rad")
    self.bmax = NumParam(default=60, info="Maximum extinction angle", unit="rad")
    self.bmin = NumParam(default=15, info="Minimum extinction angle", unit="rad")

    self.Xc = NumParam(default=0.03, info="Commutation reactance", unit="pu")
    self.kr = NumParam(default=0.995, info="consider the commutation effect")
    self.N = NumParam(default=6, info="the converter bridge number")
    self.d = NumParam(default=0.436, info="the converter power factor angle", unit="rad")

    self.ids = NumParam(default=2, info="the current set value", unit="pu")
    self.vds = NumParam(default=1, info="the voltage set value", unit="pu")
    self.pds = NumParam(default=2, info="the power set value", unit="pu")
    self.ads = NumParam(default=18, info="the firing angles set value", unit="rad")
    self.bds = NumParam(default=22, info="the extinct angles set value", unit="rad")
    self.kds = NumParam(default=1, info="the ratios set value", unit="pu")

    self.ar = NumParam(default=15, info="firing delay angle", unit="rad")
    self.bi = NumParam(default=15, info="extinction advance angle", unit="rad")

    self.idr = NumParam(default=1)
    self.idi = NumParam(default=1)
    self.R = NumParam(default=3.6)

    self.control = NumParam(info="Control method: 0-CC, 1-CV, 2-CP, 3-CIA, 4-CEA, or 5-CR", mandatory=True)

    # define variables and equations
    self.flags.update({'pflow': True})
    self.flags.update({'tds': True})
    self.group = 'StaticLCC'

    self.mode = Switcher(u=self.control, options=(0, 1, 2, 3, 4, 5))

整流器方程

    self.vd0r = Algeb(info='ideal no-load direct voltage',
                      unit='p.u.',
                      tex_name='V_{d0r}',
                      v_str='vd0r',
                      e_str='3 * 2**0.5/3.14 * KR * N * v - vd0r',
                      diag_eps=True,
                      )
    self.vdr = Algeb(info='rectifier dc voltage',
                     unit='p.u.',
                     tex_name='V_{dr}',
                     v_str='vdr',
                     e_str='3 * 2**0.5/3.14 * KR * N * v * cos(ar)- 3/3.14 * N * Xc * idr - vdr',
                     diag_eps=True,
                     )
    self.pr = Algeb(info='rectifier active power',
                    unit='p.u.',
                    tex_name='P_{r}',
                    v_str='pr',
                    e_str='vdr * idr - pr',
                    diag_eps=True,
                    )
    self.qr = Algeb(info='rectifier reactive power',
                    unit='p.u.',
                    tex_name='Q_{r}',
                    v_str='qr',
                    e_str='(vdr * idr) * tan(dr) - qr',
                    diag_eps=True,
                    )
    self.dr = Algeb(info='the phase angle between the ac voltage and fundamental current',
                    unit='p.u.',
                    tex_name=r'\phi_{r}',
                    v_str='dr',
                    e_str='acos(vdr/vd0r) - dr',
                    diag_eps=True,
                    )

逆变器方程

    self.vd0i = Algeb(info='ideal no-load direct voltage',
                      unit='p.u.',
                      tex_name='V_{d0i}',
                      v_str='vd0i',
                      e_str='3 * 2**0.5/3.14 * KR * N * v - vd0i',
                      diag_eps=True,
                      )
    self.vdi = Algeb(info='inverter dc voltage',
                     unit='p.u.',
                     tex_name='V_{di}',
                     v_str='vdi',
                     e_str='3 * 2**0.5/3.14 * KR * N * v * cos(bi)- 3/3.14 * N * Xc * idi - vdi',
                     diag_eps=True,
                     )
    self.pi = Algeb(info='inverter active power',
                    unit='p.u.',
                    tex_name='P_{i}',
                    v_str='pi',
                    e_str='vdi * idi - pi',
                    diag_eps=True,
                    )
    self.qi = Algeb(info='inverter reactive power',
                    unit='p.u.',
                    tex_name='Q_{i}',
                    v_str='qi',
                    e_str='(vdi * idi) * tan(di) - qi',
                    diag_eps=True,
                    )
    self.di = Algeb(info='the phase angle between the ac voltage and fundamental current',
                    unit='p.u.',
                    tex_name=r'\phi_{i}',
                    v_str='di',
                    e_str='acos(vdi/vd0i) - di',
                    diag_eps=True,
                    )

线路方程

    self.id = Algeb(info='dc current',
                    unit='p.u.',
                    tex_name='I_{d}',
                    v_str='id',
                    e_str='vdr - vdi - R * id',
                    diag_eps=True,
                    )

控制方程:

    self.CC = Algeb(info='constant current control',
                    unit='p.u.',
                    v_str='CC',
                    e_str='id - ids',
                    diag_eps=True,
                    )
    self.CV = Algeb(info='constant voltage control',
                    unit='p.u.',
                    v_str='CV',
                    e_str='id - vds',
                    diag_eps=True,
                    )
    self.CP = Algeb(info='constant power control',
                    unit='p.u.',
                    v_str='CP',
                    e_str='id * id - pds',
                    diag_eps=True,
                    )
    self.CIA = Algeb(info='constant firing angle control',
                     unit='raf',
                     v_str='CIA',
                     e_str='cos(ar) - cos(ads)',
                     diag_eps=True,
                     )
    self.CEA = Algeb(info='constant extinction angle control',
                     unit='rad',
                     v_str='CEA',
                     e_str='cos(bi) - cos(bds)',
                     diag_eps=True,
                     )
    self.CR = Algeb(info='constant ratios control',
                    unit='p.u.',
                    v_str='CR',
                    e_str='KR - kds',
                    diag_eps=True,
                    )

0 replies

YaeSakura1 · 2021-09-21T05:24:15Z

YaeSakura1
Sep 21, 2021
Author

After i run a case, i get the following error:

C:\Users\Administrator.andes\pycode\LCC.py:13: RuntimeWarning: invalid value encountered in true_divide
return ((1.35115945449659KRNv, 1.35115945449659KRNvcos(ar) - 0.955414012738854NXcidr, idrvdr, idrvdrtan(dr), -dr + arccos(vdr/vd0r), 1.35115945449659KRNv, 1.35115945449659KRNvcos(bi) - 0.955414012738854NXcidi, idivdi, idivditan(di), arccos(vdi/vd0i), -Rid - vdi + vdr, id - ids, id - vds, id**2 - pds, -cos(ads) + cos(ar), -cos(bds) + cos(bi), KR - kds, 0, 0, 0, 0))
C:\Users\Administrator.andes\pycode\LCC.py:16: RuntimeWarning: invalid value encountered in true_divide
return ((1.35115945449659KRN, 1.35115945449659KRNcos(ar), idr, idrtan(dr), idrvdr*(tan(dr)2 + 1), vdr/(vd0r2sqrt(1 - vdr2/vd0r2)), -1/(vd0rsqrt(1 - vdr2/vd0r2)), -1, 1.35115945449659KRN, 1.35115945449659KRNcos(bi), idi, iditan(di), idivdi(tan(di)2 + 1), vdi/(vd0i2sqrt(1 - vdi2/vd0i2)), -1/(vd0isqrt(1 - vdi2/vd0i2)), 1, -1, -R, 1, 1, 2*id))
-> Single process finished in 1.0984 seconds.

0 replies

cuihantao · 2021-09-22T02:02:45Z

cuihantao
Sep 22, 2021
Maintainer

You might have errors in the equations. One issue with your implementation is that you will need to separate the power flow model from the time-domain model. That is, use the power flow results to initialize the dynamic model. Not sure if it is implemented this way as I only see one class.

The error you are seeing is probably a division by zero. You can use a debugger to place breakpoints before entering the specific line in LCC.py and inspect the values.

0 replies

YaeSakura1 · 2021-09-27T02:12:22Z

YaeSakura1
Sep 27, 2021
Author

Dr. Cui,

self.ash = Algeb(info='voltage phase behind the transformer',
unit='rad',
tex_name=r'\theta_{sh}',
v_str='a',
e_str='u * (gsh * v2 - gsh * v * vsh * cos(a - ash) - '
'bsh * v * vsh * sin(a - ash)) - psh',
diag_eps=True,
)
What does v_str='a' and e_str= 'u * (gsh * v2 - gsh * v * vsh * cos(a - ash) - '
'bsh * v * vsh * sin(a - ash)) - psh' mean?
Is the v_str means the value string?
Is the e_str means : −𝑃𝑠ℎ+𝑢(𝑉𝑠ℎ𝑏𝑠ℎ𝑣sin(𝜃𝑠ℎ−𝑎)−𝑉𝑠ℎ𝑔𝑠ℎ𝑣cos(𝜃𝑠ℎ−𝑎)+𝑔𝑠ℎ𝑣2) = 0 ?

Thanks!
Best regards

0 replies

jinningwang · 2021-09-27T04:13:30Z

jinningwang
Sep 27, 2021
Maintainer

Hi YaeSakura1,

This is Jinning.

You can use Markdown code format ("```") to display code block better.
v_str is the variable initialized values, and e_str is the variable equations on the RHS.
For example, if

self.A = Algeb(v_str='A0',
               e_str='B - A')

It will result in:
B - A = 0
where A = A0 at initial.

1 reply

YaeSakura1 Sep 27, 2021
Author

Thank you Jinning,
Thanks for your reply!

Best regards

YaeSakura1 · 2021-09-27T06:46:24Z

YaeSakura1
Sep 27, 2021
Author

self.psh = Algeb(info='active power injection into VSC', tex_name="P_{sh}", unit='p.u.', v_str='p0 * (mode_s0 + mode_s1)', e_str='u * (mode_s0 + mode_s1) * (p0 - psh) + ' 'u * (mode_s2 + mode_s3) * (v1 - v2 - vdc0)', diag_eps=True, )
self.qsh = Algeb(info='reactive power injection into VSC', tex_name="Q_{sh}", v_str='q0 * (mode_s0 + mode_s2)', e_str='u * (mode_s0 + mode_s2) * (q0 - qsh) + ' 'u * (mode_s1 + mode_s3) * (v0 - v)', diag_eps=True, )

what does psh e_str and qsh e_str mean?

I print the mode_s0, mode_s1, mode_s2, mode_s3, and get
[1. 0.], [0. 0.], [0. 1.], [0. 0.]
how it work in the equation? and how to represent different controls?

0 replies

cuihantao · 2021-09-27T19:02:54Z

cuihantao
Sep 27, 2021
Maintainer

The mode indicators are used in the equation to construct piece-wise equations.

0 replies

YaeSakura1 · 2021-09-29T02:44:31Z

YaeSakura1
Sep 29, 2021
Author

I notice that you consider the loss coefficient in
self.k0 = NumParam(default=0.0, info="Loss coefficient - constant") self.k1 = NumParam(default=0.0, info="Loss coefficient - linear") self.k2 = NumParam(default=0.0, info="Loss coefficient - quadratic")

but seems that it doesn't show up in the equation, how does it work?

2 replies

cuihantao Sep 29, 2021
Maintainer

Looks like it has not been implemented yet..

YaeSakura1 Sep 29, 2021
Author

so this VSC model is considered lossless?

self.rsh = NumParam(default=0.0025, info="AC interface resistance", unit="ohm", z=True,tex_name='r_{sh}') self.xsh = NumParam(default=0.06, info="AC interface reactance", unit="ohm", z=True,tex_name='x_{sh}')
Is the rsh+jsh the internal VSC losses ? In Federico Milano’s book （Power System Modelling and Scripting）

cuihantao · 2021-09-29T04:40:10Z

cuihantao
Sep 29, 2021
Maintainer

It is lossless for now. Rsh and Xsh are the AC coupling impedance.

…

On Sep 28, 2021, 11:38 PM -0500, YaeSakura1 ***@***.***>, wrote: so this VSC model is considered lossless? self.rsh = NumParam(default=0.0025, info="AC interface resistance", unit="ohm", z=True,tex_name='r_{sh}') self.xsh = NumParam(default=0.06, info="AC interface reactance", unit="ohm", z=True,tex_name='x_{sh}') Is the rsh+jsh the internal VSC losses ? In Federico Milano’s book （Power System Modelling and Scripting） — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

0 replies

YaeSakura1 · 2021-10-08T02:47:28Z

YaeSakura1
Oct 8, 2021
Author

In VSC , the dc voltage droop control is also not implemented.

self.psh = Algeb(info='active power injection into VSC', tex_name="P_{sh}", unit='p.u.', v_str='p0 * (mode_s0 + mode_s1)', e_str='u * (mode_s0 + mode_s1) * (p0 - psh) + ' 'u * (mode_s2 + mode_s3) * (v1 - v2 - vdc0)', diag_eps=True, ) self.qsh = Algeb(info='reactive power injection into VSC', tex_name="Q_{sh}", v_str='q0 * (mode_s0 + mode_s2)', e_str='u * (mode_s0 + mode_s2) * (q0 - qsh) + ' 'u * (mode_s1 + mode_s3) * (v0 - v)', diag_eps=True, )

Is the psh v_str =p0, qsh v_str=q0 ?
I want to know when VSC_1 under vQ control mode and VSC_2 under PQ control mode the 'psh' and 'qsh' e_str is.

0 replies

cuihantao · 2021-10-08T17:05:12Z

cuihantao
Oct 8, 2021
Maintainer

psh and qsh can be controlled at p0 and q0 but depends on the mode.

Did you write the code above? It is different from what ANDES has in vsc.py.

        self.qsh = Algeb(info='reactive power injection into VSC',
                         tex_name="Q_{sh}",
                         v_str='q0 * (mode_s0 + mode_s2)',
                         e_str='u * (mode_s0 + mode_s2) * (q0 - qsh) + '
                               'u * (mode_s1 + mode_s3) * (v0 - v)',
                         diag_eps=True,
                         )

Take this as an example, since Control method: 0-PQ, 1-PV, 2-vQ or 3-vV, mode_s2 correspond to vQ control. Therefore, the equation corresponding to the qsh variable is that q0 - qsh = 0, namely, controlling the reactive power injection to the setpoint q0

Please take a look the piecewise equation and consider the mode as 0/1 variables to enable only one part of the equation.

1 reply

YaeSakura1 Oct 9, 2021
Author

so the psh under vQ control mode , equation is v1-v2-vdc0 ,is that right?

cuihantao · 2021-10-09T03:18:22Z

cuihantao
Oct 9, 2021
Maintainer

Yes. That is correct.

…

On Oct 8, 2021, 10:05 PM -0500, YaeSakura1 ***@***.***>, wrote: so the psh under vQ control mode , equation is v1-v2-vdc0 ,is that right? — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

0 replies

YaeSakura1 · 2021-10-20T02:52:11Z

YaeSakura1
Oct 20, 2021
Author

How do I look the Jacobian matrix after pflow?

0 replies

cuihantao · 2021-10-20T03:16:38Z

cuihantao
Oct 20, 2021
Maintainer

Hi @YaeSakura1 .

Sorry but I will not be able to answer your questions if they have already been answered in the manual.

See https://docs.andes.app/en/stable/modeling.html#dae-storage for the Jacobian storage.

0 replies

YaeSakura1 · 2021-11-02T14:30:18Z

YaeSakura1
Nov 2, 2021
Author

Hi,Dr. Cui,
Is it possible to implement electromechanical transient simulation of LCC-MMC HVDC in andes?

3 replies

cuihantao Nov 2, 2021
Maintainer

It is feasible. Please read the "Modeling Cookbook" and the source code of other implemented models.

YaeSakura1 Nov 8, 2021
Author

Thanks!
Which part in the Modeling Cookbook should I read, and which model to look at ?

cuihantao Nov 8, 2021
Maintainer

You might need to read and comprehend most of the Modeling Cookbook. I would also recommend checking out Power System Analysis Toolbox because it already has models for LCC HVDC.

YaeSakura1 · 2021-11-15T11:00:35Z

YaeSakura1
Nov 15, 2021
Author

Why does VSCShunt not have self.flags.update({'tds':True}) but can do time domain simulation？

2 replies

cuihantao Nov 15, 2021
Maintainer

Power flow models participate in time-domain simulation by default. That's why we shared the same Line model for power flow and time-domain.

Static power flow models that have been replaced by dynamic models need to be turned off manually. See the v_numeric(self, **kwargs) function in genbase.py and fload.py. By the way, I converted several model source files into packages. You can browse these files in my master branch if you haven't updated.

YaeSakura1 Nov 15, 2021
Author

Thank you very much!
How do I update your master branch to my branch?

cuihantao · 2021-11-15T17:12:35Z

cuihantao
Nov 15, 2021
Maintainer

There are multiple ways to do it. You can create a pull request to merge my master into your fork. See this link and related ones https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests Regards, Hantao Cui

…

On Nov 15, 2021, 11:10 AM -0600, YaeSakura1 ***@***.***>, wrote: Thank you very much! How do I update your master branch to my branch? — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

1 reply

YaeSakura1 Nov 15, 2021
Author

thank you!
also, how do I update my local files

cuihantao · 2021-11-15T17:49:39Z

cuihantao
Nov 15, 2021
Maintainer

You can do a `git pull` after merging the PR, assume you are on the same branch. You might want to take a tutorial of Git and GitHub as these are general questions. Regards, Hantao Cui

…

On Nov 15, 2021, 11:43 AM -0600, YaeSakura1 ***@***.***>, wrote: thank you! also, how do I update my local files — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or unsubscribe.

2 replies

YaeSakura1 Nov 15, 2021
Author

I have created a PR

YaeSakura1 Nov 15, 2021
Author

it said can’t automatically merge, is that mean i need to use the command line to merge ?

YaeSakura1 · 2021-11-16T08:46:35Z

YaeSakura1
Nov 16, 2021
Author

why i run the andes prepare command in pycharm , the following error has occurred:

andes version：1.5.5.post16.dev0+ge946af25
python version：3.9
OS：windows 10
Error Message:

Traceback (most recent call last):
File "", line 1, in
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 116, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 125, in _main
prepare(preparation_data)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 236, in prepare
_fixup_main_from_path(data['init_main_from_path'])
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 287, in _fixup_main_from_path
main_content = runpy.run_path(main_path,
File "C:\Users\Administrator\anaconda3\envs\andes\lib\runpy.py", line 268, in run_path
return _run_module_code(code, init_globals, run_name,
File "C:\Users\Administrator\anaconda3\envs\andes\lib\runpy.py", line 97, in _run_module_code
_run_code(code, mod_globals, init_globals,
File "C:\Users\Administrator\anaconda3\envs\andes\lib\runpy.py", line 87, in _run_code
exec(code, run_globals)
File "C:\Users\Administrator\ANDES\andes\test.py", line 2, in
andes.prepare()
File "C:\Users\Administrator\ANDES\andes\andes\main.py", line 740, in prepare
system.prepare(quick=quick, incremental=incremental, models=models,
File "C:\Users\Administrator\ANDES\andes\andes\system.py", line 345, in prepare
self._mp_prepare(models, quick, pycode_path, ncpu=ncpu)
File "C:\Users\Administrator\ANDES\andes\andes\system.py", line 392, in _mp_prepare
Pool(ncpu).map(_prep_model, model_list)
File "C:\Users\Administrator\ANDES\andes\andes\utils\lazyimport.py", line 80, in call
return eval(self.imported_name)(*args, **kwargs)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\pool.py", line 212, in init
self._repopulate_pool()
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\pool.py", line 303, in _repopulate_pool
return self._repopulate_pool_static(self._ctx, self.Process,
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\pool.py", line 326, in _repopulate_pool_static
w.start()
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\process.py", line 121, in start
self._popen = self._Popen(self)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\context.py", line 327, in _Popen
return Popen(process_obj)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\popen_spawn_win32.py", line 45, in init
prep_data = spawn.get_preparation_data(process_obj._name)
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 154, in get_preparation_data
_check_not_importing_main()
File "C:\Users\Administrator\anaconda3\envs\andes\lib\site-packages\multiprocess\spawn.py", line 134, in _check_not_importing_main
raise RuntimeError('''
RuntimeError:
    An attempt has been made to start a new process before the
    current process has finished its bootstrapping phase.

    This probably means that you are not using fork to start your
    child processes and you have forgotten to use the proper idiom
    in the main module:

        if __name__ == '__main__':
            freeze_support()
            ...

    The "freeze_support()" line can be omitted if the program
    is not going to be frozen to produce an executable.

please help！

2 replies

cuihantao Nov 16, 2021
Maintainer

Sorry but I have no idea.

YaeSakura1 Nov 16, 2021
Author

But I didn't seem to get this error when I run andes prepare from the command line

YaeSakura1 · 2021-11-17T03:03:13Z

YaeSakura1
Nov 17, 2021
Author

What does the last few lines of vscshunt.py mean？
self.a.e_str = '-psh'
self.v.e_str = '-qsh'
self.v1.e_str = '-pdc / (v1 - v2)'
self.v2.e_str = 'pdc / (v1 - v2)'

2 replies

cuihantao Nov 18, 2021
Maintainer

Please search for e_str in the modeling cookbook.

YaeSakura1 Nov 18, 2021
Author

Yes, i konw the e_str is the the string representation of the equation , i want to konw what is it different with the a ,V, V1, v2 in acdcbase.py?

YaeSakura1 · 2021-12-28T13:44:34Z

YaeSakura1
Dec 28, 2021
Author

Will master slave control and dc voltage droop control be added in the future？

1 reply

cuihantao Dec 29, 2021
Maintainer

It will eventually be added, but I don't have a timeline.

Power Flow algorithm #172

YaeSakura1 Sep 15, 2021

Replies: 23 comments · 18 replies

cuihantao Sep 17, 2021 Maintainer

YaeSakura1 Sep 20, 2021 Author

YaeSakura1 Sep 21, 2021 Author

整流器方程

逆变器方程

线路方程

控制方程:

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Sep 15, 2021

Replies: 23 comments 18 replies

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