Python 如何更改GEKKO变量在解算为稳定状态后的MV状态

我正在试图找出使重力排水水箱保持在所需液位的入口流量的值.在使用Imode3找到解决方案后，我想使用Imode4在一段时间内模拟处于这种状态的系统.以下是我正在使用的代码:

from gekko import GEKKO
import numpy as np
m = GEKKO(remote = False)

F_in = m.MV(value = 1, name= 'F_in')
level = m.CV(value = 1, name = 'level')
F_out = m.Var(value = 1, name = 'F_out')

level.STATUS = 1
level.SPHI = 6
level.SPLO = 4

m.Equation(level.dt() == (F_in - F_out)/5)
m.Equation(F_out == 2*(level)**0.5)

# Find the steady state.

F_in.STATUS = 1

m.options.IMODE = 3
m.options.SOLVER = 3
m.solve(disp = False)
print(F_in.value)

# Run at steady state for 5 time units.

F_in.STATUS = 0 # Turn STATUS off for 0 DOF.
m.time = np.linspace(0,5,10)
m.options.IMODE = 4
m.solve(disp = False)
print(level.value)

但是，代码会产生错误，指出Imode4需要0个自由度.将F_in状态更改为0是否不会导致0 DOF？以下是完整的错误消息:

---------------------------------------------------------------------------
Exception                                 Traceback (most recent call last)
Cell In[4], line 27
     25 m.time = np.linspace(0,5,10)
     26 m.options.IMODE = 4
---> 27 m.solve(disp = False)
     28 print(level.value)

File ~\VRMEng\VRMEng\Lib\site-packages\gekko\gekko.py:2140, in GEKKO.solve(self, disp, debug, GUI, **kwargs)
   2138         print("Error:", errs)
   2139     if (debug >= 1) and record_error:
-> 2140         raise Exception(apm_error)
   2142 else: #solve on APM server
   2143     def send_if_exists(extension):

Exception: @error: Degrees of Freedom
 * Error: DOF must be zero for this mode
 STOPPING...

任何帮助我们都将不胜感激！