在 Pyomo 约束中定义循环/周期性边界条件答案

【问题标题】：Defining cyclic/periodic boundary conditions in Pyomo constraints在 Pyomo 约束中定义循环/周期性边界条件
【发布时间】：2020-04-11 09:42:56
【问题描述】：

我正在尝试在利用循环条件的 Pyomo 模型上定义一个约束。以下是我认为它应该如何工作（来自 GAMS 的循环语法）。

from __future__ import division
from pyomo.environ import *

model = ConcreteModel()

## define sets
model.t                 = Set(initialize = [i for i in range(8760)]) 

## define variables
model.ESS_SOC           = Var(model.t, domain = NonNegativeReals) # battery state of charge
model.ESS_c             = Var(model.t, domain = NonNegativeReals) # battery charging
model.ESS_d             = Var(model.t, domain = NonNegativeReals) # battery discharging

## skip obj for this example

## define constraints
#SOC constraint
model.SOC_const = ConstraintList()
for i in model.t: 
    model.SOC_const.add( model.ESS_SOC[i] == model.ESS_SOC[i--1] + model.ESS_c[i] - model.ESS_d[i] )

但是当我运行上面的示例时，我收到以下错误消息：

KeyError: "Index '8760' is not valid for indexed component 'ESS_SOC'"

我同意给定model.t 的定义的错误，但该错误让我相信它几乎正在做我想要它做的事情，那就是：

model.ESS_SOC[0] == model.ESS_SOC[8759] + model.ESS_c[0] - model.ESS_d[0]
model.ESS_SOC[1] == model.ESS_SOC[0] + model.ESS_c[1] - model.ESS_d[1]
...
model.ESS_SOC[8759] == model.ESS_SOC[8758] + model.ESS_c[8759] - model.ESS_d[8759]

有没有办法定义约束，这就是我得到的？

【问题讨论】：

标签： python optimization constraints pyomo cyclic

【解决方案1】：

我建议使用索引约束而不是ConstraintList：

from __future__ import division
from pyomo.environ import *

model = ConcreteModel()

## define sets
model.t                 = Set(initialize = [i for i in range(8760)], ordered=True) 

## define variables
model.ESS_SOC           = Var(model.t, domain = NonNegativeReals) # battery state of charge
model.ESS_c             = Var(model.t, domain = NonNegativeReals) # battery charging
model.ESS_d             = Var(model.t, domain = NonNegativeReals) # battery discharging

## skip obj for this example

## define constraints
#SOC constraint
def _SOC_const(m, i):
    if i == m.t.first():
        return model.ESS_SOC[i] == model.ESS_SOC[m.t.last()] + model.ESS_c[i] - model.ESS_d[i]
    return model.ESS_SOC[i] == model.ESS_SOC[i-1] + model.ESS_c[i] - model.ESS_d[i]
model.SOC_const = Constraint(model.t, rule=_SOC_const)

请注意，您需要在Set 上设置ordered=True 选项才能使first() 和last() 方法起作用。

【讨论】：