DecisionModel Build Failed for network AreaBalancePowerModel with slacks

[ymiftah]

Describe the bug
Problem build fails when defining a problem with an AreaBalancePowerModel as Network model and requesting slacks

To Reproduce

using PowerSystemCaseBuilder, PowerSystems, PowerSimulations

function get_system()
  sys = build_system(PSITestSystems, "c_sys5_uc")
  
  # Extend the test case with areas
  areas = [Area("Area_1", 0,0,0), Area("Area_2", 0,0,0)]
  add_components!(sys, areas)
  for (i, comp) in enumerate(get_components(ACBus, sys))
      if i < 3
          set_area!(comp, areas[1])
      else
          set_area!(comp, areas[2])
      end
  end
  return sys
end

function define_problem(sys; output_dir=mktempdir())
    template_uc = ProblemTemplate()
    set_device_model!(template_uc, Line, StaticBranch)
    set_device_model!(template_uc, ThermalStandard, ThermalBasicDispatch)
    set_device_model!(template_uc, PowerLoad, StaticPowerLoad)
    set_network_model!(template_uc, NetworkModel(AreaBalancePowerModel, use_slacks=true,))
    solver = optimizer_with_attributes(HiGHS.Optimizer, "mip_rel_gap" => 0.5)
    problem = DecisionModel(
        template_uc,
        sys;
        optimizer=solver,
    )
    build!(problem; output_dir=output_dir)
    return problem
end

sys =  get_system()
problem = define_problem(sys; output_dir="./problem_dir/")

The error stack trace is as follows:

┌ Error: DecisionModel Build Failed
│   exception =
│    InfrastructureSystems.InvalidValue("variable SystemBalanceSlackUp__ACBus is not stored. [:ActivePowerVariable__ThermalStandard, :SystemBalanceSlackUp__Area, :SystemBalanceSlackDown__Area]")
│    Stacktrace:
│      [1] get_variable(container::PowerSimulations.OptimizationContainer, key::InfrastructureSystems.Optimization.VariableKey{SystemBalanceSlackUp, ACBus})
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/core/optimization_container.jl:998
│      [2] get_variable (repeats 2 times)
│        @ ~/.julia/dev/PowerSimulations/src/core/optimization_container.jl:1009 [inlined]
│      [3] add_to_expression!(container::PowerSimulations.OptimizationContainer, ::Type{ActivePowerBalance}, ::Type{SystemBalanceSlackUp}, sys::System, ::NetworkModel{AreaBalancePowerModel})
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/devices_models/devices/common/add_to_expression.jl:1476
│      [4] construct_network!(container::PowerSimulations.OptimizationContainer, sys::System, model::NetworkModel{AreaBalancePowerModel}, ::ProblemTemplate)
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/network_models/network_constructor.jl:36
│      [5] macro expansion
│        @ ~/.julia/dev/PowerSimulations/src/core/optimization_container.jl:715 [inlined]
│      [6] macro expansion
│        @ ~/.julia/packages/TimerOutputs/6KVfH/src/TimerOutput.jl:237 [inlined]
│      [7] build_impl!(container::PowerSimulations.OptimizationContainer, template::ProblemTemplate, sys::System)
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/core/optimization_container.jl:712
│      [8] build_model!(model::DecisionModel{GenericOpProblem})
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:408
│      [9] build_impl!(model::DecisionModel{GenericOpProblem})
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:344
│     [10] macro expansion
│        @ ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:386 [inlined]
│     [11] macro expansion
│        @ ~/.julia/packages/TimerOutputs/6KVfH/src/TimerOutput.jl:237 [inlined]
│     [12] (::PowerSimulations.var"#80#81"{DecisionModel{GenericOpProblem}})()
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:385
│     [13] with_logstate(f::PowerSimulations.var"#80#81"{DecisionModel{GenericOpProblem}}, logstate::Base.CoreLogging.LogState)
│        @ Base.CoreLogging ./logging/logging.jl:522
│     [14] with_logger
│        @ ./logging/logging.jl:632 [inlined]
│     [15] build!(model::DecisionModel{GenericOpProblem}; output_dir::String, recorders::Vector{Any}, console_level::Base.CoreLogging.LogLevel, file_level::Base.CoreLogging.LogLevel, disable_timer_outputs::Bool)
│        @ PowerSimulations ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:383
│     [16] build!
│        @ ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:364 [inlined]
│     [17] define_problem(sys::System; output_dir::String)
│        @ Main ~/workspace/experiments/ElectricityMarkets/wip.jl:56
│     [18] top-level scope
│        @ ~/workspace/experiments/ElectricityMarkets/wip.jl:75
│     [19] eval
│        @ ./boot.jl:430 [inlined]
│     [20] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
│        @ Base ./loading.jl:2734
│     [21] invokelatest(::Any, ::Any, ::Vararg{Any}; kwargs::@Kwargs{})
│        @ Base ./essentials.jl:1055
│     [22] invokelatest(::Any, ::Any, ::Vararg{Any})
│        @ Base ./essentials.jl:1052
│     [23] inlineeval(m::Module, code::String, code_line::Int64, code_column::Int64, file::String; softscope::Bool)
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:271
│     [24] (::VSCodeServer.var"#69#74"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})()
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:181
│     [25] withpath(f::VSCodeServer.var"#69#74"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams}, path::String)
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/repl.jl:276
│     [26] (::VSCodeServer.var"#68#73"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})()
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:179
│     [27] hideprompt(f::VSCodeServer.var"#68#73"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams})
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/repl.jl:38
│     [28] #67
│        @ ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:150 [inlined]
│     [29] with_logstate(f::VSCodeServer.var"#67#72"{Bool, Bool, Bool, Module, String, Int64, Int64, String, VSCodeServer.ReplRunCodeRequestParams}, logstate::Base.CoreLogging.LogState)
│        @ Base.CoreLogging ./logging/logging.jl:522
│     [30] with_logger
│        @ ./logging/logging.jl:632 [inlined]
│     [31] (::VSCodeServer.var"#66#71"{VSCodeServer.ReplRunCodeRequestParams})()
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:263
│     [32] #invokelatest#2
│        @ ./essentials.jl:1055 [inlined]
│     [33] invokelatest(::Any)
│        @ Base ./essentials.jl:1052
│     [34] (::VSCodeServer.var"#64#65")()
│        @ VSCodeServer ~/.vscode-server/extensions/julialang.language-julia-1.127.2/scripts/packages/VSCodeServer/src/eval.jl:34
└ @ PowerSimulations ~/.julia/dev/PowerSimulations/src/operation/decision_model.jl:393

Expected behavior
The problem should build with slacks and should be feasible with slacks inactive

Additional context
The issue seem to be in the add_expression! function for the ActivePowerBalance type. It expects the slack variables to be declared (in a previous step) for ACBus types, but they are actually defined per Area. Replacing the types queried from the system (i.e. ACBus -> Area), fixes the use case above.