CompositeSystems

The CompositeSystems module defines CompositeSystems and provides the means to assemble them into systems of differential(-algebraic) equations, see DAESystem and assemble.

CompositeSystem(junctions::Dtry{Junction{P}}, boxes::Dtry{InnerBox{AbstractSystem,P}}) where {P<:Union{Nothing,Position}}

A CompositeSystem is given by a Pattern, where each InnerBox is filled by a system whose interface matches that of the box.

Connection of an InnerPort to a Junction

DAEConstraint(cvar::CVar, residual::SymExpr)

The residual is forced to be zero by the corresponding constraint variable cvar.

DAEStorage(xvar::XVar, quantity::Quantity, flow::SymExpr, effort::SymExpr)

Fields

• xvar: state variable
• quantity: associated [EPHS.AbstractSystems.Quantity]
• flow: the time-derivative of the state variable
• effort: the differential of the exergy function w.r.t. the state variable

DAESystem(storage::Vector{DAEStorage}, constraints::Vector{DAEConstraint})

A DAESystem defines a system of differential(-algebraic) equations.

Fields

• storage: differential part (evolution of state variables)
• constraints: algebraic part (residuals forced to be zero by constraint variables)

See DAEStorage and DAEConstraint.

FlatSystem(pattern::Pattern, connections::Dtry(Vector(Connection)))

A flat system is a composite system without any hierarchical nesting of (sub-)systems. This struct also controls if each junction has only one provider of effort and state.

assemble(sys::CompositeSystem) -> DAESystem

Assemble the system of differential(-algebraic) equations corresponding to the given CompositeSystem.

update_parameters(dae::DAESystem, ps::Dtry{Float64}) -> DAESystem

Update the parameters of the given DAESystem according to the directory of parameters ps. Parameters that are not contained in ps remain unchanged. Parameters in ps that are not present in the system are ignored.

MoreBase.flatten(sys::CompositeSystem{P}) ->

The function flatten creates a flat system from a nested composite system using recursion.

• nested subsystems are converted into non-hierarchical systems
• connections, ports, and junctions are adjusted to assure consistency