Custom Node Types

Macro for creating a new type of dynmic nodes.

Syntax Description:

@DynamicNode MyNewNodeName(Par1, Par2, ...) <: NodeDynamicsType(N1, N2, ...) begin
    [all prepratory things that need to be run just once]
end [[x1, dx1], [x2, dx2]] begin
    [the actual dynamics equation]
    [important to set the output variables]
end

where MyNewNodeName is the name of the new type of dynamic node, Par1, Par2, ... are the names of the parameters, NodeDynamicsType the the node dynamics type (e.g. OrdinaryNodeDynamics or OrdinaryNodeDynamicsWithMass), N1, N1, ... the parameters of the dynamics type, x1, x2, ... the internal variables of the node and dx1, dx2, ... the corresponding differentials.

In the first block, the preparation code that needs to be run only once is inserted. Finally, the second block contains the dynamics description, where it's important that the output variables need to be set. In case of OrdinaryNodeDynamics and OrdinaryNodeDynamicsWithMass, these are du and the differentials of the internal variables (here dx1, dx2).

Below are two examples:

@DynamicNode SwingEqParameters(H, P, D, Ω) <: OrdinaryNodeDynamics() begin
    @assert D > 0 "damping (D) should be >0"
    @assert H > 0 "inertia (H) should be >0"
    Ω_H = Ω * 2pi / H
end [[ω, dω]] begin
    p = real(u * conj(i_c))
    dϕ = ω # dϕ is only a temp variable that Julia should optimize out
    du = u * im * dϕ
    dω = (P - D*ω - p)*Ω_H
end

@DynamicNode SlackAlgebraicParameters(U) <: OrdinaryNodeDynamicsWithMass(m_u=false, m_int=no_internal_masses) begin
end [] begin
        du = u - U
end