The terms 'transient' and 'steady-state' simulation of three-phase systems always refer to the electrical equations within a model. Other equations are not affected. The steady-state simulation is a meaningful approximation, if dynamic time-constants of electrical components are short compared to other time-constants as for example mechanical or thermal ones.
The standard transient form of an inductive and a capacitive device (for simplicity with constant coefficient matrices L and C) is given by the dual equations
L*der(i) + omega[2]*L*J*i + R*i = v C*der(v) + omega[2]*C*J*v + G*v = i
where
omega[2] = der(theta[2])
[ 0, -1, 1]
J = [ 1, 0, -1] /sqrt(3) (abc-representation)
[-1, 1, 0]
[ 0, -1, 0]
J = [ 1, 0, 0] (dqo-representation)
[ 0, 0, 0]
The simulation of a model in steady-state must assume a synchronous reference frame, i.e.
theta[1]=0
The steady-state approximation is then obtained from the above by setting the time-derivative der = 0.
omega[2]*L*J*i + R*i = v omega[2]*C*J*v + G*v = i
It is obvious that going from transient to steady-state mode, differential equations are replaced by algebraic ones.
As each model-component contains both types of equations, transient and steady, the desired case can be selected by an appropriate choice of the parameter 'sim' in 'system'.