Implement N-phase distributed parameter transmission line model with lumped losses
The Distributed Parameter Line block implements an N-phase distributed parameter line model with lumped losses. The model is based on the Bergeron's traveling wave method used by the Electromagnetic Transient Program (EMTP) . In this model, the lossless distributed LC line is characterized by two values (for a single-phase line): the surge impedance and the wave propagation speed . l and c are the per-unit length inductance and capacitance.
The figure shows the two-port model of a single-phase line.
For a lossless line (r = 0), the quantity e + Zci, where e is the line voltage at one end and i is the line current entering the same end, must arrive unchanged at the other end after a transport delay τ.
where d is the line length and v is the propagation speed.
The model equations for a lossless line are:
In a lossless line, the two current sources Ish and Irh are computed as:
When losses are taken into account, new equations for Ish and Irh are obtained by lumping R/4 at both ends of the line and R/2 in the middle of the line:
R = total resistance = r × d
The current sources Ish and Irh are then computed as follows:
r, l, c are the per unit length parameters, and d is the line length. For a lossless line, r = 0, h = 1, and Z = Zc.
For multiphase line models, modal transformation is used to convert line quantities from phase values (line currents and voltages) into modal values independent of each other. The previous calculations are made in the modal domain before being converted back to phase values.
In comparison to the PI section line model, the distributed line represents wave propagation phenomena and line end reflections with much better accuracy.
Specifies the number of phases, N, of the model. The block icon
dynamically changes according to the number of phases that you specify.
When you apply the parameters or close the dialog box, the number
of inputs and outputs is updated. Default is
Specifies the frequency used to compute the per unit length
resistance r, inductance l,
and capacitance c matrices of the line model.
The resistance r per unit length, as an N-by-N
matrix in ohms/km (Ω/km). Default is
For a symmetrical line, you can either specify the N-by-N matrix or the sequence parameters. For a two-phase or three-phase continuously transposed line, you can enter the positive and zero-sequence resistances [r1 r0]. For a symmetrical six-phase line you can enter the sequence parameters plus the zero-sequence mutual resistance [r1 r0 r0m].
For asymmetrical lines, you must specify the complete N-by-N resistance matrix.
The inductance l per unit length, as an
N-by-N matrix in henries/km (H/km). Default is
For a symmetrical line, you can either specify the N-by-N matrix or the sequence parameters. For a two-phase or three-phase continuously transposed line, you can enter the positive and zero-sequence inductances [l1 l0]. For a symmetrical six-phase line, you can enter the sequence parameters plus the zero-sequence mutual inductance [l1 l0 l0m].
For asymmetrical lines, you must specify the complete N-by-N inductance matrix.
The capacitance c per unit length, as an
N-by-N matrix in farads/km (F/km). Default is
For a symmetrical line, you can either specify the N-by-N matrix or the sequence parameters. For a two-phase or three-phase continuously transposed line, you can enter the positive and zero-sequence capacitances [c1 c0]. For a symmetrical six-phase line you can enter the sequence parameters plus the zero-sequence mutual capacitance [c1 c0 c0m].
For asymmetrical lines, you must specify the complete N-by-N capacitance matrix.
The powergui block provides the RLC Line Parameters tool, which calculates resistance, inductance, and capacitance per unit of length based on the line geometry and the conductor characteristics.
The line length, in km. Default is
Phase-to-ground voltages to
measure the sending end and receiving end voltages for each phase
of the line model. Default is
Place a Multimeter block in your model to display the selected measurements during the simulation.
In the Available Measurements list box of the Multimeter block, the measurement is identified by a label followed by the block name:
Phase-to-ground voltages, sending end
Phase-to-ground voltages, receiving end
This model does not represent accurately the frequency dependence of RLC parameters of real power lines. Indeed, because of the skin effects in the conductors and ground, the R and L matrices exhibit strong frequency dependence, causing an attenuation of the high frequencies.
illustrates a 200-km line connected on a 1 kV, 60-Hz
 Dommel, H., “Digital Computer Solution of Electromagnetic Transients in Single and Multiple Networks,” IEEE® Transactions on Power Apparatus and Systems, Vol. PAS-88, No. 4, April, 1969.