Description
The constant parameter (CP) line model assumes that the line parameters R, L, and C are independent of the frequency effects caused by the skin effect on phase conductors and on the ground. The model considers L and C to be distributed (ideal line) and R to be lumped at three places (R/4 on both ends and R/2 in the middle). The shunt conductance G is taken as zero. The frequency dependence of the line parameters (represented in the FD model) is an important factor for the accurate simulation of waveform and peak values. However, the CP model is very robust, simple, and fast. It also provides a good alternative for a first approximation analysis.
A transposed or untransposed CP line is represented by a) its sequences, or b) by its propagation modes and the transformation matrix (Ti) between mode currents and phase currents. Implementation Implementation details can be found in [1].
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Mask and Parameters
General Parameters
Name | Description | Unit | Variable = {Possible Values} | |||
|---|---|---|---|---|---|---|
Description | Use this field to add information about the component | |||||
Description = {'string'} | ||||
EMTP (.pun) file for line parameters calculation | The location (path) of the EMTP file (pun file) containing the line parameters | |||
File = {'path.name'} | ||||||
L-C units in EMTP (.pun) file | The units from the pun file can be taken using two options | L-C units = { 0, 1} | ||||
mH/km, uF/km {0} | Inductance (L), capacitance (C) | |||||
Ohm/km, uS/km {1} | Inductive reactance (Xl) and capacitive susceptance (1/Xc) | |||||
Line Length | The length of the line | km | length = {0, 1e64} | |||
R | Per unit length resistance | |||||
for each phase (mode) | Ω/km | |||
R = {'-1e64, 1e64'} | ||||||
L | Per unit length inductance for each phase (mode) | H/km | L = {'-1e64, 1e64'} | |||
C | Per unit length capacitor for each phase (mode) | F/km | C = {'-1e64, 1e64'} | |||
Base power (perPhase) | Base value for PU conversion | MVA per phase | ||||
pBase = { [1, 1e64] } | |||||
Base voltage (rmsLN) | Base value for PU conversion | kV rms LN | |||
vBase = { [1, 1e64] } | |||||
Base frequency | Base value for PU conversion | Hz | |||
fBase = { [1, 1e64] } | ||||||
Continuously transposed line | Transposition (Untransposed/Transposed) | transp = { 0, 1} | ||||
No {0} | Untransposed line | |||||
Yes {1} | Transposed line | |||||
Transformation matrix | Transformation matrix between mode current and phase current ([Iphase] = [Ti] x [Imode]); not used in the case of transposed line. | Ti = { [-1e64, 1e64] } | ||||
Ports, Inputs, Outputs and Signals Available for Monitoring
Ports
This component supports a 4-phase transmission line
Name | Description |
|---|---|
net_1_1 | Network connection of phase |
1 left (+) |
side | |
net_1_2 | Network connection of phase |
1 right |
side | |
net_2_1 | Network connection of phase |
2 left (+) |
side | |
net_2_2 | Network connection of phase |
2 right |
side | |
net_3_1 | Network connection of phase |
3 left (+) |
side | |
net_3_2 | Network connection of phase |
3 right |
side | |
net_4_1 | Network connection of phase |
4 left (+) side | |
net_4_2 | Network connection of phase |
4 right |
side |
Inputs
None
Outputs
None
Sensors
At acquisition, the signals available by the sensors are:
Name | Description | Unit |
|---|---|---|
V_Node(1,2,3,4)_(1,2) | Bus voltage for each phase (1,2,3,4) | V |
I(1,2)_Node(1,2,3,4)_(1,2) | Current for each phase (1,2,3,4) | A |
P(1,2)_Node(1,2,3,4)_(1,2) | Active power for each phase (1,2,3,4) on bus (1,2) | W |
Q(1,2)_Node(1,2,3,4)_(1,2) | Reactive power for each phase (1,2,3,4) on bus (1,2) | VAR |
The (1,2) in the previous table indicates the name of the bus at each end of the line (1 for the left (+) side and 2 for the right side)
Electrical Parameters
Calculation of electrical parameters
The
Electrical parameters of CP lines can be calculated by using the
Steps are as follows:
- Load a file into the Line Data GUI or enter the geometrical line parameters; details are found in Line Geometry.
- Select the transpositions options
- Run the program
- The electrical parameters are displayed in the Line Data Report.
To transfer the electrical parameters to the CP model, follow these steps:
Reference
H. W. Dommel, "Digital computer solution of electromagnetic transients in single and multiphase networks," IEEE Trans. Power App. Syst., vol. pas-88, pp. 388-99, 04/ 1969.