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Description

The Cable-Model module can produce transmission cable models for time domain studies.

The following cable models are available:

  • FD: Frequency dependent cable model (not implemented in HYPERSIM)
  • CP: Constant-parameter cable model
  • Exact-PI: Exact frequency domain representation of a cable at a given frequency (not implemented in HYPERSIM)
  • Scan: Cable model parameters are calculated at given frequencies. No model is generated
  • Wideband: Wideband cable model

Note that the FD model is not implemented in HYPERSIM for cables. It is possible to use a CP model; however, it is not very precise when simulating cables. The cable model used in HYPERSIM is the wide-band model, which is considered the most accurate approach.

Therefore, it is strongly recommended to use the Cable Data module to produce a wide-band cable model.


Table of Contents
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Mask and Parameters

Location of Data Parameters

NameDescription
Open an existing cable case data file or use previously saved (click OK now) data for this device

Provide an existing cable data file if you want to modify an existing case or use previously saved data for this device.

To open the previously saved version, click the OK button; in this case the data is saved within the device and not in a file.

Open an existing EMTP-V3 data file

Provide an existing EMTP-V3 (AUX) data file if you want to modify an existing old case.

This device will try to translate the existing file to create a line case data compatible with EMTPWorks/HYPERSIM. The user should verify if the translation has been performed correctly by opening the cable case data file with the first option on this page. 

The provided myfile.data will be converted to myfile.lin and can be opened using the first option on this page.

Run an existing cable case data file without opening its dataThis option submits an existing case file directly to the Cable Data Calculation function. It can be also used to run old EMTP-V3 cases without translating them.
Create a new line caseThis option creates a new case from scratch

Conductor Data Parameters

Once a (new) cable case is selected (created), a new window with following parameters is open.

The data tab allows the user to specify the geometrical and electrical characteristics of the cable system. This includes the geometrical description of the cable, the electrical and geometrical data of the conductors as well as the electrical properties of the insulation material. The data information required to describe a pipe-type cable is somewhat different than the data required for a single-core coaxial cable.

Although many data fields are similar, their descriptions are presented separately to facilitate readability.

Image Modified

NameDescriptionUnit
Cable typeUsers can select their cable type from a pull-down:
Single coreTo generate coaxial cables
Pipe typeTo generate cable models where a metallic pipe encloses the coaxial cables.
Number of cables

Indicates the number of cables in the system


Cross-bond the Sheaths

In order to model a cross-bonded cable accurately, each major section must be modeled in detail. This means that each minor section of the cable must be modeled, and the sheath bonding and sheath grounding connections must be made explicitly using the HYPERSIM node names.

Such a detailed representation can be computationally intensive because modeling short cable segments of the order of 400 meters or so, requires a very small time step (a fraction of the travel time of the fastest propagation mode). Furthermore, a number of these major sections must be connected to represent the entire cable. For example, a 12 km cable with 400 m minor sections, would require a total of 30 6-phase cable models. Nevertheless, this type of detailed representation is necessary when sheath currents and voltages have to be assessed.

The detailed representation of each minor section of a cross-bonded cable is in some ways analogous to modeling a transposed overhead transmission line by representing each transposition section explicitly, and connecting the sending and receiving node names accordingly with HYPERSIM node names.

In the case of transmission lines, this situation can be approximated by assuming that the line is balanced, and using a single line where the elements of impedance and admittance matrices have been averaged to account for the effect of transposition.

A cross-bonding option is available in the Cable Data device to provide this type of approximation. If “Cross-bond the Sheaths” is selected, then the elements of the impedance and admittance matrices of the cable are averaged to reflect the effect of cross-bonding. The grounding of the sheaths is then controlled using the KPH parameter in the "Conductor data" table. Setting KPH = 0 for the sheaths, is equivalent to assuming that the sheaths are continuously grounded (at zero potential throughout the entire cable length).

In this case, the sheaths can be eliminated and a three-conductor approximation of a cross-bonded cable is obtained. This three-conductor approximation compares quite favorably with the detailed modeling of each minor section of a cross-bonded cable, and it is ideally suited for switching transient studies of cross-bonded cables, because of its computational speed and accuracy.


Single core

The general structure of this type of cable system is shown in the following figure.


Cable numberGiven in increasing order for the entire cable system
Number of conductorsIndicating the number of concentric tubular conductors in this cable. For example, a cable with 3 conductors: the core, the sheath and the armor.
Vertical DistanceDepth (see VER-1 in Figure shown above) measured from the center of this cable to the earth's surface. This is a positive number.
Horizontal DistanceMeasured from the center of this cable to an arbitrary point of reference (see HRZ-1 in Figure shown above).m
Outer Insulation RadiusIndicating the outside radius of the insulation layer surrounding the cable. Use 0 if there is no surrounding insulation. This is the ROUT variable in the following figure.m
Conductor insulator data

This section describes the tubular conductor and their surrounding insulation ordered from inside out (the core conductor comes first, followed by sheath, etc.).

The required data for each conductor is:


Cable numberGiven in increasing order for the entire cable system
Conductor numberThe term conductor is used to designate both conductor and insulator data
Inside Radius RinInside radius of the conductorm
Outside Radius RoutOutside radius of the conductorm
Resistivity RhoResistivity of the conductorΩ-m
Relative Permeability MUERelative permeability of the conductor
Insulator Relative Permeability MUE-INRelative permeability of the surrounding insulation
Insulator Relative Permittivity EPS-INRelative permittivity of the surrounding insulation
Insulator Loss Factor LFCT-INLoss factor of the surrounding insulation
KPH

Phase-number of the conductor. Conductors of all cables must be given phase numbers starting from 1, with no gaps in phase numbering. For example, for a three conductor cable KPH = 1, 2, 3 is a legitimate numbering arrangement, while KPH = 1, 3, 4 is not.

Conductors with KPH = 0 will be grounded and all conductors with identical phase numbers will be bundled into a single equivalent conductor. The order of conductors in the Model Data File will be made according to the sequence defined by KPH.


Pipe-Type cables

Beside the two data sections of the single-core cables, the pipe-type system requires an extra section describing the geometrical and electrical property of the pipe. Since the individual cables are the same as in single-core system, the conductor and insulator data definition is the same as above.



Cable numberGiven in increasing order for the entire cable system
Number of conductorsIndicating the number of concentric tubular conductors in this cable. For example, this number is 3 for a cable with core, sheath and armor.
Distance from center of pipeThe distance measured from the center of this cable to the center of the pipe. See variable Dist in Figure above.m
Position AngleThe angle measured from the line joining the center of this cable and the center of the pipe to an arbitrary reference axis. See variable ANG in Figure above.deg
Outer Insulation radiusIndicating the outside radius of the insulation layer surrounding the cable. See variable ROUT in Figure above.m
Geometrical pipe dataThe geometrical data variables are shown in the figure above.
Inside radius of pipe (Rin)Inside radius of the pipem
Outside radius of the pipe (Rout)Outside radius of the pipem
Outside radius of tubular insulator (Rext)Outside radius of the tubular insulator surrounding the pipem
Vertical distance (depth) Vertical distance (depth) of the pipe's center from the surface of the earth (Vdpth)m
Phase-number of the pipe (zero if it is grounded)variable KPH
Electrical data of the pipeThe electrical data section of the pipe is self-explanatory.

Model Parameters

NameDescriptionUnit
Select modelThe Cable-Model module can produce various cable models for time-domain studies. However, only the CP and Wideband cable models are currently implemented in HYPERSIM. Therefore, the documentation presented in this table will be only focused on these models. 
FDFrequency dependent cable model (not implemented in HYPERSIM)
CPConstant-parameter cable model
Exact-PIExact frequency domain representation of a cable at a given frequency ()
ScanCable model parameters are calculated at given frequencies. No model is generated.
WidebandWideband cable model
FD

This produces data for a cable model that is not implemented in HYPERSIM. Thus, is not covered in this documentation. 


CP 

The CP model (constant parameter cable model) assumes that the cable parameters R, L, and C are constant, and they are calculated at a user-supplied model frequency. This model considers L and C to be distributed ("ideal cable") and R to be lumped at three places (cable ends and cable middle). The shunt conductance G is assumed to be zero.

Taking into account the frequency dependence of the cable parameters (as modeled by the Wideband model) is an important factor for the accurate simulation of transients. However, the CP model is computationally faster and it is generally used as an alternative to model secondary lines or cables. The only type of matrix that can be calculated for this model is the Real Ti . It is evaluated at the entered “Model frequency”.

After entering all required data, the Model Data Calculation Function can be invoked from the “Save and run this case” data tab to generate the model data file. The model can be used with the CP line models (CP m-phase components) by selecting the model data file (also called “pun file”) through the “Load data file” option in the device data. Note that the number of phases of the selected CP line should correspond to the number of phases of the model generated in the pun file. The format of this file can be found in the documentation of the CP m-phase device. 


Exact PI model

This produces data for a cable model not implemented in HYPERSIM. Thus, it is not covered in this documentation. 


Scan (No model)

This selection is for the Scan option where cable parameters in either phase, modal or sequence quantities are computed at the specified frequencies.

Results are shown in the output file. No model is generated


Wideband

This model represents the true nature of a transmission line by modelling the phase line parameters as complex distributed and frequency dependent. It is required to specify the 'Frequency range' for which the line propagation function and characteristic impedance are synthesized


Frequency rangeThe Frequency range represents the frequency band for the fitting of the line characteristic admittance and propagation function. The data fields required for this option are self-explanatory.

Cable Length Parameters

NameDescriptionUnit
Cable length and earth resistivityThe variables to set in this tab are:
Cable lengthLength of the cablem
Earth resistivityValue of the earth resistivityΩ-m
Earth relative permeabilityValue of the earth relative permeability
Conductance breakpoint frequency (FG0)

Breakpoint frequency (FG0) of the shunt conductance for all insulating layers. For all insulators, the shunt conductance G is described with the following function of frequency:

G = 2pi (FG0 + Frequency) * Loss Factor * Capacitance.

Hz

Output Options Parameters

NameDescriptionUnit
Special output optionsThe variables required for these settings are self-explanatory.
Extra output options

Save and run this case

NameDescriptionUnit
Options for saving this case

Before choosing to run this case, the user must provide a valid Case Data File identification which is the model identification and the device name. 
Generated model data is available in a model data file created by the Cable Data Calculation program.

  • For the "CP m-phase" device users can load the generated model data into the device forms using the "Load data from file" option.
  • For the "WB line" device the model data is selected in the WB fitter to generate line data.

Current Case Data File nameEnter a unique name to save the model.
Run this case to create a model data file for the selected cable modelSelect this option if you want to generate line model data. When you click OK, HS will start a separate Cable DATA calculation function for generating cable data.


Ports, Inputs, Outputs and Signals Available for Monitoring

Ports

None

Inputs

None

Outputs

None

Sensors

None

Example

Example

Next Figure shows a sample case of complete cable and conductor data for single-core. The data case contains three identical single-core cables, each one has two conductors.

The complete layout is shown in next. Only the outside radius of the conductors and the outer insulation radius are shown in this figure. Each conductor is associated with a non-zero phase number, thus the generated model for this example will have 6 different modes (6 wires).