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) its propagation modes and the transformation matrix (Ti) between mode currents and phase currents. Implementation details can be found in [1].

This model can be used to simulate an internal fault. However, the number of operations allowed in this model is four (4) per fault element, instead of ten (10) in normal cases.

Table of Contents

Mask and Parameters

General Parameters

Name	Description				Unit	Variable = {Possible Values}

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 (Xl) and capacitive susceptance (1/Xc)
Line Length	The length of the line		km	length = {0, 1e64}
Distance of fault from (+) side	Distance of fault from (+) side		km	fault_loc = {0, 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] }
Fault resistance	Fault resistance value per phase		Ω	RDef = {0, 1e64}
Ropen	Open resistance value per phase		Ω	ROpen = {0, 1e64}
Rclose	Closed resistance value per phase		Ω	RClose = {0, 1e64}
Chopping current	Current threshold for the opening permission operation		A	Imargin = {0, 1e64}

Line Data Parameters

Name	Description				Unit	Variable = {Possible Values}

Name	Description		Unit	Variable = {Possible Values}
Continuously transposed line	Transposition (Untransposed/Transposed)			transp = { 0, 1}
	No {0}	Untransposed line
	Yes {1}	Transposed line
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 capacitance for each phase (mode)		F/km	C = {'-1e64, 1e64'}
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] }

Timing Parameters

Name	Description		Unit	Variable = {Possible Values}

Name	Description		Unit	Variable = {Possible Values}
Time units	Units applied to the programmed state transition operations			Ut = {s, ms, c}
	Second {s}	All operations T_n are in seconds
	Millisecond {ms}	All operations T_n are in milliseconds
	Cycle {c}	All operations T_n are in electrical cycles (setting the frequency is mandatory)
Time programming	Master switch that determines whether the programmed operations will occur upon triggering an acquisition			EnaGen = {0, 1}
	Disable {0}	Programmed operations are disabled
	Enable {1}	Programmed operations are enabled
Steady-state condition	State of phase breakers in steady-state; “colored” if the breaker is open and “grey” if the breaker is closed			iniStateA = {0, 1} iniStateB = {0, 1} iniStateC = {0, 1} iniStateG = {0, 1}
Frequency	Should be set using the parameter "Base frequency".		Hz	Freq = { [45, 70] }
Switching times Line1	Enable/disable the state transition operation on the same line.			EnaT1 = {0, 1} EnaT2 = {0, 1} ...
	Disable {0}	Disable the state transition operation on the same line
	Enable {1}	Enable the state transition operation on the same line. If the line is enabled but no information is filled, the state transition operation is ignored.
Switching times Type(f,i,u,ug)	Relative time (with respect to POW synchronization) when the command is sent to the breaker (or switch) to change state. There are four ways to input this time. Important notes: For changes of state to occur, programmed operation times must always respect T_n>T_n-1. If a parameter field is blank or contains “-”, no switching will occur for this line. There is no alias for the type of timing in the API. The timing type and values are entered as a single string. If using referenced operations, the calculated time is applied after it received the command from the other component. See the Referenced Operations section for more information.		Refer to "Time units" parameter	T1 = {'string'} T2 = {'string'} ...
	Fixed	{f: fixed time} At each acquisition, T_n command is sent at the same time for all phases selected in "Phase operated".
	Incremental	{i: initial time/final time/time increment} For the first acquisition, T_n command is sent at the set initial time for all phases selected in "Phase operated". Then at each acquisition, T_n command is sent a time increment later than the previous acquisition. Once the final time is reached, the next acquisition will be done using the initial time again.
	Uniform	{u: minimal time/maximal time} At each acquisition, T_n command is sent at a random time. The probability is uniform over the specified range. All phases selected in "Phase operated" DO NOT receive the command at the same time, it is also random.
	Uniform gaussian	{ug: minimal time/maximal time/ dispersion} At each acquisition, T_n command is sent at a random time. The probability follows a gaussian distribution over the specified range. All phases selected in "Phase operated" DO NOT receive the command at the same time, it is also random.
Referenced operations	Use to refer the triggering of T_n to another breaker programmed state transition. See the Referenced Operations section for more information. NB: all columns must be filled for the referenced operation to work.
	Ref operation	Name (or path) of the breaker to which the timing is referenced		Eref1 = {'path.name'} Eref2 = {'path.name'} ...
	Ref time	Time T_n ID of the referenced breaker's step to which the timing is referenced		Tref1 = {T_n} Tref2 = {T_n} ...
	Phase/Command	Activate (Phase {1}) or deactivate (Command {0}) the reference dependency		T1RPh = {0, 1} T2RPh = {0, 1} ...
Phase operated	The list of all phases that change state when the timing condition is reached. So if after T_n-1 the A and C phases are OFF and T_n triggers B and C, after T_n phases A and B will be OFF, and C will be ON.			T1Pa, T1Pb, T1Pc = {0, 1} T2Pa, T2,Pb, T2Pc = {0, 1} ...
	ON {1}	"Colored" when a state transition shall occur
	OFF {0}	"Grayed out" when no state transition shall occur

Line Generator

For more information see Line Generator

Ports, Inputs, Outputs and Signals Available for Monitoring

Ports

This component supports a 3-phase transmission line

Name	Description

Name	Description
net_1(a,b,c)	Network connection of phases (a,b,c) of the left (+) side
net_2(a,b,c)	Network connection of phases (a,b,c) of the right side

Inputs

None

Outputs

None

Sensors

At acquisition, the signals available by the sensors are:

Name	Description	Unit

Name	Description	Unit
V(a,b,c)_Node(1,2)	Voltage of each phase on bus (1,2)	V
I(a,b,c)_Node(1,2)	Currents of each phase on bus (1,2)	A
V(a,b,c)_FLT	Voltage on fault bus phases (a,b,c)	V
I(a,b,c,n)_FLT	Fault current (a,b,c,n)	A
CMD(a,b,c,n)_FLT	Command for states of phase and ground breakers

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). Note that the Fault bus referred to in the previous table is the point of fault on the line indicated in the form of the model (distance of fault from (+) side).

Electrical Parameters

Calculation of electrical parameters

The Electrical parameters of CP lines can be calculated by using the Line Generator .

Propagation Delay

The propagation delay is calculated as follows:

Where i is for each of the phases, L and C stands for the inductance and capacitance of the line per unit length.

When the propagation delay is smaller than the time step, the Constant Param block is automatically replaced by an equivalent PI Line.

If the 'Transposed' parameter is set to 'yes', the following warning is printed in the console:

^{WARNING in line: <Name of Block>: The propagation delay ( X ) is less than the sample time ( Y ). A PI line is automatically used.}

If the 'Transposed' parameter is set to 'no', an error message with similar text appears.

Types of fault

The fault breakers are shown in the following figure. The types of faults according to the state of the breakers are listed in the table.

Note: For a phase to ground fault, we strongly recommend using the ground in steady state instead of programming a time of operation in transient state.

Types of fault according to the state of breakers

State of Breaker	A	B	C	Ground

State of Breaker	A	B	C	Ground
No fault	0	0	0	0
Fault between phase C and Ground	0	0	1	1
Fault between phase B and Ground	0	1	0	1
Fault between phases B and C	0	1	1	0
Fault between phases B, C and Ground	0	1	1	1
Fault between phases A and Ground	1	0	0	1
Fault between phases A and C	1	0	1	0
Fault between phases A, C and Ground	1	0	1	1
Fault between phases A and B	1	1	0	0
Fault between phases A, B and Ground	1	1	0	1
Fault between phases A, B and C	1	1	1	0
Fault between phases A, B, C and Ground	1	1	1	1

In the case of a 3-phase line with fault, the user has two options to simulate:

1 line section - no fault
2 line sections - fault on the line

The user must specify the fault distance on the line. This distance must be calculated from side “1” of the line. For example, if the user wants to simulate a fault on the line at a distance of 125 km he must enter the value in the fault distance fields. If the user does not want to use the fault element, he must set the value of the fault distance to 0. Note that the fault distance must be lower than the line length.

References

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.

HYPERSIM Documentation

Constant Param, 3-ph with Fault