Network Coupler (Transmission Line)

R2026b

Split network with transmission line

Since R2026b

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  • Network Coupler (Transmission Line) block

Libraries:
Simscape / Network Couplers

Description

The Network Coupler (Transmission Line) block provides a starting point for you to split a Simscape™ network into two coupled networks either by splitting an existing transmission line, or by adding a transmission line at the point where you want to separate the networks. Use this block for splitting large power networks consisting of multiple loads, generators, and distribution lines.

The block models the transmission line as a fixed impedance, irrespective of frequency, plus a delay term. The defining equations are

v1( t ) – i1( t ) Z0 = v2( t – τ ) + i2( t – τ ) Z0

v2( t ) – i2( t ) Z0 = v1( t – τ ) + i1( t – τ ) Z0

where:

  • v1 is the voltage across the left-hand end of the transmission line.

  • i1 is the current into the left-hand end of the transmission line.

  • v2 is the voltage across the right-hand end of the transmission line.

  • i2 is the current into the right-hand end of the transmission line.

  • τ is the transmission line delay.

  • Z0 is the line characteristic impedance.

The block models a one-port transmission line that has two physical electrical connections at each end, such as a coaxial cable or twisted pair cable. This block cannot model a three-phase transmission line.

Working with the Block on the Model Canvas

When you add the block to your model and double-click it, the Network Coupler (Transmission Line) subsystem opens.

Network Coupler (Transmission Line) subsystem diagram

Unlike most of the other coupler blocks, both Port 1 Interface and Port 2 Interface contain the dynamics that break the algebraic loop. Double-click these blocks to set the Network Coupler (Transmission Line) subsystem parameters and view the derived values. You must set the parameters separately for each of the two blocks.

The rate transition blocks are, by default, commented through. Uncomment them if at least one of the coupled networks is running fixed step.

Using the Derived Values to Estimate Block Parameters

The Analysis tab asks you for information about the series resistance and inductance of the connected network and provides advice on the minimum recommended characteristic impedance, to ensure stability.

If the recommended values for the Port 1 Interface and Port 2 Interface blocks are different, select the larger of the two values and apply it to both blocks.

The Update button lets you recalculate the derived values after you change the parameters of the connected networks.

Ports

Conserving

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Electrical conserving port associated with the inner conductor of the first transmission line. If one of the coupled networks is running variable step, connect it to this port. If both networks are running fixed step, connect this port to the network with the smaller sample time.

Electrical conserving port associated with the external shielding conductor of the first transmission line. If one of the coupled networks is running variable step, connect it to this port. If both networks are running fixed step, connect this port to the network with the smaller sample time.

Electrical conserving port associated with the inner conductor of the second transmission line. If one of the coupled networks is running variable step, connect this port to the fixed-step network. If both networks are running fixed step, connect this port to the network with the larger sample time.

Electrical conserving port associated with the external shielding conductor of the second transmission line. If one of the coupled networks is running variable step, connect this port to the fixed-step network. If both networks are running fixed step, connect this port to the network with the larger sample time.

Parameters

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Main

Characteristic impedance of the transmission line. The parameter value must be greater than zero. You must set this parameter to the same value for both the Port 1 Interface and Port 2 Interface blocks.

For numerical stability, set this parameter to a value larger than the minimum recommended characteristic impedance on the Analysis tab. If the recommended values for the Port 1 Interface and Port 2 Interface blocks are different, use the larger of the two values.

If you use the Network Coupler (Transmission Line) block to split an existing transmission line, match the Characteristic impedance parameter value to the impedance of the connected network.

Select this option to simplify the block parameterization. If the block uses the minimal possible delay, you do not need to specify the transmission line delay for the connected networks.

Connected transmission line delay, in seconds. If one or both networks are running fixed step, the block approximates the transmission delay as an integer number of sample times. If both networks are running fixed step, the parameter value must be larger than the slowest fixed step rate. If your transmission line delay is smaller than the slowest fixed step rate, select the Use minimal possible delay check box instead of specifying the parameter value.

If you clear the Use minimal possible delay check box both for Port 1 Interface and Port 2 Interface blocks, you must set this parameter to the same value for both blocks.

Dependencies

To enable this parameter, clear the Use minimal possible delay check box.

Specify whether the network connected to the interface block ports is running variable step or fixed step.

Specify sample time for the network connected to the interface block ports, in seconds.

Dependencies

To enable this parameter, set the Sampling type parameter to Fixed step.

Analysis

Specify approximate series resistance of the network connected to the interface block ports, in ohms.

Specify approximate series inductance of the network connected to the interface block ports, in H.

For information on how to use the Derived values section, see Using the Derived Values to Estimate Block Parameters.

Initial Conditions

Specify initial condition for the voltage at the interface block ports, in V.

Specify initial condition for the current flowing into the block, in A.

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2026b

See Also

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