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Voltage-Current Simscape Interface

Ideal coupling between Simscape Electrical Specialized Power Systems and Simscape electrical circuits

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  • Voltage-Current Simscape Interface block

Libraries:
Simscape / Electrical / Specialized Power Systems / Utilities

Description

The Voltage-Current Simscape Interface block connects Simscape™ Electrical™ Specialized Power Systems circuits with electrical elements from the Simscape Foundation library. This block preserves current through the block and voltage across the block, conserving electrical power.

  • On the Simscape Electrical Specialized Power Systems side, the electrical connector ports +sps and -sps act like a controlled voltage source, feeding voltage from the Simscape side to the connected Simscape Electrical Specialized Power Systems elements, while maintaining the current through the block.

  • On the Simscape side, the electrical connector ports +ssc and -ssc act like a controlled current source, feeding current from the Simscape Electrical Specialized Power Systems side to the connected Simscape elements, while maintaining the voltage across the block.

The following figure gives an overview of the interface.

The block measures the voltage between the +ssc and -ssc ports and propagates it to the +sps and -sps ports, preserving the polarity. The block also measures the current flowing from the +sps to the -sps port and propagates it from the -ssc to the +ssc port.

You can specify a filter to break the algebraic loop between Simscape Electrical Specialized Power Systems and Simscape ports. You can specify the filter as a first order continuous transfer function or as a discrete unit delay block. You can apply it on the Simscape Electrical Specialized Power Systems side, to the measured voltage, or on the Simscape side, to the measured current. Depending on the measured signal where the filter is applied, the other signal is always a direct feedthrough.

If you do not specify a filter, direct feedthrough is applied on both measured signals. However, this configuration results in an algebraic loop containing the Voltage Sensor, Controlled Voltage Source, Current Measurement, and Controlled Current Source blocks, which might cause numerical issues.

Examples

Interfacing Simscape Models with Simscape Electrical Specialized Power Systems

Interfacing Simscape Models with Simscape Electrical Specialized Power Systems

The interface between Simscape™ and Simscape Electrical™ Specialized Power Systems to design a breaker model.

Limitations

When simulating Simscape Electrical Specialized Power Systems models along with Simscape blocks, select the Simulink® solver carefully.

Use the ode23tb solver for solving Simscape Electrical Specialized Power Systems circuits containing switches or nonlinear element. If you use other stiff solvers, Simscape Electrical Specialized Power Systems software gives you the following warning:

Warning: You have required continuous-time simulation of a system containing 
switches or nonlinear elements. The ode23tb variable-step stiff solver with 
relative tolerance set to 1e-4 is recommended in order to get best accuracy 
and simulationperformance. For some highly nonlinear models it may be 
necessary to set the "Solver reset method" parameter to "Robust".
See "Improving Simulation Performance" chapter in Simscape Electrical 
Specialized Power Systems documentation for additional information on how to 
select an appropriate integration method.
'To ignore Simscape Electrical Specialized Power Systems warnings, select
"Disable Simscape Electrical SPS warnings" in the Powergui Preferences tab.';

The Simscape Electrical Specialized Power Systems warning can be disabled, as described in the warning message. However, if you use the ode23tb solver for solving models containing Simscape blocks, Simscape software gives you the following warning:

Warning: The solver chosen is not recommended if the model is stiff, which is
typical for models containing Simscape components. These solvers are typically
preferred for Simscape models:ode23t, ode15s or ode14x (fixed-step). To disable
this diagnostic,change the explicit solver diagnostic setting on the Simscape
panel of the model Configuration Parameters.

The Simscape warning can also be disabled, as described in the warning message.

Ports

Conserving

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Specialized electrical conserving port associated with the positive terminal of the Specialized Power Systems circuit.

Specialized electrical conserving port associated with the negative terminal of the Specialized Power Systems circuit.

Specialized electrical conserving port associated with the positive terminal of the Simscape circuit.

Specialized electrical conserving port associated with the negative terminal of the Simscape circuit.

Output

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Bus signal that contains the Simscape Electrical Specialized Power Systems current and voltage and the Simscape current and voltages.

Dependencies

To enable this port, select the Show measurement ports parameter.

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

When you select this parameter, the block applies direct feedthrough between Simscape Electrical Specialized Power Systems and Simscape ports on both sides.

Set this parameter to Low pass filter (continuous) (default) to implement a first order continuous transfer function filter between Simscape Electrical Specialized Power Systems and Simscape ports.

Set this parameter to Unit delay (discrete) to implement a discrete unit delay filter between Simscape Electrical Specialized Power Systems and Simscape ports.

Set this parameter to First-order input filtering to implement a first order continuous transfer function filter with first-order filtering of the Simulink-PS Converter block that provides one derivative. You can apply this filter only on the Simscape Electrical Specialized Power Systems side.

Set this parameter to Second-order input filtering to implement a first order continuous transfer function filter with second-order filtering of the Simulink-PS Converter block that provides derivatives one and two. You can apply this filter only on the Simscape Electrical Specialized Power Systems side.

Dependencies

To enable this parameter, clear the Direct feedthrough (no filter) parameter.

Time constant of low pass filter, in seconds.

Dependencies

To enable this parameter, set Filter type to Low pass filter (continuous), First-order input filtering, or Second-order input filtering.

Sample time of the unit delay filter, in seconds.

Dependencies

To enable this parameter, set Filter type to Unit delay (discrete).

Initial voltage value of the measured Simscape Electrical Specialized Power Systems voltage.

Dependencies

To enable this parameter, set Apply filter on to Simscape side.

Initial current value of the measured Simscape Electrical current.

Dependencies

To enable this parameter, set Apply filter on to Specialized Power Systems side.

Set this parameter to Specialized Power Systems side (default) to apply the filter on the measured Simscape Electrical Specialized Power Systems voltage.

Set this parameter to Simscape side to apply the filter on the measured Simscape current.

Dependencies

To enable this parameter, clear the Direct feedthrough (no filter) parameter and set Filter type to Low pass filter (continuous) or Unit delay (discrete).

If selected, the block exposes a Simulink output that returns the Simscape Electrical Specialized Power Systems current and voltage and to the Simscape current and voltages in a bus signal.

Extended Capabilities

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

Version History

Introduced in R2011b

See Also

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