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Build and Simulate Composite Resistive and Reactive Three-Phase Models

This tutorial shows how to build a Simscape™ Power Systems™ Simscape Components model. The model simulates the behavior of a three-phase AC voltage source driving a simple load.

To see the completed model, click Simple Three-Phase Model.

Select System Component Blocks

  1. Open a blank model.

  2. Add these blocks to the model.

    Block

    Purpose

    Library Path

    Quantity

    ScopeDisplay phase voltages and currents for the three-phase system.

    Simulink > Sinks

    1

    Electrical ReferenceProvide the ground connection for electrical conserving ports.

    Simscape > Foundation Library > Electrical > Electrical Elements

    1

    PS-Simulink ConverterConvert the physical signals to a Simulink® signals.

    Simscape > Utilities

    2

    Solver ConfigurationDefine solver settings that apply to all physical modeling blocks.

    Simscape > Utilities

    1

    Grounded NeutralProvide an electrical ground connection for each phase of the three-phase system.

    Simscape > Power Systems > Simscape Components > Connections

    2

    RLCModel the resistive, inductive, and capacitive properties of the three-phase load.

    Simscape > Power Systems > Simscape Components > Passive Devices

    1

    Current SensorConvert the electrical current flowing in each phase of the three-phase load into a physical signal proportional to that current.

    Simscape > Power Systems > Simscape Components > Sensors

    1

    Phase Voltage SensorConvert the voltage across each phase of the three-phase system into a physical signal proportional to that voltage.

    Simscape > Power Systems > Simscape Components > Sensors

    1

    Voltage SourceProvide an ideal three-phase voltage source that maintains a sinusoidal voltage across its output terminals, regardless of the current flowing in the source.

    Simscape > Power Systems > Simscape Components > Sources

    1

  3. Add a second input port to the Scope block.

    1. Right-click the Scope block.

    2. From the context menu, select Signals & Ports > Number of Input Ports > 2

  4. Connect the blocks as shown.

  5. Save the model using the name simplethreephasemodel.

    The blocks in this model use composite three-phase ports. For more information, see Three-Phase Ports.

Specify Simulation Parameters

As with Simscape models, you must include a Solver Configuration block in each topologically distinct physical network. This model has a single physical network, so use one Solver Configuration block.

  1. In the Solver Configuration block, select Use local solver and set Sample time to 0.0001.

    In Simscape-based models, the local solver is a sample-based solver that represents physical network states as discrete states. For most Simscape Power Systems Simscape Components models, the local solver is an appropriate first choice. The solver updates block states once per simulation time step, as determined by Sample time. For simulation of a 60-Hz AC system, an appropriate sample time is a value in the order of 1e-4. For more information on solver options, see Solver Configuration.

    If you prefer to use a continuous solver instead of a discrete solver, clear the Use local solver check box in the Solver Configuration block. The simulation then uses the Simulink solver specified in the model configuration parameters (Simulation > Model Configuration Parameters). For Simscape Power Systems Simscape Components models, an appropriate solver choice is the moderately stiff solver ode23t. For a 60-Hz AC system, specify a value for Max step size in the order of 1e-4. For more information, see Variable-Step Continuous Explicit Solvers (Simulink).

  2. In the Simulink Editor, set the simulation Stop time to 0.1.

Load Impedance Parameters

The RLC block models resistive, inductive, and capacitive characteristics of the three-phase load. Using the Component structure parameter, you can specify a series or parallel combination of resistance, inductance, and capacitance.

In the RLC block, the defaults are:

  • Component structureR.

  • Resistance1 Ω.

Using the default Component structure value, R, models a three-phase load that is purely resistive in nature. The resistance in each phase is 1 Ω.

Specify Display Parameters

Sensor blocks in the model convert the current and voltage in each phase of the three-phase system to proportional physical signals. PS-Simulink Converter blocks convert the physical signals into Simulink signals for the Scope block to display.

  1. Of these three types of blocks, only the converter blocks have parameters. For this example:

    • Set Output signal unit of the PS-Simulink Converter block to A. This setting ensures that the block outputs a signal with the same magnitude as the ampere signal that enters it.

    • Set Output signal unit of the PS-Simulink Converter1 block to V. This setting ensures that the block outputs a signal with the same magnitude as the voltage signal that enters it.

  2. Label the input signals to the Scope block. Double-click each line, and type the appropriate label, Currents or Voltages, as shown in the model graphic.

You are ready to simulate the model and analyze the results.

Save and Simulate the Model

  1. Save the model.

  2. Simulate the model. In the menu bar of the Simulink Explorer, click the Run button.

Analyze the Resistive Three-Phase Model Simulation Results

  1. View the phase currents and voltages. Double-click the Scope block.

  2. To scale the scope axes to the data, click the Autoscale button .

In this simulation, the Component structure parameter of the RLC block specifies that the electrical characteristics of the three-phase load are purely resistive. Therefore, for each phase of the three-phase system, the voltage and current remain in phase with each other. Because the resistance in each phase is 1 Ω, the magnitude of the phase voltage is equal to the magnitude of the phase current.

Create and Simulate a Reactive Three-Phase Load

This procedure shows you how to modify the model to create a reactive load. A reactive load has inductive or capacitive characteristics.

  1. Save this version of the model using the name simplethreephasemodel_reactive.

  2. In the RLC block, set:

    • Component structure to Series RL

    • Inductance to 0.002

  3. Simulate the model.

Analyze the Reactive Three-Phase Model Simulation Results

  1. View the simulation results. Autoscale the scope axes.

  2. Examine the results in closer detail. For example, click the Zoom button and drag a box over the first third of one of the plots.

    The electrical characteristics of three-phase load are no longer purely resistive. Because the load has an inductive characteristic, the current flowing in each phase lags the voltage.

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