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Essential Power Engineering Modeling Techniques

Overview of Modeling Rules

SimPowerSystems™ Simscape™ Components models are essentially Simscape block diagrams refined for modeling three-phase electrical systems. SimPowerSystems Simscape Components blocks feature these port types:

  • Three-phase ports, which connect the phases of a three-phase electrical system between SimPowerSystems Simscape Components blocks.

    There are two three-phase port types in SimPowerSystems Simscape Components blocks, composite and expanded. You can connect a composite three-phase port only to another composite three-phase port. You can connect the individual electrical conserving ports of an expanded three-phase port only to other electrical conserving ports. For more information, see Three-Phase Ports.

  • Electrical and mechanical rotational conserving ports, which connect directly to Simscape foundation blocks.

    Each port type has specific Across and Through variables associated with it. To learn about the rules to follow when building an electromechanical model, see Basic Principles of Modeling Physical Networks in the Simscape documentation.

  • Physical signal ports, which connect to Simulink® blocks through the Simulink-PS Converter and PS-Simulink Converter blocks from the Simscape Utilities library. These blocks convert physical signals to and from Simulink mathematical signals.

Keep these rules in mind when using each port type in SimPowerSystems Simscape Components blocks.

  • You can connect physical conserving ports only to other conserving ports of the same type. Electrical conserving ports in SimPowerSystems Simscape Components blocks can connect directly to SimElectronics® blocks and Simscape electrical components. Mechanical rotational conserving ports in SimPowerSystems Simscape Components blocks can connect directly to Simscape mechanical rotational components.

  • The physical connection lines that connect conserving ports are nondirectional lines that carry physical variables (Across and Though variables) rather than signals. You cannot connect physical conserving ports to Simulink ports or to physical signal ports.

  • You can branch physical connection lines. When you do so, directly connected components share the same Across variables. The value of any Through variable (e.g., current or torque) transferred along the physical connection line is divided among the multiple components connected by the branches.

    For each Through variable, the sum of the values flowing into a branch point equals the sum of the values flowing out.

  • You can connect physical signal ports to other physical signal ports using regular connection lines, similar to Simulink signal connections. These connection lines carry physical signals between SimPowerSystems Simscape Components blocks.

  • You can connect physical signal ports to Simulink ports through converter blocks. Use the Simulink-PS Converter block to connect Simulink outports to physical signal inports. Use the PS-Simulink Converter block to connect physical signal outports to Simulink inports.

  • Unlike Simulink signals, physical signals can have units. In SimPowerSystems Simscape Components block dialog boxes, you can specify the units along with the parameter values, where appropriate. Use the converter blocks to associate units with an input signal and to specify the desired output signal units.

For an example of these rules applied to an electromechanical model, see Three-Phase Asynchronous Machine Starting.

Required Blocks

Each topologically distinct physical network in a diagram requires exactly one Solver Configuration block from the Simscape Utilities library. The Solver Configuration block specifies global environment information for simulation and provides parameters for the solver that your model needs for simulation.

Each electrical network requires an Electrical Reference block. This block establishes the electrical ground for the circuit. Networks with electromechanical blocks also require a Mechanical Rotational Reference block. For more information about using reference blocks, see Grounding Rules.

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