Three-phase load wired in delta configuration

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## Description

The Delta-Connected Load block models a three-phase load wired in a delta configuration. Each limb of the load can include any combination of a resistor (R), capacitor (C), and inductor (L), connected in series or in parallel.

You can specify values for the R, L, and C components directly in terms of resistance, inductance, and capacitance, or by rated powers at a rated voltage and frequency.

• If you parameterize the block directly in terms or R, L, and C values, then for initialization provide a three-element row vector of initial voltages for a capacitor, and a three-element row vector of initial currents for an inductor.

• If you parameterize the block in terms of rated powers, then specify initial conditions in terms of an initial voltage, initial voltage phase, and initial frequency. For example, if the load is connected directly to a three-phase voltage source, then the initial conditions are identical to the source values for RMS line voltage, frequency, and phase shift. To specify zero initial voltage magnitude, set the initial voltage to 0.

For certain combinations of R, L, and C, for some circuit topologies, specify parasitic resistance or conductance values that help the simulation to converge numerically. These parasitic terms ensure that an inductor has a small parallel resistive path and that a capacitor has a small series resistance. When you parameterize the block in terms of rated powers, the rated power values do not account for these small parasitic terms. The rated powers represent only the R, L, and C values of the load itself.

### Block parameterization

The following two tables list the block parameters for each Component structure, based on the selected Parameterization option:

• Specify by rated power

• Specify component values directly

Specify by Rated Power

Component StructureMain ParametersParasitics ParametersInitial Conditions Parameters

`R`

Rated voltage

Real power

None

None

`L`

Rated voltage

Rated electrical frequency

Inductive reactive power

Parasitic parallel conductance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`C`

Rated voltage

Rated electrical frequency

Capacitive reactive power

Parasitic series resistance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Series RL`

Rated voltage

Rated electrical frequency

Real power

Inductive reactive power

Parasitic parallel conductance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Series RC`

Rated voltage

Rated electrical frequency

Real power

Capacitive reactive power

None

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Series LC`

Rated voltage

Rated electrical frequency

Inductive reactive power

Capacitive reactive power

Parasitic parallel conductance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Series RLC`

Rated voltage

Rated electrical frequency

Real power

Inductive reactive power

Capacitive reactive power

Parasitic parallel conductance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Parallel RL`

Rated voltage

Rated electrical frequency

Real power

Inductive reactive power

None

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Parallel RC`

Rated voltage

Rated electrical frequency

Real power

Capacitive reactive power

Parasitic series resistance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Parallel LC`

Rated voltage

Rated electrical frequency

Inductive reactive power

Capacitive reactive power

Parasitic series resistance

Terminal voltage magnitude

Terminal voltage angle

Frequency

`Parallel RLC`

Rated voltage

Rated electrical frequency

Real power

Inductive reactive power

Capacitive reactive power

Parasitic series resistance

Terminal voltage magnitude

Terminal voltage angle

Frequency

Specify Component Values Directly

Component StructureMain ParametersParasitics ParametersInitial Conditions Parameters

`R`

Resistance

None

None

`L`

Inductance

Parasitic parallel conductance

Initial inductor current [ Ia Ib Ic ]

`C`

Capacitance

Parasitic series resistance

Initial capacitor voltage [ Va Vb Vc ]

`Series RL`

Resistance

Inductance

Parasitic parallel conductance

Initial inductor current [ Ia Ib Ic ]

`Series RC`

Resistance

Capacitance

None

Initial capacitor voltage [ Va Vb Vc ]

`Series LC`

Inductance

Capacitance

Parasitic parallel conductance

Initial inductor current [ Ia Ib Ic ]

Initial capacitor voltage [ Va Vb Vc ]

`Series RLC`

Resistance

Inductance

Capacitance

Parasitic parallel conductance

Initial inductor current [ Ia Ib Ic ]

Initial capacitor voltage [ Va Vb Vc ]

`Parallel RL`

Resistance

Inductance

None

Initial inductor current [ Ia Ib Ic ]

`Parallel RC`

Resistance

Capacitance

Parasitic series resistance

Initial capacitor voltage [ Va Vb Vc ]

`Parallel LC`

Inductance

Capacitance

Parasitic series resistance

Initial inductor current [ Ia Ib Ic ]

Initial capacitor voltage [ Va Vb Vc ]

`Parallel RLC`

Resistance

Inductance

Capacitance

Parasitic series resistance

Initial inductor current [ Ia Ib Ic ]

Initial capacitor voltage [ Va Vb Vc ]

### Variables

Use the Variables tab to specify the priority and initial target values for the block variables before simulation. For more information, see Set Priority and Initial Target for Block Variables.

To enable the Variables tab, set the Parameterization parameter to ```Specify component values directly```. The tab is not visible if you set Component structure to `R`.

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## Parameters

expand all

Whether to model composite or expanded three-phase ports.

Composite three-phase ports represent three individual electrical conserving ports with a single block port. You can use composite three-phase ports to build models that correspond to single-line diagrams of three-phase electrical systems.

Expanded three-phase ports represent the individual phases of a three-phase system using three separate electrical conserving ports.

### Main

Select one of these values:

• `Specify by rated power` — Specify values for the R, L, and C components by rated powers at a rated voltage and frequency. This is the default.

• `Specify component values directly` — Specify values for the R, L, and C components directly in terms of resistance, inductance, and capacitance.

Switching the Parameterization value resets the Component structure value. Select the component parameterization option first, and then the component structure. If you later switch the Parameterization value, check the Component structure value and reselect it, if necessary.

Select the desired combination of a resistor (R), capacitor (C), and inductor (L), connected in series or in parallel.

Voltage for which load powers are specified. This parameter is visible only when you specify values by rated power.

#### Dependencies

This parameter is visible only when you select `Specify by rated power` for the Parameterization parameter.

Total real power dissipated by three-phase load when supplied at the rated voltage. The value must be greater than 0.

#### Dependencies

This parameter is visible only when you select `Specify by rated power` for the Parameterization parameter and select a component structure that includes a resistor.

Frequency for which reactive load powers are specified.

#### Dependencies

This parameter is visible only when you select `Specify by rated power` for the Parameterization parameter.

Total inductive reactive power taken by the three-phase load when supplied at the rated voltage. The value must be greater than 0.

#### Dependencies

This parameter is visible only when you select `Specify by rated power` for the Parameterization parameter and select a component structure that includes an inductor.

Total capacitive reactive power taken by the three-phase load when supplied at the rated voltage. The value must be less than 0.

#### Dependencies

This parameter is visible only when you select `Specify by rated power` for the Parameterization parameter and select a component structure that includes a capacitor.

The resistance of each of the load limbs.

#### Dependencies

This parameter is visible only when you select `Specify component values directly` for the Parameterization parameter and select a component structure that includes a resistor.

Inductance of each of the load limbs.

#### Dependencies

This parameter is visible only when you select `Specify component values directly` for the Parameterization parameter and select a component structure that includes an inductor.

Capacitance in each of the load limbs.

#### Dependencies

This parameter is visible only when you select `Specify component values directly` for the Parameterization parameter and select a component structure that includes a capacitor.

### Parasitics

Represents small parasitic effects. The parameter value corresponds to the series resistance value added to all instances of capacitors in the load.

Represents small parasitic effects. The parameter value corresponds to the parallel conductance value added across all instances of inductors in the load.

If you set Component structure to either `Series RL`, ```Series LC```, or `Series RLC`, the parasitic parallel conductance is connected across the full branch of the block.

## Version History

Introduced in R2013b