# Parallel RLC Load

Implement linear parallel RLC load

## Library

Simscape / Electrical / Specialized Power Systems / Passives

## Description

The Parallel RLC Load block implements a linear load as a parallel combination of RLC elements. At the specified frequency, the load exhibits a constant impedance. The active and reactive powers absorbed by the load are proportional to the square of the applied voltage.

Only elements associated with nonzero powers are displayed in the block icon.

## Parameters

### Parameters Tab

**Nominal voltage Vn**The nominal voltage of the load, in volts RMS (Vrms). Default is

`1000`

.**Nominal frequency fn**The nominal frequency, in hertz (Hz). Default is

`60`

.**Active power P**The active power of the load, in watts. Default is

`10e3`

.**Inductive reactive power QL**The inductive reactive power QL, in vars. Specify a positive value, or 0. Default is

`100`

.**Capacitive reactive power QC**The capacitive reactive power QC, in vars. Specify a positive value, or 0. Default is

`100`

.**Set the initial capacitor voltage**If selected, the initial capacitor voltage is defined by the

**Capacitor initial voltage**parameter. If cleared, the software calculates the initial capacitor voltage in order to start the simulation in steady-state. Default is cleared.The

**Set the initial capacitor voltage**parameter have no effect on the block if the capacitive reactive power is equal to zero.**Capacitor initial voltage (V)**The initial capacitor voltage used at the start of the simulation. The

**Capacitor initial voltage**parameter have no effect on the block if the capacitive reactive power is equal to zero and if the**Set the initial capacitor voltage**parameter is cleared. Default is`0`

.**Set the initial inductor current**If selected, the initial inductor current is defined by the

**Inductor initial current**parameter. If cleared, the software calculates the initial inductor current in order to start the simulation steady-state. Default is cleared.The

**Set the initial inductor current**parameter have no effect on the block if the inductive reactive power is equal to zero.**Inductor initial current (A)**The initial inductor current used at the start of the simulation. The

**Inductor initial current**parameter have no effect on the block if the inductive reactive power is equal to zero and if the**Set the initial inductor current**parameter is cleared. Default is`0`

.**Measurements**Select

`Branch voltage`

to measure the voltage across the Parallel RLC Load block terminals.Select

`Branch current`

to measure the current flowing through the Parallel RLC Load block.Select

`Branch voltage and current`

to measure the voltage and the current of the Parallel RLC Load block.Default is

`None`

.Place a Multimeter block in your model to display the selected measurements during the simulation. In the

**Available Measurements**list box of the Multimeter block, the measurement is identified by a label followed by the block name.Measurement

Label

Branch voltage

`Ub:`

Branch current

`Ib:`

### Load Flow Tab

The Load Flow tool of the powergui block uses the parameters on this tab. These load flow parameters affect only model initialization. They do not affect simulation.

**Load type**Specify the load type. The default value is

`constant Z`

.If you select

`constant Z`

, the load impedance is determined from the nominal phase-to-phase voltage Vn, active power P, and reactive power (QL-QC) specified on the**Parameters**tab of the block dialog box. During the load flow solution, the impedance is kept constant. The effective P and Q therefore vary proportionally to the square of the bus voltage computed by the Load Flow tool.If you select

`constant PQ`

, the active power P and reactive power Q are kept constant and equal to the values specified on the**Parameters**tab of the block dialog box. When you apply the load flow solution to the model (by clicking**Apply**in the Load Flow tool), the**Nominal phase-to-phase voltage Vn**parameter on the**Parameters**tab is automatically adjusted to the phase-to-phase bus voltage computed by the Load Flow tool.If you select

`constant I`

, the load current is kept constant at its nominal value determined from the base voltage specified in the dialog box of the associated Load Flow Bus block and from active power P and reactive power QL and QC specified on the**Parameters**tab of the block dialog box. The effective P and Q therefore vary proportionally to the bus voltage computed by the Load Flow tool. When you apply the load flow solution to the model (by clicking**Apply**in the Load Flow tool), the pu value of the nominal voltage Vn on the**Parameters**tab is automatically adjusted to the square root of the load voltage (in pu) computed by the Load Flow tool.

## Examples

The `power_paralload`

example uses a Parallel RLC Load block to implement a load.

## Version History

**Introduced before R2006a**