Wye-Connected Variable Load (Lagging)
Three-phase AC load connected in a Star pattern.
Description
The Wye-Connected Variable Load (lagging) unit simulates a variable active-inductive three-phase load connected in a Star pattern. Each phase of the load contains a resistor R and an inductor L. The block calculates the resistance and inductance required to extract the active and reactive powers given by the values at the P and Q inputs at nominal voltage and nominal frequency. Thus, the block can represent an active-inductive load.
To ensure that the resistance and inductance are always greater than zero, specify the minimum active and reactive powers that the load consumes. These values must be greater than zero.
Equations
The series resistance and inductance of each phase are determined as follows:
,
Where:
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- is the series resistance of each phase.
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- series inductance of each phase.
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- RMS nominal line voltage.
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- rated electrical frequency of the alternating current.
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- required three-phase real power.
-
- required three-phase reactive power.
Inductance is defined as the ratio of the magnetic flux to the steady-state current:
.
Therefore, the voltage dependence of current for an inductor is as follows:
.
Ports
Parameters
Main
Rated voltage - rated line voltage
`24e3 V (By default)
RMS value of the nominal linear voltage for the resistance equation.
Rated electrical frequency - rated electrical frequency
50 Hz (By default).
The nominal or nominal frequency of the AC mains to which the transformer is connected. The value must be greater than 0.
Minimum real power - minimum active power
1e3 W (by default).
The minimum active power dissipated by a three-phase load when the nominal voltage is applied. The value must be greater than 0.
Minimum reactive power - minimum reactive power
1e3 V*A (by default).
The minimum reactive power consumed by a three-phase load when the nominal voltage is applied. The value must be greater than 0.