Question

what is the impact of changing the values of RLC load PQ in the Simulink ( Load flow ) ?

Answer 1

The Series RLC Load block implements a linear load as a series combination of R L C 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.

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.