Difference in Active and Reactive power input and output.

In my Simulink project, I have used wye connected lagging power loads (in which I have specified the values of Active and Reactive power) these loads are connected to three phase synchronous machine. The machine is connected to a Automatic voltage regulator modeled using a SMAC1C model. The issue I am facing is when I am keeping the P and Q values fixed at the load side, the results which I am getting for the values of P and Q are not matching. For example when I am putting a load of 880KW and 660KVAR the results obtained are 705kW (0.641 pu)and 468KVAR (0.425 pu). I have put the reference value of voltage as 1pu in the AVR model.

Answer 1

[Riya]

Hello Shagun,

As per my understanding you are facing issue when keeping the values fixed in load side but getting different values.

Please note that the main difference between active power (P) and reactive power (Q) lies in their physical characteristics and how they affect the electrical system.

In an electrical system, the total power (S) is the combination of active power (P) and reactive power (Q). It is measured in volt-amperes (VA) or kilovolt-amperes (kVA). The relationship between active power, reactive power, and total power is defined by the power factor (PF), which is the cosine of the angle between the voltage and current waveforms.

In your Simulink project, it seems that the discrepancy between the specified load values of active power (880 kW and 660 kVAR) and the obtained results (705 kW and 468 kVAR) might be due to the power factor.

The power factor determines the ratio between active power and total power. If the power factor is less than 1, it means that there is a reactive power component present in the system.

To resolve this issue, you can check the power factor settings in your Simulink model and ensure that it is accurately representing the power factor of your load. Additionally, verify the accuracy of the reference voltage value (1 pu) used in the AVR model as it can also affect the calculated power values.

Hope it helps.