Power Factor Correction
When we talk about reactive power and power factor, we're referring to fundamental sinewave signals where current and voltage are at a different angle.
Typically the reactive power is calculated by the cos ϕ (also referred to as power factor, pf).
Why consider fundamental reactive power?
1) Power factor:
In many regions, utilities charge customer based on power factor. Due to inefficient use, a low power factor usually lead to higher charges.
2) Infrastructure efficiency:
Reactive power needs to be generated, transferred nd distributed. At all times, this will cause losses in the system.
3) Infrastructure costs:
Though reactive power doesn;t create any real work in the application, reactive power still increase the current in the whole system. This causes high costs due to necessary oversizing of equipment such as transformers and switches.
4) Voltage stability:
Avoiding reactive power and ensuring a stable pf stabilises the voltage and helps avoiding fluctuations in the voltage.
Navigating harmonics
With more complex loads, such as a combination of VFDs and inductive loads, accurately evaluating reactive power requires considering the distortion power caused by harmonics.
Looking at the true power factor this is affected by both THDi and cos(ϕ):
Therefore when improving power factor both harmonics and fundamental reactive power should be treated, rather than dealing with these two issues individually.
This leads to some advantages in the solution itself due to the calculation of the RMS current:
Using the equation above, fundamental current and harmonic currents are added as square sum. In a system with 100A of harmonic currents and 150A of reactive current, they would typically require two individual solutions with 100A and 150A. This leads to 250A compensation current in total.
100 A + 150 A = 250 A
By using the REVCON RPC-eSVG or RHF-Active, significant savings can be archieved.
The required compensation current in this example is reduced by 28% by a smarter connection.
