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Optimize Your Power Factor with Clean Power VFD

Optimize Your Power Factor with Clean Power VFD by SmartD Technologies: Reducing Harmonics and Boosting Efficiency

POOR POWER FACTOR CAN STRAIN THE ELECTRICAL GRID AND INCREASE ENERGY COSTS

Conventional VFDs are non-linear loads that create harmonics in the electrical system, which leads directly to poor power factor and harmonics in the electrical system.

Strain on the electrical grid:

Increased current demand:

Poor power factor means more current is needed to deliver the same amount of useful power.
This increased current flow can strain the electrical grid and distribution system.

Voltage drops and regulation issues:

Higher currents can cause significant voltage drops across conductors, leading to voltage regulation problems.
This affects the stability and reliability of the electrical supply. 

Higher energy costs:

Increased Operational Costs:

Lower power factor can lead to increased operational costs due to the need for larger capacity transformers, generators, and other infrastructure to handle the higher currents.

Utility Penalties:

Many utility companies charge extra for low power factor because it requires them to generate and manage more power to deliver the same amount of real power to customers.
These penalties compensate for the additional costs associated with managing low power factor loads.

Equipment overheating and damage:

Overloading:

Persistent low power factor can cause electrical equipment to operate at higher currents than designed, leading to overheating and potential damage.

Reduced Lifespan:

Reduced Lifespan: Overheating can shorten the lifespan of equipment, resulting in more frequent maintenance and replacement, which adds to operational costs.

ACTIVE POWER FACTOR CORRECTION AND REDUCED REACTIVE POWER

The Clean Power VFD uses an Active Front End (AFE) to reduce harmonics distortion compared to traditional rectifiers. This AFE actively corrects the power factor in real time and prevents the creation of additional reactive power, which can harm the power factor.

By outputting three sine wave signals with minimal harmonics, the Clean Power VFD ensures that the current waveform aligns closely with the voltage waveform.
This alignment reduces the phase difference between voltage and current, thus decreasing reactive power and achieving a power factor closer to unity. This indicates voltage and current, thus decreasing reactive power and achieving a power factor closer to unity.

EXTERNAL LAB TEST SETUP

An autotransformer with an impedance of less than 2% is used to supply the systems under test with voltage of 480V. In addition, 500ft of VFD cable is used to connect a 25HP motor to the systems. Moreover, an electrical generator (not shown) is used to provide the mechanical load of the motor. The load is controlled by modifying the generator field current.

Drive Systems Under Test (DUT)
The same tests were performed on three (3) drive systems:
1. Clean Power VFD
2. Conventional 6 6-pulse VFD without filters
3. Conventional 6 6-pulse VFD with a passive harmonic filter and  sinewave filter

Diagram of lab test setup for harmonic measurement, including utility power, transformer, DUT, and motor

Performance Comparison Results

Input Line Voltage and Current Waveforms

Figure 1 shows the captured voltage and current waveforms for the Clean Power VFD operating at 60 Hz under full load conditions. It clearly shows that the Clean Power VFD supply voltage and current are aligned, minimizing the phase difference, thus reducing the reactive power and resulting in a power factor near unity. (from 0.992 to 0.996)

Graph showing the input voltage and current waveforms for the Clean Power VFD, with three distinct sine waves in pink, yellow, and blue, demonstrating minimal phase difference and harmonic distortion
Figure 1

Figure 2 shows the power factor on the line side for the conventional VFD. It illustrates how harmonics distort the Current, causing misalignment between the voltage and current waveform creating lower power factor (0.94 to 0.95).

Graph showing the input voltage and current waveforms for a conventional VFD, with three sine waves in pink, yellow, and blue displaying significant distortion and phase misalignment
Figure 2

Figure 3 shows the power factor on the line side for the conventional VFD with a passive harmonic filter. It shows that the harmonic filter helps to re-align the voltage and current, which helps to improve the power factor.

Graph showing the input voltage and current waveforms for a conventional VFD with filters, with three sine waves in pink, yellow, and blue demonstrating improved but still imperfect alignment
Figure 3

Power Factor Comparison

Figure 4 shows the power factor on the line side for the tested systems. As expected when the load increases, the conventional VFD’s power factor becomes greater with close to 0.95 at full load.
Adding the passive harmonic filter to the conventional VFD, the power factor is improved, closer to the unit. The decrease of power factor could be caused by the reactor power of the capacitors of the passive harmonic filter.
The Clean Power VFD has better performance in terms of power factor near unity, from 0.992 at to 0.996 .

Line graph showing the power factor performance of three VFDs—SmartD Clean Power VFD, Conventional VFD, and Conventional VFD with filters—across motor loads ranging from 65% to 100%

Conclusion

The test report compares the performance of the Clean Power VFD with a conventional VFD and a combination of a conventional VFD and filters, focusing on input voltage and current waveforms and power factor results.

The Clean Power VFD demonstrates a superior power factor performance due to its high switching frequency, active front end, and integrated filters. These features enable it to generate clean input and output signals, reducing harmonic distortion.

By minimizing the impact of harmonics on voltage and current waveforms, the Clean Power VFD achieves a power factor close to unity. This results in optimal power efficiency
and reduced energy costs.

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