Electrical distribution systems work on real power, and they also need the supply of reactive power that is supplied by capacitor banks.

Power factor correction stabilizes the electrical distribution system and prolongs the life of devices.

But power factor correction can be done using different methods. Here, you’ll learn all about them. You’ll learn about:

  • Active power factor correction
  • Passive power factor correction
  • Power factor correction due to the location of the capacitor.

So, keep reading further. It’ll benefit you.

 

What is Power Factor Correction?

A method of raising a power supply’s power factor is power factor correction. Without power factor adjustment, switching power supplies drain current in brief, intense pulses. Both active and passive methods can be used to smooth out these pulses. This lowers the perceived input power and RMS current, raising the power factor.

In order to optimize the amount of real power from the AC supply, the power factor correction modifies the input current. Electrical equipment should ideally simulate a pure resistor by simulating a load with zero reactive power. And the waveforms of the current and voltage would be identical sine waves that were in phase with one another. However, there is always a power lag that results in lower power factors because the majority of circuits have reactive components.

In a perfect system, all of the power drained from the AC mains is put to good use. Only when the current and voltage are in phase is this possible. A portion of the energy from the AC outlet is lost when the phase between the two changes because it cannot be put to good use.

In order to meet the demand for both lost and useable energy, the energy producer must increase output. More capital expenditures will be necessary for generation, transmission, distribution, and control. The consumer bears the costs, which also contribute to global warming.

Even while power factor correction doesn’t quite reach 1, it does come as close as 0.95, which is suitable for most applications. Power factor correction attempts to push the power factor of the electrical system, such as the power supply, towards 1.

 

Power Factor Correction Methods

The passive PFC and the active PFC are the two most used methods of power factor correction for power supplies.

Passive Power Factor Correction

A small power supply of up to 100W is utilized for this. The correction technique employs a series resonance circuit made up of a capacitor, an inductor, and a low-pass harmonic filter at the AC input. Smaller components can nevertheless provide an effective and affordable power factor adjustment.

The passive PFCs are easy to use, reliable, and resilient for reduced power needs. Additionally, they don’t produce EMI. However, the inductor makes them large and hefty.

passive PFCsPros

  • Inexpensive
  • Efficient
  • Simple construction

Cons

  • Heavy and large size
  • No voltage regulation
  • Limited range of input voltages

 

Active Power Factor Correction

For power supplies that are greater than 100W, active PFC techniques are preferred. This approach is lighter and less bulky, and it offers a more effective correction.

In order to ensure that the input voltage and current are in phase, a control circuit that measures the input voltage and current changes the switching time and duty cycle. This offers automatic AC input voltage adjustment, producing a potential power factor of greater than 0.95. The active PFC can function over a wider range of input voltages than the passive PFC. However, it needs more parts, which increases its complexity and cost.

active PFC

Pros

  • Attains PF of 0.95 or higher
  • Small and light
  • Large range of AC input voltage and frequency
  • More flexible
  • Greater control

Cons

  • Complex
  • Higher cost

 

Power Factor Correction Methods Depending Upon the Location of Capacitor Bank

 

Capacitor installation is theoretically possible anywhere. However, we must assess the relevant economic and practical viability. The types of power factor correction are as follows, depending on where the capacitor is located.

Distributed power factor correction

Capacitor banks are directly linked to the terminal of the load that requires reactive power in this method of power factor correction. This style of installation is incredibly affordable and straightforward. The load and the capacitor bank can both employ the same overcurrent protection mechanism, as indicated in the image below. It can therefore be attached and disconnected at the same time.

Distributed PFC

This kind of power factor correction is recommended for heavy loads that are connected to the system for an extended period of time. Induction motors and fluorescent lights typically use distributed power factor correction.

Group power factor correction

This approach is typically employed for loads that function similarly. To increase the power factor, a common capacitor bank is offered, as seen in the picture.

Group PFC

Therefore, you can use a shared capacitor bank for power factor adjustment if, for example, you have three similar induction motors that are employed for the same purpose. Although this approach is similarly cost-effective, it is only advised for light loads.

Centralize power factor correction

Centralize PFC

 

Not all loads in a system are connected 24 hours a day. There are some loads that are ON for a very little period of time. Utilizing distributed power factor adjustment in such circumstances is not a wise move. So it is preferred to use centralized power factor correction whose capacitor banks are situated at the system’s starting point or centre. This enables a notable reduction in the installed capacitors’ overall power. As keeping capacitor banks permanently connected to the system is not a good idea, the capacitor banks must be installed with a switching device.

Combined power factor correction

As implied by the name, it combines two distinct approaches, namely distributed power factor correction and centralized power factor correction. For a big load that operates continuously, distributed power factor correction is applied in this method. Additionally, a centralized power factor correction method is employed to enhance the power factor of tiny equipment.

Automatic power factor correction

Automatic PFC

Due to the equipment’s working cycle, the majority of systems do not absorb reactive power continuously. There are methods for automatic power factor correction included in such installations. It enables switching between several capacitor banks as necessary. These APFC panels, also known as automatic power factor control panels, are often utilized. The following are the key components of these panels.

  • Sensors for measuring voltage and current
  • Devices for switching and protection
  • a sophisticated system that assesses the difference between the present and needed power factors
  • APFC panel

 

Benefits of Power Factor Correction

Lower losses and effective use of all produced power are achieved with a power factor of 1 or as close to 1.

  • Technical Benefits

Enhanced effectiveness and decreased power demand resulted in less strain on the cables and switching equipment, lower prices for the consumer, and support for a higher load.

  • Commercial Benefits

System losses are decreased, and the cost of capital for the generating business is lower. Since there are no fees for the extra reactive power, there are also savings on electricity expenditures. The systems and equipment used in transmission and distribution operate more efficiently and survive longer as a result.

  • Environmental Benefits

Power factor correction reduces CO2 emissions.

 

Conclusion

Now, you know all types of power factor corrections. Remember, you must use the right power factor correction method for your electrical distribution systems. Otherwise, the life of your devices can decrease.

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