Power factor correction (PFC) is a technique used in electrical systems to improve the efficiency and utilization of electrical power. It involves adjusting the phase relationship between voltage and current in an electrical circuit, aiming to make them as closely in-phase as possible. The power factor is a measure of how effectively the current is being converted into useful work (real power) in a circuit.
In an AC electrical circuit, power is the product of voltage (V), current (I), and the power factor (PF):
Real Power (P) = V x I x PF
The power factor can range from 0 to 1. A power factor of 1 (or 100%) means that the current and voltage are perfectly in phase, resulting in efficient utilization of electrical power. A power factor less than 1 indicates that the current and voltage are out of phase, leading to less efficient use of power and potentially higher energy costs.
Power factor correction strategies are employed to bring the power factor closer to 1. This is typically done by adding power factor correction devices or equipment to the electrical system. There are two main types of power factor correction:
Capacitive Power Factor Correction:
Capacitors are added to the circuit to supply reactive power (kVAR) to the system.
Reactive power is required by inductive loads (such as motors and transformers) to maintain their magnetic fields but doesn't contribute to useful work.
Capacitors introduce leading reactive power, offsetting the lagging reactive power from inductive loads, and thus improving the power factor.
Inductive Power Factor Correction:
Inductors (or reactors) are added to the circuit to introduce lagging reactive power, compensating for excessive leading power factor caused by capacitors.
Power factor correction improves power factor utilization in the following ways:
Energy Efficiency: By bringing the power factor closer to 1, the system becomes more energy-efficient. This reduces the amount of reactive power flowing through the system, which in turn reduces energy losses and increases the effective utilization of the power supply.
Reduced Energy Costs: Many utility companies charge customers based on both real power (kW) and reactive power (kVAR). A poor power factor results in higher kVAR, leading to increased energy bills. Power factor correction reduces the reactive power component, lowering energy costs.
Reduced Overloading: Improved power factor reduces the strain on electrical equipment, such as transformers, cables, and switchgear. This can extend the lifespan of equipment and reduce the risk of overloading.
Optimized System Capacity: Power factor correction can free up capacity in the electrical system, allowing more real power (kW) to be delivered without overloading the equipment.
In summary, a power factor correction strategy involves adjusting the reactive power component of an electrical system to improve the power factor, resulting in increased energy efficiency, reduced energy costs, and improved overall utilization of electrical power.