What functions does the APF (Active Power Filter) have?

In today's industrial and living environments, a large number of non-linear loads have become the main consumers of electricity. These devices not only enhance efficiency and convenience but also inject a significant amount of harmonic current into the power grid, resulting in a severe deterioration of power quality. The active power filter (APF) is like an intelligent "power grid cleaner" and "stabilizer", capable of real-time and dynamically compensating for harmonics and purifying the power grid environment. So, what are the core functions of APF?

Ⅰ. Core Function: Harmonic Compensation and Suppression

This is the most core and fundamental function of APF. It can detect the harmonic current in the power grid in real time and generate a compensation current of the same magnitude but opposite direction as the harmonic current, thereby effectively canceling out the harmonics.

Effect: It can effectively suppress the total harmonic distortion rate (THDi) of current on the power grid side from a very high level (such as above 30%) to below 5%, fully meeting the strict requirements of domestic and international power quality standards such as IEEE 519 and GB/T 14549.

II. Reactive Power Compensation

Apart from harmonics, many inductive loads (such as motors and transformers) also consume a large amount of reactive power, resulting in a low power factor, causing electricity penalty charges and additional losses in the lines. The APF can perform reactive power compensation in phases and continuously while compensating for harmonics.

Effect: The system's power factor can be stably compensated to above 0.98, even approaching 1. This effectively reduces the apparent power, lowers line losses and the burden on transformers, and avoids penalties for power adjustment fees.

III. Three-phase Load Imbalance Compensation

In low-voltage power distribution systems, the random connection of single-phase loads can easily lead to three-phase current imbalance, which may result in excessive neutral line current and reduced transformer efficiency. APF can effectively compensate for three-phase imbalance.

Effect: Significantly reduces neutral line current, balances the load of each phase, enhances the utilization rate of transformers and distribution facilities, and ensures the safe operation of the system.

IV. Suppressing Grid Resonance

The capacitive and inductive components in the power grid (such as compensation capacitor cabinets) may experience parallel or series resonance at specific harmonic frequencies, amplifying harmonic currents and even damaging equipment. The APF has an active damping function, which can effectively suppress this resonance.

Effect: Protect equipment such as capacitor compensation cabinets from damage caused by harmonic amplification, and enhance the stability and security of the entire power distribution system.