User:Thedinoman123/sandbox/active power filter

An active power filter(APF) is an electronic device used to compensate for power quality problems that may arise through current harmonics. Active power filters are able to compensate for the current harmonics in a system in real-time, by monitoring the current and voltage of a system at all times and injecting an equal, but opposite current harmonic. All distribution circuits for modern electronic devices have some degree of harmonic frequencies, making the device viable in many situations. Due to the device's usefulness, you can find active power filters in many industrial and commercial settings.

Current harmonics are created by nonlinear loads must be compensated for due to potential problems such as:

• Malfunction of sensitive equipment
• Random tripping of circuit breakers
• Flickering lights
• very high neutral currents
• overheated phase conductors, panels, and transformers
• premature failure of transformers and uninterruptible power supplies
• reduced power factor
• reduced system capacity

The alternative filter for power filtering is the passive filter, which is a much simpler device. The passive power filter combines inductance, capacitance, and resistance parts to control harmonics. The device detours the harmonic current to take it out of the nonlinear load. The device is highly reliable and very cheap, making it a great alternative. However, the downsides include having to be specified for a different harmonic current for different systems and that resonance is created whenever the passive filter is in use, which damages the system.

Method of Operation

The basic method of operation includes 3 steps.

1. Signal conditioning
   • Signal conditioning is the detection of harmonics in a power distribution line.
2. Derivation of compensating signal
   • Creation of a potential signal that can compensate the current harmonic from the load.
3. Generation of gating signal
   • Generating that potential signal to go through the circuit and compensate for the current harmonic coming from the load.

The different types of active power filters follow these three steps in different ways.

Variations

Shunt

The shunt active power filter is the most widely used type of filter.

- injects harmonic current with the same magnitude but with 180 degrees phase in difference with the harmonic current

- most important and widely used type

- purpose is to cancel the load current harmonics fed to the supple

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Pros and Cons

Pros

• Can suppress both supply current harmonics and reactive currents.

External links

• www.example.com