What's the difference of passive harmonic filter, active harmonic filter andtuned harmonic filter

Passive harmonic filters, active harmonic filters, and tuned harmonic filters are all used to mitigate harmonics in electrical systems, but they operate differently and have distinct characteristics. Here's a breakdown of their differences:

1. Passive Harmonic Filter

• Definition: Passive harmonic filters are devices that use passive components like resistors, capacitors, and inductors to filter out specific harmonic frequencies.
• Operation: They work by creating a low-impedance path for certain harmonic frequencies, effectively shunting them away from the power system.
• Advantages:

1. Simple design and low cost.
2. Requires no external power source.
3. Effective for specific and predictable harmonic frequencies.

• Disadvantages:

1. Limited flexibility; designed for specific harmonics.
2. May cause resonance issues if not properly designed.
3. Performance can degrade if system conditions change.

2. Active Harmonic Filter

• Definition: Active harmonic filters use electronic components to actively counteract harmonic currents by injecting opposing currents into the system.
• Operation: They continuously monitor the current waveform and inject corrective currents to cancel out harmonic distortions.
• Advantages:

1. Flexible and can adapt to varying loads and harmonic conditions.
2. Effective across a wide frequency range.
3. Can improve power factor in addition to reducing harmonics.

• Disadvantages:

1. Higher initial cost and complexity.
2. Requires a power supply and control system.
3. Maintenance may be more involved than passive filters.

3. Tuned Harmonic Filter

• Definition: Tuned harmonic filters are a specific type of passive filter designed to target and mitigate particular harmonic frequencies, typically the 5th and 7th.
• Operation: These filters are tuned to resonate at specific harmonic frequencies, allowing them to effectively reduce the magnitude of those harmonics in the system.
• Advantages:

1. More effective than general passive filters for targeted harmonics.
2. Can be designed to avoid resonance with the system's natural frequencies.

• Disadvantages:

1. Still limited to specific harmonics; less flexible than active filters.
2. Requires careful design to avoid resonance issues.

Summary

• Passive filters are simple and cost-effective but less adaptable.
• Active filters provide dynamic and flexible solutions for a wide range of harmonics but come at a higher cost.
• Tuned filters are specialized passive filters effective for specific harmonics but lack the adaptability of active filters.

Each type of filter has its own applications and suitability depending on the specific requirements of the electrical system being addressed.