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Transformer harmonic mitigation is an essential aspect of power quality management in electrical systems, particularly those involving non-linear loads. Non-linear loads, such as variable frequency drives (VFDs), rectifiers, and electronic devices, draw current in a non-sinusoidal manner, which results in the generation of harmonic currents. These harmonic currents can cause various issues in electrical systems, including transformer overheating, increased power losses, interference with sensitive equipment, and even failure of protective devices.

Here are some strategies for transformer harmonic mitigation:

1. Harmonic Filtering: Installing harmonic filters is a common method to mitigate harmonics. Passive filters, which consist of combinations of inductors, capacitors, and sometimes resistors, are designed to resonate at specific harmonic frequencies, absorbing or diverting harmonic currents. Active filters, on the other hand, use power electronics to generate counteracting currents that cancel out harmonics.

2. Low Pass Harmonic Filters: Specifically designed for transformers, these filters are installed at the input or output of the transformer to attenuate high-frequency harmonic currents before they can affect the transformer or the rest of the system.

3. Transformer Design: Using transformers with special winding configurations, like delta-wye or interlaced windings, can help reduce harmonic effects. These designs offer improved impedance characteristics that limit harmonic current flow.

4. K-Rated Transformers: K-rated transformers are specifically designed to withstand the thermal and magnetic stresses caused by harmonic currents. They have higher temperature ratings and are more robust, allowing them to handle harmonic loads without premature failure.

5. Harmonic Mitigating Transformers: These are specialized transformers designed with additional winding layers or magnetic shunts to provide a low-impedance path for harmonic currents, thereby reducing their impact on the transformer and the system.

6. Distributed Capacitor Banks: Instead of having a single large capacitor bank for power factor correction, using several smaller capacitor banks distributed throughout the system can help dampen harmonic resonance and reduce harmonic amplification.

7. Active Power Conditioning: This involves using advanced power electronics to not only filter harmonics but also regulate voltage and improve power quality overall. It's a comprehensive solution but can be more expensive.

8. Load Balancing: Ensuring balanced loading on all phases of the transformer can help minimize harmonic distortion by preventing the amplification of specific harmonics due to uneven current distribution.

9. Separation of Linear and Non-Linear Loads: Physically separating linear and non-linear loads and feeding them through different transformers or circuits can limit the spread of harmonics throughout the system.

Implementing one or a combination of these strategies can significantly improve transformer performance and overall power quality in systems prone to harmonic disturbances. The choice of mitigation technique depends on the specific harmonic spectrum present, system configuration, and economic considerations.