Define harmonic distortion and its impact on electrical equipment; what mitigation techniques are used?

Define harmonic distortion and its impact on electrical equipment; what mitigation techniques are used?

• A. Harmonics are integer multiples of the fundamental frequency; cause overheating, equipment nuisance and misoperation; mitigation includes filters (passive/active), proper transformer sizing, and harmonic studies.
• B. Harmonics are random frequencies that have no impact; mitigation is unnecessary.
• C. Harmonics are beneficial to power systems and improve efficiency; mitigation involves adding more capacitors.
• D. Harmonics occur only in DC systems and are mitigated by increasing DC link voltage.

Answer: (A)

Harmonic distortion happens when non-linear loads draw current that isn’t sinusoidal, producing currents at integer multiples of the fundamental frequency. Those harmonics distort both current and voltage waves, raise RMS currents, and can cause overheating in transformers, cables, and motors, nuisance tripping or misoperation of protection and control equipment, and even resonance with system impedances that worsens voltage distortion. Mitigation centers on shaping or reducing those harmonic currents. Using filters to attenuate problematic harmonics is common: passive filters tuned to specific harmonic orders or active filters that actively cancel harmonics provide targeted attenuation. Ensuring equipment and conductors are appropriately sized and rated to handle distorted current helps prevent overheating and voltage drop. Conducting harmonic studies (to quantify distortion levels, identify resonance risks, and determine optimal filter placement and sizing) guides the plan and verification. Additional approaches include using power-electronic devices with better input filtering or active front-end designs, phase-shifting or multi-pulse configurations to reduce certain harmonic orders, and proper transformer sizing and impedance management to limit amplification of harmonics.

Harmonic distortion happens when non-linear loads draw current that isn’t sinusoidal, producing currents at integer multiples of the fundamental frequency. Those harmonics distort both current and voltage waves, raise RMS currents, and can cause overheating in transformers, cables, and motors, nuisance tripping or misoperation of protection and control equipment, and even resonance with system impedances that worsens voltage distortion.

Mitigation centers on shaping or reducing those harmonic currents. Using filters to attenuate problematic harmonics is common: passive filters tuned to specific harmonic orders or active filters that actively cancel harmonics provide targeted attenuation. Ensuring equipment and conductors are appropriately sized and rated to handle distorted current helps prevent overheating and voltage drop. Conducting harmonic studies (to quantify distortion levels, identify resonance risks, and determine optimal filter placement and sizing) guides the plan and verification. Additional approaches include using power-electronic devices with better input filtering or active front-end designs, phase-shifting or multi-pulse configurations to reduce certain harmonic orders, and proper transformer sizing and impedance management to limit amplification of harmonics.