Wie Oberschwingungen Wechselstromkreise beeinflussen

Welcome to our exploration of power system harmonics, a fundamental concept in electrical engineering.In power systems, the fundamental frequency is 50 Hertz, creating a perfect sine wave.Harmonics are multiples of this fundamental frequency. The third harmonic at 150 Hertz is particularly common.The fifth harmonic at 250 Hertz and seventh harmonic at 350 Hertz also frequently appear in power systems.These harmonics are primarily generated by nonlinear loads in our power systems.When these harmonics combine with the fundamental wave, they create a distorted waveform that deviates from the ideal sine wave.In a frequency spectrum, we can clearly see the relative magnitudes of each harmonic component.Harmonics cause significant heating in transformers due to additional core and winding losses.In cables, harmonics lead to increased power losses and temperature rise, reducing their current-carrying capacity.The third harmonic currents can sum up in the neutral conductor, potentially leading to overload conditions.In motors, harmonics cause additional losses, leading to vibrations and premature wear.These effects combine to reduce system efficiency and reliability, while increasing maintenance costs.To combat harmonics, we can use passive filters consisting of inductors and capacitors.These LC filters can target specific frequencies for reduction.Active filters use power electronics and can dynamically adapt to changing loads.They continuously monitor the signal and generate compensating waveforms.Using 12-pulse rectifiers instead of 6-pulse systems can significantly reduce harmonics.Regular measurements help identify harmonic issues early, allowing for timely intervention.By implementing these measures, we can significantly improve power quality and reduce harmonic distortion.