What is power quality?

Power quality refers to the quality of the power in the power system. Ideally, the power should be a perfectly symmetrical sine wave. Some factors can cause the waveform to deviate from the symmetrical sine, which results in power quality problems. On the one hand, we study what factors can cause power quality problems, on the other hand, we study what problems these factors can cause, and finally, we study how to eliminate these factors so that the power can be as close to a sine wave as possible.