In modern energy supply, a large number of single-phase and three-phase, non-linear consumers are used, from industrial networks to office buildings. This includes lighting technology, such as light controllers for headlamps or energy-saving lamps, numerous frequency converters for heating, air conditioning, and ventilation systems, frequency converters for automation technology or elevators, as well as the entire IT infrastructure with the regulated switching power supplies typically used. Inverters for photovoltaic systems (PV) and uninterruptible power supplies (UPS) are also widespread today. All these non-linear electrical loads cause more or less large grid distortions, with a distortion of the originally "clean" sinusoidal shape. As a result, the current voltage waveform is also distorted. The reliable operation of modern installations and systems always requires a high level of supply reliability and good power quality, and the load on the grid infrastructure from electrical and electronic consumers with grid distortions has increased significantly in recent years. Depending on the type of generation system and equipment (grid feeder with inverter, generator), grid rigidity at the connection point and the relative size of the non-linear consumers, different levels of grid distortions and interference occur.