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A compact fluorescent lamp is one example of an electrical load with a non-linear characteristic, due to the rectifier circuit it uses. The current waveform, blue, is highly distorted. Current harmonics are caused by non-linear loads. When a non-linear load, such as a rectifier is connected to the system, it draws a current that is not sinusoidal.
Non-linear systems generate harmonics in response to sinusoidal input, meaning that if the input of a non-linear system is a signal of a single frequency, , then the output is a signal which includes a number of integer multiples of the input frequency signal; (i.e. some of ,,,, …).
To understand a system with an input and an output, such as an audio amplifier, we start with an ideal system where the transfer function is linear and time-invariant.When a sinusoidal signal of frequency ω passes through a non-ideal, non-linear device, additional content is added at multiples nω (harmonics) of the original frequency.
Non-linear loads create harmonic currents in addition to the original (fundamental frequency) AC current. This is of importance in practical power systems that contain non-linear loads such as rectifiers, some forms of electric lighting, electric arc furnaces, welding equipment, switched-mode power supplies, variable speed drives and other ...
By definition, the AC harmonic is a multiple of the electrical quantity (voltage or current) at multiples of the fundamental frequency of the system, produced by the action of non-linear loads such as rectifier, lighting, or saturated magnetic devices. Harmonic frequencies in the power grid are a frequent cause of power quality problems and can ...
With linear loads, the neutral only carries the current due to imbalance between the phases. Devices that utilize rectifier-capacitor front ends (such as switch-mode power supplies for computers, office equipment and the like) introduce third order harmonics.
Harmonics often occur in power systems as a consequence of non-linear loads. Each order of harmonics contributes to different sequence components. The fundamental and harmonics of order + will contribute to the positive sequence component.
The development of CPC-based power theory by Leszek S. Czarnecki was initiated in 1983 when he challenged the correctness of existing power theories as applied to single-phase linear, time-invariant (LTI) loads with nonsinusoidal voltage, and next, he revealed the existence of a scattered current, and invented a method of reactance compensation.