Fast-individual-harmonic-extraction technique

Abstract

Harmonic distortion in power networks is continuously increasing owing to the increased use of nonlinear loads in power-distribution networks. Consequently, harmonic monitoring and control are becoming particularly important for both utilities and consumers to reduce their harmful effects. In some applications, such as real-time harmonic monitoring and active filters, techniques for fast extraction of individual harmonic components are required. The relatively long response time of conventional techniques make them less appealing when the speed of response is important. The paper deals with the problem of individual-harmonic extraction for the purpose of harmonic filtering and compensation. A common problem associated with existing individual-harmonic-extraction techniques is the speed of extracting a single harmonic component, which determines the response of the compensator. Standard harmonic-extraction techniques are investigated and a new fast-individual-harmonic-extraction (FIHE) technique is proposed. It is shown that the proposed FIHE is capable of performing harmonic extraction six times faster than the Fourier transform and provides better filtering characteristics than traditional filters such as Butterworth and FIR filters. Computer simulation and laboratory experimental results are provided to illustrate the characteristics and performance of the proposed technique.

DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

“…For the harmonics extraction algorithm, the synchronous reference frame (SRF) principle [12,31,40] is used. Meanwhile, a synchronizer is utilized to provide referencing signals to the harmonics extraction algorithm.…”

“…Meanwhile, the minimum capacitance value C dc for each capacitor can be determined as follows [36][37][38][39]: For the harmonics extraction algorithm, the synchronous reference frame (SRF) principle [12,31,40] is used. Meanwhile, a synchronizer is utilized to provide referencing signals to the harmonics extraction algorithm.…”

“…Under influence of the nonlinear loads, the actual I Ld and I Lq components are polluted by the generated current harmonics and thus resulting in the formation of new current relationship given as: [12, 31,40] is used. Meanwhile, a synchronizer is utilized to provide referencing signals to the harmonics extraction algorithm.…”

“…For the purpose of harmonics extraction, both I Ldpacq and I Lqpacq components are required for reference current generation. Generally, the ac components are obtained through indirect identification approach [46] where a tuned numerical low pass filter (LPF) is usually employed to detect the dc component which is then being removed from the actual load current in dq frame [12,31,40]. This approach can be represented as:…”

“…The filter used is a second order Butterworth-typed LPF with a cutting frequency of 10 Hz. This type of filter is recognized as the best "all-round" filter which provides fast dynamic response with acceptable filtering features [12,31,40].…”