A Harmonic Current Detection Method And Its Application

As technique of power electronics develops, the load with nonlinear, impactive, unbalanced characteristics such as current rectifiers, frequency converters, arc furnaces have been increasingly used in power network in recent years. They generate lots of harmonics and cause distortion in power electrical network current (voltage). Power networks had been polluted by harmonics, which do harm to electrical equipments. Harmonic pollution has been one of the non-negligible problems in power supply systems and catches people' s eye.Firstly, to the problems that caused by harmonic, this paper depicts the reason of harmonic' s bringing, the harm and the standard of harmonics, and introduces the initiative and passive methods of harmonic restraining; Secondly, the theory, the class and the basic composing of the active power filter are described in detail; At last, the various harmonic current detection methods of power filter are introduced in detail. The points of harmonic current detection are analyzed and their advantages and disadvantages are pointed out. The drawback of instantaneous reactive power theory is expoundedBased on the analysis of various harmonic current detection methods and the drawback of instantaneous reactive power theory, the concept of power factor is introduced into the control system of active power filter. The harmonic and reactive current detection technique based on unity power factor and its application in shunt active power filter is described in detail. This transient characteristic of the detection method is analyzed and the detail method of shortening the detection delay is provided. In order to prove the correctness of the approach, some necessary reasoning and a simulation research used by MATLAB based on the approach and many experiments done bythe experimental equipment of shunt active power filter based on DSP are done in this paper, the results verify the effectiveness of harmonic detection and control method based on unity power factor and validity of theoretical analysis.