Research On The Harmonic Current Detection Method Based On The Theory Of Instantaneous Reactive Power

In recent years, the electrical harmonic pollution becomes more serious with the widely application of power electronics technologies. It deteriorates the quality of electric energy, has become a curse to power system .Active Power Filter (APF) is an advanced power electronic device which can be used for compensating of harmonic. Compared with some conventional compensating measures, active power filter has many advantages and favorable prospects.Harmonic current detection technology is one of the critical technologies of active power filters. The development of harmonic current detection technology directly effects the development of APF technology. It is very significant to improving the property of APF with the improvements of the harmonic current detection technology. The theory of instantaneous reactive power has been widely applied in real-time detection of harmonic current in active power filters since it was proposed in 1980s.This paper research on the harmonic current detection method based on the theory of instantaneous reactive power, especially on the influence of harmonic current detection with the different types of the low-pass digital filters. And the low pass digital filter which can satisfy the general requirements for harmonic current detection is designed and implemented by DSP.For the influence of APF's performance by the delay, a modified current detecting algorithm based on adaptive predictive filter is presented. The least mean square algorithm is used to predict the signals to be detected. The conflict between detecting accuracy and real time in harmonic current detection can be solved through combine this algorithm with the method based on instantaneous reactive power theory. The simulation results show its validity.