Fundamental wave positive sequence active current detection method

Abstract

The invention discloses a fundamental wave positive sequence active current detection method and is applied to a voltage asymmetric or distortion three-phase system. The method comprises the following steps: step one, acquiring three-phase asymmetric voltage values for converting onto two mutually perpendicular coordinates through coordinate transformation; step two, after calculation of what is obtained from the first step, obtaining DC components through a low pass filter; step three, respectively multiplying the DC components obtained in the second step by the sine and cosine signal matrix of an initial phase angle pi/4, and finally removing a negative sequence component including voltage fundamental waves through addition and subtraction operation; and step four, eliminating the sine and cosine signal matrix of the pi/4 phase angle by use of the characteristic of a trigonometric function to obtain a voltage fundamental wave positive sequence component; and step five, after the voltage fundamental wave positive sequence component Uall is obtained, by use of a phase-locked loop and sine and cosine generation circuit, providing sine and cosine signals which have the same phase as an a-phase voltage fundamental wave positive sequence for a system, and finally obtaining fundamental wave positive sequence active current values. The detection method provided by the invention can accurately detect the fundamental wave positive sequence active currents in real time.

Description

technical field [0001] The invention relates to a detection method of fundamental positive sequence active current, which belongs to the field of electric energy quality control. Background technique [0002] With the rapid development of power electronics technology, in the three-phase four-wire distribution network, the use of nonlinear impact loads is becoming more and more widespread, which makes a large number of harmonic components appear in the grid current, especially the zero-sequence harmonic current of each phase. And the accumulation of unbalanced current on the neutral line caused by the unbalanced load has a serious impact on the stable operation of the distribution network. Using power quality control devices to quickly compensate harmonics, reactive power and unbalance has important practical significance for improving the stability of power systems. [0003] Compensation current detection is an important part of the power quality control device, and the rea...

AI Technical Summary

Problems solved by technology

In engineering, when the three-phase voltage of the power grid is asymmetrical or distorted, the voltage will contain negative sequence components and zero sequence components, that is, there is a phase difference between the phase of the grid voltage and the positive sequence component of the voltage fundamental wave, and this phase difference will cause Detection Error of Fundamental Positive Sequence Active and Reactive Current

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