Hybrid power filter harmonic current detection method based on generalized weighted morphological filtering theory

Abstract

The invention provides a hybrid power filter harmonic current detection method based on the generalized weighted morphological filtering theory. The method includes the steps of firstly, selecting main structure elements and driven structure elements; secondly, constructing a master and slave opening-closing iteration morphological filter and a master and slave closing-opening iteration morphological filter; thirdly, adding the product of F[oc](n) and the sine value of the base wave positive sequence voltage to the product of F[co](n) and the cosine value of the base wave positive sequence voltage so as to obtain the direct current component of the base wave positive sequence current; fourthly, conducting dq coordinate inverse conversion and alpha beta coordinate inverse conversion on the direct current component, obtained in the third step, of the base wave positive sequence current so as to obtain a base wave positive sequence current signal, and subtracting an input signal from the base wave positive sequence current signal to obtain a harmonic current signal. According to the method, the harmonic current can be accurately detected, a traditional low-pass filter is replaced by the generalized weighted morphological filtering link, and the minimum error compensation is achieved. Simulation and experiment results show that the method has the advantages of being high in detection accuracy, good in compensation effect, and the like.

Description

[0001] technical field [0002] The invention relates to a detection method for a harmonic current of a power filter, in particular to a detection method for a harmonic current of a hybrid power filter based on generalized weighted morphological filtering theory. technical background [0003] Due to the rapid development of modern power electronics technology and the use of a large number of nonlinear electrical equipment, a large number of power quality problems such as voltage and current have appeared in the power grid. With the continuous improvement of energy penetration in the power grid, the operation stability of the power grid will be greatly impacted, and the power quality pollution will be significantly aggravated. In recent years, the development of UHV power grids has also put forward strict requirements for power quality. Among many power quality adjustment devices, the hybrid active power filter (HAPF) is widely used due to its outstanding advantages, and one ...

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Problems solved by technology

In "Electrical Measurement and Instrumentation", Volume 49, Issue 4, 2012, the article "A New Harmonic Detection Algorithm Based on Instantaneous Reactive Power Theory" proposed to combine the phase detection part of the phase-locked loop in the harmonic detection link with the Park transformation phase Combined with a new harmonic detection algorithm, this method does not use voltage information to directly extract harmonics, reduces the amount of calculation in the harmonic extraction link, and can detect harmonics quickly and accurately; The article "Application of Wavelet Packet Transform and Generalized Morphological Filter in Partial Discharge Detection" in "Measuring and Instrumentation" proposes a new method combining wavelet packet transform and generalized morphological filter to remove partial discharge signals containing strong noise. Noise processing, this method can well retain the characteristics of the original signal, and can also smoothly transition to the detection and processing of other signals; in "Automation of Electric Power Systems", Volume 27, Issue 19, 2003, "A Mathematical Form Based In the article "Rapid positioning method of power quality signal based on science", the mathematical morphology operation is directly performed on the signal, and the disturbance signal detection method is constructed by referring to the denoising method of wavelet soft threshold algorithm. This method is simple in calculation and easy to implement in hardware, but it is difficult to implement Threshold, there is a possibility to detect failure

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