Detection method for variable step length LMS (Least Mean Square) harmonic current based on versiera

A technology of harmonic current and skip wire, which is applied in the field of harmonic current detection, can solve the problems of numerical calculation difficulties, failure to eliminate fundamental wave reactive current interference, slow convergence speed, etc., and achieve accurate detection results

What is AI technical title?
AI technical title is built by PatSnap AI team. It summarizes the technical point description of the patent document.
A technology of harmonic current and skip wire, which is applied in the field of harmonic current detection, can solve the problems of numerical calculation difficulties, failure to eliminate fundamental wave reactive current interference, slow convergence speed, etc., and achieve accurate detection results

CN102707122AInactive Publication Date: 2012-10-03SOUTHWEST JIAOTONG UNIV

2 Cites 24 Cited by

Image

Smart Image Click on the blue labels to locate them in the text.

Viewing Examples

Smart Image

Examples

Experimental program

Comparison scheme

Effect test

Embodiment

[0055] A kind of specific embodiment of the present invention is, a kind of variable step length LMS harmonic current detection method based on skip line, its steps are as follows:

[0056] A. Sampling

[0057] For periodic non-sinusoidal load current i L (t) and the reference signal x(t)=sin(2πft) of the fundamental active current are sampled synchronously to obtain the discrete value i of the load current L (n) and the discrete value x (n) of reference signal; Wherein, f=50Hz, n is the discrete point of time t;

[0058] B. Estimation of fundamental active current

[0059] After the discrete value x(n) of the reference signal is filtered by the LMS adaptive filter, the estimated value of the fundamental active current is obtained Among them, w(n) is the weight coefficient of the LMS adaptive filter calculated at time n-1 at time n, if time n is the initial time, its value is zero;

[0060] C. Estimation of generalized harmonic current

[0061] The discrete value i of ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

Login to View More

PUM

Login to View More

Abstract

The invention discloses a detection method for a variable step length LMS (Least Mean Square) harmonic current based on versiera. The method comprises the steps of: sampling, estimating an active current of a fundamental wave, estimating a general harmonic current, updating a weight coefficient, updating the step length and iterating. According to the orthogonal characteristics of a trigonometric function, the current error output by a filter and an instantaneous cross-correlation time mean value are subtracted from a load current to eliminate interference of the harmonic current and the active current of the fundamental wave on update of the step length. Furthermore, update of the step length is controlled by an improved versiera function. Meanwhile, in the updating process of the weight coefficient, variation of the weight coefficient is imported so that the steady state error is very small and the calculated amount is smaller. The detection method for the variable step length LMS harmonic current based on versiera provided by the invention is suitable for occasion where the load current has saltus and value of the optimal parameter provided by the invention is less dependent on the load current.

Description

technical field [0001] The invention belongs to the technical field of harmonic current detection of power systems. Background technique [0002] In recent years, with the application of a large number of power electronic devices in the power grid, the problem of harmonic pollution in the power grid has become increasingly prominent, seriously affecting the quality of the power grid and the safe operation of user equipment. Therefore, it is very important to effectively control harmonics to improve power quality. Active power filter (APF) is based on the real-time detection of grid harmonics, and correspondingly injects an anti-phase harmonic current into the grid, so as to realize compensation and suppression of harmonic pollution to the grid. The quality of its performance largely depends on the real-time and accurate detection of harmonic current, so the detection method of harmonic current is very important. With the development of adaptive filter, it is applied to har...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

Login to View More

Application Information

Patent Timeline

03 Oct 2012

Publication

CN102707122A

IPC: G01R19/00

Inventors: 赵海全; 喻翌