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Variable step size affine projection harmonic current detection method based on time coherent average

A technology of affine projection and harmonic current, applied in the direction of measuring current/voltage, measuring device, measuring electrical variables, etc., can solve the problems of slow algorithm convergence speed, poor tracking ability of jump system, slow convergence speed, etc. Improve convergence speed, short dynamic response time, and small step size

Inactive Publication Date: 2013-09-25
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

[0005] Reference "A Novel Variable Step size Adaptive Harmonic Detecting Algorithm Applied to Active Power Filter" (Hui Li, Zhengguo Wu, Fei Liu, Industrial Technology, 2006.ICIT2006.IEEE International Conference:15-17Dec.2006On Page(s):574 –578) This method uses the proportion K(n) of the error signal e(n) in the total signal as the adaptive feedback amount, and controls the update of the step size through the coherent average estimation of K(n), so that even in It has a strong ability to resist harmonic interference, and the algorithm is universal under different grid power levels. However, due to the rapid change of the step size of the algorithm under the influence of the error signal, the convergence speed of the algorithm is slowed down, and when the load current jumps After changing, the error signal e(n) and load current i L (n) changes at the same time, so the method has a small step size change, which is still a small step size, poor tracking ability to the jump system, and slow convergence speed

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  • Variable step size affine projection harmonic current detection method based on time coherent average
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[0038] A generalized harmonic current detection method based on time coherent averaging with variable step size affine projection, the steps are as follows:

[0039] A. The signal x(t)=[sin(2πft) cos(2πft)] of the power frequency fundamental wave voltage after the amplitude normalization is shifted by 90° phase-locked loop (PLL) T =[x 1 (t) x 2 (t)] T As a reference signal, for the reference signal x(t)=[sin(2πft) cos(2πft)] T =[x 1 (t) x 2 (t)] T and the periodic non-sinusoidal load current i to be detected L (t) Perform synchronous sampling to obtain the load current i L (t) discrete value i L (n) and the discrete value of the reference signal x(n)=[x 1 (n)x 2 (n)] T ;Load current i L (t) discrete value i L The matrix expression of (n) is I L (n), I L (n)=[i L (n)i L (n-1)...i L (n-K+1)] H , the discrete value of the reference signal x(n)=[x 1 (n)x 2 (n)] T The matrix expression for X(n)=[x(n) x(n-1)...x(n-K+1)] H ; Among them, f=50Hz, n is the discret...

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Abstract

The invention discloses a variable step size affine projection generalized harmonic current detection method based on time coherent average. The variable step size affine projection generalized harmonic current detection method based on time coherent average mainly comprises the following main steps that: a load current at the current time n and the previous (k-1) time is adopted as a column vector; the column vector subtracts the output of the time corresponding to an affine projection filter so as to obtain an error (generalized harmonic current); the step size is updated by utilizing the moving time average value of the ratio occupied in a to-be-detected signal by the error so as to eliminate the interference to the step size update by the harmonic current. The method is high in convergence rate, is high in convergence accuracy in a steady state, is high in tracking capability in jumping, and is good in timeliness.

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 continuous development of science and technology, the continuous adoption of power electronics technology, and the wide application of thyristor rectification and commutation technology, 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. "Harmonic" pollution is one of the three major public hazards recognized internationally, so effective control of harmonics is very important for improving power quality. Harmonic cancellation can be done by passive power filters and active power filters. The passive power filter has a simple structure but can only suppress fixed harmonics, and the filtering effect is poor. Based on the real-time detection of grid harmonics, the active power fil...

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Application Information

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IPC IPC(8): G01R19/00G01R23/16
Inventor 赵海全雷翼龙
Owner SOUTHWEST JIAOTONG UNIV
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