Affine Projection Harmonic Current Detection Method Based on Time Coherent Averaging with Variable Step Size
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 poor tracking ability of jump system, slow algorithm convergence speed, small step size change, etc. Achieve short dynamic response time, improve convergence speed, and small step size
Inactive Publication Date: 2016-03-02
SOUTHWEST JIAOTONG UNIV
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[0005] Reference "ANovelVariableStepsizeAdaptiveHarmonicDetectingAlgorithmAppliedtoActivePowerFilter" (HuiLi, ZhengguoWu, FeiLiu, IndustrialTechnology, 2006.ICIT2006.IEEEInternationalConference: 15-17Dec.2006OnPage(s): 574–578) This method is the proportion of the error signal e(n) in the total signal K(n) is used as the adaptive feedback amount, and the update of the step size is controlled by the coherent average estimation of K(n), so that even with strong anti-harmonic interference ability, the algorithm has versatility under different grid power levels , but because the step size of the algorithm changes too fast under the influence of the error signal, the convergence speed of the algorithm slows down, and after the load current jumps, the error signal e(n) and the 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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[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 normalized power frequency fundamental wave voltage after phase-locked loop (PLL) 90° phase shift 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 of X(n)=[x(n)x(n-1)...x(n-K+1)] H ; Among them, f=50Hz, n is the discrete point of time t, n=1, 2...
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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.
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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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IPC IPC(8): G01R19/00G01R23/16
Inventor 赵海全雷翼龙
Owner SOUTHWEST JIAOTONG UNIV