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Harmonic current estimation method under condition of unknown harmonic impedance

A technology of harmonic current and unknown conditions, applied in the field of harmonic current estimation, can solve the problems of not considering the measurement noise, not solving the problem of quantitative estimation of harmonic current amplitude and phase, etc.

Inactive Publication Date: 2016-08-31
SHANGHAI MUNICIPAL ELECTRIC POWER CO +1
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Problems solved by technology

This method determines the position of the harmonic current, but does not solve the problem of quantitative estimation of the amplitude and phase of the harmonic current, nor does it consider the problem of measurement noise in practical applications

Method used

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  • Harmonic current estimation method under condition of unknown harmonic impedance
  • Harmonic current estimation method under condition of unknown harmonic impedance
  • Harmonic current estimation method under condition of unknown harmonic impedance

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Embodiment

[0089] like Figure 7 As shown, a harmonic current estimation method under the condition of unknown harmonic impedance includes the following steps:

[0090] S1, respectively setting monitoring points at grid nodes, and obtaining measurement data of each monitoring point within a period of time, the measurement data including harmonic voltage observation signals and harmonic current observation signals;

[0091] S2, using a smoothing filter to separate the fast fluctuation components of the measurement data, saving the remaining slow fluctuation components, removing the mean value and whitening the fast fluctuation components;

[0092] S3, taking the measurement error as an unknown parameter, taking the fast fluctuation component of the harmonic current obtained in step S2 as a latent variable, and establishing an ICA model with noise interference

[0093] x t = AS t +η

[0094] Among them, X t is the fast fluctuation component of the M-dimensional harmonic voltage observ...

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Abstract

The invention relates to a harmonic current estimation method under the condition of unknown harmonic impedance, and the method comprises the steps: taking a harmonic voltage as a measurement quantity and taking a harmonic current as a state quantity according to the statistic independence and super-Gaussian distribution characteristics of a harmonic current quick fluctuation quantity, and building a harmonic state estimation model comprising measurement noise; enabling the noise and impedance parameters in an ICA model to serve as unknown variables, enabling the harmonic current to serve as a hidden variable, and obtaining a harmonic current optimal solution which cannot be affected by noise through employing the variational Bayesian learning capability for unknown variables; neglecting linear load admittance according to the characteristic that the linear load admittance is far less than system side admittance, eliciting a harmonic current amplitude proportion coefficient, and determining the current amplitude. Compared with the prior art, the method can effectively eliminate the uncertainty of an independent component analysis algorithm and restores the amplitude of the harmonic current with no need of harmonic impedance parameters, obtains an estimated harmonic current, can effectively reduce the impact on the estimation result from measurement noise, and is stronger in robustness.

Description

technical field [0001] The invention relates to a method for estimating harmonic current, in particular to a method for estimating harmonic current under the condition of unknown harmonic impedance. Background technique [0002] The power properties of an ideal power system have the characteristics of a certain waveform and frequency, and several voltage levels. The highest efficiency mode of electric energy transmission is the voltage and current with the same waveform and the same frequency and phase, which is also the best form of electric energy for the production, transmission, conversion and guarantee of grid safety. Because the actual power system is affected by system planning, regulation, load change and other unforeseen faults, it is difficult to achieve the ideal state. Therefore, power quality is usually used to describe the degree to which the power system deviates from the ideal state, and its indicators include frequency and voltage offsets, electromagnetic t...

Claims

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Application Information

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IPC IPC(8): G01R19/25
CPCG01R19/2506
Inventor 凌平张弛周健杨增辉金家培陈甜甜潘爱强
Owner SHANGHAI MUNICIPAL ELECTRIC POWER CO
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