Harmonic current compensating method based on fast Fourier transform

A Fourier transform and harmonic current technology, which is applied in harmonic reduction devices and AC networks to reduce harmonics/ripples, etc. It can solve the problem of increased delay, reduced control loop bandwidth, and the influence of harmonic current compensation accuracy. and other problems, to achieve the effect of fast response, wide application range and clear control objectives

Active Publication Date: 2012-04-11
CHINA ELECTRIC POWER RES INST +1
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Problems solved by technology

However, adding a notch filter in the current control loop will reduce the bandwidth of the control loop and increase the delay, which will affect the accuracy of harmonic current compensation

Method used

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  • Harmonic current compensating method based on fast Fourier transform
  • Harmonic current compensating method based on fast Fourier transform
  • Harmonic current compensating method based on fast Fourier transform

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Embodiment Construction

[0037] The control method of the present invention will be described in further detail below in conjunction with the accompanying drawings.

[0038] The system voltage, load current, and chain-type converter output current in the content are all obtained by the measurement link. When the electrical quantity signal is used to achieve the control target, it has been filtered and reduced.

[0039] In order to more clearly set forth the working principle of the harmonic current compensation algorithm based on fast Fourier transform of the present invention, now in conjunction with the cascaded H-bridge type STATCOM control algorithm analysis and description, the STATCOM structure is as attached figure 1 shown. Each phase is composed of N cascaded single-phase inverters with independent DC capacitors in series, and the three-phase commutation chain adopts star connection. u in the picture sA , u sB , u sC is the AC voltage of the system, i fa i fb i fc Respectively, STATCOM...

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Abstract

The invention provides a harmonic current compensating method based on fast Fourier transform. For an occasion that double-sequence current decoupling control is adopted for chain static synchronous compensator (STATCOM) inner loop circuit control, and harmonic current compensating precision is ensured by correcting a harmonic current instruction under the condition that inner loop control bandwidth is relatively low. The compensating method comprises the following steps of: firstly, respectively performing fast Fourier transform (FFT) analysis on load current and current converter output current; secondly, calculating the errors of a load current amplitude value, a current converter output current amplitude value, a load current phase and a current converter output current phase, and respectively correcting a harmonic current amplitude value and a phase instruction according to the errors; and finally, reconstructing the corrected amplitude values/phases to obtain the harmonic current instruction of a chain current converter. The influence of the bandwidth and delay of a controller on the harmonic current compensating precision is considered to keep the errors of the output current and the load harmonic current within hysteresis width, the harmonic current compensating precision is improved, and the practical engineering value is relatively high.

Description

technical field [0001] The invention belongs to the technical field of power electronic device control, and in particular relates to a harmonic current compensation method based on Fast Fourier Transform. Background technique [0002] The chain-link converter is widely used in engineering, and it is composed of multiple single-phase converter chains, and each single-phase converter chain is composed of at least one single-phase chain link (ie figure 1 The cascading modules 1, 2...n) in the chain are composed, and the chain links can be connected in series or in parallel, and each chain link includes an H-bridge voltage source converter. [0003] The chain-type converter has many advantages, and can realize independent phase separation control, which is beneficial to solve the phase balance problem of the system. The basic unit structure of all links is exactly the same, which can realize modular design, facilitate expansion and maintenance, and avoid problems caused by the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/01
CPCY02E40/40
Inventor 田鑫周飞蔡林海宗波蒋晓春赵国亮荆平
Owner CHINA ELECTRIC POWER RES INST
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