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A composite control method of active power filter based on llcl filtering

A power filter and composite control technology, applied in active power filtering, AC network to reduce harmonics/ripples, etc., can solve the problems of parameter robustness, unfavorable efficiency, grid inductance uncertainty, etc., to avoid Effects of additional losses, reduced total inductance, reduced system cost and harmonic output capability

Inactive Publication Date: 2017-05-17
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

at the cost of additional sensors and increased control loop complexity
The second method is state feedback pole configuration and damping function method, but due to the uncertainty of grid inductance, there may be parameter robustness problems
The passive damping scheme is not conducive to the improvement of efficiency in large-capacity APF applications; and a hybrid damping scheme with active damping and passive damping in parallel can improve the stability of LLCL grid-connected inverters in weak power grids Although it improves the efficiency, it introduces a certain amount of additional loss

Method used

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  • A composite control method of active power filter based on llcl filtering
  • A composite control method of active power filter based on llcl filtering
  • A composite control method of active power filter based on llcl filtering

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Embodiment

[0034] figure 1 It is a specific implementation block diagram of an active power filter.

[0035] In this embodiment, the internal structure of the active power filter is described first, such as figure 1 As shown, the active power filter mainly includes the main circuit and the control part.

[0036]Wherein, the main circuit further includes a three-level VSI 1 , an LLCL filter 2 , and a nonlinear load 3 . The three-level VSI 1 is connected to the power grid through the LLCL filter 2, and the nonlinear load 3 is directly connected to the power grid, thereby forming a complete main circuit of an active power filter.

[0037] The control part includes: phase-locked loop PLL 4, abc-dq0 coordinate system transformation module 5, DC voltage control module 6, harmonic current detection module 7, current control module 8, grid voltage feedforward module 9, dq0-abc coordinate system transformation 10. The SPWM modulation module 11 constitutes the control part of the active power f...

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Abstract

The invention discloses a composite control method of an active power filter based on LLCL filtering. Through the inherent time delay of the digital system, the unstable pole position of the LLCL filter is configured to realize the non-damping resistance self-stabilizing control of the LLCL filter. In the specific configuration, the LLCL filter is directly connected to the power grid, which reduces the total inductance, reduces system cost and harmonic output capability, and avoids the additional loss of traditional passive damping and the need for additional sensors or active damping. The problem of model accuracy impact is very suitable for high-power inverter applications.

Description

technical field [0001] The invention belongs to the technical field of active power filter current control, and more specifically relates to a composite control method of an active power filter based on an LLCL filter without damping resistance. Background technique [0002] In recent years, active power filters (APF) have increasingly adopted high-order filters, such as LC, LCL, and LLCL filters, to replace traditional single-inductor grid-connected inverters. The filtering effect of the LCL filter is better than that of the single inductor filter, and the filtering effect of the LLCL filter is better than that of the LCL filter. To obtain the same ripple filtering effect, LLCL can obtain the smallest inductance. [0003] The parameter design and stable control of LCL and LLCL filters for APF applications are a hot topic in inverter research. The design of the LLCL filter needs to determine four free parameters: three inductors and one capacitor, and it is difficult to co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/01
CPCH02J3/01Y02E40/20
Inventor 张刚李凯郑宏邹见效徐红兵何东
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA