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Grid-connected inverter LLCL hybrid damping filter design method

A technology of filter design and hybrid damping, applied to AC networks to reduce harmonics/ripples, harmonic reduction devices, single-network parallel feeding arrangements, etc., can solve the problem that the harmonic suppression effect is not obvious at the switching frequency Inverter instability, poor filtering effect and other problems, to achieve the effect of increasing damping, suppressing harmonics, and reducing THD value

Pending Publication Date: 2020-03-24
WUHAN UNIV OF TECH
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Problems solved by technology

The single-inductor L-type filter has a simple structure, but its filtering effect is poor. Compared with the single-inductor, the LCL filter has a better filtering effect, but the LCL filter will resonate under certain high-order harmonics, resulting in a resonance peak. The inverter is unstable, and its harmonic suppression effect at the switching frequency is not obvious

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  • Grid-connected inverter LLCL hybrid damping filter design method
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  • Grid-connected inverter LLCL hybrid damping filter design method

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Embodiment Construction

[0017] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings in the specification to make the technical solution of the present invention and its beneficial effects clearer and clearer. The following description of the embodiments by referring to the drawings is exemplary, and is intended to explain the present invention, but should not be understood as a limitation to the present invention.

[0018] The additional aspects and advantages of the present invention will become apparent in the following description, or be understood through the practice of the present invention.

[0019] 1) Mathematical model of LLCL filter:

[0020] Such as figure 1 As shown, a three-phase grid-connected inverter circuit topology diagram of a grid-connected inverter LLCL hybrid damping filter.

[0021] E is the DC input voltage source, Q 1 ~Q 6 Is the switch tube, V a , V b , V c Is the output voltage on the bridge arm side of t...

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Abstract

The invention discloses a grid-connected inverter LLCL hybrid damping filter design method which is characterized in that an LLCL filter is arranged at the output position of a three-phase grid-connected inverter and used for filtering network access current harmonics. The LLCL filter adopts hybrid damping control combining a passive damping method and an active damping method based on capacitivecurrent feedback of an LC branch, and the passive damping method is characterized in that a resistor R is connected to the LC branch in series to further suppress a resonance peak. According to the invention, through arranging the LLCL filter at the output part of the three-phase grid-connected inverter, and combining two control methods of an active damping method and a passive damping method, the damping of the LLCL filter at the resonant frequency is increased, the resonance peak of the system is suppressed, and the resonance peak is further suppressed by connecting a resistor R to an LC branch in series by utilizing the passive damping method. The harmonic waves of the network access current are effectively suppressed, the THD value of the network access current is reduced, and the stability of the system is enhanced. Meanwhile, the design method is simple to implement.

Description

Technical field [0001] The invention relates to the field of grid-connected inverters, in particular to a design method of a grid-connected inverter LLCL hybrid damping filter. Background technique [0002] Energy is the foundation for the development of the national economy. However, with the development of the economy and the massive increase in population, energy consumption has increased rapidly. The development and utilization of new energy is urgent. Countries in the world are actively developing new and renewable energy. At present, the research of photovoltaic power generation technology is progressing rapidly, and the proportion of new energy is relatively prominent. The most important thing in photovoltaic power generation technology is the inverter module. How to improve the quality of grid-connected inverter current is the most important thing for inverters. One of the properties. [0003] At present, the filters that suppress the current harmonics of the three-phase g...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/01H02J3/38H02M1/12
CPCH02J3/01H02J3/38H02M1/126Y02E40/40
Inventor 黄亮杨雪梅张锐明谢长君徐爱华
Owner WUHAN UNIV OF TECH
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