llccl type npc inverter control system and inverter side current resonance suppression method

Abstract

The invention discloses an LLCCL-type NPC (neutral-point-clamped) inverter control system and an inverter side current resonance inhibition method thereof; main topology of an inverter comprises a neutral-point-clamped three-level inverter circuit and an LLCCL-type filter, system equivalent switching frequency can be improved effectively, filter inductance value can be decreased effectively, and energy density of the inverter can be increased effectively; switch sub-harmonic and high-frequency harmonic can be inhibited better, and grid-connected current distortion rate can be reduced better; in addition, the two-DOF (degrees of freedom) inverter side current resonance inhibition method provided herein mainly comprises quasi-proportional resonance control and inverter current feedback active damping control; the method has no need for extra sensors, and system reliability is improved. Equivalent impedance of inverter current feedback active damping exhibits zero attenuation at high frequency in terms of damping features, and double-harmonic peaks of the LLCCL-type filter are inhibited effectively; inductivity is present at low frequency, and system control dynamicity is improved.

Description

technical field [0001] The invention relates to the field of distributed power generation and grid-connected power generation, in particular to an LLCCL type NPC inverter control system and an inverter side current resonance suppression method. Background technique [0002] At present, more and more distributed generation and renewable energy sources (such as wind energy, solar energy, etc.) are connected to the public grid or local loads through inverters. The proportion of distributed power generation in total energy is constantly increasing, and grid-connected inverters are gradually developing in the direction of high-efficiency and low-cost high-power. Therefore, for high-power grid-connected inverters, it is desired to have better grid-connected power quality while reducing the size of the hardware. Most of the traditional inverter structures are three-phase bridge structures, which have the advantages of low hardware cost and simple control methods. However, the fre...

AI Technical Summary

Problems solved by technology

However, most of the active damping control strategies proposed so far require additional sensors, which increases the hardware cost of the system, reduces the system reliability, and increases the difficulty of engineering practice.

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