Inverter parallel harmonic wave ring current restraining method for controlling harmonic wave droop

Abstract

The invention discloses an inverter parallel harmonic wave ring current restraining method for controlling harmonic wave droop. The method comprises a harmonic wave droop control, a power droop control and a voltage control. During the harmonic wave droop control, feature subharmonic power is detected through a rapid Fourier FFT (fast fourier transform algorithm) commutation fractional frequency, according to a harmonic wave droop feature, and a feature subharmonic reference voltage output by an inverter is calculated; and during the power droop control, the fundamental wave reference voltage is calculated, the feature subharmonic reference voltage and the fundamental wave reference voltage are combined into the reference voltage output by the inverter, the output voltage distortion of the inverter is effectively reduced, the inter-harmonic ring current of the inverter is controlled, and the power accurate allocation is realized. The inverter parallel harmonic wave ring current restraining method provided by the invention can be used for solving the problems that when a large number of non-linear loads are switched on the parallel system, the voltage distortion of a system is serious, a harmonic wave ring current is magnified and the like, the inverter parallel harmonic wave ring current restraining method is effectively applied to an industry special power supply, a UPS (uninterrupted power supply) and a distributed energy system.

Description

technical field [0001] The invention relates to the field of multi-inverter parallel systems in distributed power generation, UPS, and special power supplies, in particular to a method for suppressing parallel harmonic circulation of inverters with harmonic droop control. Background technique [0002] In order to make full use of distributed power generation and renewable energy (such as wind energy, solar energy, tidal energy, etc.), it has become the current field of new energy power generation to organize its access in the form of microgrids and operate in the form of isolated islands or grid-connected. research hotspots. Due to the increase of load capacity and the limitation of the capacity of power electronic devices, distributed power sources are generally connected to microgrids in parallel with inverters. Therefore, the stable parallel operation of inverters will greatly improve the overall capacity and reliability of the microgrid system. [0003] Aiming at the p...

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a harmonic droop control inverter parallel harmonic circulation suppression method to solve the problem of applying the existing method to the multi-inverter parallel system with nonlinear load operation When , the inverter output voltage is distorted, resulting in harmonic circulation between the inverters, and the problem of low power distribution accuracy between the inverters

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