Micro-grid multi-inverter parallel self-adaptive harmonic impedance remodeling control method and system

Abstract

The invention discloses a micro-grid multi-inverter parallel connection adaptive harmonic impedance remodeling control method. The method comprises three parts of harmonic impedance remodeling control, impedance remodeling factor adaptive control and voltage and current double-loop control. The harmonic impedance remodeling control can reduce the harmonic impedance of the inverter, reduce the voltage distortion rate and improve the voltage quality of the micro-grid. Impedance harmonic impedance self-adaptive remodeling can be achieved through impedance remodeling factor self-adaptive control, line impedance parameters and a micro-grid structure do not need to be known, and inverter equivalent harmonic impedance is self-adaptively remodeled by introducing output current harmonic component feedforward and combining a consistency algorithm. The outer voltage loop adopts multi-quasi-resonance control, can track a fundamental voltage instruction in a zero-static-error manner, and can reduce harmonic impedance, and the inner current loop adopts proportional control, so that the response speed of the system can be improved. According to the invention, harmonic current equalization of the multi-inverter parallel system of the micro-grid can be realized, the voltage quality of the micro-grid is improved, and the electric energy quality of the micro-grid is improved.

Description

technical field [0001] The invention relates to the field of inverter control, in particular to an inverter adaptive harmonic impedance remodeling control method and system. Background technique [0002] There are a large number of nonlinear loads in the microgrid, and the connection of a high proportion of nonlinear loads will introduce a large amount of harmonic current. The power quality of the microgrid is greatly challenged, and the inaccurate sharing of harmonic current may cause inverter Overload and false trigger protection, so the harmonic components of nonlinear loads must be evenly distributed to avoid overloading some distributed power sources while others are lightly loaded. Therefore, the equal sharing of harmonic power is also an equally important issue as the equal sharing of active power and reactive power. [0003] The traditional droop control is only for the fundamental wave domain, and is only used to share the fundamental wave component of the load pow...

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Problems solved by technology

[0003] The traditional droop control is only aimed at the fundamental wave domain, and is only used to share the fundamental wave component of the load power, and basically has no effect on the equal share of the harmonic current

In order to realize harmonic current sharing, the existing technology proposes a virtual impedance control method, but the introduction of virtual impedance will lead to the contradiction between harmonic sharing accuracy and voltage quality. Excessive virtual impedance can improve system harmonic sharing. Accuracy, but it will also cause large voltage distortion and reduce the voltage quality. Although the virtual impedance is too small, although the impact on the voltage quality is small, it cannot guarantee accurate harmonic equalization.

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