Multi-inverter micro-grid harmonic resonance suppression method based on adaptive virtual impedance remodeling

Abstract

On the basis of the inverter-side current feedback control strategy, the invention presents a multi-inverter micro-grid harmonic resonance suppression method based on adaptive virtual impedance remodeling. The method includes a virtual impedance remodeling unit, a parameter adaptive adjustment unit and a grid impedance online detection unit. The virtual impedance remodeling unit can improve the output impedance characteristics of grid-connected inverters and inject certain damping components into a micro-grid. The parameter adaptive adjustment unit adaptively adjusts the control parameters ofthe virtual impedance remodeling unit and a current regulating controller according to the impedance parameters of the grid to maintain the stability of the system. The grid impedance online detectionunit provides the equivalent impedance of the grid as the input of the parameter adaptive adjustment unit. The method improves the characteristics of the current loop, and enables inverters to maintain stability under various grid impedance conditions. The method can solve the problems of complex control system, fixed control parameters and low efficiency of the regulation process in the existingmulti-inverter micro-grid system.

Description

technical field [0001] The invention belongs to the field of power electronics and new energy power generation, and in particular relates to a multi-inverter microgrid harmonic resonance suppression method for adaptive virtual impedance reshaping. Background technique [0002] As the global energy crisis and environmental problems continue to intensify, the rapid development of grid-connected technologies for renewable energy (such as solar energy, wind energy, and biomass energy, etc.) has been stimulated. Microgrid is a unified whole composed of local multi-distributed power sources, energy storage devices and power consumption units, and is one of the key technologies of the future energy chain. As the key equipment connecting the distributed generation system and the public grid, the grid-connected inverter's performance and control method directly determine the quality of grid-connected power. [0003] The harmonic resonance problem in the LCL grid-connected inverter w...

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Problems solved by technology

[0004] Because the grid-side current feedback LCL filter grid-connected inverter cannot achieve single closed-loop control stability, other feedback control variables need to be introduced in the grid-side current feedback control. The present invention adopts the inverter machine-side current feedback control strategy (like figure 1 As shown), the algorithm is simple, under the condition that the controller is properly designed and the control parameters are selected properly, the current control of the inverter machine side can keep the system stable and avoid the occurrence of inverter resonance. The purpose of the present invention is to In the existing multi-inverter microgrid system, there are problems such as complex control system, fixed control parameters, and low efficiency of the adjustment process. A method for suppressing harmonic resonance of multi-inverter microgrid with adaptive virtual impedance reshaping is proposed. The method can not only effectively suppress the series-parallel harmonic resonance caused by the parallel connection of multiple inverters, but also adaptively adjust the control parameters in the virtual impedance reshaping unit and the current regulation controller according to the microgrid system conditions

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