Reactive Power Sharing Control Method for Parallel Virtual Synchronous Machines Based on Online Impedance Identification

Abstract

The invention provides a parallel virtual synchronous machine reactive power sharing control method based on online impedance identification, which belongs to the field of control, including: obtaining the direct-axis current, adding pulse current disturbance to the obtained direct-axis current, and adjusting the current after adding the disturbance The voltage is sampled, and the line impedance is obtained based on the sampling result; the obtained line impedance and current are imagined as the PCC point voltage, and a voltage control loop and a power control loop are added to the control loop to realize VSG control; The voltage compensation value ΔU used to eliminate the error caused by the power angle error interference. According to its voltage drop, the voltage of the common coupling point is obtained, which is introduced into the original VSG control, so as to eliminate the influence of line impedance. In addition, the corresponding calculated voltage compensation value is superimposed in the traditional virtual synchronous machine control to eliminate the error caused by power coupling and realize accurate reactive power sharing when multiple VSGs are connected in parallel.

Description

technical field [0001] The invention belongs to the field of control, in particular to a method for controlling reactive power equalization of parallel virtual synchronous machines based on online impedance identification. Background technique [0002] With the continuous development of technology, the application of distributed energy (DG) is more extensive, and the parallel operation of multiple inverters has also become a research hotspot. The virtual synchronous machine (VSG) technology adds inertia and damping links on the basis of traditional droop control, which makes the inverter simulate the operating characteristics of synchronous generators and improves the stability of the system's transient frequency. However, when multiple inverters are connected in parallel, the problem of unbalanced reactive power distribution caused by power coupling caused by line impedance differences cannot be solved. [0003] Due to the line voltage drop, there is coupling between activ...

AI Technical Summary

Problems solved by technology

However, when multiple inverters are connected in parallel, the problem of unbalanced reactive power distribution caused by power coupling caused by line impedance differences cannot be solved

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