Impedance measurement method based on disturbance frequency and amplitude adaptive control

Abstract

The invention provides an impedance measurement method based on disturbance frequency and amplitude adaptive control. An impedance measurement device involved in the method comprises a disturbance injection unit and a disturbance control unit. According to the impedance measurement method, impedance to be measured is predicted through interpolation; the amplitude of injected disturbance is adjusted according to the amplitude of the predicted impedance; the linearity of the impedance is judged according to an error between the predicted impedance and actual measured impedance; and the next frequency step size is adjusted. The method is simple to implement; and grid-connected equipment with the completely unknown impedance characteristics can be more intensively measured in a frequency bandwith irregular impedance, so that information loss due to excessively large frequency step size can be prevented. According to the predicted impedance, the magnitude of an injected disturbance voltageis adjusted, so that the damage to the equipment caused by excessively high injected disturbance voltage can be effectively prevented; and the provided impedance measurement method can realize adaptive control of the disturbance frequency step size and amplitude. A foundation is provided for impedance-based stability analysis.

Description

technical field [0001] The invention belongs to the field of power quality and control, and relates to an impedance measurement method for adaptive control of disturbance frequency and disturbance amplitude under grid-connected conditions. In the research of distributed power generation, it provides a disturbance frequency and Amplitude selection method. [0002] technical background [0003] The impedance-based grid-connected system stability analysis needs to know the grid impedance and the impedance of the grid-connected equipment. The impedance measurement experiment can obtain the output impedance of the grid-connected equipment through the impedance measurement experiment without obtaining the control structure and parameters of the grid-connected equipment. In the application of existing impedance measurement technology, the frequency of the injected signal is generally given manually by the measurer, and it is measured with equal steps; the amplitude of the disturban...

AI Technical Summary

Problems solved by technology

It is used to solve the loss of impedance information at the place where the impedance changes greatly when the disturbance frequency step is constant, and to solve the safety problem of the grid-connected equipment when the impedance at the measurement frequency point is too small and the response current is too large when the disturbance amplitude is constant.

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