A Stability Criterion Method for Parallel Systems of DC Converters Based on Impedance Decomposition

Abstract

The invention discloses a method for judging the stability of a DC converter parallel system based on impedance decomposition, and belongs to the technical field of power systems. The method of stability criterion is as follows: firstly, the mathematical model of the DC bus voltage at the common analysis node in the DC converter parallel system is determined; then, based on the Nyquist stability theorem, a method for judging the system stability based on the impedance of the source-load cascaded system is proposed ; Finally determine the dominant subsystem that causes instability at the instability frequency of the source-load cascade system, and correct the stability of the source-load cascade system. The invention can realize the impedance stability judgment of the DC power distribution system in a wide frequency range, analyze the system stability from the perspectives of positive and negative damping and resonance sources, and explain the instability from the aspect of physical essence, so as to reshape the impedance Provide guidance.

Description

technical field [0001] The invention belongs to the technical field of power systems, and relates to a method for judging the stability of a DC converter parallel system based on impedance decomposition. Background technique [0002] In a DC microgrid, there are a large number of power electronic components, motors, and loads connected to the DC bus through power electronic converters. The switching power supply device composed of switching power electronic components is affected by the switching characteristics and closed-loop control during operation, resulting in nonlinear characteristics of the input and output impedance characteristics of the power electronic power supply or load device. In particular, in order to ensure fast response characteristics, the power electronic load has its own input impedance characteristics showing negative impedance characteristics due to the introduction of negative feedback. With the increase of power electronic devices in the DC power ...

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Problems solved by technology

[0004] The present invention provides a stability criterion method of DC converter parallel system based on impedance decomposition, which solves the problems of low accuracy of impedance analysis in DC power distribution system, unclear physical mechanism, difficulty in finding weak links of the system and problems in the prior art. Difficult Quantification of Positive and Negative Damping in Impedance Mismatched Oscillation

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