DC converter parallel system stability criterion method based on impedance decomposition

Abstract

The invention discloses a DC converter parallel system stability criterion method based on impedance decomposition, and belongs to the technical field of power systems. The DC converter parallel system stability criterion method specifically comprises the following steps of: firstly, determining a DC bus voltage mathematical model at a common analysis node in the DC converter parallel system; based on a Nyquist stability theorem, proposing a method for judging the stability of a system according to the impedance of a source-load cascade system; and finally, determining a dominant subsystem causing instability at the instability frequency of the source-load cascade system, and correcting the stability of the source-load cascade system. According to the DC converter parallel system stability criterion method, the impedance stability of the direct-current power distribution system can be judged in a wide-frequency domain range, the system stability is analyzed from the two aspects of positive and negative damping and a resonance source, instability is explained from the aspect of physical essence, and guidance is provided for impedance remodeling.

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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