Small signal modeling and stability analysis method of single-phase cascaded island inverter system

Abstract

A small signal model based on a single-phase cascaded island ACHB inverter system and a stability analysis method based on a floquet theory are provided. The single-phase cascaded island ACHB invertersystem includes a digital controller with double closed loop control, an LC filter, a load and three single-phase H-bridge inverters operating at low voltage, medium voltage and high voltage respectively. The digital controller is connected to a filter capacitor. The small signal model based on the single-phase cascaded island ACHB inverter system, in consideration of a linear resistive load withsmall signal disturbance, separates a disturbance component, obtains a modulation signal expression by coordinate transformation, and analyzes the system stability by using the floquet theory. The beneficial effect is that a multi-level inverter reduces the harmonic components in the output voltage due to the increase of the output level of a main circuit, and the stability analysis of the smallsignal model solves the difficulty of modeling the nonlinear circuit of a converter, the dynamic characteristics of steady-state operating point of the converter are described by unified differentialequations, the stability domain of the system is accurately verified by the floquet theory, and a reliable criterion is provided for the stable operation of the whole single-phase cascaded island inverter system.

Description

technical field [0001] The invention belongs to the technical field of power systems, and in particular relates to a small-signal model of a single-phase cascaded island type inverter system and a stability analysis method based on the floquet theory. Background technique [0002] In general, modeling is necessary when designing any system, and power electronic converters are no exception. For the design of power electronic converters, the fundamental requirement is to achieve high-performance power conversion, and the system performance indicators involved include stability, robustness, dynamic response capability, and steady-state error characteristics. The performance of a power electronic converter depends largely on its control system, and the design of an efficient and precisely controlled power electronic control system must be based on an accurate and effective mathematical model. Modeling is an important part of power electronic converter design, and the mathematic...

AI Technical Summary

Problems solved by technology

Judging from the existing literature, the single-phase cascaded island inverter system usually adopts the method based on impedance theory for modeling and stability analysis. This method mainly studies the influence of the underlying control on the system stability. Able to conduct a comprehensive and comprehensive stability analysis on the upper and lower layers of the system

Therefore, the stable and reliable operation of power electronic devices cannot be guaranteed

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