Method for improving stability of virtual synchronous machine grid-connected inverter system with consideration of sampling delay

Abstract

The invention discloses a method for improving the stability of a virtual synchronous machine grid-connected inverter system with the consideration of sampling delay. The method comprises the steps: establishing a small signal state space model of a VSG grid-connected inverter system; analyzing the structure of the VSG grid-connected inverter system, and determining the position of a delay link; determining a small signal state space equation of each link in the VSG grid-connected inverter system; establishing a small signal state space delay correction model of the VSG grid-connected invertersystem according to the small signal state space model of the VSG grid-connected inverter system and the small signal state space equation of each link of the VSG grid-connected inverter system; on the basis of the delay correction model, analyzing the stability of the VSG grid-connected inverter system, and determining a control parameter value range capable of enabling the VSG grid-connected inverter system to stably operate, thereby improving the stability of the VSG grid-connected inverter system. The problem that an existing VSG model is not accurate enough is solved, and the problem that the stability of the VSG grid-connected inverter system is not high due to the fact that the stability of the VSG grid-connected inverter system is analyzed on the basis of an ideal VSG model is solved.

Description

Technical field [0001] The invention belongs to the technical field of virtual synchronous machine grid-connected technology, and relates to a method for improving the stability of a virtual synchronous machine grid-connected inverter system considering the influence of sampling delay. Background technique [0002] In response to the energy crisis and environmental pressures, a new round of energy reform with new energy as the core is booming. Distributed power sources such as photovoltaics and wind power are connected to the power system through power electronic inverter grid-connected devices. However, power electronic devices lack rotational inertia because they do not have rotating parts. In a new power system with a high penetration rate of power electronic devices, when power fluctuations or system failures occur in the large power grid, the inverters that operate synchronously with the power grid cannot provide balanced energy injection to the power grid, and relying on tr...

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Problems solved by technology

[0005]The purpose of the present invention is to provide a method for improving the stability of the virtual synchronous machine grid-connected inverter system considering the sampling delay, so as to solve the problem that the existing VSG model only considers the VSG The dynamic characteristics of the algorithm link, ignoring the dynamic performance of the voltage and current dual-loop controller, making the modeling inaccurate, and based on the ideal VSG model to analyze the stability of the virtual synchronous machine grid-connected inverter system without considering the control delay, resulting in the use of digital The problem that the controlled VSG grid-connected inverter system has disadvantages in response characteristics and control accuracy and the problem of low operational stability of the digitally controlled VSG grid-connected inverter system

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