Virtual impedance design method for grid-following type inverter based on parameter stability boundary

Abstract

The invention discloses a parameter stability boundary-based grid-following inverter virtual impedance design method, which comprises the following steps of: 1, analyzing system parameters of a power grid system formed by a grid-following inverter to obtain initial values, actual values and stability boundary values of the system parameters which influence the stability of the power grid system; and step 2, calculating virtual impedance Rv introduced into the following grid type inverter according to the initial value, the actual value and the stable boundary value of each system parameter. According to the method disclosed by the invention, the impedance value of the accessed impedance is quantitatively calculated based on the parameter stability boundary, and the calculation steps are simpler and more convenient; the impedance value of the impedance is determined by using the system equivalent resistance of the stability boundary and the instability boundary of the system parameters, and the system parameters which have great influence on the stability of the system are selected as the basis for calculating the impedance value, so that the required impedance value can be quantitatively calculated, and the result is more accurate.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a virtual impedance design method of a grid-following inverter based on a parameter stability boundary. Background technique [0002] With the rapid development of renewable energy sources such as wind power and photovoltaics, the penetration rate of power electronic converters as an important interface for new energy grid connection in the power system continues to increase, and the development of modern power systems is gradually showing a "double high" trend. . [0003] Most of the new energy grid-connected inverters are grid-following inverters, and their external characteristics are current sources. By directly controlling the output current, efficient utilization of distributed power sources is achieved, but they lack frequency and voltage support capabilities. In the 100% new energy island microgrid system dominated by power electronic converters, du...

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Problems solved by technology

[0003] Most new energy grid-connected inverters are grid-connected inverters, whose external characteristics are current sources. By directly controlling the output current, the efficient utilization of distributed power sources is realized, but they lack frequency and voltage support capabilities.

However, in the 100% new energy island microgrid system dominated by power electronic converters, due to its own low inertia, weak damping characteristics and lack of stable frequency and voltage support of the large power grid, when the system parameters are not set properly, it may As a result, the phase-locked loop of the grid-following inverter loses stability due to lack of damping, making the grid-following inverter unable to keep pace with the grid-constructed inverter, and finally the island microgrid system cannot maintain stable operation

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