Analysis method of interaction influence among multi-inverter grid-connected control channels

Abstract

The invention discloses an analysis method of an interaction influence among multi-inverter grid-connected control channels. The method is characterized by through establishing a multi-inverter grid-connected structure model and calculating a relative yield value of an input quantity and an output quantity pieces, acquiring a relative gain matrix; through the relative yield value, analyzing whether an interaction influence exists among the different control channels; introducing an NI index to measure an interaction influence degree; and according to a positive or negative sign, determining stability and integrity of a system. In the invention, a relative gain matrix RGA based on a frequency is used to quantitatively analyze a size of an interaction effect of control channels when multiple inverters are in a grid-connected state; a low-frequency stage interaction influence presents a forceful negative interaction effect along with changes of a grid-connected number, a control parameter and a power grid equivalence impedance, and a high-frequency stage interaction influence is a positive interaction influence, which is generally helpful for restraining a corresponding frequency harmonic wave; through the introduction of the NI index, the interaction influence is analyzed and simultaneously stability of a grid-connected system is determined; and the method possesses high accuracy and practicality.

Description

technical field [0001] The invention relates to the technical field of analyzing the influence of multi-inverter grid-connection under the connection of a weak power grid, in particular to an analysis method for the interactive influence between multi-inverter grid-connection control channels. Background technique [0002] In recent years, due to resource constraints such as land and light, large-scale new energy stations are mostly built in remote areas or desert / semi-desert areas in western my country. The long-distance transmission lines make the grid impedance cannot be ignored when multiple inverters are connected to the grid. In the design and analysis of inverters, the PCC (Point of Common Coupling) voltage is generally considered constant, regardless of the coupling effect of grid impedance, and the operation of the inverter is not subject to output fluctuations of other parallel inverters Impact. In fact, under the weak grid connection, due to the existence of grid...

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Problems solved by technology

The biggest advantage of RGA is that it is easy to calculate, but because RGA ignores the dynamic information of the process, it can only analyze the static coupling effect between variables, and cannot analyze the interaction of control channels and judge the stability of the grid-connected system.

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