A grid-connected inverter control method with grid voltage feed-forward lag compensation in a weak grid

Abstract

The invention discloses a grid-connected inverter control method with grid voltage feed-forward lag compensation in a weak grid. In the invention, with consideration given to the grid stability problem caused by grid voltage direct feed-forward in the weak grid, a grid voltage feed-forward lag compensation control method is brought forward. According to the method, through a way of adding a low pass filtering link in a grid voltage feed-forward channel, fundamental wave gains of the grid-connected inverter and grid voltage direct feed-forward control are ensured to be the same, and astable error tracking of the fundamental waves is realized. According to the invention, grid background harmonic waves can be suppressed; phase margins of the grid-connected inverter in the weak grid are greatly increased; and the grid adaptability of the grid-connected inverter is raised.

Description

technical field [0001] The invention relates to a control method for a grid-connected inverter system, in particular to a control method for a grid-connected inverter with grid voltage feed-forward lag compensation under a weak grid. Background technique [0002] With the rapid development of distributed power generation systems, grid-connected inverters are widely used. In remote distributed power generation systems, the presence of long-distance transmission lines and a large number of transformer devices will bring a non-negligible equivalent impedance to the grid, making the grid show weak grid characteristics. In the case of a weak grid with high impedance, a dynamic interconnection system will be formed between the inverter and the grid. decline, affecting its control stability. The grid-connected inverter adopts the grid voltage direct feed-forward control, which can effectively compensate the current harmonics caused by the grid background harmonics, and thus has b...

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Problems solved by technology

[0006] (1) For the situation of weak grid, the method of direct feed-forward control of grid voltage in the existing literature will cause the stability of grid-connected inverter to be greatly reduced, and the system stability can be improved by reducing the feed-forward gain of grid voltage, but this method It will reduce the fundamental wave gain and increase the steady-state error between the grid-connected current feedback value and the command value, which is not conducive to fundamental wave tracking;

[0007] (2) None of the existing control schemes based on grid voltage feedforward involves adding a low-pass filter to the grid voltage feedforward channel to form grid voltage feedforward lag compensation to achieve grid-connected stability of the inverter

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