Phase-locked loop bandwidth adaptive grid-connected inverter control method based on state feedback

Abstract

The invention discloses a phase-locked loop bandwidth adaptive grid-connected inverter control method based on the state feedback. In the case of a weak grid, the stability margin of a grid-connectedinverter is degraded or even unstable, low-frequency resonance of the grid-connected inverter is realized by state feedback control based on differential negative feedback while the harmonic amplitudein a low-frequency band of the grid-connected inverter is detected by the discrete Fourier algorithm to adaptively adjust phase-locked loop bandwidth of the grid-connected inverter, the phase marginof the grid-connected inverter under the weak grid is further guaranteed, and grid adaptability of the grid-connected inverter is improved.

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 phase-locked loop bandwidth self-adaptive grid-connected inverter based on state feedback. Background technique [0002] With the rapid development of distributed power generation systems, grid-connected inverters are widely used. In the case of a weak grid with high impedance, a dynamic interconnection system will be formed between the inverter and the grid, resulting in a decrease in the bandwidth of the grid-connected inverter control system and affecting its control stability. [0003] In the case of a weak power grid, the scheme of weakening or suppressing resonance by means of increasing the control loop is called an active damping scheme, and usually all or part of the state variables are fed back to the forward channel of the inverter to configure the pole of the closed-loop system Position to stabilize the system, this type ...

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Problems solved by technology

[0008] In order to overcome the limitations of the above-mentioned various technical solutions, and aiming at the problem that the stability margin of the grid-connected inverter decreases or even becomes unstable under the condition of a weak grid, a phase-locked loop bandwidth adaptive grid-connected inverter control based on state feedback is proposed. method, the method realizes the low-frequency resonance of the grid-connected inverter through the state feedback control based on differential negative feedback, and at the same time detects the harmonic amplitude of the low-frequency band of the grid-connected inverter through the discrete Fourier algorithm to adaptively adjust and The phase-locked loop bandwidth of the grid-connected inverter further ensures the phase margin of the grid-connected inverter in a weak grid and improves the grid adaptability of the grid-connected inverter

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