A control device and system for a single-stage multi-input grid-connected inverter

Abstract

The present invention provides a control device and system for a single-stage multi-input grid-connected inverter. The input current of the input source is collected by the MPPT controller to generate the maximum power point current, which is sent to the corresponding computing node and the PI regulator to generate the corresponding The error amplification signal of the DSP controller receives the error amplification signal of each modulation circuit, and sends it to the second operation node of the first modulation circuit after performing a summation operation, and the first modulation circuit generates a grid-connected current reference signal according to the sum value, The current regulator generates the first modulation signal according to the feedback signal and the reference signal, and the multi-channel second modulation circuit directly multiplies the second error amplification signal and the grid voltage sinusoidal synchronous signal to obtain the second modulation signal, and the logic circuit generates the second modulation signal according to the first modulation signal and The second modulation signal generates a control signal and sends it to the inverter, which realizes direct control of the grid-connected current, ensures the waveform quality of the grid-connected current, and improves the dynamic performance and anti-interference ability of the inverter.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a control device and system for a single-stage multi-input grid-connected inverter. Background technique [0002] Single new energy power generation systems such as photovoltaic cells and wind turbines usually have defects such as unstable power supply, discontinuity, and changes with climate conditions, which seriously affect the quality and efficiency of power generation. In order to improve the quality and efficiency of power generation, it is necessary to adopt a distributed power generation system that is jointly powered by multiple new energy sources. The single-stage multi-input grid-connected inverter can directly convert the energy of multiple same or different new energy sources into low-frequency alternating current and feed it into the AC grid. It has the advantages of simple circuit structure, single-stage power conversion, and high conversion efficiency. Distribute...

AI Technical Summary

Problems solved by technology

[0004] The single-stage multi-input grid-connected inverter using the input power control method realizes the maximum power output of multiple new energy sources, but there is an obvious defect: because there is no control of the grid-connected current iL or the filter inductor current iLf (Note: iL=iLf), the quality of the grid-connected current waveform is poor, and due to the slow response speed of the MPPT loop, when the external conditions such as light intensity or wind speed change suddenly, it fails to cause a rapid response of the grid-connected current, resulting in an instantaneous power imbalance, and the grid-connected current Distortion occurs and damages the inverter

It can be seen that the single-stage multi-input grid-connected inverter adopting this control method has poor dynamic performance and weak anti-interference ability, and its practicability is greatly limited.

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