LCL type three-phase grid-connected inverter control method

Abstract

The invention relates to an LCL type three-phase grid-connected inverter control method. The method includes first obtaining a preliminary PWM modulation signal by a traditional active damping controlmethod, then estimating the current after the resonance peak is suppressed according to the feature that an L-type filter and an LCL filter are consistent in characteristic at the low and medium frequency, obtaining the difference between the current and the actual current to be corrected by a current observer at the low and medium frequency, meanwhile feeding the higher harmonic part of the error current back to a control loop and introducing a network voltage feed forward item to obtain a final modulation signal and further control the access current of a grid-connected inverter. The accesscurrent is controlled in a two-phase rotating coordinate system, and the shortcoming that PI control cannot track an AC signal without static difference is overcome. On the basis of taking into account the advantages of active damping, the access harmonic components are further attenuated, and the grid-connected current quality and the system rapid response capability are improved. The method hasthe advantages of high control precision, high reaction speed and high reliability and is suitable for new energy integration grid-connected power generation systems.

Description

technical field [0001] The invention relates to an inverter control technology, in particular to an LCL type three-phase grid-connected inverter control method based on active damping and current error feedback control. Background technique [0002] In the 21st century, countries all over the world pay more and more attention to the control of energy crisis and environmental pollution. Facing the grim situation of energy depletion and increasing environmental pollution, people are paying more and more attention to the infinite possibilities brought by new energy sources such as wind energy, solar energy, and nuclear energy. The research of inverter control technology has become a very important content. The filters commonly used in inverters are L-type, LC-type and LCL-type filters. Compared with the first two filters, the LCL filter has a higher attenuation ability for high-frequency harmonics and a smaller volume. It is widely used, but the third-order characteristics of...

AI Technical Summary

Problems solved by technology

However, the adaptive controller designed by it can only compensate harmonics of a specific order, and the design of the controller is relatively complex

The improved WACC damping method with an additional capacitive current feedback loop improves the adaptability of the WACC method in weak power grids, but its parameter selection process needs to consider many factors at the same time, and it is cumbersome

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