Method for controlling grid-connected inverter of micro grid based on fuzzy PI algorithm

Abstract

The invention discloses a method for controlling a grid-connected inverter of a micro grid based on the fuzzy PI algorithm. The method comprises the steps that (1) the voltage of the current power grid, the output current of the current grid-connected inverter and the capacitive current of a current filter are sampled; (2) the command value of a grid-connected current is determined; (3) the proportionality coefficient and the integral coefficient of a PI controller are adjusted; (4) the command value of the capacitive current of the filter is acquired through the adjusted PI controller; (5) the command value of the output voltage of the grid-connected inverter is acquired through the PI controller; (6) a control signal is generated to control switch-on or switch-off of a switching tube of the grid-connected inverter, and an expected output voltage is generated at the power output end of the grid-connected inverter; (7) the step (1) to the step (6) are repeatedly executed to make the output current of the grid-connected inverter trace the command values all the time. According to the method, by adjusting the control parameter of the PI controller in an on-line mode through the fuzzy algorithm, the output current of the grid-connected inverter can trace a current command signal quickly and accurately.

Description

technical field [0001] The invention belongs to the technical field of power electronic device control, and more specifically relates to a control method of a microgrid grid-connected inverter based on a fuzzy PI algorithm. Background technique [0002] The so-called microgrid is a small and complete power grid, which includes power generation devices, energy storage devices, very short transmission lines, loads and control systems. It is a single controllable unit, a small autonomous system capable of self-control, protection and management. Its operation mode is flexible, and it can be connected to the external large power grid for grid-connected operation, and can also operate independently from the large power grid. [0003] Consortium for Electric Reliability Technology Solutions (CERTS) is an authoritative organization for research on microgrids. In 2002, CERTS gave a relatively complete definition of microgrid, mainly including: (1) microgrid is a small power grid, ...

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Problems solved by technology

However, in the above method, the proportional and integral coefficients of the PI controller are constant, which leads to certain system structure changes or parameter fluctuations (such as failure of the external grid structure or a sharp increase in the internal DC bus voltage), etc., The inverter cannot quickly and accurately track the control command, and cannot adjust the input and output active and reactive power in time

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