Grid-connected current regulator based on auto-disturbance rejection control

Abstract

The invention discloses a grid-connected current regulator based on auto-disturbance rejection control. The grid-connected current regulator comprises an auto-disturbance rejection controller and a controlled object LCC grid-connected inverter, and the auto-disturbance rejection controller comprises a tracking differentiator controller, an extension state observer and a non-linear state error feedback control law; the output of the tracking differentiator controller and the output of the extension state observer serve as the input of the state error feedback control law after being conducted with subtraction comparison; a value obtained by subtraction comparison carried out on the output of the state error feedback control law and output of the extension state observer serves as a first input signal of the extension state observer; the output of the state error feedback control law and the output of the extension state observer firstly are conducted with subtraction comparison, and then serve as an input signal of a controlled object after 1 / b gain is carried out; and the output of the controlled object serves as a second input signal of the extension state observer. The grid-connected current regulator based on the auto-disturbance rejection control has the advantages of improving the disturbance rejection capacity and static and dynamic performance of the system fundamentally.

Description

technical field [0001] The invention relates to a current regulator, in particular to a grid-connected current regulator based on active disturbance rejection control, and belongs to the technical field of micro-grid grid-connection. Background technique [0002] At this stage, most renewable energy cannot be used directly and needs to be connected to the grid through a distributed generation system. The key link is the grid-connected inverter, which is the interface connecting renewable energy and the grid. Grid-connected inverters are divided into single-phase and three-phase. Single-phase grid-connected inverters are mainly used in household power generation systems with small capacity, while three-phase grid-connected inverters are used in large-scale distributed Power stations have many applications. The grid-connected inverter usually adopts the pulse width modulation (PWM) strategy, and its output voltage has a large number of switching harmonics. In order to suppres...

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Problems solved by technology

(3) When using a digitally controlled grid-connected inverter, the calculation delay and modulation delay may affect the characteristics of active damping, and make the closed-loop control of the grid-connected current unable to achieve the expected effect, so it is necessary to take effective measures to reduce Detrimental effects of delay

(4) The actual grid voltage is connected at the public grid connection point (PCC), and there are usually local loads connected near the PCC. The harmonic current generated by the nonlinear equipment makes the grid voltage at the PCC contain background harmonics, which will affect and The waveform quality of the network current and the performance of the phase-locked loop need to take effective suppression measures

(5) From the PCC point, the power grid can be regarded as a series connection of a voltage source and line impedance. At this time, this line impedance may have a certain negative impact on the stability of the grid-connected inverter

Since a single PR controller cannot block all harmonics, the PR controller may not be able to make high quality current flow into the grid

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