Dimension reduction observer design method based on grid-connected LCL filter system

Abstract

The invention discloses a dimension reduction observer design method based on a grid-connected LCL filter system. An active damping control method based on a state observer is disclosed. Through feedforward, a capacitance current is observed so as to restrain a system resonance. For a completely observable system, a system can be reconstructed, a variable which can be directly measured in an original system, such as an input quantity and an output quantity, is used and taken as an input signal so that the output quantity is equivalent to a state variable of the original system under a certain index. After observability analysis is performed on the grid-connected LCL filter system and the system is demonstrated to be the completely observable system, through the input quantity and the output quantity of the LCL filter system, the system state variable is estimated so that purposes of saving an additional sensor and increasing system reliability are reached. In the invention, an LCL grid-connected inverter based on a dimension reduction observation method can effectively carry out grid connection on an intermittent power generation system, active and reactive power control is performed on a network-access current, and simultaneously and more importantly, a harmonic current can be reduced.

Description

technical field [0001] The invention belongs to the fields of new energy power generation and grid-connected technology, digital control technology, power electronics technology and motion control technology, and in particular relates to a design method for a dimensionality reduction observer based on a grid-connected LCL filter system. Background technique [0002] The intermittent power generation system supplements the traditional power generation method to meet the demand of the power market, and it is also becoming more and more mature as a clean energy power generation. The power electronic equipment connected to the power grid is increasing, and the generator capacity and power plant (field) scale of such systems are increasing year by year. [0003] In order to improve the quality of electric energy integrated into the grid by new energy power generation systems and reduce the switching subharmonic content of converter-type grid-connected systems, large-capacity grid...

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Problems solved by technology

[0008] The purpose of the embodiments of the present invention is to provide a design method for a dimensionality reduction observer based on a grid-connected LCL filter system, which aims to solve the problem of the high sampling channel inevitably introduced in the prior art due to the use of capacitive voltage or capacitive current sampling sensors. Subharmonics, which interfere with the control process and cause system instability and other problems

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