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Method for adaptively controlling hybrid damping of grid-connection inverter applicable to weak grid access conditions

A technology of adaptive control and hybrid damping, which is applied in the direction of electrical components, AC power input conversion to DC power output, single-net parallel feeding arrangement, etc., can solve the problem of system bandwidth reduction, stability degradation, and grid-connected inverter control System impact and other issues

Active Publication Date: 2014-01-29
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +1
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Problems solved by technology

However, in the actual power grid, due to the influence of parameters such as transmission cables, the grid impedance is not zero, which will have a great impact on the grid-connected inverter control system
If the grid impedance is too large, the system bandwidth will be significantly reduced, the stability will be reduced, and even the system will be unstable.

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  • Method for adaptively controlling hybrid damping of grid-connection inverter applicable to weak grid access conditions
  • Method for adaptively controlling hybrid damping of grid-connection inverter applicable to weak grid access conditions
  • Method for adaptively controlling hybrid damping of grid-connection inverter applicable to weak grid access conditions

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Embodiment Construction

[0024] Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

[0025] figure 1 It is a block diagram of single-phase LCL grid-connected inverter system under weak grid conditions. The single-phase LCL grid-connected inverter includes a DC source 1, an inverter bridge 2, an LCL filter 3, a weak grid 4, a controller 5, and a grid impedance detection and variable parameter control module 6. Among them, the inverter bridge 2 is composed of the switching tube Q 1 ~Q 4 Composition; LCL filter 3 is composed of filter inductor L 1 , L 2 , filter capacitor C f and damping resistor R d Composition; weak grid 4 is composed of ideal voltage source u g and grid impedance R g and L g Equivalent in series.

[0026] figure 2 Bode plot of system impedance under grid impedance variation. It can be seen that when the grid inductive reactance L g When it increases, the bandwidth of the control system decreases sh...

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Abstract

The invention relates to a method for adaptively controlling hybrid damping of a grid-connected inverter applicable to weak grid access conditions. Most existing methods are used for optimally controlling fixed impedance of grids at present, but grid access conditions of grid-connected inverters are dynamic and varied, so that adaptive control under different grid impedance conditions has high application value. The method includes measuring impedance information of a weak grid by a harmonic injection process; enabling a controller to adaptively modify loop parameters and active damping coefficients; ensuring a wide stability margin and a proper control bandwidth of a control system. The method has the advantages that the novel method for adaptively controlling the hybrid damping is based on real-time measurement on impedance of the grid, and optimal control parameters in a DSP (digital signal processor) are automatically selected, so that the control bandwidth and a phase margin of the inverter under different grid impedance access conditions can be guaranteed, and the grid-connected inverter can safely and reliably run under the various grid impedance conditions.

Description

technical field [0001] The invention relates to a hybrid damping control method of a grid-connected inverter based on grid impedance dynamic feedback and self-adaptive variable parameter control, which belongs to the inverter control technology in the power conversion technology. Background technique [0002] Almost all renewable energy is connected to the AC grid through grid-connected inverters. A dynamic interconnection system is formed between the grid-connected inverters and the grid. However, there may be some Unexpected dynamic interaction effects. [0003] For an ideal grid-connected system, all parameters of the system are fixed. According to a reasonable design, the control system can have a suitable bandwidth and high stability. However, in the actual power grid, due to the influence of parameters such as transmission cables, the grid impedance is not zero, which will have a great impact on the grid-connected inverter control system. If the grid impedance is to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02M7/5387
Inventor 陈新华淼杰刘飞王赟程薛济萍薛群山冯志阳
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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