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A hybrid damping adaptive control method for grid-connected inverters suitable for weak grid access conditions

An adaptive control and hybrid damping technology, which is applied to electrical components, AC power input conversion to DC power output, single-network parallel feeding arrangement, etc. Bandwidth reduction and other issues

Active Publication Date: 2015-11-25
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.

Method used

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  • A hybrid damping adaptive control method for grid-connected inverters suitable for weak grid access conditions
  • A hybrid damping adaptive control method for grid-connected inverters suitable for weak grid access conditions
  • A hybrid damping adaptive control method for grid-connected inverters suitable for 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 Patents(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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