Grid connected inverter control method based on hysteresis modulation under unbalanced grid voltage condition

A technology of grid voltage and control method, applied in the field of power electronics, can solve problems such as grid voltage imbalance of grid-connected inverters, and achieve the effects of reducing voltage fluctuation, improving stability, and ensuring stability

Active Publication Date: 2014-03-26
DONGFANG ELECTRIC CORP LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] At present, there is no patent or literature that proposes a grid-connect

Method used

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  • Grid connected inverter control method based on hysteresis modulation under unbalanced grid voltage condition
  • Grid connected inverter control method based on hysteresis modulation under unbalanced grid voltage condition
  • Grid connected inverter control method based on hysteresis modulation under unbalanced grid voltage condition

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Embodiment Construction

[0047] Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:

[0048] Such as figure 1 As shown, the three-phase grid-connected device is mainly composed of DC bus capacitors, grid-connected inverters, grid-connected filter reactors and the grid. Detect the three-phase grid voltage u through the sensor abc , three-phase grid current i abc and the DC bus voltage u dc .

[0049] 1. PLL

[0050] Transform the three-phase grid voltage through the 3s / 2s coordinate system, and its expression is:

[0051] u α u β = 2 3 1 - 1 2 ...

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Abstract

The invention relates to a grid connected inverter control method based on hysteresis modulation under the unbalanced grid voltage condition. The control method comprises that the voltage of a dc bus is detected, and a reference active power value is calculated via a PI (Proportion Integration) regulator; the positive sequence components and the negative sequence components of the grid voltage under a two-phase rotating coordinate system are obtained by processing three phases of detected grid voltages via coordinate conversion and positive/negative sequence component decomposition; three phases of instantaneous reference-current values are obtained from the reference active power value and the positive and negative sequence components of the grid voltage via calculation, coordinate conversion and the like; and finally, the three phases of instantaneous reference-current values are compared with three phases of practical current values, a certain hysteresis width is set, and driving pulses are emitted in a hysteresis control principle. The control method requires no parameters of grid connected filtering reactors, and only includes the PI regulator, thereby providing convenience for construction realization; and under the unbalanced grid voltage condition, the stability of instantaneous grid power can be effectively ensured, the voltage fluctuation of the dc bus can be lowered, and the stability of the grid connected inverters is improved.

Description

technical field [0001] The invention belongs to the field of power electronics, and specifically relates to a control method for a grid-connected inverter based on hysteresis modulation when the grid voltage is unbalanced. Background technique [0002] At present, grid-connected inverters have been widely used in the field of new energy power generation, such as wind power generation and photovoltaic power generation. Due to grid faults or uneven load distribution, the power grid often has unbalanced three-phase grid voltage, which easily leads to failure or even damage to the grid-connected inverter. The main reason is that when the grid voltage is unbalanced, there is a negative sequence component in the grid-side voltage. The control premise of the traditional grid-connected inverter is that the three-phase grid voltage is balanced, and it does not decompose the positive and negative sequence components of the three-phase voltage. The positive sequence voltage of the pow...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02M7/48
Inventor 于海坤周宏林代同振况明伟吴建东
Owner DONGFANG ELECTRIC CORP LTD
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