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Control method of LCL (Lower Control Limit) type grid-connected inverter

A control method and inverter technology, which are applied to the parallel feeding arrangement of a single network, the conversion of AC power input to DC power output, and the conversion device of output power, etc. The grid-connected current does not meet the grid-connected standards, grid-connected current distortion and other problems, to achieve the effect of good grid-connected current waveform quality, improving grid-connected power factor, and suppressing influence

Inactive Publication Date: 2014-03-05
HUAZHONG UNIV OF SCI & TECH
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  • Summary
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  • Application Information

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Problems solved by technology

The fundamental wave of the grid voltage will affect the phase of the grid-connected current, and the harmonics of the grid voltage will cause distortion of the grid-connected current
If effective measures are not taken to suppress the influence of the grid voltage on the grid-connected current, the grid-connected current output by the grid-connected inverter will inevitably fail to meet the grid-connected standard

Method used

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  • Control method of LCL (Lower Control Limit) type grid-connected inverter
  • Control method of LCL (Lower Control Limit) type grid-connected inverter
  • Control method of LCL (Lower Control Limit) type grid-connected inverter

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Embodiment Construction

[0029] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0030] The control method provided by the present invention is as figure 2 As shown, the steps are:

[0031] (1) Current sensor H using capacitive current respectively i1 and filter inductor L 2 The current sensor H i2 Detection capacitor current i C and grid current i L2 , the capacitive current feedback signal i is collected C_of and grid-connected current feedback signal i L2_of ;Using the voltage sensor H v2 Detect grid voltage v g , the grid voltage feed-forward signal v is acquired g_fd .

[0032] (2) According to the current feedback signal i L2_of and its reference signal i ref Calculated error signal e 1 , its formula is formula I.

[0033] e 1 = i ref -i L2_of Formula I

[0034] (3) The controller’s response to the error signal e 1 Perform closed-loop processing to obtain the capacitor curren...

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Abstract

The invention discloses a control method of an LCL (Lower Control Limit) type grid-connected inverter for restricting the influence of grid voltage on grid-connected current. The method comprises the following steps of: (1) detecting capacitance current iC and grid-connected current iL2 by respectively utilizing a current sensor Hi1 of capacitance current and a current sensor Hi2 of filtering capacitance, acquiring a capacitance and current feedback signal iC_of and a grid-connected current feedback signal iL2_of, detecting grid voltage vg by utilizing a voltage sensor Hv2 of the grid voltage and acquiring a grid voltage feedforward signal vg_fd; (2) calculating an error signal e1 according to the iL2_of and iref; (3) carrying out closed-loop processing on the error signal e1 through a controller to obtain a reference signal iC_ref of the capacitance and a current feedback signal iC_of, adding iC_ref to vg_fd, and subtracting the added signal to iC_of to obtain an error signal e2; and (4) generating a PWM (Pulse Width Modulation) control signal for controlling an inverter bridge switching tube by utilizing the error signal e2. The control method of the LCL (Lower Control Limit) type grid-connected inverter for restricting the influence of grid voltage on grid-connected current, provided by the invention, can effectively restrict the influence of the grid voltage on the wave quality of the grid-connected current and improves the grid access power factor. In addition, wave quality of the grid-connected current is good.

Description

technical field [0001] The invention relates to a control method of an LCL type grid-connected inverter, in particular to a control method for suppressing the influence of the grid voltage on the quality of the grid-connected current waveform. Background technique [0002] figure 1 It is the structural diagram of the LCL type grid-connected inverter. The LCL grid-connected inverter includes a DC power source 1 , an inverter bridge 2 , an LCL filter 3 , a public grid 4 , and a controller 5 . Among them, the inverter bridge 2 is composed of the switch tube S 1 ~S 4 and freewheeling diode D 1 ~D 4 Composition; LCL filter 3 is composed of filter inductor L 1 , L 2 And filter capacitor C composition. h i1 and H i2 Respectively, the detection capacitor current and the filter inductance L 2 The grid-connected current sensor, H v2 For the voltage detection sensor. [0003] exist figure 1 In the structure, the grid-connected current command is input to the controller 5 ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02M7/5395
Inventor 王学华阮新波刘尚伟
Owner HUAZHONG UNIV OF SCI & TECH
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