LCL type grid-connected inverter control method

A control method and inverter technology, applied in the direction of irreversible DC power input conversion to AC power output, single-network parallel feeding arrangement, output power conversion device, etc., can solve the problem of low quality of incoming current and total incoming current. Harmonic distortion and other problems, to achieve the effect of enhancing suppression ability, reducing total harmonic distortion, and reducing THD

CN105337481AInactive Publication Date: 2016-02-17XUCHANG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2016-02-17
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses an LCL type grid-connected inverter control method. The method comprises: comparing a grid access current command signal igrid for an LCL type grid-connected inverter with the detected grid access current signal i for the LCL type grid-connected inverter, obtaining a first error signal, wherein the first error signal takes actions through a first controller so that an output signal iL is obtained; comparing the output signal iL with the detected capacitance current signal for an LCL filter, obtaining a second error signal, wherein the second error signal takes actions through a second controller so that a voltage modulation signal Uab for the LCL type grid-connected inverter is obtained; and driving a switch device of the LCL type grid-connected inverter through high frequency PWM, and obtaining the expected inverter grid access current. The LCL type grid-connected inverter control method can improve the quality of the grid access current for the grid-connected inverter, and can reduce the total harmonic distortion of the grid access current.
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Description

technical field

[0001] The invention relates to the technical field of power electronic device control, in particular to a control method for an LCL type grid-connected inverter. Background technique

[0002] The grid-connected inverter is a device that feeds the DC side electric energy into the grid in the form of a sine wave current, and it is a form of inverter application. Grid-connected inverters are widely used. For example, in the occasions of AC electronic loads and large-scale grid-connected power generation of renewable energy, inverters are required to run grid-connected to feed back the power in the system to the grid. However, in order to avoid grid-connected current with poor quality polluting the grid, the waveform quality of the grid-connected current has strict requirements. The current is a sine wave with the same frequency and opposite phase as the voltage, and meets the standards of the International Electrotechnical Commission. International regulations...

Examples

Embodiment 1

[0036] Embodiment 1 of the present invention provides a control method for an LCL type grid-connected inverter, such as figure 1 As shown, the method includes:

[0037] 101. LCL type grid-connected inverter grid-connected current command signal i grid Compared with the detected grid-connected current signal i of the LCL type grid-connected inverter, the first error signal is obtained, and the first error signal is acted on by the first controller to obtain the output signal i L .

[0038] Wherein, the first error signal is the input current command signal i grid The difference with the incoming current signal i.

[0039] The expression of the first controller is:

[0040] Among them, K P is the proportional parameter of the first controller, K i is the integral parameter of the first controller, and s is the sampling step size.

[0041] 102. The output signal i L Compared with the detected LCL filter capacitor current signal, the second error signal is obtained, and ...

Embodiment 2

[0048] When the power of the inverter is large, affected by the switching speed and power loss, the frequency of the power switching device of the inverter is reduced, and the single-inductor structure of the filter will increase the size and cost. At present, grid-connected inverter systems using LCL filters are more and more widely used.

[0049] The control method of the LCL type grid-connected inverter provided by Embodiment 2 of the present invention adopts the LCL type filter structure such as figure 2 shown.

[0050] Among them, L 1 ——The filter inductor on the side of the inverter;

[0051] L 2 - grid side filter inductance;

[0052] C - filter capacitor.

[0053] Compared with the L-type filter, the LCL filter utilizes the characteristics of the impedance difference between the inductance and the capacitance for different frequency components, and the filter increases the filter capacitor C f and grid side filter inductance L 2 , the impedance of the inductive...