Active damping control method for grid-connected inverter
A technology of damping control and inverter, applied in AC network to reduce harmonics/ripples, harmonic reduction devices, etc., can solve problems such as current instability, feedback and control lag, poor damping effect, etc., to achieve suppression Effect of harmonics, reduction of harmonic content, good damping effect
Inactive Publication Date: 2015-03-11
天津天传新能源电气有限公司 +1
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[0003] Since the inverter usually adopts digital control, there is a problem of feedback and control lag, so the more common filter capacitor current proportional feedback is adopted (the control structure is as follows figure 1 As shown), the damping effect of the method is not good, and even current instability may occur (see literature [1] Stewart Geoffrey Parker, Brendan P. McGrath, Donald Grahame Holmes, "Regions of Active Damping Control for LCL Filters", in IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS,VOL.50,NO.1,JANUARY / FEBRUARY 2014,pp.424-432
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[0025] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
[0026] An active damping control method for grid-connected inverters is an improvement on the existing active damping control method. It uses a proportional-resonant control method in the grid-connected current controller to directly adjust the sine; Corresponding to this, the proportional-inertia link in the filter capacitor current feedback channel becomes proportional-resonant link accordingly, such as image 3 Shown. Figure 1 to Figure 3 In, i s * Is the given value of grid-connected current of the inverter, i s Is the grid-connected current feedback value, i c Is the filter capacitor current feedback value, i f Is the output filter inductor current value of the inverter, U i It is a modulated signal. P and R respectively represent the proportion and resonance link, and k is the proportional coefficient.
[0027] This control method controls...
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The invention relates to an active damping control method for a grid-connected inverter. The method is technically characterized by comprising the following steps: sampling grid-connected current and filter capacitance current of the inverter and working out an average value in a control cycle; performing subtraction on a given value and a feedback value of the grid-connected current and performing proportional resonance adjustment on a deviation value; performing proportional resonance adjustment on a feedback value of the filter capacitance current; performing subtraction on output of a grid-connected current regulator and output of a filter capacitance current regulator, and multiplying by a proportional coefficient to serve as a modulation signal of the inverter; comparing the modulation signal of the inverter with a triangular carrier wave to form a PWM (pulse width modulation) pulse of the inverter. According to the method, the proportional inertial feedback of the filter capacitance current is introduced in a grid-connected current loop, and the feedback and the output of the grid-connected current regulator are subjected to proportional regulation, so that the effect similar to serial connection between a filter capacitance branch and a resistor can be achieved, a relatively good damping effect can be realized, harmonic waves can be effectively inhibited, and the harmonic content can be greatly reduced.
Description
Technical field [0001] The invention belongs to the technical field of grid-connected inverters, and particularly relates to an active damping control method for grid-connected inverters. Background technique [0002] For grid-connected inverters, the grid-connected current distortion rate is an important technical indicator. At present, the AC output side of the inverter usually uses an LCL filter to filter out high-order harmonics near the switching frequency in the PWM waveform. Compared with the L filter, the LCL filtering effect is better and the inductance can be smaller. However, the LCL filter is a third-order link, and there is a resonance problem, and the inverter adopts a grid-connected current closed loop that cannot suppress this resonance. To solve this problem, a method of connecting a resistor in series with the filter capacitor branch is generally used. This method is simple, reliable and effective. The disadvantage is that there is additional loss on the resist...
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IPC IPC(8): H02J3/01
CPCH02J3/01Y02E40/40
Inventor 董钺刘江华邱晗邢文超王雨龙
Owner 天津天传新能源电气有限公司