A control method for a single-phase grid-connected inverter and a method for obtaining control parameters thereof
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A control method and inverter technology, applied in the direction of single network parallel feeding arrangement, AC network to reduce harmonic/ripple, harmonic reduction device, etc. System calculations and other issues
Inactive Publication Date: 2019-01-08
GUANGDONG UNIV OF TECH
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[0003] For the control of single-phase inverter grid-connected system, the control system usually adopts the current inner loop control strategy based on the proportional-integral controller of the stationary or rotating coordinate system, but the proportional-integral controller cannot effectively process the AC signal in the stationary coordinate system The steady-state error; in the rotating coordinate system, the signal decoupling between the two coordinate transformations and the dq axis increases the amount of calculation of the system
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Embodiment 1
[0100] A method for controlling a single-phase grid-connected inverter, comprising the following steps:
[0101] Step 1. Through the grid voltage detection link, the grid voltage effective value U is collected and obtained g ;
[0102] Step 2. U g Input the phase-locked loop algorithm link to get the phase angle θ of the grid voltage;
[0103]Step 3. Given the magnitude I of the grid reference current m , using the equation I ref =I m sin(θ) to get the grid current reference value I ref ;
[0104] Step 4.I ref and the current output value I of the grid side inductance obtained by collecting g Subtracting each other, the obtained error E enters the proportional resonance controller and the harmonic compensation controller respectively;
[0105] Step 5. The output of the proportional resonant controller U pr and the output of the harmonic compensation controller U hc Add and compare the resulting sum U ab Perform clipping to obtain the reference value I of the filter...
Embodiment 2
[0146] A specific solution is used to further illustrate the control method of the single-phase grid-connected inverter of the present invention.
[0147] figure 1 It is a topological structure diagram of a single-phase LCL grid-connected inverter utilizing the control method of the invention. Neglecting the parasitic resistance of the device, L 1 , L 2 and C to form an LCL filter; to simplify the analysis, set the DC bus voltage U dc is a constant; U AB is the output voltage of the inverter bridge; U g is the grid voltage.
[0148] The system parameters of this embodiment are shown in Table 1.
[0149] Table 1 System parameters
[0150]
[0151]
[0152] figure 2 is a control block diagram of a system control method according to an embodiment of the present invention, refer to below figure 2 The composition of the system control method and the functions of each component in this embodiment will be described.
[0153] This embodiment proposes a dual current l...
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Abstract
The invention discloses a control method for a single-phase grid-connected inverter and a control parameter obtaining method therefor. The control method comprises the steps of collecting a power grid voltage value Ug, and inputting a phase-locked loop algorithm to obtain a phase angle <theta> of the power grid voltage; setting an amplitude value Im of a power grid reference current, and obtaining the power grid reference current Iref; enabling Iref and Ig to be subtracted obtain an error E, and enabling the obtained error E to pass through a proportional resonant controller and a harmonic compensation controller separately; enabling the output Upr of the proportional resonant controller to be added with the output Uhc of the harmonic compensation controller to obtain a sum Uab, and carrying out amplitude limiting on the obtained sum Uab to obtain a capacitive current reference value Icref of the filter; enabling the Ic and a feedback coefficient Kc to be multiplied to obtain a capacitive current feedback signal Ikc of the filter; enabling the difference value between the Ic and Ikc to be multiplied by a gain coefficient Kpwm of a PWM to form a modulation signal of a single-phase full-bridge inversion unit; and generating the driving pulse of the single-phase full-bridge inversion unit by the modulation signal. The control method is simple and feasible and capable of effectively restraining low-order harmonics.
Description
technical field [0001] The invention belongs to the technical field of grid-connected inverters, and in particular relates to the control of a single-phase grid-connected inverter and a method for obtaining control parameters thereof. Background technique [0002] Affected by factors such as increased awareness of environmental protection and rapid technological development, the application of distributed energy has become more and more widespread. Renewable energy feeds energy to the grid through grid-connected inverters to form a micro-grid. Therefore, grid-connected inverter technology is receiving more and more attention. Due to grid interference, grid-connected converter switching element dead zone effect and voltage drop and other factors, the working current of grid-connected converter contains a large number of low-order harmonics, and increasing the switching frequency can reduce the influence of low-order harmonics. But it brings a lot of high-order harmonics. LC...
Claims
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