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Current tracking control method of lcl type pwm rectifier in unbalanced power grid

A technology of current tracking and control method, which is applied in the direction of high-efficiency power electronic conversion, conversion of AC power input to DC power output, electrical components, etc. Achieve the effect of improving current quality, ensuring sinusoidal, and improving grid-connected current quality

Active Publication Date: 2022-06-07
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, both double closed-loop control and direct power control require positive and negative sequence decomposition of voltage and current, phase-locked loop, and coordinate rotation transformation, which require a large amount of computation
Although the model predictive control based on finite set does not require carrier modulation and positive and negative sequence decomposition, it still needs grid voltage phase-locking and power compensation in order to make the grid-connected current sinusoidal, which takes up a lot of computing resources and makes it difficult to improve the control frequency and accuracy

Method used

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  • Current tracking control method of lcl type pwm rectifier in unbalanced power grid
  • Current tracking control method of lcl type pwm rectifier in unbalanced power grid
  • Current tracking control method of lcl type pwm rectifier in unbalanced power grid

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Embodiment 1

[0046] as Figure 1 、 Figure 2 and Figure 3 As shown, embodiment 1 of the present disclosure provides a simplified current tracking control method for LCL type PWM rectifiers under unbalanced power grids, comprising:

[0047] Step 1: Perform Clark coordinate conversion on the sampled three-phase grid voltage, capacitance voltage and converter side inductor current; e to the converted grid voltage αβ Delay 90 electrical angle, the resulting delayed voltage signal is e' αβ ；

[0048] Step 2: Calculate the active power reference value p using the DC voltage outer loop ref , the value of which is the product of the output of the PI regulator and the DC voltage error. It should be noted that steps one and two are implemented in no particular order and can be executed in parallel if conditions permit.

[0049] Step 3: Calculate the initial reference current, the calculation formula is as follows:

[0050]

[0051] where e' α and e'β Grid voltage α axis and β axis delay signals under th...

Embodiment 2

[0070] Embodiment 2 of the present disclosure provides a current tracking control system for LCL type PWM rectifier under an unbalanced power grid, comprising:

[0071]The αβ conversion module is configured to obtain the three-phase grid voltage, capacitance voltage and converter side inductor current of the LCL filter, perform clark coordinate conversion, and obtain the voltage value and current value under the αβ two-phase stationary coordinate system;

[0072] The initial reference current acquisition module is configured to obtain the initial reference current according to the delay signal and the original signal in the two-phase stationary coordinate system of active power reference value, grid voltage αβ;

[0073] The final reference current acquisition module is configured to extract the high-frequency component of the capacitor voltage in the αβ two-phase stationary coordinate system by using a second-order elliptic filter, multiply it by the preset scale coefficient and a...

Embodiment 3

[0078] Embodiment 3 of the present disclosure provides a computer-readable storage medium on which a program is stored, the program is executed by the processor to implement the unbalanced grid under the unbalanced power grid under the LCL type PWM rectifier as described in the steps in the current tracking control method.

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Abstract

The disclosure provides a current tracking control method of an LCL PWM rectifier under an unbalanced power grid, which belongs to the technical field of power electronics-grid-connected converter control; the converter side inductance reference is calculated by using the voltage delay signal in the static coordinate system Current, indirectly tracking the grid-connected current; no current or power compensation, no phase-locked loop and voltage and current positive and negative sequence decomposition, to achieve the basic goal of DC voltage stability and unit power factor, while ensuring the sinusoidal grid-connected current, improving It improves the current quality and reduces the calculation load of the CPU, which is of great significance to the digital control of the rectifier.

Description

Technical field [0001] The present disclosure relates to the field of power electronics - grid-connected converter control technology, in particular to a current tracking control method of LCL type PWM rectifier under unbalanced power grid. Background [0002] The statements in this section merely provide background technology related to this disclosure and do not necessarily constitute prior art. [0003] Compared with traditional L-type filters, LCL filters are widely used in grid-connected PWM rectifiers due to their small size and good high-frequency rejection effect. However, filter capacitors introduce delays between the grid and the converter, increasing the complexity of directly controlling the grid-connected current and power. In addition, the inherent resonant frequency present in the LCL filter increases the harmonic content of the grid-tied current and must be suppressed by appropriate methods. [0004] The inventors found that in the case of unbalanced grid voltage,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/219
CPCH02M7/219Y02B70/10
Inventor 陈阿莲高翔任其财
Owner SHANDONG UNIV
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