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Właściwości przekształtnika sieciowego z filtrem LCL ze sprzężeniem od wspólnego pomiaru prądów cewek filtru

Iwański Grzegorz, Chustecki Patryk, Gałecki Andrzej

Przegląd Elektrotechniczny

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2023

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R. 99, nr 3

30--35

PL

Artykuł przedstawia właściwości układu przekształtnika sieciowego z filtrem typu LCL z wykorzystaniem sprzężenia od wspólnego pomiaru prądu cewek filtru. Przedstawiono analizę porównawczą układów wykorzystujących sprzężenie od pojedynczego prądu jednej bądź drugiej cewki filtru LCL oraz możliwości poprawy odpowiedzi na wymuszenie prądu zadanego w układzie ze sprzężeniem zawierającym wyłącznie człon proporcjonalny. Przedstawiono wyniki symulacji i eksperymentu potwierdzającego pewne korzystne cechy wykorzystania wspólnego czujnika prądu.

EN

The paper presents properties of grid converter with LCL filter utilizing a common measurement and feedback of filter inductors currents. Comparative analysis of single inductor current feedback (inverter side or grid side inductor of LCL filter) and improvement of response on reference current change using only proportional term in the feedback loop are presented. Simulation and experimental tests results confirming some positive features of single current measurement of both inductors currents are shown.

2

Properties of active rectifier with LCL filter in the selection process of the weighting factors in finite control set-MPC

Falkowski P., Sikorski A., Kulikowski K., Korzeniewski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 1

51--60

EN

One of the main problems of multivariable cost functions in model predictive control is the choice of weighting factors. Two finite control set model predictive control algorithms, applied to the three-phase active rectifier with an LCL filter, are described in the paper. The investigated algorithms, i.e. PCicuc and PCigicuc, implement multivariable approaches applying line (grid) current, capacitor voltage and converter current. The main problem dealt with in the paper is the choice of optimum values of the cost function weighting factors. The values of the factors calculated using the method proposed in the paper are very close to the values represented by the lowest THDi of the line current. Moreover, simulations verifying the equations used in the prediction of controlled values, i.e. line current, capacitor voltage and converter current, are presented. Both simulation and experimental results are presented to verify effectiveness of the investigated control strategies under change of the load (P = 5 kW and 2.5 kW), during transient states, under unbalanced and balanced line voltage.

3

Finite control set MPC of LCL-filtered grid-connected power converter operating under grid distortions

Falkowski P., Godlewska A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 5

1069--1076

EN

Most of the basic control methods of the grid-connected converter (GCC) are defined to work with a sine wave grid voltage. In that case if the grid voltage is distorted by higher harmonics, the grid current may be distorted too, which, in consequence, may increase the value of the THD of the grid voltage. The paper deals with an improved finite control set model predictive control (FCS-MPC) method of an LCL-filtered GCC operating under distorted grid conditions. The proposed method utilizes supplementary grid current feedback to calculate the reference converter current. The introduced signal allows to effectively improve the operation when the grid is subject to harmonic distortion. The paper shows a simulation analysis of the proposed control scheme operating with and without additional feedback under grid distortions. To validate the practical feasibility of the proposed method an algorithm was implemented on a 32-bit microcontroller STM32F7 with a floating point unit to control a 10 kW GCC. The laboratory test setup provided experimental results showing properties of the introduced control scheme.

4

Investigation of a High-efficiency and High-frequency 10-kW/800-V Three-phase PWM Converter with Direct Power Factor Control

Barlik Roman, Grzejszczak Piotr, Leszczyński Bernard, Szymczak Marek

International Journal of Electronics and Telecommunications

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2019

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Vol. 65, No. 4

619--624

EN

The paper presents a concept of a control system for a high-frequency three-phase PWM grid-tied converter (3x400 V / 50 Hz) that performs functions of a 10-kW DC power supply with voltage range of 600÷800 V and of a reactive power compensator. Simulation tests (in PLECS) allowed proper selection of semiconductor switches between fast IGBTs and silicon carbide MOSFETs. As the main criterion minimum amount of power losses in semiconductor devices was adopted. Switching frequency of at least 40 kHz was used with the aim of minimizing size of passive filters (chokes, capacitors) both on the AC side and on the DC side. Simulation results have been confirmed in experimental studies of the PWM converter, the power factor of which (inductive and capacitive) could be regulated in range from 0.7 to 1.0 with THDi of line currents below 5% and energy efficiency of approximately 98.5%. The control system was implemented in Texas Instruments TMS320F28377S microcontroller.

5

Research on interaction of APFs based on relative gain array

Feng X., Sun T., Ma W.

Archives of Electrical Engineering

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2018

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Vol. 67, nr 1

165--177

EN

Different APFs (Active Power Filter) interact with each other when multiple APFs are connected to the grid, and the interactions deteriorate the control performance of APFs and even lead to system instability. This paper presents a method to analyze the dynamic interaction of multiple APFs in a weak grid. This method uses the Norton equivalent principle to establish the mathematical model of a single APF. The mathematical model of the multiple APFs connected to the grid is set up based on the single APF mode. The RGA (Relative Gain Array) principle is used to analyze the interactions among multiple APFs. Besides, this paper analyzes the effect of changing circuit parameters and controller parameters on the change of the interactions. The strategy of weakening and eliminating the interaction is proposed based on rational selection and combination of parameters. Analysis, along with time domain simulation and experimental results, is presented to verify the feasibility and effectiveness of the proposed method and strategy.

6

Efficiency comparison between the LLCL and LCL-filters based single-phase grid-tied inverters

Wu W., Huang M., Blaabjerg F.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 1

63-79

EN

An LLCL-filter is becoming more attractive than an LCL-filter as the interface between the grid-tied inverter and the grid due to possibility of reducing the copper and the magnetic materials. The efficiency of the LLCL-filter based single-phase grid-tied inverter also excites interests for many applications. The operation of the switches of the VSI is various with different modulation methods, which lead to different efficiencies for such a single-phase grid-tied inverter system, and therefore important research has been carried out on the effect of the choice of PWM schemes. Then power losses and efficiencies of the LLCL-filter and the LCL-filter based single-phase grid-tied inverters are analyzed and compared under the discontinuous unipolar, the dual-buck and the bipolar modulations. Results show that the efficiency of LLCL-filter based inverter system is higher than the LCL- filter based independent on the modulation method adopted. Experiments on a 2 kW prototype are in good agreement with results of the theoretical analysis.

7

Control of Voltage Source Inverter with an LCL Filter without Voltage Sensors

Wang H., Yu C., Zhang J., Cai X.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 5b

119-122

EN

The voltage source inverter with LCL filter has to adopt damping method to suppress the resonance of LCL filter, which increases of losses and sensors. With virtual flux estimation idea, grid voltage-sensor-less technology is applied to design observers for the grid voltage, capacitor voltage and current. The observed grid voltage and capacitor voltage is used to realize voltage orientation control and grid current compensation for unit power factor. The observed capacitor current was fed forward to restrain LCL response and keep the control stable. The simulation results verify the correctness of observes design and the control method.

PL

W artykule analizuje się przekształtnik o źródle napięciowym VSI z filtrem LCL w zastosowaniu do sieci elektrowni wiatrowych. Analizę przeprowadza się na podstawie monitorowania napięcia sieci, prądu sieci i napięcia na kondensatorze.

8

Averaged and switching function modelling for the active power filter with LCL- type coupling impedance

Han Y., Xu L.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 4

176-181

EN

This paper presents the averaged and switching function modelling for the active power filter (APF) with LCL-type coupling impedance. The mathematical model of the LCL-type APF is derived using switching function modelling technique, followed by the Fourier series analysis of the switching functions. The equivalent circuits are presented from the averaged and switching ripple model. The presented technique is also extended to the analysis of the modulation signal and inverter dc-link voltage. Finally, the experimental results are presented for verification.

PL

Artykuł prezentuje modelowanie uśredniającej i przełączającej funkcji aktywnego filtru z impedancja sprzęgającą typu LCL. Model matematyczny jest wyprowadzony przy modelowaniu funkcji przełączającej a następnie przez analizę Fouriera tej funkcji. Zaprezentowano schemat zastępczy. Przedstawiona technika może być rozszerzona do analizy sygnału modulowanego i przekształtnika. Na zakończenie przedstawiono wyniki eksperymentów.