Control in Power Electronics : selected problems

This paper presents two new implementations of finite control set model predictive control (FCS-MPC) methods applied to ac–dc converters with an inductive.capacitive.inductive (LCL) filter. The LCL filter, despite its advantages, can cause a strong resonance in the grid current and also pose a substantially more complex control problem. The new solutions improve the FCS-MPC with an active damping algorithm by eliminating low-order grid current harmonics and decreasing sensitivity to grid voltage distortion. The new methods, i.e., PCi1i2uc and PCi1i2uc-2steps propose multivariable approaches using converter-side current, line-side current, and capacitor voltage. Another improvement involves extending the prediction horizon in PCi1 i2uc-2steps. Both methods have been tested and compared in steady and transient states as well as under grid voltage disturbances. The methods were also compared with a predictive control algorithm with active damping. The simulation results and experimental measurements validate the developed control schemes and show high quality of grid current (low THDi value), high dynamic performance, and immunity under distorted grid voltage conditions.

Finite Control Set Model Predictive Control for Grid-Connected AC–DC Converters With LCL Filter

Переклад англомовного варіанту міжнародного документу “Directive 2009/28/EC of the european parliament and of the council of 23 April 2009 on the promotion of the use of energy renewable sources” українською мовою як навчальний ресурс літньої практики студентів-перекладачів

Power electronics and variable frequency drives are continuously developing multidisciplinary fields in electrical engineering and it is practically not possible to write a book covering the entire area by one individual specialist Especially by taking account the recent fast development in the neighboring fields like control theory, computational intelligence and signal processing, which all strongly influence new solutions in control of power electronics and drives Therefore, this book is written by individual key specialist working on the area of modern advanced control methods which penetrates current implementation of power converters and drives Although some of the presented methods are still not adopted by industry, they create new solutions with high further research and application potential The material of the book is presented in the following three parts:Part I: Advanced Power Electronic Control in Renewable Energy Sources (Chapters 1-4), Part II: Predictive Control of Power Converters and Drives (5-7), Part III: Neurocontrol and Nonlinear Control of Power Converters and Drives (8-11) The book is intended for engineers, researchers and students in the field of power electronics and drives who are interested in the use of advanced control methods and also for specialists from the control theory area who like to explore new area of applications

Advanced and Intelligent Control in Power Electronics and Drives

A review of computer tools for modeling electric vehicle energy requirements and their impact on power distribution networks

This paper presents the design process of a 6-kVA quasi-Z-source inverter built with SiC power devices, in particular, employing SiC MOSFETs and SiC Schottky diodes. The main design target is to find the optimal parameters and a good agreement between the efficiency and power density of the converter. The performance of the system may be influenced not only by the switching frequency but also from the specific pulsewidth modulated (PWM) method or type of SiC MOSFET, and, therefore, various design cases are analyzed. At a final step, the 6 kVA/3 × 400 VAC inverter employing the 80 mΩ SiC MOSFETs and operating at 100 kHz with the minimum switching number method is chosen for investigation and a laboratory prototype is built. From experiments, the high performance of the designed system is confirmed. More specifically, it is shown that an efficiency above 95.6% (at 400 VDC, B = 1.9) and a power density higher than 2 kW/dm3 have been reached. Last but not least, the obtained results, which can be recognized as leading in the area of impedance source converters, show the great benefits gained by employing the new power semiconductor devices.

On the Design Process of a 6-kVA Quasi-Z-inverter Employing SiC Power Devices

Purpose – The purpose of this paper is to consider both sides of a back‐to‐back AC‐DC‐AC interface.Design/methodology/approach – The paper presents a mathematical analysis, simulation, laboratory test in scaled model.Findings – The two main findings comprised concept of control methods for grid AC‐DC‐AC converter applied in renewable energy sources with variable speed operation under distorted grid. Active filtering functionality in case of non‐linear current of a parallel load. Second, a control algorithm dedicated for two‐level AC‐DC converter applied in industrial networks with high‐order harmonics compensation working under hard conditions – balanced and unbalanced voltage dips.Research limitations/implications – The paper shows preliminary results for AC‐DC‐AC converter and active filter (AF) during voltage dips and for harmonics compensation. Control methods and/or topology should be improved and tested in scale and after at high‐power system.Practical implications – Power quality supplied/received ...

Brief view on control of grid‐interfacing AC‐DC‐AC converter and active filter under unbalanced and distorted voltage conditions

In this chapter operation of a reliable control method of a Grid Connected Converter (GCC) under grid voltage disturbances is presented. As a GCC authors understand power electronic AC-DC converter with AC side filter and DC-link capacitor operating as an interface between the electrical grid and Active Loads (AL). At the beginning short introduction to selected grid voltage disturbances is given. Afterwards, the chosen modeling approach of a GCC is discussed and the example of passive components calculation are provided. In the next sections a brief review of a basic GCC control methods is described. A control method: Direct Power Control with Space Vector Modulation (DPC-SVM) is chosen for further development process. For the basic scheme of DPC-SVM special control modules for voltage dips and higher harmonics compensation are presented. Due to the development of new control modules and its integration with the classical DPC-SVM a new reliable (robust to selected grid voltage disturbances such as dips, higher harmonics) control method is proposed: Robust Direct Power Control with Space Vector Modulation (RDPC-SVM). The term “robust” in the name of proposed control refers to the fact that the RDPC-SVM method is expected to operate in an uncertain environment with respect to the system dynamics. This new control method can assure sinusoidal like and balanced AC current in extremely distorted grid voltage. Based on the case study from series 5–400 kVA of Voltage Source Converters (VSCs) it was verified that the control dynamic and features of the RDPC-SVM fulfill requirements of sinusoidal and balanced currents under uncertain grid voltage distortions. Moreover, the quality of current and power is significantly improved in comparison to classical methods. Hence, the negative impact of the GCC on the grid voltage (through its inner impendence) is significantly reduced i.e.: lower Total Harmonics Distortion (THD) factor of a grid current, control of active and reactive power flow assure good quality of integration with a grid even in case of increased impedance within operation limits.

Control of Grid Connected Converter (GCC) Under Grid Voltage Disturbances

The paper presents overview of high-order harmonics compensation methods applied for control of grid-connected converter. Two harmonic compensation methods are presented. One based on band-pass filers cooperating with Direct Power Control with Space Vector Modulation (DPC-SVM) is dedicated for renewable energy interface. Second method based on resonant controllers applied in Voltage Oriented Control (VOC) adds an active filtering function to PWM rectifier. Simulation and preliminary experimental results for these two methods are presented. Streszczenie. Artykul prezentuje wybrane metody kompensacji wyzszych harmonicznych. Pierwszą bazującą na filtrach cyfrowych przedstawiono w aplikacji, w bezpośrednim sterowaniu mocy z modulacją wektorową (DPC-SVM) przeksztaltnikiem sieciowym. Drugą bazującą na regulatorach rezonansowych przedstawiono w sterowaniu napieciowo zorientowanym (VOC) jako funkcje aktywnej filtracji sterowanego prostownika sieciowego. Na zakonczenie przedstawiono wstepne wyniki badan symulacyjnych i eksperymentalnych. (Kompensacja wyzszych harmonicznych w sieciowym przeksztaltniku PWM)

Higher harmonics compensation in grid-connected PWM converters for renewable energy interface and active filtering

The paper presents a simulation study of the Support Converter (SC) for passive front-end 55 kVA AC drive, which is aimed to improve the system performance. Most of time, the converter acts as a parallel Active Power Filter (APF) taking advantage from fast SiC devices application. During the regenerative breaking the SC may feed energy back to the supply grid. The complete system, including an advanced control system based on Direct Power Control with Space Vector Modulation concept, is modeled with the use of Saber package. Moreover, an estimation of the power losses is presented on the base of simulation results and switching performance tests of SiC MOSFETs and Schottky diodes. When harmonic compensation mode is considered semiconductor power losses are expected to be on the level of 120W (0.22% of nominal drive power). The converter is also expected to restore major part of energy from regenerative braking (power limit up to 28 kW) of the drive with total efficiency around 97.5%.

Szymon Piasecki

Papers

On the Design Process of a 6-kVA Quasi-Z-inverter Employing SiC Power Devices

Brief view on control of grid‐interfacing AC‐DC‐AC converter and active filter under unbalanced and distorted voltage conditions

Control of Grid Connected Converter (GCC) Under Grid Voltage Disturbances

Higher harmonics compensation in grid-connected PWM converters for renewable energy interface and active filtering

SiC-based Support Converter for passive front-end AC drive applications