Расчет трансформатора -Transformer power calculation

 In this article I will try to tell you how to calculate a transformer for a welding machine.

EMC Aspects of PWM Controlled Loads in Vehicles Sabine Marksell-Department of Industrial Electrical Engineering and Automation Lund University-Licentiate Thesis

EMC Aspects of PWM Controlled Loads in Vehicles Sabine Marksell-Department of Industrial Electrical Engineering and Automation Lund University-Licentiate Thesis

Abstract The number of electrically driven loads in a modern vehicle is constantly increasing. Many loads that former were mechanically driven will in the future be driven by electricity. This implies that a number of electronic systems have to be packed together in the limited space in a vehicle. When different electronic systems are placed close to each other, there is always a risk for electromagnetic interference between the different systems causing malfunction or even failure. It is important to ensure that this does not happen, and this concept is called electromagnetic compatibility, EMC. EMC implies that different electrical systems should be able to work in close proximity without affecting each other. From the EMC point of view, integration of electric traction drives in present vehicles represents a considerable challenge. In order to save energy, many electrical loads can be controlled on demand. A common and energy efficient way to do this is to use a method called pulse width modulation, PWM, where the load voltage is pulsed in order to create the desired average output voltage. When this method is employed, the voltage pulses are present on the conductors between the power electronic converter and the load. Since the space in a vehicle is limited, it is often not possible to place the power electronic converter close to the load. Consequently, long conductors are often required between the power electronic converter and the load. The steep edges of the voltage pulses and the fundamental of the square wave, called the switching frequency, together with the long conductors cause electromagnetic interference problems. These disturbances could interfere with, for example, the radio in the vehicle. In this thesis, different electromagnetic compatibility aspects of a pulse width modulated system are investigated. Some solutions are proposed in order to mitigate the disturbances. The solutions involve increasing the rise and fall times of the voltage pulses and employing a randomly varying switching frequency. Also the effects from different conductor layouts, such as using the vehicle body sheet metal as a current return path or having the lead-in and return conductor close to each other, are investigated. In order to evaluate the results from the different setups, the voltage across the load and the radiated magnetic field are measured. The experimental results in this thesis show that a conductor should be used for current return and that this conductor should be placed as close to the lead-in conductor as possible in order to suppress electromagnetic noise. It is also shown that a randomly varying switching frequency will give a more broadband noise in the switching frequency range. Increasing the resistance of the gate resistor mitigates the disturbance in the higher frequency areas at the expense of increased switching losses.

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https://www.iea.lth.se/publications/Theses/LTH-IEA-1041.pdf

Electromagnetic compatibility of voltage source inverters for uninterruptible power supply system depending on the pulse-width modulation scheme-Krzysztof Bernacki, Zbigniew Rymarski ✉ Institute of Electronics, Faculty of Automatic Control and Computer Science of the Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland

 IET Power Electronics Research Article Electromagnetic compatibility of voltage source inverters for uninterruptible power supply system depending on the pulse-width modulation scheme ISSN 1755-4535 Received on 22nd August 2014 Accepted on 6th January 2015 doi: 10.1049/iet-pel.2014.0637 www.ietdl.org Krzysztof Bernacki, Zbigniew Rymarski ✉ Institute of Electronics, Faculty of Automatic Control and Computer Science of the Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland ✉ E-mail: zbigniew.rymarski@polsl.pl 

Abstract: The pulse-width modulation (PWM) scheme is an algorithm for inverter switch control. A two-leg bridge and three-level PWM are typical solutions in voltage source inverters in uninterruptible power supply systems. The three PWM schemes that are used in inverters are compared herein. Each scheme has different features, including the level of noise generated and interference in the different frequency ranges. The aim of this study is to analyse the characteristics and electromagnetic interference that is generated by an inverter using different PWM schemes. 

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https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-pel.2014.0637

Design and Implementation of Hybrid Active Power Filter (Hapf) for UPS System Mahendar Kumar1*, Zubair .A Memon1, M .Aslam Uqaili1-1Institute of Information & Communication Technologies (IICT) Mehran University of Engineering & Technology (MUET), Jamshoro Sindh, 76090, PAKISTAN

Design and Implementation of Hybrid Active Power Filter (Hapf) for UPS System Mahendar Kumar*, Zubair .A Memon, M .Aslam Uqaili 

Abstract: 

Hybrid Active Power Filter (HAPF) is designed and applied for Uninterrupted Power Supply (UPS) System to mitigate harmonic currents in UPS during the power conversion from rectifiers to inverters (AC-DC-AC Converters). Various UPS types and topologies are used for continuous power supply without delay and protection to connected loads. In spite of the fact that UPS is one of the power quality apparatus but it has also drawback of disturbing the power system quality of system by current harmonics and voltage distortion during conversion of power. Passive and EMI Filters could not eliminate harmonics effectively from UPS system therefore it requires modern, rapid filtering method as well combination of Active and Passive Filters. Proposed model of HAPF for UPS System could mitigate current harmonics for optimal power transfer and minimize losses, increase overall efficiency, reliability and life span of equipment. Higher harmonic current and higher voltage distortion leads to greater power loss. In this paper the (d-q) theorem is applied for the identification of harmonic currents. The d-q theorem and calculation creates the signal of reference compensation current and this produced signal of current is tracked by the yield current of the voltage source converter.. Hysteresis based controller for HAPF is applied to create the switching signals to regulate and maintain the voltage source converter output currents. Harmonics and efficiencies are analyzed at different loads and on charging and discharging of batteries of various UPS System in different industries and sectors on the basis of experimental investigation then HAPF is designed and implemented. In simulation results, it is observed that THD reduced from 46 to 10%, the harmonic currents were compensated and eliminated effectively which improved power quality of UPS System. Furthermore, addition of proposed HAPF could save the power up to 15 % which lost due to poor power quality of UPS System.

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https://publisher.uthm.edu.my/ojs/index.php/ijie/article/download/6727/3715/

Pulse Circuits by V.T. Frolkin; L.N. Popov

 

Pulse Circuits by V.T. Frolkin; L.N. Popov 

 This book explains the analysis and operation of all the most frequently used pulse circuits. It covers solid-state circuits, including their IC forms. The text contains a large number of problems and review questions that will help the reader to get better insight into the subject-matter. The authors start with pulse waveforms, move through RS-networks, to diode and transistor switching, logic gates, various forms of multivibrators, and flipflops as building blocks for the more complex networks. The material also covers sawtooth voltage and current generators, relaxation oscillators, and their applications.

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https://archive.org/details/v.-t.-frolkin-l.-n.-popov-pulse-circuits-mir-1982

IET Renewable Power Generation Research - Optimal sizing of a wind/solar/battery hybrid grid-connected microgrid system-José Luis Monroy-Morales, Rafael Peña-Alzola2,Rafael Sebastián-Fernández, David Campos-Gaona,Jerónimo Quesada Castellano, José L. Guardado

 Frequency control in an isolated wind-diesel hybrid system with energy storage and an irrigation water supply system José Luis Monroy-Morales1 Rafael Peña-Alzola2 Rafael Sebastián-Fernández3 David Campos-Gaona2 Jerónimo Quesada Castellano4 José L. Guardado 1Electrical Engineering, TecNM/Instituto Tecnológico de Morelia, Morelia, Mexico 2Electronic and Electrical Engineering, University of Strathclyde, Glasgow, UK 3Department of Electrical, Electronic and Control Engineering, UNED, Madrid, Spain 4Electronic Technology, University of the Basque Country, Vitoria, Spain

 Abstract 

Wind-Diesel Hybrid Systems (WDHSs) integrate wind turbines into diesel power systems, reducing costs and emissions in isolated grids. Due to the no-load consumption of the Diesel Generators (DGs), fuel savings are only possible when the DGs are shut down. This requires a proper implementation of the frequency control to avoid perturbations because of the wind speed variations. During wind-only (WO) operation, the Synchronous Machine (SM) generates the isolated grid voltage and the frequency controller varies the energy stored/supplied by an Energy Storage System and consumed by the controllable loads to balance the power. In this paper, a Battery-based Energy Storage System (BESS) uses Li-Ion batteries with a Dual Active Bridge (DAB) and a grid-tie inverter connected to the isolated network. The controllable load is an Irrigation Water Supply System (IWSS), consisting of a pump supplying water to a reservoir tank. The pump is driven by a variable speed drive that uses a Permanent Magnet Synchronous Motor (PMSM). The coordinated control of BESS and IWSS gives full priority to the BESS for harnessing the wind potential whereas the IWSS consumes the excess of wind power. The full Wind Diesel Power System (WDPS) is modelled and simulated to validate the proposed system for different case scenarios.

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https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/rpg2.12950

Optimal sizing of a wind/solar/battery hybridgrid-connected microgrid system-BY-Umer Akram, Muhammad Khalid, Saifullah Shafiq, Department of Electrical Engineering, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia

 IET Renewable Power GenerationResearch ArticleOptimal sizing of a wind/solar/battery hybridgrid-connected microgrid system Umer Akram1 , Muhammad Khalid1, Saifullah Shafiq1 1Department of Electrical Engineering, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia E-mail: g201512930@kfupm.edu.sa

 Abstract: Higher cost and stochastic nature of intermittent renewable energy (RE) resources complicate their planning,integration and operation of electric power system. Therefore, it is critical to determine the appropriate sizes of RE sources andassociated energy storage for efficient, economic and reliable operation of electric power system. In this study, two constraint-based iterative search algorithms are proposed for optimal sizing of the wind turbine (WT), solar photovoltaic (PV) and thebattery energy storage system (BESS) in the grid-connected configuration of a microgrid. The first algorithm, named as sourcessizing algorithm, determines the optimal sizes of RE sources while the second algorithm, called as battery sizing algorithm,determines the optimal capacity of BESS. These algorithms are mainly based upon two key essentials, i.e. maximum reliabilityand minimum cost. The proposed methodology aims to avoid over- and under-sizing by searching every possible solution in thegiven search space. Moreover, it considers the forced outage rates of PV, WT and utilisation factor of BESS which makes itmore realistic. Simulation results depict the effectiveness of the proposed approach.

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A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Microgrids for Both Grid-Connected and Islanded Modes Zhehan Yi, Student Member, IEEE, Wanxin Dong, and Amir H. Etemadi, Member, IEEE

 A Unified Control and Power Management Scheme for PV-Battery-Based Hybrid Microgrids for Both Grid-Connected and Islanded Modes 

Zhehan Yi, Student Member, IEEE, Wanxin Dong, and Amir H. Etemadi, Member, IEEE 

 Abstract 

 Battery storage is usually employed in Photovoltaic (PV) system to mitigate the power fluctuations due to the characteristics of PV panels and solar irradiance. Control schemes for PV-battery systems must be able to stabilize the bus voltages as well as to control the power flows flexibly. This paper proposes a comprehensive control and power management system (CAPMS) for PV-battery-based hybrid microgrids with both AC and DC buses, for both grid-connected and islanded modes. The proposed CAPMS is successful in regulating the DC and AC bus voltages and frequency stably, controlling the voltage and power of each unit flexibly, and balancing the power flows in the systems automatically under different operating circumstances, regardless of disturbances from switching operating modes, fluctuations of irradiance and temperature, and change of loads. Both simulation and experimental case studies are carried out to verify the performance of the proposed method.

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https://www.researchgate.net/publication/316655655_A_Unified_Control_and_Power_Management_Scheme_for_PV-Battery-Based_Hybrid_Microgrids_for_Both_Grid-Connected_and_Islanded_Modes

Smart inverters for seamless voltage and frequency dynamics in microgrids by Mohsen Shid Pilehvar-DISSERTATION submitted in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY Mike Wiegers Department of Electrical & Computer Engineering --KANSAS STATE UNIVERSITY Manhattan, Kansas 2021-

 

Smart inverters for seamless voltage and frequency dynamics in microgrids by Mohsen Shid Pilehvar

 AN ABSTRACT OF A DISSERTATION submitted in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY Mike Wiegers 

Department of Electrical & Computer Engineering Carl R. Ice College of Engineering 

KANSAS STATE UNIVERSITY 

Manhattan, Kansas 2021 

 Abstract 

This dissertation focuses on improving the dynamic behavior of microgrids during the abnormal conditions. For this purpose, novel approaches are presented to turn the conventional inverters implemented in distributed generation (DG) units into smart inverters capable of dealing with disturbances. In the context of microgrids, the smartness of an inverter is tied to its ability to cope with abnormalities such as sudden load changes, loss of generation, and transitions between different modes of operation. Founded on these principles, this dissertation advances the state-of-the-art in enhancing the dynamic response of microgrids. To this end, firstly, a new approach of forming smart loads in a fleet of nanogrids, which is also referred as a grid of nanogrids (GNG), is presented in this dissertation. The proposed smart load configuration is obtained via series connection of electric dampers (EDs) with critical loads to cope with disturbances at the point of critical loads. A systematic approach is presented for modeling of the proposed smart loads considering the switching states of EDs. The stability of the smart loads is then studied using the developed state-space model. Secondly, the conventional controllers of battery energy storage system (BESS) and photovoltaic (PV) units are modified in this dissertation in order to enable them to participate in dynamic-response enhancement of islanded mixed-inertia microgrids. For this purpose, two piecewise linear-elliptic (PLE) droops are proposed and employed in BESS to improve the voltage and frequency profiles during abnormalities. Besides, the controllers of PV units are equipped with an adaptive piecewise droop (APD) to cope with disturbances. Lastly, an approach is presented in this dissertation for seamless interconnection of three singlephase feeders at distribution level for residential communities that are suffering from power imbalance within the phases during islanded mode. To attain this, a seamless transition algorithm is presented which monitors the system condition in real time and sends appropriate commands to the static transfer switches (STSs) and modified controllers of single-phase inverters. Using the proposed method for interconnecting the isolated single-phase feeders results in forming a unified single-phase residential microgrid and maintaining the power balance and voltage level within all three phases. Moreover, the proposed approach enables the residential community to seamlessly reconnect to the main grid after resolving the abnormal condition on the grid side. In this dissertation, numerous case studies are carried out in PSCAD/EMTDC environment to validate the viability of proposed approaches in improving the dynamic behavior of microgrids.

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https://www.researchgate.net/publication/355709899_PDF_file

Comparison Between Different Droop Based Control Techniques and a Virtual Control Oscillator Carlos G. C. Branco1,*, Jordi El Mariachet Carreno1, Mingshen Li1, Francisco Kleber de A. Lima2, José Matas1, Josep M. Guerrero3

 Comparison Between Different Droop Based Control Techniques and a Virtual Control Oscillator Carlos G. C. Branco1,*, Jordi El Mariachet Carreno1, Mingshen Li1, Francisco Kleber de A. Lima2, José Matas1, Josep M. Guerrero Abstract: This work presents a literature review about control techniques for parallel connected power inverters under microgrid applications. Some control strategies, based on droop control for parallel inverters of distributed generation units in an ac distribution system will be presented in this work. Finally, an important method called Virtual Oscillating Control (VOC) is suggested for connecting voltage source inverters. Inverters are able to work in parallel with a constant-voltage constant frequency system, as well as with other inverters and also in standalone operation. The different power sources can share the load also under unbalanced conditions. Throughout this work several simulation results are presented in order to demonstrate the behaviour.

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https://upcommons.upc.edu/bitstream/handle/2117/387291/331.pdf?sequence=1&isAllowed=y

Compensation of Voltage Sags and Swells Using Dynamic Voltage Restorer Based on Bi-Directional H-Bridge AC/AC Converter Yu-KChen , Xian-Zhi Qiu , Yung-Chun Wu , and Chau-Chung Song Citation: Chen, Y.-K.; Qiu, X.-Z.; Wu, Y.-C.; Song, C.-C. Compensation of Voltage Sags and Swells Using Dynamic Voltage Restorer Based on Bi-Directional H-Bridge AC/AC Converter. Academic Editors: Chang-Hua Lin and Jahangir Hossain Received: Published: 30 August 2021 Department of Aeronautical Engineering, National Formosa University, Hu-Wei 632, Taiwan

 

Abstract: In this paper, the compensation of voltage sags and swells using a dynamic voltage restorer (DVR) based on a bi-directional AC/AC converter is presented for stabilizing single-phase AC line voltage. The H-bridge AC/AC converter with bi-directional switches and without bulk capacitor is adopted as the power topology of the proposed system. The proposed novel topology of DVR is adopted to compensate both voltage sag and swell conditions. Additionally, the power factor is closed to unity because a bulk capacitor is not required. The inner and outer loop control is proposed to improve the response with gain scaling; gain control is adopted to reduce the overshoot. Finally, a 2 kVA prototype has been implemented to verify the performance and accuracy of the control method for the DVR system. The peak efficiency of the system is up to 94%, and it can compensate 50% voltage swells and 25% voltage sags.

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A Study of Control Technique in Stationary Reference Frame for Improving the Disturbance Rejection Performance in Parallel Operation of Multi-Modular UPS--Hyo-Jun Ryu-- Department of Automotive Engineering (Automotive-Computer Convergence) Graduate School of Hanyang University

 A Study of Control Technique in Stationary Reference Frame for Improving the Disturbance Rejection Performance in Parallel Operation of Multi-Modular UPS--Hyo-Jun Ryu-- Department of Automotive Engineering (Automotive-Computer Convergence) Graduate School of Hanyang University

ABSTRACT

 This paper proposes a control technique for improving the disturbance rejection performance of a voltage controller during the parallel operation of multi modular UPS. In a single operation of the modular UPS, it is possible to improve disturbance rejection performance by conducting the feed-forward compensation for the load current, which is the disturbance of the voltage controller. However, a circulating current may occur when the modular UPS operates in parallel with the feed-forward control compensates for the load current. As a result, load sharing between UPS modules becomes uneven, and in severe cases, the parallel operation may not be possible. In this paper, the circulating current impedance model according to the load current feed-forward compensation gain explains the circulating current occurrence during the modular UPS parallel operation. In addition, a control technique, which is the feed-forward compensation for a portion of the load current considering a decrease of circulating current impedance, is proposed. However, the load current feed-forward compensation technique that considers circulating current impedance deteriorates disturbance rejection performance compared to a single operation of modular UPS, which is possible to apply for the load current feedforward compensation regardless of circulating current impedance. Therefore, this paper proposes another feed-forward compensation technique with a 2-DOF voltage controller structure to improve the reduced disturbance rejection performance. This technique ensures the cascade control performance of the structure of the voltagecurrent controller by maintaining the voltage controller's reference tracking performance and improving the disturbance rejection performance of the voltage controller. The effectiveness of the proposed feed-forward compensation technique is demonstrated by experimental results obtained through the operation of the fourparallel connected the 500 W modular double conversion UPS.