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Search results for: VOLTAGE MEASUREMENT , TOPOLOGY , CONTROL SYSTEMS , VOLTAGE CONTROL , FIELD PROGRAMMABLE GATE ARRAYS , CAPACITORS , PULSE WIDTH MODULATION
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Hydro Power Plant in the Process of Voltage Control in the Electric Power System and the System Restoration
PublicationThe article covers selected issues related to the share of hydroelectric power in the process of rebuilding the power system after black-out and voltage control during that process. Selected results of measurements made during the creation of the transmission chain for the need to start a block of a thermal power plant from a hydroelectric power plant were presented.
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A new method of fault loop resistance measurement in low voltage systems with residual current devices
PublicationThis paper presents a new method of fault loop resistance measurement in low voltage systems with residual current devices. The method enables measuring fault loop resistance without nuisance tripping of residual current devices, by application an unconventional waveform of measurement current. It is important for proper verification of the effectiveness of protection against electric shock.
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Integrated algorithm for selecting the location and control of energy storage units to improve the voltage level in distribution grids
PublicationThis paper refers to the issue that mainly appears in distribution grids, where renewable energy sources (RES) are widely installed. In such grids, one of the main problems is the coordination of energy production time with demand time, especially if photovoltaic energy sources are present. To face this problem, battery energy storage units (ESU) can be installed. In recent years, more and more attention has been paid to optimizing...
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Control systems with programmable controllers - teaching aspects.
PublicationSterowniki programowalne są obecnie podstawowymi urządzeniami wykorzystywanymi w systemach sterowania i dlatego od absolwentów uczelni technicznych, a szczególnie absolwentów wydziałów elektrycznych, oczekuje się posiadania przynajmniej podstawowej wiedzy o sterownikach programowalnych i ich zastosowaniach. W pracy przedstawiono wybrane aspekty wprowadzenia do dydaktyki przedmiotu ''Systemy sterowania ze sterownikami programowalnymi''...
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The adaptive backstepping control of PMSM supplied by current source inverter for the field weakening region
PublicationThe sensorless control system of permanent magnet synchronous motor PMSM supplied by current source inverter for field weakening operation is presented in this paper. The adaptive backstepping control system and the backstepping speed observer are presented. The control system is based on multi-scalar variables. The control variables are: dc-link voltage and the output current vector pulsation. The control system was named voltage...
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Closed-Loop Control System Design for Wireless Charging of Low-Voltage EV Batteries with Time-Delay Constraints
PublicationThis paper presents an inductive power transfer system on the basis of a double single- phase three-level T-type inverter and two split transmitting coils for constant current and constant voltage wireless charging of low-voltage light electric vehicle batteries with closed-loop control, considering time-delay communication constraints. An optimal control structure and a modified control strategy were chosen and implemented to...
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Space Vector Pulsewidth Modulation Strategy for Multilevel Cascaded H-Bridge Inverter With DC-Link Voltage Balancing Ability
PublicationSpace vector pulsewidth modulation (SVPWM) algorithms for cascaded H-bridge multilevel (CHB ML) inverter usually provide the possibility of using several combinations of active voltage vectors to generate the same output voltage vector. For preselected H-bridges, some of them may generate output voltages opposite to the assumed direction. This results in the change of the dc-link voltages of these H-bridges in the opposite direction...
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A DFT+U study of carbon nanotubes under influence of a gate voltage
PublicationA possibility of appearance of antiferromagnetic ordering in armchair carbon nanotubes and graphene is studied using density functional theory within a DFT+U approach. It is shown that the Coulomb repulsion between electrons in the -orbitals of graphene would need to reach a threshold value of ,...
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Predictive Current Control of Voltage-Source Inverter.
PublicationW artykule przedstawiono regulator prądu stojana silnika asynchronicznego z predykcją napiecia wyjściowego. Rozważono aspekty praktycznej realizacji algorytmu w układzie z procesorem sygnałowym związane z opóźnieniami pomiaru prądu przy zastosowaniu przetwornika A/C. Układ zrealizowano praktycznie przy wykorzystaniu układu FPGA. W pracy zamieszczono wyniki badań symulacyjnychi eksperymentalnych.
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Optimized Space Vector Modulation strategy for five phase voltage source inverter with third harmonic injection
PublicationThis paper presents a simple and an effective SVM algorithm for five-phase Voltage-Source Inverters with the possibility to control independently the voltage vectors for fundamental and auxiliary orthogonal subspaces. The essential benefit is that output voltage is generated using only four active voltage vectors with limited numbers of switching. In the proposed solution, four active vectors are arbitrary chosen, independent of...
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Verification of a Novel Method of Detecting Faults in Medium-Voltage Systems with Covered Conductors
PublicationThis paper describes the use of new methods of detecting faults in medium-voltage overhead lines built of covered conductors. The methods mainly address such faults as falling of a conductor, contacting a conductor with a tree branch, or falling a tree branch across three phases of a medium-voltage conductor. These faults cannot be detected by current digital relay protection systems. Therefore, a new system that can detect the...
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Hybridized Space-Vector Pulsewidth Modulation for Multiphase Two-Level Voltage Source Inverter
PublicationIn space vector pulsewidth modulation (SVPWM) algorithms for multiphase two-level voltage source inverters (VSI), the components of active vectors in all orthogonal spaces have to be calculated within the processor and stored in its memory. These necessitate intensive computational efforts of the processor and large memory space. This article presents a hybridized SVPWM for multiphase two-level VSI. In this algorithm, elements...
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Voltage Transients Transfer over Medium Voltage Instrument Transformers
PublicationThis paper presents voltage harmonic transfer accuracy problems through voltage transformers which are used in power quality monitoring systems in medium and high voltage grids. A simplified lumped parameters circuit model of the voltage transformer is proposed and verified by simulation and experimental investigations. A number voltage transformers typically used in medium voltage grid has been tested in the conducted disturbances...
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Integrated monitoring, control and security of Critical Infrastructure Systems
PublicationModern societies have reached a point where everyday life relies heavily on desired operation of critical infrastructures, in spite of accidental failures and/or deliberate attacks. The issue of desired performance operation of CIS at high security level receives considerable attention worldwide. The pioneering generic methodologies and methods are presented in the paper project for designing systems capable of achieving these...
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Voltage Harmonics Transfer through Medium Voltage Instrument Transformers
PublicationVoltage transformers are widely used in power quality monitoring systems in medium and high voltage grids. This paper presents accuracy problems related to voltage harmonics transfer through instrument transformers. A simplified lumped-parameters wideband circuit model of the voltage transformer is proposed and verified by simulation and experimental investigations. A number of voltage transformers have been tested in the frequency...
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Static Shunt PE Voltage-Quality Controllers
PublicationThis chapter focuses on power electronics (PE)-based solutions used in distribution networks for reduction of supply-voltage-quality deterioration, from long interruptions to the harmonics. Various PE devices and their combinations are addressed for particular or a range of voltage disturbances. A particular solution is applied taking into account demands for voltage quality and network configuration. In general, there are three...
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Voltage Source Power Line Conditioner for Applications in Local Supply Systems
PublicationThe paper presents the basic principles of operation of voltage source power line conditioners (VSPLC) as well as their energy and filtration properties. A 4-level cascade based Voltage Source Converter (VSC) is used as a voltage source. The advantages of this topology is relatively simple construction and simple way of balancing DC link voltages. Results of the theoretical and experimental investigations confirm good energetic...
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Problems with microprocessor voltage-to-frequency and frequency-to-voltage converters implementation
PublicationThe article presents the problems of digital voltage-to-frequency and frequency-to-voltage processing. Transducer systems implemented in microprocessor technology are presented, the timing of signals and functioning algorithms are discussed. An analysis of processing errors has been performed and the results of experimental studies of realized systems are presented.
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Hierarchical predictive control of integrated wastewater treatment systems
PublicationThe paper proposes an approach to designing the control structure and algorithms for optimising control of integrated wastewater treatment plant-sewer systems (IWWTS) under a full range of disturbance inputs. The optimised control of IWWTS allows for significant cost savings, fulfilling the effluent discharge limits over a long period and maintaining the system in sustainable operation. Due to the specific features of a wastewater...
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Experimental test results of an automatic voltage regulator with independent phase voltage controllers
PublicationThe growing number of distributed renewable energy sources and dynamic constant-power loads (e.g. electric vehicle charging stations) pose new challenges for network operators. These changes result in alterations to network load profiles and load flows, leading to greater voltage volatility. One effective solution to these problems can be the use of automatic voltage regulators (AVRs), which stabilize and symmetrize voltage output,...
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Voltage Conditions in Low Voltage Grid with Connected Mictogeneration
PublicationThe introduction of distributed generation into a low voltage grid may cause voltage problems in it. The paper discusses the effect of microgeneration on voltage levels in a low voltage grid. A real low voltage grid of considerable length was selected for the analysis. The grid primarily supplies residential buildings in a rural area. Results of tests that consider potential measures which could be applied in this grid to improve...
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THE INFLUENCE OF PHASE SHIFTERS ON THE VOLTAGE STABILITY OF CONNECTED POWER SYSTEMS
PublicationThe paper presents the results of simulation tests of connected power systems in which phase shifters were installed on cross-border links. The analysis was carried out in terms of assessing the impact of shifters on node voltage stability. Individual systems were characterized by different balance of active power: deficit or excess. The evaluation of voltage stability was based on the dU/dQ and dU/dP criteria.
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Voltage Harmonic Distortion Measurement Issue in Smart-Grid Distribution System
PublicationThis paper presents the investigation results ofvoltage harmonic transfer accuracy problems through voltagetransformers which are widely used in power quality monitoringsystems in medium and high voltage grids. A simplified lumpedparameters circuit model of the voltage transformer is presentedand verified by simulation and experimental investigations. Anumber voltage transformers typically used in medium voltagegrid has been tested...
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Sensorless control system of induction machine supplied by voltage source inverter with output filter
PublicationThe paper focuses on sensorless control of the induction machines supplied by inverter with the output filters. “The novel” idea of the speed observer which is based on the backstepping approach is shown. The standard structure of the exponential observer is extended by the integrators and additional Z vector. The simulation and experimental results validate the proposed solution.
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Digital Processing of Frequency–Pulse Signal in Measurement System
PublicationThe work presents the issue of the use of multichannel measurement systems of sensors processing input value to impulse signal frequency. The frequency impulse signal obtained from such sensors is often required to be processed at the same time with a voltage signal which is obtained from other sensors used in the same measurement system. In such case, it is usually necessary to sample the output signals from all sensors in the...
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Method of earth fault loop impedance measurement without nuisance tripping of RCDs in 3-phase low-voltage circuits
PublicationVerification of electrical safety in low-voltage power systems includes the measurement of earth fault loop impedance. This measurement is performed to verify the effectiveness of protection against indirect contact. The widespread classic methods and meters use a relatively high value of the measuring current (5–20) A, so that they are a source of nuisance tripping of residual current devices (RCDs). The meters dedicated to circuits...
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PROGRAMMABLE YANG - BASED INTERFACE IN CONTROL OF OPTICAL TRANSPORT NETWORK
PublicationSince over a decade we observe intensive effort of research institutions and industrial consortia on extending flexibility and automation of the transport network control also known under the term network programmability. Key aspect of each programming interface is ability to evolve but also sensitivity to future modifications. As indicated in the past work in the specific context of optical transport networks an important criterion...
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A High-Efficient Low-Voltage Rectifier for CMOS Technology
PublicationA new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two nchannel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and...
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Control of voltage source inverter without dead-time effects.
PublicationW artykule zaproponowano metodę dokładnego generowania wektora napięcia o małej amplitudzie w falowniku napięcia. Zaprezentowano metodę modulacji szerokości impulsów, w której wyeliminowano koniecznosć wprowadzania czasów martwych oraz kompensacji ich wpływu na napięcie wyjsciowe przekształtnika
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Voltage Harmonics Measuring Issues in Medium Voltage Systems
PublicationW rozdziale przedstawiono zagadnienia związane z dokładnością pomiarów zniekształceń harmonicznych napięcia z wykorzystaniem przekładników napięciowych w sieciach średnich napięć.
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Improving voltage levels in low-voltage networks with distributed generation – case study
PublicationThe use of distributed generation in low-voltage networks may cause the voltage variation in them, within the wide range. In unfavourable circumstances, the voltage may reach unacceptable values. The paper presents the effect of distributed generation on voltage levels in a selected low-voltage rural distribution network in Poland. An analysis of possible methods for improving voltage levels in this network is conducted. The most...
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Analysis of Ferroresonance Mitigation Effectiveness in Auxiliary Power Systems of High-Voltage Substations
PublicationFerroresonance in power networks is a dangerous phenomenon, which may result in overcurrents and overvoltages, causing damage to power equipment and the faulty operation of protection systems. For this reason, the possibility of the occurrence of ferroresonance has to be identified, and adequate methods need to be incorporated to eliminate or reduce its effects. The aim of this paper is to evaluate the effectiveness of ferroresonance...
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Programmable Input Mode Instrumentation Amplifier Using Multiple Output Current Conveyors
PublicationIn this paper a programmable input mode instrumentation amplifier (IA) utilising second generation, multiple output current conveyors and transmission gates is presented. Its main advantage is the ability to choose a voltage or current mode of inputs by setting the voltage of two configuration nodes. The presented IA is prepared as an integrated circuit block to be used alone or as a sub-block in a microcontroller or in a field...
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Sensorless Control of Induction Machine Supplied by Current Source Inverter
PublicationThe paper describes the voltage control technique of induction machines supplied by a current source inverter. The control system is based on proposed new multi-scalar variables, which are named “r.” The control system contains the output filter capacitor's model. In the sensorless control system the Z type backstepping speed observer was applied. The mathematical dependences are confirmed by simulation and experimental research.
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AC Motor Voltage and Audible Noise Dataset
PublicationThe dataset titled AC motor voltage and audible noise waveforms in ship’s electrical drive systems with frequency converters contains the voltage and sound measurement results recorded in a marine frequency controlled AC drive system. The dataset is part of research focussing on the impact of the ship’s electrical drive systems with frequency converters on vibrations and the level of audible noise on ships. The dataset allows the...
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Quality assessment of high voltage varistors by third harmonic index
PublicationHigh voltage varistors that consist of grained ZnO have to be tested before assembling into a surge arrester. The existing methods demand a usage of high voltages and intensive currents that is inconvenient, destructive and needs extensive power consumption. Additionally, these methods require metallization of the prepared varistor structures that increases costs. We propose another method of varistors quality assessments by a...
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Design of synchronous generator voltage regulator based on H control theory
PublicationSystemy dużej mocy są z reguły systemami o dużej nieliniowości. Wynika to z dynamiki takiego obiektu jak również jego konfiguracji itd. Istnieje wiele metod umożliwiających sterowanie czy testowanie zaprojektowanych generatorów. W artykule analizowana jest metoda projektowania regulatora napięcia w oparciu o H. Wyniki symulacji są zadowalające, ponieważ tak zaprojektowany regulator lepiej tłumi kołysania elektromechaniczne niż...
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Control of a wind power generator in case of voltage sags in power network
PublicationW artykule poruszono problem związany ze sposobem sterowania generatorem elektrowni wiatrowej w przypadku wystąpienia po stronie sieci zapadów napięcia.Jako generator wykorzystano maszynę dwustronnie zasilaną której stojan podłączono bezpośrednio do sieci natomiast wirnik zasilano poprzez kaskadę przekształtników. Wystąpienie spadku lub zapadu napięcia sieci w przypadku pracy tego typu generatora może doprowadzić do uszkodzenia...
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Voltage variations and their reduction in a rural low-voltage network with PV sources of energy
PublicationRenewable sources of energy (RES), especially photovoltaic (PV) micro-sources, are very popular in many countries. This way of clean power production is applied on a wide scale in Poland as well. The Polish legal regulations and tariffs specify that every prosumer in a low-voltage network may feed this network with a power not higher than the maximum declared consumed power. In power networks with RES, the voltage level changes...
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A Measurement-Based Approach for Speed Control of Induction Machines
PublicationThis paper presents an approach to design a measurement-based controller for induction machines. The proposed control approach is motivated by the fact that developing an appropriate mechanical model of such induction machines is a challenging task. Since our proposed control methodology is only on the basis of measured data, the controller design does not require any information about the model of the mechanical part. The control...
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Decentralized control of a different rated parallel UPS systems
PublicationThe paper presents the single phase uninterruptible power supply (UPS) system with galvanic separated DC-AC-DC-AC converters operating in parallel. The CAN physical layer based system of communication between converters has been developed and applied, which allow to utilize a decentralized master-slave control providing high availability factor of the whole UPS system. The control system of particular converters has been developed...
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Experimental verification of a new method of loop resistance testing in low voltage systems with residual current devices
PublicationA periodical verification of the effectiveness of protection against electric shock shall be performed in low voltage systems. The scope of this verification includes loop impedance/resistance testing. If a residual current device is installed in a tested circuit, this testing is problematic. A residual current device trips out during the test, because of the high value of measurement current. This precludes the execution of the...
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Approaching Secure Industrial Control Systems
PublicationThis study presents a systematic approach to secure industrial control systems based on establishing a business case followed by the development of a security programme. To support these two fundamental activities the authors propose a new method for security cost estimation and a security assessment scheme. In this study they explain the cost evaluation technique and illustrate with a case study concerning the assessment of the...
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Modification of current-voltage characteristics of planar organic systems by nm-thick interlayer
PublicationEffect of nm-thick interlayer of copper phthalocyanine (CuPc) or perylene dye (MePTCDI) on current-voltage characteristics of planar organic systems is discussed in the work. The MePTCDI layer strongly limits injection of holes from ITO into CuPc, while CuPc limits injection of electrons from ITO into MePTCDI. In the systems with CuPc/MePTCDI heterojunction an explicit photovoltaic effect occurs.
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Verification of safety in low-voltage power systems without nuisance tripping of residual current devices
PublicationLow-voltage power systems require initial and periodical verification to check the effectiveness of protection against electric shock. As a protection in case of fault, automatic disconnection of supply is most often used. To verify such a protection measure, the earth fault loop impedance or resistance is measured. This measurement is easy to perform in circuits without residual current devices. When residual current devices are...
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Sensorless induction motor drive with voltage inverter and sine-wave filter
PublicationThis paper presents a speed sensorless control system of an induction motor with an output LC filter. It is known that the parameters design of the filter gives sine wave motor supply voltage but complicates control and estimation process. The reason is that the voltage drop and phase shift between filter input and output signals are imposed, and hence the motor voltages and currents differ from the inverter output waveforms. To...
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Multipulse inverter structures with low voltage distortion
PublicationA novel approach to the voltage source inverters (VSI) construction is presented in the paper. The invented inverter structures allow to operate several DC/AC converters in parallel resulting in lower voltage distortions at extremely low switching frequency. The research presented in the paper describes such a parallel operation of the VSI’s which is possible thanks to the use of coupled inductors. The eighteen-pulse three-level...
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The extended model predictive-sliding mode control of three-level AC/DC power converters with output voltage and load resistance variations
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Cooperative control in production and logistics
PublicationClassical applications of control engineering and information and communication technology (ICT) in production and logistics are often done in a rigid, centralized and hierarchical way. These inflexible approaches are typically not able to cope with the complexities of the manufacturing environment, such as the instabilities, uncertainties and abrupt changes caused by internal and external disturbances, or a large number and variety...
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<title>Measurement and control of field in RF GUN at FLASH</title>
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