Сравнительный анализ мероприятий и технических средств для подавления апериодической составляющей в токе линейного выключателя

Electromagnetic transients are considered in the implementation of three-phase automatic reclose on the transmission line of extra high voltage 750 kV. The influence of automatic shunting of phases and pre-insertion active resistance for limiting the characteristics of the aperiodic component of the current, which obstructs the transition of full current through zero, is evaluated. The paper analyses measures taking into account the effect of changing the degree of compensation of charging power and the angles of switching on an SF6 circuit breaker. Sub-schemes of disconnected undamaged phases of the extra high voltage transmission line for the investigation of the aperiodic current component have been developed. The values of the pre-insertion active resistances of different connection and automatic shunting of the phases are determined at which there is an effective reduction of the characteristics of the aperiodic component of the current. In the software environment, a model was developed and switching transient processes were simulated in the 750 kV transmission line. Operating modes that are potentially dangerous for SF6 circuit breakers are determined and recommendations are given to avoid them. Currently the technical and economic requirements for power transmission lines designed for the transport of electricity from large power plants and for the communication of powerful energy systems are increasing. Today there is the importance of reducing specific investment in the construction of new and reconstruction of existing lines. The solution of these issues is associated with the maximum use of power lines by increasing their power transfer capability and controlling modes, especially in operating emergency conditions and post-emergency operation of power systems.  В статье рассматриваются электромагнитные переходные процессы при реализации трехфазного автоматического повторного включения на линии электропередачи сверхвысокого напряжения 750 кВ. Анализируются предвключенные активные сопротивления, управляемые шунтирующие реакторы, неполнофазные режимы работы шунтирующих реакторов, автоматические шунтирования фазы с учетом изменения степени компенсации зарядной мощности и углов включения элегазовых выключателей. Разработаны схемы замещения отключенных неповрежденных фаз линии сверхвысокого напряжения для исследования апериодической составляющей тока. Оценены значения активных предвключенных сопротивлений и автоматического шунтирования фаз на снижение характеристик апериодической составляющей тока. Разработана имитационная модель и смоделированы переходные процессы на линии электропередачи 750 кВ. Выполнены серии моделирований электромагнитных переходных процессов на реальных линиях электропередачи сверхвысокого напряжения. Проанализированы причины аварий линейных элегазовых выключателей при коммутации компенсированных воздушных линий 750 кВ. Изучены электромагнитные процессы в компенсированных линиях электропередачи в зависимости от начальных условий в момент коммутации. Выявлены моменты резкого изменения параметров переходных процессов при коммутации в линиях сверхвысокого напряжения. Оценено влияние суммарных индуктивностей и активных сопротивлений на характеристики апериодической составляющей. Выведены аналитические зависимости постоянной времени апериодической компоненты от момента коммутации и значений суммарного активного сопротивления и индуктивности. Рассмотрены мероприятия для ограничения продолжительности сущест-вования апериодической составляющей тока. Указано, что избежать аварийного режима работы можно соответствующей настройкой устройства контроля коммутации элегазовых выключателей. Даны рекомендации по предупреждению возникновения и развития аварийного режима на подстанциях с элегазовыми выключателями.

Sidelobe Suppression Methods for Cognitive Radio Applications A ReviewÂ

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Development of a high-fidelity model for an electrically driven energy storage flywheel suitable for small scale residential applications

Energy storage systems (ESS) are key elements that can be used to improve electrical system efficiency by contributing to balance of supply and demand. They provide a means for enhancing the power quality and stability of electrical systems. They can enhance electrical system flexibility by mitigating supply intermittency, which has recently become problematic, due to the increased penetration of renewable generation. Flywheel energy storage systems (FESS) are a technology in which there is gathering interest due to a number of advantages offered over other storage solutions. These technical qualities attributed to flywheels include high power density, low environmental impact, long operational life, high round-trip efficiency and high cycle life. Furthermore, when configured in banks, they can store MJ levels of energy without any upper limit. Flywheels configured for grid connected operation are systems comprising of a mechanical part, the flywheel rotor, bearings and casings, and the electric drive part, inclusive of motor-generator (MG) and power electronics. This contribution focusses on the modelling and simulation of a high inertia FESS for energy storage applications which has the potential for use in the residential sector in more challenging situations, a subject area in which there are few publications. The type of electrical machine employed is a permanent magnet synchronous motor (PMSM) and this, along with the power electronics drive, is simulated in the MATLAB/Simulink environment. A brief description of the flywheel structure and applications are given as a means of providing context for the electrical modelling and simulation reported. The simulated results show that the system run-down losses are 5% per hour, with overall roundtrip efficiency of 88%. The flywheel speed and energy storage pattern comply with the torque variations, whilst the DC-bus voltage remains constant and stable within ±3% of the rated voltage, regardless of load fluctuations

Methodology and Guidelines for Designing Flexible BMS in Automotive Applications

The fragile characteristics of Li-ion batteries lead to the need of battery management system (BMS) to carefully supervise them during the operation. Since there are so many variations in battery configurations, the BMS usually must undergo many iterations of the development cycle, which take a long time to optimize and finalize the design. Previously, many works adopted the idea of modularized BMS to address these issues, but they still have some skeptical issues such as measurement approaches or difficulties in reconfiguration. This paper presents a guideline on the crucial aspects of flexible BMS designs for automotive applications, which aims to reduce time and effort for developing a new BMS for automotive battery pack. The guideline covers some crucial aspects pertaining the automotive BMS hardware implementation, SOC estimation algorithm and its computational performance based on Extended Kalman Filter (EKF) and Luenberger Observer (LO) with 3 levels of Electrochemical model (ECM). All of the tests were carried out in a small-scale microcontroller. It was found that 2-RC ECM gives the best trade-off between SOC estimation accuracy and computational time. While the 3-RC ECM provides 9.5% and 31% higher accuracy than the 2-RC and 1-RC ECM, respectively, but taking 88% and 240% higher computational time than the latter two cases. The optimal speed of the observer poles of LO algorithm are suggested to be in the range of 2-5 times faster than the system poles, which makes the convergence speed to be comparable to the EKF algorithm but is still able to keep the SOC estimation error in the range of 3-5%. These results can be used to make a trade-off between estimation accuracy and computational time, to select the optimal SOC estimation algorithm for onboard BMSs

A FEASIBILITY STUDY OF HIGH-VOLTAGE COMPARATORS USING SILICON METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS

The overall trend of transistor scaling has resulted in distinct, application-specific manufacturing processes. Two of these specialized devices scaled complementary metal-oxide-semiconductor field-effect transistors (CMOS) and power transistors, typically have inversely related performance in speed, power handling, and size. This work develops a novel comparator circuit to explore the potential benefits of integrating these two technology schemes to achieve improved power handling capabilities for signal processing and communication systems through the development of a Silicon-based high-voltage comparator. The study produced a final circuit with a flat-band gain of 20dB across the high frequency (HF) range with a projected input voltage tolerance above 10V. The development process indicates that the physical characteristics of the power transistor, a laterally-diffused MOSFET (LDMOS), constrains frequency response and therefore, ultimately, comparator performance. Although the demonstrated device does not achieve the target performance, the investigation suggests that integrating the power transistors at the integrated circuit (IC) level is a promising approach to producing a competitive high-voltage Silicon-based comparator.M.S

High Performance Optical Transmitter Ffr Next Generation Supercomputing and Data Communication

High speed optical interconnects consuming low power at affordable prices are always a major area of research focus. For the backbone network infrastructure, the need for more bandwidth driven by streaming video and other data intensive applications such as cloud computing has been steadily pushing the link speed to the 40Gb/s and 100Gb/s domain. However, high power consumption, low link density and high cost seriously prevent traditional optical transceiver from being the next generation of optical link technology. For short reach communications, such as interconnects in supercomputers, the issues related to the existing electrical links become a major bottleneck for the next generation of High Performance Computing (HPC). Both applications are seeking for an innovative solution of optical links to tackle those current issues. In order to target the next generation of supercomputers and data communication, we propose to develop a high performance optical transmitter by utilizing CISCO Systems®\u27s proprietary CMOS photonic technology. The research seeks to achieve the following outcomes: 1. Reduction of power consumption due to optical interconnects to less than 5pJ/bit without the need for Ring Resonators or DWDM and less than 300fJ/bit for short distance data bus applications. 2. Enable the increase in performance (computing speed) from Peta-Flop to Exa-Flops without the proportional increase in cost or power consumption that would be prohibitive to next generation system architectures by means of increasing the maximum data transmission rate over a single fiber. 3. Explore advanced modulation schemes such as PAM-16 (Pulse-Amplitude-Modulation with 16 levels) to increase the spectrum efficiency while keeping the same or less power figure. This research will focus on the improvement of both the electrical IC and optical IC for the optical transmitter. An accurate circuit model of the optical device is created to speed up the performance optimization and enable co-simulation of electrical driver. Circuit architectures are chosen to minimize the power consumption without sacrificing the speed and noise immunity. As a result, a silicon photonic based optical transmitter employing 1V supply, featuring 20Gb/s data rate is fabricated. The system consists of an electrical driver in 40nm CMOS and an optical MZI modulator with an RF length of less than 0.5mm in 0.13&mu m SOI CMOS. Two modulation schemes are successfully demonstrated: On-Off Keying (OOK) and Pulse-Amplitude-Modulation-N (PAM-N N=4, 16). Both versions demonstrate signal integrity, interface density, and scalability that fit into the next generation data communication and exa-scale computing. Modulation power at 20Gb/s data rate for OOK and PAM-16 of 4pJ/bit and 0.25pJ/bit are achieved for the first time of an MZI type optical modulator, respectively

Performance analysis of electric drives using slotless motors

La tesi descrive le principali criticità nel controllo di macchine elettriche di tipo 'slotless'; con particolare riguardo alle prestazione della macchina stessa in relazione alle tecniche di controllo utilizzate (SVM o controllo trapezoidal e)

Semiconductor devices in solid-state/hybrid circuit breakers: current status and future trends

Circuit breakers (CBs) are the main protection devices for both alternating current (AC) and direct current (DC) power systems, ranging from tens of watts up to megawatts. This paper reviews the current status for solid-state circuit breakers (SSCBs) as well as hybrid circuit breakers (HCBs) with semiconductor power devices. A few novel SSCB and HCB concepts are described in this paper, including advantage and limitation discussions of wide-band-gap (WBG) devices in basic SSCB/HCB configuration by simulation and 360 V/150 A experimental verifications. Novel SSCB/HCB configurations combining ultra-fast switching and high efficiency at normal operation are proposed. Different types of power devices are installed in these circuit breakers to achieve adequate performance. Challenges and future trends of semiconductor power devices in SSCB/HCB with different voltage/power levels and special performance requirements are clarified

Symmetry in Electromagnetism

Electromagnetism plays a crucial role in basic and applied physics research. The discovery of electromagnetism as the unifying theory for electricity and magnetism represents a cornerstone in modern physics. Symmetry was crucial to the concept of unification: electromagnetism was soon formulated as a gauge theory in which local phase symmetry explained its mathematical formulation. This early connection between symmetry and electromagnetism shows that a symmetry-based approach to many electromagnetic phenomena is recurrent, even today. Moreover, many recent technological advances are based on the control of electromagnetic radiation in nearly all its spectra and scales, the manipulation of matter–radiation interactions with unprecedented levels of sophistication, or new generations of electromagnetic materials. This is a fertile field for applications and for basic understanding in which symmetry, as in the past, bridges apparently unrelated phenomena―from condensed matter to high-energy physics. In this book, we present modern contributions in which symmetry proves its value as a key tool. From dual-symmetry electrodynamics to applications to sustainable smart buildings, or magnetocardiography, we can find a plentiful crop, full of exciting examples of modern approaches to electromagnetism. In all cases, symmetry sheds light on the theoretical and applied works presented in this book