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.

High Voltage Direct Current transmission

This thesis is focused on the application and development of HVDC transmission technology based on thyristor without turn-off capability. Compared with other macroelectronics in the power field, thyristor without turn-off capability has successful operation experience to ensure reliability and high power ratings to transfer bulk energy. This thesis covers converter station design and equipments, reactive power compensation and voltage stability, AC/DC filters design, control strategy and function, fault analysis, overvoltage and insulation co-ordination, overhead line and cable transmission, transmission line environmental effects, earth electrode design and development. With the development of new concepts and techniques, the cost of HVDC transmission will be reduced substantially, thereby extending the area of application

A review on power electronics technologies for power quality improvement

Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number of power electronics converters, indispensable for the integration of key technologies, such as renewable energies, electric mobility and energy storage systems, which adds importance to power quality issues. Addressing these topics, this paper presents an extensive review on power electronics technologies applied to power quality improvement, highlighting, and explaining the main phenomena associated with the occurrence of power quality problems in smart grids, their cause and effects for different activity sectors, and the main power electronics topologies for each technological solution. More specifically, the paper presents a review and classification of the main power quality problems and the respective context with the standards, a review of power quality problems related to the power production from renewables, the contextualization with solid-state transformers, electric mobility and electrical railway systems, a review of power electronics solutions to compensate the main power quality problems, as well as power electronics solutions to guarantee high levels of power quality. Relevant experimental results and exemplificative developed power electronics prototypes are also presented throughout the paper.This work has been supported by FCT-Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017 and by the FCT Project newERA4GRIDs PTDC/EEIEEE/30283/2017

Integration of offshore wind farms through High Voltage Direct Current networks

The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared

Stability, Transient Response, Control, and Safety of a High-Power Electric Grid for Turboelectric Propulsion of Aircraft

This document contains the deliverables for the NASA Research and Technology for Aerospace Propulsion Systems (RTAPS) regarding the stability, transient response, control, and safety study for a high power cryogenic turboelectric distributed propulsion (TeDP) system. The objective of this research effort is to enumerate, characterize, and evaluate the critical issues facing the development of the N3-X concept aircraft. This includes the proposal of electrical grid architecture concepts and an evaluation of any needs for energy storage

Solid-state transformers in locomotives fed through AC lines: A review and future developments

One of the most important innovation expectation in railway electrical equipment is the replacement of the on-board transformer with a high power converter. Since the transformer operates at line-frequency (i.e., 50 Hz or 16 2/3 Hz), it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET), Medium Frequency Topologies or Solid-State Transformers (SST). Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e., 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application