High-voltage Installations Research Articles

About the Biot-Savart-Laplace law and its use for calculations in high-voltage AC installations

About the Biot-Savart-Laplace law and its use for calculations in high-voltage AC installations

Earthing systems connected via metallic screens of the 20 kV underground cables in non-urban areas

Secondary substations' earthing systems are connected to each other via metallic screens of the 20 kV underground cables also in suburban and rural areas nowadays. Topology is different from the earthing systems in city centres, where earthings are connected via multiple mesh connections forming a solid ground level. The standards EN 61936-1, EN 50522 and the Finnish SFS 6001 (high-voltage installations) do not clearly consider the case of connected earthings. In 2015, studies were launched to investigate this issue. According to results of the studies, the connected earthings should be evaluated as a whole, and not separately as in the overhead networks. There is a need for renewing earthing network design principles because at the moment, the connections between the secondary substations are not systematically taken into account in the non-urban areas' earthing design. Results show that the resulting impedance was typically 50–80% lower than the secondary substations' individual earthing resistances. It means that there is great potential for savings in the earthing network without risking the safety. Furthermore, there is a need to develop earthing impedance measuring methods. Methods that are used for overhead network earthing measurements are not often suitable for cable network.

사물인터넷 기반의 자가용 전기설비 안전 관리 구조 연구

사물인터넷 기반의 자가용 전기설비 안전 관리 구조 연구

Desarrollo de un entorno virtual para la simulación de maniobras eléctricas en subestaciones: un caso práctico

Introducción: resultado de una investigación que pretende mostrar la importancia de la inclusión del simulador de subestaciones eléctricas en la asignatura que lleva el mismo nombre (Facultad de Ingeniería, Universidad Distrital Francisco José de Caldas). Se propone una versión mejorada del simulador que incluya todas las configuraciones existentes y los módulos de diseño. Metodología: se emplearon encuestas muestrales para conocer la percepción de los estudiantes frente al simulador de subestaciones eléctricas, como metodología de aprendizaje y su incidencia en las cifras de repitencia. Se realiza una síntesis de la forma en que se desarrolló el software y su validación mediante una simulación que permite mostrar las ventajas de su uso para el tema de maniobras eléctricas, junto con las modificaciones recientes. Resultados: se muestra la potencialidad de la herramienta mediante la simulación de una maniobra eléctrica. A través de las encuestas muestrales, se obtuvo que más de un 80 % de los estudiantes encuestados afirman que el simulador fue una herramienta útil en el tema de maniobras eléctricas, ya que presentaba mayor dificultad de aprendizaje entre los estudiantes; por ello, puede contribuir a reducir los índices de repitencia. Conclusiones: la inclusión del simulador permitió demostrar la utilidad de esta herramienta virtual para la comprensión de procesos de operación y mantenimiento de instalaciones de alta y extra alta tensión (subestaciones eléctricas), enmarcado en el concepto de laboratorios virtuales, válido para la formación de estudiantes de ciencias e ingenierías, de manera que contribuya a mejorar su desempeño en diferentes asignaturas.

Improving technical maintenance of systems of mini hydropower plants: Analysis of causes of malfunctions, faults, failures and system failures

The paper presents many years of experience related to the activities of technical maintenance of mechanical and electrical plants. It shows the analysis of the cause of many malfunctions, faults, failures and system failures that occur in mini hydropower plants. Systems of mini hydropower plants are discussed in terms of improving the technical maintenance by functional units: turbine regulator with turbine, mechanical assemblies (multiplier and flywheel), flexible couplings that connect plant assemblies, electrical circuits, lubrication systems, automation and high-voltage installations. Below is a brief overview of the application possibilities of technical diagnostics i.e. of a monitoring system in mini hydropower plants.

Физико-технические проблемы управляемого термоядерного синтеза

The lines of scientific activity and the results of investigations carried out at the MPEI Department of General Physics and Nuclear Fusion are briefly reviewed. The conducted activities are mainly focused on the problems of controlled thermonuclear fusion and plasma technologies. Efforts are taken to study heat transfer and hydrodynamics in the plasma-facing structural components of thermonuclear reactors, one-sided heating of which results in essentially nonuniform distributions of heat flux density and wall temperature over the pipe inner perimeter. Another line of research activities is concerned with experimental investigations of nucleate boiling and heat transfer in essentially subcooled flow, of enhanced heat transfer in annular channels and models of pebble fuel element beds, and of heat transfer enhancement as applied to the problems concerned with cooling the International thermonuclear experimental reactor (ITER). A large-scale test bench for studying thermal-hydraulic processes in the models of advanced nuclear fuel assemblies operating with the parameters of a VVER-type reactor has been constructed. Activities are underway on studying the resistance of refractory metals to the effect of powerful plasma and heat fluxes expected to take place in a tokamak-type thermonuclear reactor. A plasma installation equipped with a linear multicusp magnetic system featuring uniquely high parameters has been constructed, which is used to perform tests of materials exposed to megawatt-scale hot plasma. The unique plasma installation has been constructed for studying plasma-to-surface interaction and high-temperature plasma testing of refractory materials like tungsten, molybdenum, steel, etc. The experiments to be performed on the installation are aimed at developing a new technology for producing a highly porous surface nanostructure of refractory metal, including tungsten “fuzz”. Such investigations are topical for inventing new materials that are of considerable interest for nuclear, chemical, power, and biomedical technologies. The main lines of activities on nanotechnologies include obtaining, studying and using carbon nanostructures such as fullerenes, carbon nanotubes, graphene, and their derivatives. Within the framework of studying the strengthening phenomenon, the extent of steel surface strengthening as a function of the type and intensity of incident radiation, and the type of nanocarbon material is considered. The interaction of charged particles and radiation with structural materials is investigated. Experimental and theoretical investigations of the interaction of electrons and light ions with inhomogeneous solid bodies are continued to solve the problems concerned with scattering ion beams in inhomogeneous media. Innovative methods for destructive and non-destructive analysis of thin films are developed, including layer-wise analysis techniques. Unique plasma installations have been constructed at the department, such as a high-frequency induction plasmatron for carrying out chemical spectral analysis, an arc plasmatron for studying the free plasma burning processes, a high-voltage installation for studying streamer and arc discharges with electrolysis, and a cold plasma installation for studying the effect of discharge on biological tissues. All these installations are successfully used for carrying out both research activities and student training laboratory works.

ELABORATION OF HIGH-VOLTAGE PULSE INSTALLATIONS AND PROVIDING THEIR OPERATION PROTECTIVE MEASURES

The article presents design engineering methods for the high-voltage pulse installations of technological purpose for disinfection of drinking water, sewage, and edible liquids by highfield microand nanosecond pulsing exposure. Designing potentialities are considered of the principal elements of the high-voltage part and the discharge circuit of the installations towards assuring the best efficient on-load utilization of the source energy and safe operation of the high-voltage equipment. The study shows that for disinfection of drinking water and sewage it is expedient to apply microsecond pulse actions causing the electrohydraulic effect in aqueous media with associated complex of physical processes (ultraviolet emission, generation of ozone and atomic oxygen, mechanical compression waves, etc.) having detrimental effect on life activity of the microorganisms. In case of disinfecting edible liquids it is recommended to use the nanosecond pulses capable of straight permeating the biological cell nucleus, inactivating it. Meanwhile, the nutritive and biological values of the foodstuffs are saved and their organoleptic properties are improved. It is noted that in elaboration process of high-frequency pulse installations special consideration should be given to issues of the operating personnel safety discipline and securing conditions for the entire installation uninterrupted performance. With this objective in view the necessary requirements should be fulfilled on shielding the highand low-voltage installation parts against high-frequency electromagnetic emissions registered by special differential sensors. Simultaneously, the abatement measures should be applied on the high-voltage equipment operational noise level. The authors offer a technique for noise abatement to admissible levels (lower than 80 dB⋅A) by means of coating the inside surface with shielded enclosure of densely-packed abutting sheets of porous electro-acoustic insulating material.

Application of HFCT and UHF sensors in on-line partial discharge measurements for insulation diagnosis of high voltage equipment.

Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment.

Analysis of high-voltage cascede generator pulsations of a direct current

In the article the issue of modes calculation for the high-voltage cascade generator with nonlinear loading by means of an analytical method is resolved. For a cascade high-voltage source of a direct current the analytical solution for its pressure and a nonlinear pulsation is found. Research of pulsations amplitude versus oscillator circuit parameters is conducted. The offered analytical method of research for high-voltage installations of a direct current allows perfroming analytical, high precise parameters calculations of cascade voltage generators that is used for the first time. The conducted researches showed that the voltage ripple factor significantly depends on the installation mode of a high direct current voltage and its loading. The obtained results show that the offered analytical method allows perfroming the precise calculations of voltage modes for high-voltage cascade generators with nonlinear loading defining its qualitative characteristics as power supplies of high-voltage technological installations. Carrying out further investigations parameters of a high voltage installations of a direct current with nonlinear loading is relevant and will allow defining its characteristics that influence on quality of the technological processes constructed with use of such units.

Review on partial discharge detection techniques related to high voltage power equipment using different sensors

When operating an equipment or a power system at the high voltage, problems associated with partial discharge (PD) can be tracked down to electromagnetic emission, acoustic emission or chemical reactions such as the formation of ozone and nitrous oxide gases. The high voltage equipment and high voltage installation owners have come to terms with the need for conditions monitoring the process of PD in the equipments such as power transformers, gas insulated substations (GIS), and cable installations. This paper reviews the available PD detection methods (involving high voltage equipment) such as electrical detection, chemical detection, acoustic detection, and optical detection. Advantages and disadvantages of each method have been explored and compared. The review suggests that optical detection techniques provide many advantages in the consideration of accuracy and suitability for the applications when compared to other techniques.

Damping Efficiency Analysis of Metal Dampers for a High-Voltage Electrical Arrester

Metal passive energy dissipation dampers are widely used in building structures, but research into their use in high-voltage electrical installations has been limited. This paper employs the passive energy dissipation method for a high-voltage arrester as an example. Metal energy dissipation dampers are designed using the bilinear restoring force model. The factors affecting the damper, including the yield force, yield displacement and ratio between initial and postyield stiffness, which affect the damping efficiency, were analyzed in finite element numerical simulation. The dampers were designed with the optimum parameters found in numerical simulation and were installed at the bottom of an arrester in shake table tests. The dynamic reactions of the arrester with and without dampers were analyzed under the excitation of a resonance wave and artificial waves E and T. Results of simulation and tests show that the dampers designed with the optimum parameters significantly reduced the strain of the bottom of the porcelain bushing, and the damping efficiency increased with the acceleration peak.

Characterizing a sustained short-circuit current with the use of reed relays

We propose to characterize the short-circuit current in high-voltage electrical installations by measuring the closing time of contacts of closing and switching reed relays, their closed-state time, or the time elapsed between the closing (opening) of contacts of a reed-relay pair. Techniques for determining the amplitude of this current and the errors are outlined. It is shown that the laboratory dependences of the current amplitude in the solenoid coil on the indicated time may be used to determine the Im.a value. The experimental results are presented.

25th anniversary article: Rise to power--OPV-based solar parks.

A solar park based on polymer solar cells is described and analyzed with respect to performance, practicality, installation speed, and energy payback time. It is found that a high voltage installation where solar cells are all printed in series enables an installation rate in Watts installed per minute that far exceed any other PV technology in existence. The energy payback time for the practical installation of polymer solar cell foil on a wooden 250 square meter platform in its present form is 277 days when operated in Denmark and 180 days when operated in southern Spain. The installation and de-installation rate is above 100 m min⁻¹, which, with the present performance and web width, implies installation of >200 W min⁻¹. In comparison, this also exceeds the overall manufacturing speed of the polymer solar cell foil with a width of 305 mm which is currently 1 m min⁻¹ for complete encapsulated and tested foil. It is also significant that simultaneous installation and de-installation which enables efficient schemes for decommissioning and recycling is possible. It is highlighted where research efforts should most rationally be invested in order to make grid electricity from OPV a reality (and it is within reach).

Pollution Maintenance Techniques in Coastal High Voltage Installations

Pollution of outdoor high voltage insulators is a common problem for utilities, with a considerable impact to power system reliability. In an effort to prevent possible flashovers due to pollution, many methods have been applied, aiming to improve the insulation performance, either by suppressing the formation of surface conductivity or by increasing the possible insulation level. In the case of substations, the selection of the appropriate technique is complex due to certain issues correlated to the nature of the installation. In this paper, several techniques usually implemented by utilities, are investigated based on the experienced gained in the case of Crete, a Greek island in southern Europe, where due to the coastal development of the power system, the majority of high voltage installations are exposed to intense marine pollution. The technique of coating insulators with Room Temperature Vulcanized Silicone Rubber (RTV SIR) has proved rather efficient and therefore is presented extendedly. Correlation of the material behaviour with environmental conditions is discussed and results from long term monitoring, including environmental parameters and leakage current measurements, in a 150 kV Substation are presented. It is shown that RTV SIR coatings have remarkably suppressed surface activity and that porcelain insulators exhibit different activity period when coated.

Pollution Maintenance Techniques in Coastal High Voltage Installations

Pollution of outdoor high voltage insulators is a common problem for utilities, with a considerable impact to power system reliability. In an effort to prevent possible flashovers due to pollution, many methods have been applied, aiming to improve the insulation performance, either by suppressing the formation of surface conductivity or by increasing the possible insulation level. In the case of substations, the selection of the appropriate technique is complex due to certain issues correlated to the nature of the installation. In this paper, several techniques usually implemented by utilities, are investigated based on the experienced gained in the case of Crete, a Greek island in southern Europe, where due to the coastal development of the power system, the majority of high voltage installations are exposed to intense marine pollution. The technique of coating insulators with Room Temperature Vulcanized Silicone Rubber (RTV SIR) has proved rather efficient and therefore is presented extendedly. Correlation of the material behaviour with environmental conditions is discussed and results from long term monitoring, including environmental parameters and leakage current measurements, in a 150 kV Substation are presented. It is shown that RTV SIR coatings have remarkably suppressed surface activity and that porcelain insulators exhibit different activity period when coated.

Calibration of the ISOLDE acceleration voltage using a high-precision voltage divider and applying collinear fast beam laser spectroscopy

A high-voltage divider with accuracy at the ppm level and collinear laser spectroscopy were used to calibrate the high-voltage installation at the radioactive ion beam facility ISOLDE at CERN. The accurate knowledge of this voltage is particularly important for collinear laser spectroscopy measurements. Beam velocity measurements using frequency-comb based collinear laser spectroscopy agree with the new calibration. Applying this, one obtains consistent results for isotope shifts of stable magnesium isotopes measured using collinear spectroscopy and laser spectroscopy on laser-cooled ions in a trap. The long-term stability and the transient behavior during recovery from a voltage dropout were investigated for the different power supplies currently applied at ISOLDE.

Proposal for measurement of earth impedance using variable frequency injection

Measurement of the impedance of earthing systems of high voltage installations at power fundamental frequency has been studied extensively, and standards are available which provide guidance on methods of measurement and types of instrumentation. In the UK, the staged-fault test is seldom performed. Therefore, it is necessary to measure earth impedance without any circuit interruption by injecting current into the earthing system using an auxiliary test circuit. This type of ‘fall-of-potential’ test generally uses low voltage energization and produces test currents of the order of only a few amperes. At this level of current, potential measurements are made difficult due to the presence of relatively high standing voltages in the earthing system. In this paper, a new earth impedance measurement system which is able to overcome the effects of system noise and provide accurate measurements is described. Initial laboratory tests which resulted in optimized instrument settings and subsequent field tests demonstrated successful application at a range of operational electricity installations.

SF 6 leak detection of high-voltage installations using TEA-CO 2 laser-based DIAL

SF 6 is known as an effective insulator due to its high dielectric strength. Because of this property, it is vastly used in the sealed high-voltage (HV) installations and compact electrical distribution sites. Since then, sensing of SF 6 leakage takes significant environmental and economical advantages due to its high greenhouse effect. Here, we have quantitatively shown that our homemade differential absorption lidar (DIAL), using a pair of pulsed CO 2 lasers, enables us to detect efficiently remote SF 6 effluent up to ppm level. Moreover, the instantaneous spatial distribution of SF 6 emission were recorded at various meteorological conditions to indicate that SF 6 molecules are reluctant to diffuse quickly, willing to accumulate over the ground at definite location. The lidar attenuation and backscattering coefficients were determined for three typical meteorological conditions based on the best fitting using the least-square method. In addition, according to the spectral response, the remote isotopic identification of the abundant 32SF 6 and rare 34SF 6 species were done using dual tunable TEA-CO 2 lasers. Logarithmic derivative and Klett inversion approximations were subsequently used to determine SF 6 concentration based on DIAL equation.

Selection of operating fluid for electrodischarge submersible installations

The technique and results of experimental studies of high-voltage discharge in aqueous electrolytes and water-oil emulsions with a view to determine their applicability as operating fluids for closed electrode systems in high-voltage electrodischarge submersible installations are presented.

Technique and results of experimental investigations of the influence of the elastic barrier on pressure wave parameters in electric discharge in water

The paper describes the technique and results of experimental investigations on the influence of the elastic barrier of various materials on transformation of the pressure wave parameters in electric discharge in water for application in closed electrode systems of high-voltage electric discharge immersion installations for treatment of water and oil wells.