High-voltage Distribution Systems Research Articles

Minimization of Losses by Implementing High Voltage Distribution System in Agricultural Sector

The main object of the paper is to implement a distribution system having negligible losses, high quality of supply and reliability.As, average transmission and distribution losses in India have been officially indicated as 23% of the electricity generated because of the fact that in Indian distribution system, energy is transformed into many intermediate stages before it reaches the consumer. Currently, power supplies are distributed at low voltage leading to the inefficiencies in the system. The main reason for high losses is considered to be the use of low voltage for the distribution of power leading to the high current and thus, more resulting in losses. The work reported in this paper involves the analysis of present condition of electric supply, laying down the general outlines of the most economical distribution system in order to distribute the power safely without affecting the performance of the system and shifting of existing low voltage distribution network to high voltage distribution and then, comparing both the systems in terms of losses. In overall economic point of view, annual savings and payback period is also determined. Keywords- Distribution transformer (DTR), high voltage distribution system (HVDS), low voltage distribution system (LVDS), power losses.

Development of a positive creeping discharge along an aerial insulated wire

AbstractIn high‐voltage aerial distribution systems, the insulated cables are supported by the binding wire with the post insulator at the utility pole. When a lightning strike occurs in the neighborhood of the insulated cable in an aerial power distribution system, inductive lightning surges invade the central line of the cable. Then, creeping discharges develop along the cable surface from the binding wire tip at the same time as flashover of the post insulator at a supporting point of the cable. If the cable insulator has weak points such as pinholes, a malfunction near the cable supporting point may occur, with melting of the wire due to punch‐through breakdown. To prevent such accidents, it is important to clarify the mechanism of the creeping discharge along the insulated cable caused by the lightning strike. The polarity of creeping discharges depends on the polarity of the inductive lightning surges, and the extension length and aspect of the discharge differ greatly depending on the discharge polarity. The development of these creeping discharges is attributed to complicated behavior of the positive and negative electric charges.In the present study, we examined in detail the development of a positive creeping discharge along a wire surface by using a high‐speed image converter camera. This paper describes the mechanism of development of a positive creeping discharge based on the experimental results. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 20–29, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20997

Enhancement of Surface Flashover Performance of High Voltage Ceramic Disc Insulators

In this paper, an effort is made to study accurately the field distribution for various types of ceramic insulators used for high-voltage transmission. The surface charge simulation method (SCSM) is employed for the field computation. With the help of SCSM program, a Novel field reduction electrode is designed and developed to reduce the maximum field around the pin region. In order to experimentally analyze the performance of discs with field reduction electrode, special artificial pollution test facility was built and utilized. The experimental results show better surface flashover performance of ceramic insulators used in high-voltage transmission and distribution systems.

An Identification Method of Magnetizing Inrush Current Phenomena in Distribution System

In high voltage distribution systems, there are many power quality troubles due to voltage dips. Otherwise, a magnetizing inrush current causes the voltage dip. To suppress voltage dips, it is necessary to identify the magnetizing inrush current phenomena. In this paper, the authors propose a new identification method. The principles are that the saturation start/end flux is equal and the inrush current pattern exists. And to avoid a interfere with saturation area overlap; the rectangular coordinate method is adopted.

Climate co-benefit policies for the Indian power sector: domestic drivers and North—South cooperation

The Indian electricity sector offers the possibility for efficiency improvements across power generation, transmission and end-use of electricity. Three specific climate co-benefit policy options are identified which have significant potential to mitigate CO2 emissions in the Indian power sector: (1) the adoption of clean and efficient coal-based generation technology, (2) upgrading the low-tension (LT) distribution network to a high-voltage distribution system (HVDS), and (3) the adoption of efficient agricultural pump sets. Policy simulations suggest that an agricultural pump set replacement programme could reduce emissions by 5–30% per annum. In addition to improving technical efficiency, this could also help to improve economic efficiency if implemented jointly with electricity metering. The implementation requires the engagement of various stakeholders. The need for up-front capital requirements is a significant barrier for implementation but creates opportunities for international cooperation. Policy relevance: The study identifies three features of an effective approach to realize energy efficiency and lowcarbon opportunities. First, a comprehensive analysis can identify energy savings opportunities along the entire value chain. Second, technical linkages between the quality of the distribution network and the requirements of efficient pumps create benefits from the combined implementation of individual measures. Third, the sharing of energy savings between stakeholders can create political support for actions and can contribute to long-term objectives; for example the delivery of new pumps with electricity meters. This illustrates the benefit of an overall low-carbon development strategy capturing analytical, technological and political links. It allows for the identification of specific transitions and can be implemented with a set of policies and actions that are supported by domestic stakeholders, and can be enhanced if also supported by international support mechanisms.

The high-voltage system for the LHCb RICH hybrid photon detectors

We describe the characterization of the high-voltage (HV) distribution system designed and produced for the pixel hybrid photon detectors of the ring imaging Cherenkov counters of the LHCb experiment. The HV system consists of a series of printed circuit boards with a specific layout designed to prevent any discharge arising from high electric fields. The system has dedicated monitoring and control features to supervise HV set-up during data taking. The full production of the HV system has been now completed and all the boards have been fully characterized and installed in the detector, which is currently being commissioned.

PSCAD/EMTDC를 이용한 철도 고압 배전계통의 과도특성 해석 및 1선 지락사고에 대한 보호방안

철도에서의 고압배전선로는 역사조명 및 동력설비, 그리고 열차의 안전운행을 위한 신호설비의 전력을 공급해 주는 설비로 열차의 안전운행 및 철도 이용자의 서비스 향상을 위한 중요한 역할을 담당하고 있다. 또한 각종 전력기기의 전자화, 자동화로 인해 양질의 전력공급이 요구되며, 철도 이용자에 대한 보다 향상된 서비스를 제공과 역사내 전기에너지 사용의 급증으로 인한 전력공급의 신뢰성 확보가 요구된다.BR 본 논문에서는 철도고압배전계동의 고장현상을 분석하기 위하여 철도고압배전 설비중 접지계통과 비접지계통에 대해서 사고시 전압강하가 발생 여부와 사고를 제거하기 위해 차단기를 동작시켰을 때의 서지전압에 의한 과도특성을 PSCAD/EMTDC를 이용하여 모의하였으며, 이 사고모의 결과를 토대로 비접지 고압배전계동의 보호방법에 대한 대안을 제시하였다.

A Novel Active Power Filter for High-Voltage Power Distribution Systems Application

In this paper, a novel principle of an active power filter based on the harmonic impedance control of a transformer is proposed for high-voltage power distribution systems application. A linear transformer with multiple secondary windings is adopted. The primary winding is shunted with harmonic-producing loads, while the secondary windings are connected with inverters. The primary harmonic current is detected and then tracked by the inverters with fixed compensation coefficient. When the harmonic current compensation condition is satisfied, the transformer can really exhibit nearly zero impedance to harmonic current and primary self-impedance to fundamental current. As a result, the harmonic currents in power systems can be led to flow into the transformer branch. The operation principle, the control scheme, and the harmonic current detection method are discussed in detail. Finally, simulated waveforms and experimental results are presented to verify the effectiveness of the active power filter

Prediction of Flashover Voltage of Contaminated Insulator Using Artificial Neural Networks

Insulator contamination has been identified as the most important factor in the design of external insulation of high voltage transmission, sub-transmission and distribution systems throughout the world. In the electrical design of high voltage insulators, the design engineers need a simple and reliable tool when calculating the flashover voltages of contaminated insulators. This article presents an artificial neural network (ANN) based technique that predicts the flashover voltages of the insulator under contaminated conditions energized by AC voltage. The results indicate strong agreement between the model prediction and observed values. The statistical analysis shows that the R 2 value for the sixteen cases in the training set was 0.9986. These results demonstrate that the ANN-based model developed in this work can predict the flashover voltage and ESDD, before and after applying a mitigation system, with 99.86% accuracy and with 99.3%, respectively. It was also found that the contribution of the salinity level was approximately 46.51%; the effect of the solution current was 31.78%, while the remaining 21.71% was attributed to the resistivity. These results clearly indicate that salinity is an important factor in determining ESDD and FOV, and its level should be determined carefully.

The high voltage distribution system for the hybrid photodetector arrays of RICH1 and RICH2 at LHCb

Two ring imaging Cherenkov detectors, RICH1 and RICH2, will provide the particle identification of the LHCb experiment. The Cherenkov light cones produced in three different refractive media are projected onto four arrays of hybrid photon detectors (HPDs), with 484 HPD units in total. In order to accelerate and focus the photoelectrons resulting from the conversion of photons in the HPD photocathode, the electron optics of an HPD requires three different high voltages (HVs): -20 kV, -19.7 kV and -16.4 kV. We describe in this paper the HV distribution system that has been designed for this purpose. The HV is supplied by printed circuit boards specially developed to prevent electrostatic discharges and/or corona effects across the volume of the HPD arrays. The circuits allow for the splitting, distribution, protection and monitoring of the high voltages. Each board is covered with silicone rubber, which prevents electrostatic breakdown, and a study has been made on its radiation tolerance. A prototype HV system has demonstrated compliance with all experimental requirements. Finally, a production test system has been implemented to provide for a precise characterization of each HV board, in order to guarantee optimal yield.

計器用変圧器の高周波振動の解析

The high frequency oscillation in voltage transformer is analyzed using an equivalent lumped circuit with FFT method. Such analysis has been regarded difficult since those used in high voltage distribution systems have a large number of turns. The constants of equivalent circuit are evaluated on turn-to-turn basis. The frequency domain analysis is followed by the time domain using FFT technique. The both characteristics are verified by the experiment on a 6.6kV voltage transformer. The nature of high frequency oscillation is shown for a simpler model. It is found the interlayer voltage is highest at the entrance of incoming surge.

Optically isolated high-voltage digital-to-analog converter

We have designed, prototyped and characterized a High-Voltage Digital-to-Analog Converter (HV–DAC) with a dynamic range of 600 V. When configured as a series voltage drop element in a High-Voltage (HV) distribution system, the HV–DAC can be used in high-energy physics experiments where individual high-voltage control of many channels is needed. The design and performance of the HV–DAC and a prototype two-channel programmable HV distribution system are presented here.

Inverter topologies for DSTATCOM applications—a simulation study

This paper describes a few different topologies of inverters used for realizing a distribution static compensator (DSTATCOM). A brief introduction of the need for shunt compensation as well as the requirements of the shunt compensator has also been given. An algorithm for generating references has been described. Three major topologies of inverters – three-leg inverter with single dc capacitor, three-leg inverter with neutral clamped dc capacitors, four-leg inverter and three single-phase inverters with common dc capacitor – have been described and simulated. DSTATCOM topologies for high voltage distribution systems have also been described. The Voltage Source Converter (VSC) topologies have been compared on the basis of the performance of the inverter for certain chosen system conditions and the number of switch devices and dc capacitors used. All simulations have been performed using PSCAD/EMTDC.

各種インパルス電圧による架空絶縁電線表面の沿面放電特性

When the lightning occurs at the neighborhood of outdoor high voltage distribution lines, the creeping discharges propagate along the wire surface from the binding wire tip just after the flashover of insulator. These discharges give rise to the various disasters at distribution lines, for instance, disconnection and melting of wire, punch-through breakdown etc. We must clarify the creeping discharge characteristics under various inductive lightning surges from a viewpoint of a safety in high voltage distribution systems. In our previous paper, it was reported that the lengths and aspects of the negative creeping discharges were influenced by the duration of wave front of impulse voltage applied to the central line under the grounded binding wire. The present study was accomplished in order to obtain more information on such creeping discharges.This paper describes the distinctive characteristics of creeping discharge along the insulated wire surface when the impulse voltages with various durations of wave front are applied to the binding wire.

The influence of wave front duration of impulse voltage on creeping discharges along aerial insulated wire

AbstractIn high‐voltage aerial distribution systems, creeping discharges progress along the cable surface from the free end of the binding wire when overvoltages caused by a lightning surge have invaded the central line of an insulated cable. Consequently, various accidents such as punch‐through breakdown, melting, or snapping of a cable, often occur at these systems. In our previous studies, it has been clarified that the lengths and aspects of creeping discharges under a 1.2/50 µ s impulse voltage condition can be markedly affected by changes in the electric field strength on the cable surface. However, lightning impulse surges which may invade the central line of a cable have various wave front durations. This will further complicate creeping discharge phenomena due to lightning.In this paper, we report the influence of the wave front duration on both the lengths and the aspects of the creeping discharges which progress on the cable on application of lightning impulse voltages. It has been shown that the behavior of negative creeping discharges reveals pronounced changes in response to the duration of the wave front of the applied voltage. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(2): 30–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10263

Discussion of "Fault-current limiter applications in medium- and high-voltage power distribution systems" [and reply

The author makes five comments on the paper by A.Y. Wu and Y. Yin (see ibid., vol.34, p.236-42, 1998). The author points out that there are no fault current limiters available for applications above 38 kV, discusses two sensing modes for current limiters, zero current crossings for fault currents, coordination between the current limiter and the phase overcurrent relays, and briefly mentions reactor bypass schemes. The original authors reply to the comments.

Fault-current limiter applications in medium- and high-voltage power distribution systems

Electronically triggered fault-current limiters have been used in medium- and high-voltage power distribution systems to limit the available short-circuit current to a lower level, so that the underrated switchgear can be operated safely. However, to insure a safe and proper usage of these devices, the following major operating parameters need to be considered: (1) selection of trigger level; (2) selection of di/dt; (3) effect of the capacitor bank and stray capacitances; and (4) coordination between these devices and phase overcurrent (o/c) relays at the faulted breaker. This paper will examine these major operating parameters, evaluate the performance of the current limiters under various simulated fault conditions, and develop application guidelines for current limiters.

History of a single-phase high-voltage distribution system

For over 70 years, a considerable part of Southport received an electricity supply through a single-phase high-voltage distribution network. This was developed from a system established in 1894 when the municipal authority pioneered one of the earliest generating stations to operate at 50 Hz. Designs introduced for distribution pillars used in conjunction with transformers located in pavement pits formed the basis of the supply system. This, developed to meet the increasing demand for electricity, became one of the most extensive of its kind in Britain, and the generating plant progressed from rope drive to turbo alternators. Street lighting employing high-voltage direct current derived from synchronous rectifiers remained in use for several years. When single-phase generation generation ceased in 1921, single-phase high-voltage distribution was maintained and extended for a further 45 years, until its final displacement following a programme of voltage standardisation initiated by the nationalised electricity supply industry. >

Overvoltage protection scheme for series capacitor banks on high voltage distribution systems

An analysis of the overvoltage protection requirements for a series capacitor bank on a high-voltage distribution system (16/27.6 kV) is presented. The problems encountered in providing the required degree of protection are illustrated with an actual case study of an installation implemented by Ontario Hydro. The overvoltage protection scheme, an essential component of the series capacitor bank installation, was reliable and effective in two years of service that saw no capacitor failures. The scheme is based on readily available, off-the-shelf equipment and can be easily adapted to any installation with similar operating requirements. The ring gap, which is the only custom-made component of the system, is simple and could be fabricated by most utilities' machine shops.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design and construction of a 5.7-MJ, 10-kV multi-stage capacitor power supply

A 5.7 MJ, 10 kV capacitor power supply was designed and constructed primarily to power an electromagnetic launcher. The power supply consists of five subsystems: capacitor bank, capacitor charging supplies and high-voltage distribution system, coaxial bus system, inductors (solenoid and coaxial), and control system. Each subsystem is described in detail. The overall power supply program has exceeded all design objectives. The supply has been operated at over 150 discharges. The capacitor power supply has proved itself to be highly reliable, safe, and easy to operate. >