Relay Equipment Research Articles

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

VIBROSIEVE DIAGNOSTICS OF ELECTROMAGNETIC EQUIPMENT

In the article one of variants of checking the operability of relay equipment for railway automation is examined with the use of method of noise diagnostics (an identification of noise signals on the basis of using the moments of density of probability distribution for random noise signals).

Optimal placement and channel assignment of relay stations in heterogeneous wireless mesh networks by modified Bender’s decomposition

Fixed Broadband Wireless Access (FBWA) technology is designed to serve as a wireless DSL replacement to provide broadband Internet access in underserved areas where no other access technology exists. Due to the enormousness of the target service area, relay equipment play an important role in such networks, and the installation and maintenance cost of the network is directly proportional to the cost of the relay equipment. To minimize the network operational cost, an optimization framework which computes the minimum number of relay stations and their corresponding placements and channel assignments in the network is desired. Because the problem is NP-hard, we propose an efficient optimization algorithm based on a modified version of Bender’s decomposition to iteratively compute converging bounds to the problem solution. Our numerical results show that by using a few relay stations in a rural community, broadband Internet access can be established in a cost effective manner.

세라믹 필터를 이용한 동축 서지어레스터의 잔류전압 저감

현재 급속한 발전을 거듭하고 있는 이동통신 및 무선 멀티미디어 관련 서비스(W-CDMA, DMB, WiBro 등)의 확장은 이들 시스템을 구현하기 위한 수많은 기지국과 안테나 및 다수의 신호전송선로를 필요로 한다. 기지국 또는 중계시설의 안테나는 신호전송선로를 동하여 고가의 동신 네트워크 장비들과 결합되어 있으므로 주요 통신기기 시스템은 안테나를 통해 유입하는 직격뢰 및 유도뢰에 의한 순간적인 과전압의 위험에 항시 노출되어 있다. 현재 통신용 보호기로 사용되고 있는 가스방전튜브(GDT) 또는 협대역 스터브형 어레스터는 고속 광대역의 통신설비에 대한 뇌서지 보호수단으로서는 한계점이 드러나고 있다. 따라서 본 연구에서는 안테나를 통해 입사하는 뇌서지를 효과적으로 저감시켜주는 서지어레스터의 성능향상을 위해 세라믹 필터를 적용하였으며, 잔류전압 저감에 효과적임을 성능실험을 통해 입증하였다.

Fundamental study on rationalization of maintenance procedure based on reliability analysis

AbstractWe have developed the Reliability Analysis System for Protective Relays (RASPR), which is composed of a database for protective relay equipment and its failures, and reliability analysis part. The data for relay systems and their failures have been collected since fiscal 1997. Copyright © 2004 Wiley Periodicals, Inc.In this paper, the following suggestions were made from the analysis of the reliability for protective relays: (1) Omission of interruption of automatic checking at fault does not exert an influence on the reliability such as the availability. (2) Improvement of the availability was cleared from the analysis of effect of shortening of the testing time required. (3) The extension of the periodic testing period could be possible if 70% of failures discovered in a periodic testing were detected by continuous monitoring. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 25–31, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20161

Fundamental Study on Rationalization of Maintenance Procedure based upon Reliability Analysis

We have developed the Reliability Analysis System for Protective Relays (RASPR), which is composed of a database for protective relay equipment and its failures, and reliability analysis part. The data for relay systems and their failures have been collected since fiscal 1997.In this paper, the following suggestion was made from the analysis of the reliability for protective relays; 1) Omission of interruption of automatic checking at fault doesn’t have an influence on the reliability such as the availability, 2) Improvement of the availability was cleared from the analysis of effect of shortening of the testing time required, 3) The extension of the periodic testing period could be possible if 70% of failures discovered in a periodic testing were detected by continuous monitoring.

Differential Current Relaying System with Optical Phase Detection Using the Flint Glass Fiber Type Optical Current Transducers.

We propose an optical current sensing system which has a function of the differential electric current calculation being done in the protective relay equipment. In the proposed system a new scheme of common pass fiber-optic interferometer is formed. The interferometer is composed of the flint glass fiber as multiple Faraday sensing elements, quarter wave plates as polarization mode converters, and polarization maintaining fiber as signal transmission lines. By using this system, stable output proportional to the total value of current detected by the multiple sensing elements can be obtained. In order to confirm the principle, an experimental set up including three sensors was built and characteristics of the system were examined. From results of the experiment, it became clear that function of the experimental system agreed well with the principle. Following the successful experimental results, two basic model sensors for practical use were manufactured and were incorporated into the system. Good test results of the system with the model sensors were also obtained.

Local area supervisory protection system transformer taps

Abstract Connecting a transformer directly to the high voltage transmission line is a practical and relatively inexpensive way of providing service. The use of many circuit breakers is usually not justified, particularly at higher voltages. Motor operated air break switches (MOABs) instead of circuit breakers are used. To cope with the difficulty of switching arrangements, detection and clearing of transformer faults excluding the ground switch for MOABs operation, local area supervisory protection (LASP) system is proposed. LASP System collects current and voltage data from different locations on the power system through integrated equipment (IE) to relay equipment (RE). Asynchronous transfer mode (ATM) is a connection-oriented, packet-switched networking model between the LASP system and the equipment. Some attention is given to the architecture of a solution and some guidelines as to how this structure might be built to match with the next generation substation network architecture are also provided. The environment opens up new vistas for protection applications in the power systems.

保護リレー技術革新の歴史

As for the protection relay, the innovations of relay technology was accomplished for 30 years leaping-ly. This relay technology innovations corresponded to the expansion of the electric power system are accomplished by the foresight.In the composition of the protection relay equipment, it improved from the mobile contact-type relay of electromagnetic power to the solid state-type relay and moreover the technology was innovative at the digital-type relay by MPU. Then, the innovations of this hardware technology could be achieved by the establishment of the technology which make relay systems a high degree of the reliability by automatic and watching over equipment itself. On the other hand, because the innovations of this relay hardware technology could leave out the limitation of the protection relay function, it brought about the innovations of the software technology which protect bulk power systems to a high degree. The protection relay technology in Japan is the technology which have been most advanced in the world and is the technology which fitted in with the Japanese state of the affairs. As for this paper, it introduces the outline about the contents of the technology innovations and the big results of the technology innovations.

A Case of an Accident about Failed Relay Equipments for Specified Users' Telecommunication Lines at NTT Higashi-Yodogawa Relay Station

A Case of an Accident about Failed Relay Equipments for Specified Users' Telecommunication Lines at NTT Higashi-Yodogawa Relay Station

New protection method for HVDC lines including cables

For the third project of the Hokkaido-Honshu HVDC Link in Japan, called the HVDC Link III project (rated at 250 kVDC-1200 A-300 MW), we developed an HVDC transmission line protection method based on a new working principle that allows high-speed and highly sensitive detection of faults, enhancing reliability in the supply of electric power. In general, increasing the sensitivity of relays will lead to an increased likelihood of undesired operation whereas lowering the sensitivity will impair the responsiveness of the relays. Our proposed method meets these apparently incompatible requirements very well. Basically classified as a differential scheme, the HVDC transmission line protection method compensates for a charging and discharging current that flows through the line-to-ground capacitance at times of voltage variations caused by a line fault or by the operation of DC power systems. The developed protection method is also characterized in that it uses current changes induced by voltage variations to restrain the operation of a relay. This configuration has made the proposed method far superior in responsiveness and sensitivity to the conventional protection method. A simulation using an EMTP (Electro-Magnetic Transients Program) was conducted on this method. Developed relay equipment embodying the new protection method was subjected to various verification tests, where this equipment was connected to a power system simulator, before being delivered to the HVDC Link III facility. >

Effects on electrical distribution networks of dispersed power generation at high levels of connection penetration

SYNOPSIS The advent and deployment of significant levels of photovoltaic and wind energy generation in the spatially dispersed mode (i.e. residential and intermediate load centres) may have deleterious effects upon existing protective relay equipment and its time-current co-ordination on radial distribution circuits to which power conditioning equipment may be connected for power sell-back purposes. Note that significant in this context is now generally agreed to mean greater than 50% of a feeder's minimum load capacity rating. The problems that may arise involve harmonic injection from power conditioning inverters that can affect protective relays and cause excessive voltage and current from induced series and parallel resonances on feeders and connected passive equipment. Voltage regulation, var requirements, and consumer metering can also be affected by this type of dispersed generation. The creation of “islands” of supply is also possible, particularly on rural supply systems. This paper deals mainly ...

4‐GHz band bandpass filter using orthogonal array coupling TM110 dual mode dielectric resonator

AbstractUsing monoblock ceramics, we developed a TM110 dual mode resonator with a fixed coupling coefficient. In this structure, a wide range of coupling coefficients was obtained, and the unloaded Q was not decreased due to the coupling coefficient. The coupling of the resonator was explained in terms of the principle of even and odd modes and the design procedure was presented. Using this resonator, a 4‐GHz band bandpass filter with a bandwidth of 500 MHz was fabricated. The insertion loss was found to be 0.2 dB and the temperature stability of the frequency was 0.35 MHz. This filter is useful as the input filter for satellite communication relay equipment.

Cuber predistortion linearizer for relay equipment in 800 MHz band land mobile telephone system

New relay equipment for a tunnel relay system used in an 800 MHz band land mobile telephone network has been developed. Significant improvements in size and power consumption have been achieved using a predistortion (PD) circuit to compensate for third-order intermodulation (IM) distortion generated in the power amplifier. This predistortion circuit features a simple configuration and easy adjustment, as well as high distortion reduction performance. The circuit configuration is derived from an analysis based on a complex power series representation of input-output nonlinearities for microwave transistor amplifiers. This analysis shows that two kinds of nonlinearities, AM-AM and AM-PM conversions, are uniquely related through the third-order distortion phase, In addition, an automatically controlled predistortion system is introduced to establish an adjustment and maintenance-free compensator. Using the developed predistortion circuit, a stable distortion reduction of more than 20 dB per 25 MHz bandwidth has been attained.

Recent advances in digital protection

The development of digital protection in Japan is determined by an industry policy which gives priority to the commercial development of products aimed at replacing conventional protective relay equipment. As a result of this policy, the use of digital relays has spread through Japan faster than in other countries. Major efforts have been made to establish the reliability of the dedicated digital hardware and improve the economics of digital protection. Progress in the use of digital protection will lead, in the near future, to the totally computerized substation system.

Practical results from the performance evaluation of an 11 Ghz 140 Mbit/s digital radio relay system

This paper describes the results and conclusions from a two-year field evaluation programme of 11 GHz 140 Mbit/s q.p.s.k. digital radio relay equipment conducted on three hops in the UK by British Telecom. In the first part of the paper the general features of system performance are described, including month-by-month outage results, error distributions, outage event durations, and error-free-secondperformance. The relative effect on performance of rainfall attenuation and multipath propagation are illustrated and discussed, together with effects of variations in hop length and the use of height diversity facilities. Worst-month outage results are compared with CCIR performance requirements to determine planning criteria for diversity. The second part describes in detail the system behaviour during multipath conditions, and examines whether the outage primarily resulted from noise, interference, or distortion conditions. The signature method of characterizing tolerance to distortion is described in order to explain observed results, and the effect of adaptive equalizer techniques is examined. Finally results from the evaluation of an automatic slipless protection switching system are presented, showing probability of slipless operation and performance improvements achieved in multipath conditions.

Design of a tunnel relay system with a leaky coaxial cable in an 800-MHz band land mobile telephone system

System design of a tunnel relay system in an 800-MHz band land mobile telephone system is described. Several dozen RF signals from a base station or many different mobile units in the tunnel are directly amplified in the RF stage, without frequency conversion, by a common amplifier in the relay equipment installed near the tunnel entrance, then radiated into the tunnel through a leaky coaxial cable (LCX) or to the base station by a unidirectional antenna. Repeaters are inserted along the LCX to compensate for transmission loss in RF signal power inside the cable. Amplifying a number of RF signals simultaneously, a common amplifier generates intermodulation products and radiates spurious signals. The required amplifier linearity to suppress the spurious signals is discussed in detail. The combination of LCX and service area in the tunnel is determined according to the amplifier performance, the number of radio channels assigned to the base station, and the radio wave propagation characteristics in the tunnel.

Integrated circuit lick/contact sensor which is compatible with relay programming equipment

A lickometer or contact-sensing circuit is presented which has been used in the author's lab for about two years. The circuit has proven to be highly reliable, trouble free, easy to build, and low in cost.

Delay of Reinforcement in Fixed-Ratio Behavior

When E manipulates the delay before reinforcement in free operant situations, he also manipulates the interval between the last response leading to the n - 1 reinforcement and the first response leading to the nth reinforcement. The present experiment studied effects of delaying reinforcement when the interval between these responses was not varied hv r! -, -. Three white rats of the Sprague-Dawley strain, maintained at 80% of free-feeding weight, were trained in a Lehigh Valley cage (Model 143-26) enclosed in a sound actenuating chamber. Relay and programming equipment were located in an adjacent room. Upon completion of a fixed-ratio of 45 responses (FR 45) the response lever retracted from the cage for 30 sec. A 45-mg. food pellet was delivered either 0, 5, or 10 sec. after lever retraction. Each S was given 15 daily sessions of 50 reinforcements each at each delay interval starting with the 0-sec. interval and increasing progressively in 5-sec. increments. Performance was reevaluated at the 0-sec. condition after all other conditions had been presented. Cumulative post-reinforcement pauses (time between entrance of the lever into the cage and S's first response) and responding time (time elapsing from the first response until the lever retracted) were recorded for the 50 trials of each session, and only data from the last five days at each condition were used in the analysis. With this rechnique reinforcement delay was varied within a constant interval (30 sec.) between S's last response before a given reinforcement and until he could resume responding after thac reinforcement. TABLE 1

Transient potency factor of protective current transformer–a new standard for transient behaviour

The correct performance of protective current transformer during transient is very important to ensure dependable service of the protective equipment. The existing method of measuring the accuracy of a current transformer for accuracy limit primary current; which is a multiple of normal load current ; does not take into account the time constant of aperiodic component of primary fault current. The increase in speed of operation of high speed relays and switch gear now calls for a very short time for the fault detection by the relay apparatus. Times of the order of 20 to 40 ms are not uncommon. In such a short time, the transient currents and fluxes in a current transformer do not reach steady state values and as such application of steady state standard in such case do not give accurate results and may frequently cause maloperations of the connected relay equipment. As far as the author is aware, no standard for transient performance of current transformers have been adopted. This paper presents a new standard for indicating the transient potentialities of a current transformer.