Stephan Pack

Fire losses and human accidents caused by lightning — An Austrian overview

Fire losses and human accidents caused by lightning are recorded in Austria since more than 20 years with an appropriate quality. The used data of fire losses and human accidents of a 10 years period are based on official documents summarized by the National Organization of Fire Prevention every year. Additionally a huge number of newspaper reports from 2001 to 2010 could be obtained. The investigations and the correlations are based on the lightning density, recorded by of the Austrian Lightning Detection and Information System (ALDIS). In a period of 10 years a total number of 8.662 fire losses by lightning and 76 human accidents including 11 fatalities were recorded in the federal territory of Austria. In the western part of Austria with the provinces Vorarlberg, Tirol and Salzburg, 74 fire losses caused by lightning were recorded, that are 5% of all fire losses caused by lightning in the year 2010 on an area with 27.244 flashes per year, that are 14% of all flashes per year in Austria. The northern part, with the provinces Oberösterreich and Niederösterreich and Wien with 76.199 flashes in the year 2010, that are 40% of all flashes has got 1.017 fire losses caused by lightning, that means 65% of all fire losses caused by lightning in the year 2010. The eastern part with the province Burgenland with 14.584 flashes, that are 8% of all flashes in Austria has got 92 fire losses caused by lightning, that are 6% of all fire losses caused by lightning in the year 2010. In the southern part of Austria with the provinces Steiermark and Kärnten 367 fire losses caused by lightning were recorded in the year 2010. That means that 24% of all fire losses caused by lightning were in an area with 73.610 flashes (38%).

Usage and Benefit of an Overhead Line Monitoring System

Overhead lines are the backbone of the electrical power transmission. Contrary to the distributions networks, the transmission system consists only in exceptional cases of longer cable lines. Typical exceptions are connections of cavern power plants, approaches to airports or bird sanctuaries and lines in urban centres. In the majority of cases, an overhead line is the most economic and practicable solution for the energy transmission. In tourism regions, an overhead line will be seen as impairment of nature or landscape and so the approval chain and procedure is in most countries long-winded and circumstantial. At the other hand, the energy consumption in Europe is growing and the volatility of transmitted power is also increasing during the last decade caused by the opening of the electric energy market. This opening process leads to a stopping of the enlargement of the interoperation network and to a minimisation of the maintenance of existing lines. Today the network operates more often at the limit of the equipment and the small and large-areas disturbances and blackouts are increasing. The operators of transmission lines are forced to ensure the electrical power supply and so they have to improve the reliability of the network. One solution is to monitor the critical (heavy loaded) overhead lines. For example with the knowledge of the thermal condition, the risk of unexpected outages can be reduced. Today several monitoring systems are available on the market. They differ in the principle and techniques of the condition evaluation. The three most interesting output variables are the line temperature, the capable transmission power and the actual sag of the investigated section. In this paper an overview of existing overhead line monitoring system and also an outline over the usage and benefit for the application will be given. Thermal monitoring is one technique to improve the reliability of the network and for increasing or optimising the capable transmission power.

Experiences with the Weather Parameter Method for the use in overhead line monitoring systems

SummaryOverhead lines are essential components of high voltage power systems worldwide. The performance of this network element is important for a save and reliable transmission of electrical energy. The load capability of a line is related basically to the line design itself and takes centre stage of the economic operation whereas the sag behaviour and the technical condition of the conductor and their components are more related to the line and network safety. Based on this situation overhead line monitoring systems are actually under discussion in many committees worldwide. This auxiliary equipment for overhead power lines helps to evaluate the actual transfer capability and/or to increase the system reliability. Therefore, a number of systems using different measuring methods and monitoring techniques are available on the market. More or less all methods are based on physical data and process information to achieve a suitable output to control the line stress. One of these methods is called the Weather Parameter Method, which uses local metrological weather data and system load information to estimate the conductor temperature. In a research project running over years an overhead line monitoring system was set up in cooperation with the Austrian transmission utility APG. After these years of experience a number of information and data based on the principle of the Weather Parameter Method is available and gives the scientific basement for this contribution. Three observation stations are collecting data all over the year; two stations are at a 220 kV overhead line and one station at the open air test field of the IHS in Graz in use. This contribution focuses on the coherences of the different parameters collected for the evaluation of the conductor temperature and it is not the main goal to discuss the improved performance by using a thermal management system, as mentioned in many other papers. By the knowledge of the punch-through of significant parameters in combination with the appearance probability a more accurate scheduling of the utilisation of the line under observation will be possible. A well prepared processing of many significant parameters for an overhead line monitoring system and a scientific approach based on some years of practical experience is presented in this contribution.

Aspects of High Voltage Cable Sections in Modern Overhead Line Transmission Systems

Electrical power transmission is dominated by overhead line systems at present. This is mainly based on more than hundred years of experience of utilities in running overhead lines. Furthermore, overhead lines have proven their operational reliability and functional assurance. In the past, cables were used in distribution networks in urban areas for the most part with the exception of direct current submarine cables. New developments of high voltage XLPE cables make it possible to use this technology for EHV-level applications in transmission networks. Within this paper, mixed network configurations, consisting of overhead lines and high voltage cables, are investigated. An exemplary EHV transmission line with a total length of about 100 km, which is quite typical for Central Europe, has been studied. Several different line combinations are discussed with varied rates between overhead line sections and cable sections length in practice. The length of the cable sections are ranging from several kilometers up to lengths of 100 km. In this paper the work focuses on the transient behavior of combined 400 kV overhead and cable lines during switching processes and lightning impacts. A number of calculations were carried out to get an overview of the transient stress in numerous network nodes along the transmission system. Numerical programs like ATP/EMTP have been used for these simulations. Peak values and wave shapes of the transient voltage stress have been evaluated, based on different systems and within possible combinations. In respect of the insulation coordination and transient stress at network nodes, the voltage time trends are also analyzed. The combination of high voltage overhead and cable transmission systems, especially such with lengths of more than about 50 km, are making tightened and extended demands to the network design, to the operational management and of course to the network protection also. As an output of this investigations, the results might influence the strategy in running this new type of combined transmission systems.

Thermography of aged contacts of high voltage equipment

New developments in diagnostic tools and systems are necessary for a reliable and economic evaluation of the condition of equipment in power systems. In a research project a tool for the condition of contacts of centre break disconnector, which is used under normal operation by the aid of a thermography measurement system, has been developed. In this paper, an overview about the laboratory investigation of the temperature load behaviour and the environmental influence on-site for new and aged disconnector contacts are given. A condition evaluation tool for contacts, which was the aim of the project, has been created. The basic method for the evaluation is presented, and also two additional easements for a fast identification of suspect contacts are presented. With this evaluation tool and the usage of a thermography based measuring system, a condition based maintenance strategy can be applied, whereby an early detection of damages is possible and so power quality and reliability increase.Neue Entwicklungen auf dem Gebiet der Diagnosewerkzeuge sind für eine zuverlässige und ökonomische Zustandsbeurteilung an Hochspannungskomponenten notwendig. In einem Forschungsprojekt wurde ein Werkzeug entwickelt, mit dem der Kontaktzustand eines Zwei-Säulen-Drehtrennschalters unter Normalbetrieb mit Hilfe eines Thermographiemessverfahrens bestimmt werden kann. In diesem Beitrag wird ein Überblick über das Temperatur-Lastverhalten unter Laborbedingungen und über die Klimaeinflüsse vor Ort für neue und gealterte Trennerkontakte gegeben. Das Ziel des Projektes war es, ein praxisorientiertes Werkzeug für die Kontaktbeurteilung zu erstellen. Methoden für die Auswertung und für eine rasche Erkennung von möglicherweise defekten Kontakten werden dabei dargestellt. Mit diesem Auswertungswerkzeug und der Verwendung eines Thermographie-basierenden Messverfahrens kann die zustandsorientierte Instandhaltungsstrategie für diese Systemkomponente angewendet werden. Damit ist eine Früherkennung von Kontaktveränderungen möglich, wodurch Versorgungssicherheit und Zuverlässigkeit weiter gesteigert werden können.

Validation of detection of positive flashes by the austrian lightning location system ALDIS

In this paper we present a detailed evaluation of the performance of the Austrian Lightning location system (LLS) ALDIS regarding detection of positive flashes. Additional to the performance of the LLS some parameters of positive flashes are determined. We also present detailed information about two positive flashes with a subsequent stroke following the same channel to ground as the first stroke.

An algorithm for the three-pole controlled auto-reclosing of shunt compensated transmission lines with an optimization for the second and third pole

This article presents an algorithm for auto-reclosing of shunt compensated transmission lines. The algorithm uses signal analysis methods to estimate the future voltage shape over the circuit-breaker. Based on this voltage shape switching instants are estimated in the zero crossings. The minimization of the probability of a prearcing is reduced be adding time shift parameters. These parameters take the limited rise of strength recovery of the circuit breaker and the mutual influence of the coupling of the poles by a three-pole auto-reclosing into consideration. The advantage of the descript method is significant reduction of the switching overvoltage.ZusammenfassungDieser Artikel beschreibt einen Algorithmus für die kontrollierte Wiedereinschaltung auf parallel-kompensierten Übertragungsleitungen. Der Algorithmus verwendet ein Signalanalyseverfahren zur Berechnung des zukünftigen Verlaufs der Spannung über dem Leistungsschalter. Mit Hilfe des berechneten Spannungsverlaufs ist eine Bestimmung von Nulldurchgängen als Einschaltzeitpunkte möglich. Die Wahrscheinlichkeit eines Vorüberschlages wird durch Addition eines Verschiebezeitparameters minimiert. Dieser Parameter berücksichtigt den Verlauf der Einschaltkennlinie des Leistungsschalters und die Beeinflussung der einzeinen Leiter untereinander bei einer dreipoligen automatischen Wiedereinschaltung. Der Vorteil des beschriebenen Verfahrens ist eine bedeutende Reduzierung der Schaltüberspannung.

Monitoring und Diagnostik in der Hochspannungstechnik

ZusammenfassungUm elektrische Betriebsmittel wirtschaftlich einzusetzen, ist es von Vorteil, ihren Nutzungsvorrat zu kennen. Mit Hilfe der technischen Diagnostik werden signifikante Größen aufgezeichnet, aus denen man Rückschlüsse auf das zukünftige Betriebsverhalten ziehen kann. Diese, das Betriebsverhalten beschreibenden Größen, entsprechen dabei Temperaturen, optischen, elektrischen und mechanischen Variablen sowie der Kombination dieser Größen. Anhand dieser erhaltenen Daten lassen sich Veränderungen im Betriebsverhalten diagnostizieren sowie Tendenzen erkennen und geeignete Gegenmaßnahmen ergreifen. Als ein Teilgebiet und somit wichtiges Diagnoseinstrumentarium ist die Teilentladungsmesstechnik anzusehen. Dabei stehen für deren Detektion und Ortung unterschiedliche Methoden zu Verfügung.AbstractTo use electrical resources economically, it is useful to know the available remaining service life of used resources. With the use of technical diagnostic systems significant variables can be recorded. On the basis of these variables (temperatures, optical, electrical and mechanical variables etc.), conclusions concerning the future behaviour of the technical resources will be made. Based on the received data information, modifications in the operation behaviour can be diagnosed; tendencies can be detected and suitable counter measures can be set. The so-called “partial discharge measuring technique” can be regarded as a subsection and an important diagnostic equipment. For the detection of partial discharges different methods can be used.

Transient measurements in the Austrian high voltage transmission system

Transient measurements in several substations in the Austrian transmission system were performed in the last years. Based on these measurements it was possible to detect signal sequences which show direct and nearby lightning discharges as well as the coupling effects between phases and ground wire after lightning strikes. These transient voltages were measured by using resistive-capacitive voltage dividers (RC-divider) to generate a high quality dataset. The high bandwidth of the RC-divider and its resulting frequency stability is needed to analyzed such transient events. A correlation between the measurements and the data of the Austrian Lightning Location System was performed. In this paper, three different representative measurements of atmospheric discharges to or close to transmission lines will be presented.

Von der Blitzentladung bis zu ESD-Testverfahren@@@From the lightning discharge to ESD test methods. Stress effects to devices and integrated circuits with respect to the standards: Beanspruchungen von Geräten und integrierten Schaltungen sowie normative Anforderungen

ZusammenfassungElektrische und elektronische Systeme sowie informationstechnische Infrastrukturen sind den Ein- und Auswirkungen atmosphärischer Entladungen ausgesetzt. In diesem Beitrag sollen die Zusammenhänge zwischen atmosphärischen Entladungen in Verbindung mit elektrischen Systemen, elektronischen Geräten und integrierten Schaltungen aufgezeigt werden. Dabei wird auf die Prüfverfahren und Normen zur Sicherstellung der elektromagnetischen Verträglichkeit gegenüber transienten Störgrößen eingegangen.AbstractElectrical and electronic systems and information technology infrastructures are exposed to the influences and effects of atmospheric discharges. This paper examines the relationships between atmospheric discharges in connection with electrical systems, electronic devices and integrated circuits. A focus is put on the standards and test methods to ensure the electromagnetic compatibility against transient disturbances.