2000

Diendorfer G., A. Pistauer: Lightning Performance of High Voltage Power Lines

16^th International Lightning Detection Conference (ILDC), Tucson, Arizona, 2000 Lightning is one of the major sources for power line outages. We have correlated outages of unknown reason and when lightning was already assumed to be the reason with the archived lightning data from ALDIS for about 25 power lines (400 kV and 220 kV). For about 25% of the outages we found very good correlation with a lightning discharge in a corridor of up to +/- 5000 m. Some of the remaining outages are assumed to be either caused by other events (strong wind, moisture on insulators, etc) or by lightning flashes that have not been detected by the LLS. In the past there have been claims of increased lightning activity in the vicinity of high voltage power lines. Detailed analysis of the lightning data near power lines does not support this claim. Power lines in flat area exhibit no effect to the local ground flash density near the power line. We have also determined values for the actual ground flash densities for the individual lines and we used the software IEEE-FLASH to estimate the number of outages per 100 km and year assuming two distinct peak current distributions (CIGRE distribution with 31 kA and LLS based distribution with 12 kA mean). Comparison of the estimated values and the actual observed number of outages are not well correlated. This leaves some open questions, whether the FLASH program is not applicable for the type of power lines used in Austria or the number of reported outages caused by lightning is not well defined. PDF File (51 KB)

Diendorfer G., W. Schulz, M. Mair: Evaluation of a LLS based on lightning strikes to an instrumented tower

16^th International Lightning Detection Conference (ILDC), Tucson, Arizona, 2000 In 1998 a radio tower on a mountain near Salzburg was instrumented for direct measurements of lightning currents. When lightning strikes the tower, the entire lighting current pulse is recorded using a shunt and a PC based digitizing system. This experimental setup allows to analyze the performance of the Austrian LLS (ALDIS) in terms of location accuracy, detection efficiency and it's ability to provide an estimate for the stroke peak currents. Since the beginning of the tower measurements we have recorded about 100 events with a total of about 500 strokes. Almost all of the events are assumed to be upward flashes as typical for elevated objects. In the paper we will present some initial results for the above mentioned performance parameters of ALDIS. Due to the integration of LPATS sensors in Germany installed close to the experimental site, we have both sensor types available for our analysis. PDF File (219 KB)

Schulz W., G. Diendorfer, M. Dorninger, N. Daly: Comparison of Lightning Data Collected by Location Systems of Different Technology

16^th International Lightning Detection Conference (ILDC), Tucson, Arizona, 2000 Different lightning location systems provided lightning data for the MAP database during the MAP SOP. In this paper we compare lightning data sets recorded during the MAP-SOP from two different lightning location systems, the so called SOP-lightning location system (SOP-LLS) and the lightning location system from the British Met. Office called ATD. The SOP-LLS was designed [Dorninger, 1999] to provide the best detection efficiency (DE) over the entire alpine region that can be achieved with today's available technology for a large region like the Alps. Thus it was assumed that this system detects more flashes than the ATD system which covers a much larger area than the Alps and had, at the time, a low processing ability. We will show that this assumption was correct and we will determine the overall DE of the ATD system relative to the SOP-LLS. Comparison of the lightning peak current distributions of both systems indicates that the ATD system mainly detects flashes of higher peak currents. PDF File (270 KB)

Schulz W., G. Diendorfer: Evaluation of a lightning location algorithm using an elevation model

25^th International Conference on Lightning Protection (ICLP), Rhodos, Greece, 2000 Location accuracy is one of the important performance parameters of a lightning location system. With more and more sophisticated applications of lightning data also an increasing demand on improved location accuracy is observed. Today lightning location systems are mainly using GPS synchronized time information to locate a lightning discharge. The location is calculated based on the time differences between sensor arrival times and estimated impact time. Assuming speed of light (c0) for the field propagation velocity from this time differences the propagation distances to the sensors are calculated assuming the earth as an ideal ellipsoid. Distances calculated this way do not take into account any elongation of the propagation path due to mountains. This is assumed to be one of the reasons for the existence of a systematic location error in mountainous regions [Schulz, 1997]. In this paper we show how calculated lightning locations are affected by taking into account the wave travelling path elongation due to mountains by applying an elevation model for the earth. Any possible improvement of the resulting locations is evaluated by using data from lightning strikes to high towers. PDF File (35 KB)

Diendorfer G., M. Mair, W. Schulz, W. Hadrian: Lightning Current Measurements in Austria - Experimental Setup and First Results

25^th International Conference on Lightning Protection (ICLP), Rhodos, Greece, 2000 In a recent investigation on ground flash density around elevated objects in Austria it was found, that the telecommunication tower at mount Gaisberg near Salzburg would be one of the most suitable sites for an experiment to measure direct lightning currents. This about 100 m tall telecommunication tower is located 1287 m above sea level and about 5 km east of the city of Salzburg. Based on the data from the Austrian Lightning Location System (ALDIS), 40 - 50 flashes with about 200 strokes per year were expected. The installation of an automatic measuring system to record currents of direct lightning strikes to the tower was started in August 1998. In this paper we present a detailed description of the experimental setup and show first results of recorded current waveforms in 1999. PDF File (197 KB)