Lightning Stroke Current Research Articles

Minimisation methods for lightning stroke current digital acquisition

Statistical data on lightning stroke currents represent a basis for the risk of failure analysis of different stricken objects and insulation coordination of the electric power systems. Collecting these data is a time consuming process consisting of measurements spanning at least eleven years, i.e. one solar cycle, due to cyclic changes taking place in the atmosphere. Minimisation methods of lightning current digital acquisition enabling construction of an autonomous digital transient recorder for this application are presented. In this way, long-term data collection in unmanned automated registration stations is made possible. These methods are based on maximum utilisation of lightning current properties obtained from different previous measurements. Functional test results of the solutions applied in the developed prototype transient recorder are also presented.

Observation of current waveshapes of lightning strokes on transmission towers

Considerable cost reductions have been achieved through rationalizing insulation design for substation equipment based on the application of high-performance surge arresters and improvement in analysis techniques. For further rationalization in insulation design and cost reduction, it is important to evaluate the lightning stroke current waveshape in detail. Some studies to observe current waveshapes have been conducted before, but they were ones conducted on independent towers and do not provide many data in a large-current region. So, the authors have been observing lightning stroke currents larger than 9 kA on 60 transmission towers (mainly 500 kV lines) since 1994. In this paper, they present some lightning parameters for insulation design of substations, drawn from current waveshape data, which have been collected so far. In addition, they report on the relationships among the peak value, the front steepness and the front duration, which heavily affect the insulation design of substations.

Distribution arrester outages caused by lightning backflow current flowing from customer's facility into power distribution lines

Direct lightning strokes are considered to be a main cause of damage to surge arresters on power distribution lines. Recently, lightning performance of distribution lines has been observed using still cameras, and lightning-caused distribution outages on hilltop areas on the coast of the Sea of Japan have been investigated. This research has shown a possibility that lightning backflow current flowing from customer facilities into distribution lines causes damage to surge arresters on the distribution lines. We have investigated the lightning backflow current flowing from customer facilities into distribution lines as a cause of damage to surge arresters. The main results are as follows: (1) The electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current. (2) If the grounding resistance of the customer's facility is not low, the failure rates of a surge arrester caused by backflow current due to winter lightning is more than 90% of that caused by direct lightning strokes. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 9–20, 1999

需要家設備落雷時の配電線への雷電流逆流現象による 避雷器焼損事故に関する検討

Direct lightning strokes are considered to be a main cause of damage to surge arresters on power distribution lines. Recently, lightning performance of distribution lines has been observed using still cameras, and lightning-caused distribution outages on hilltop areas on the coast of the Sea of Japan have been investigated. This research has shown a possibility that lightning backflow current flowing from customer facilities into distribution lines causes damage to surge arresters on the distribution lines. We have investigated the lightning backflow current flowing from customer facilities into distribution lines as a cause of damage to surge arresters. The main results are as follows: (1) The electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current. (2) If the grounding resistance of the customer's facility is not low, the failure rates of a surge arrester caused by backflow current due to winter lightning is more than 90% of that caused by direct lightning strokes. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 9–20, 1999

Lightning overvoltage protection of the Paddock 362-145 kV gas-insulated substation

Backflashovers close to the Paddock 362-145 kV gas-insulated substation (GIS) have been analyzed with the electromagnetic transient program (EMPT) using a frequency-dependent multiconductor system. The severities of the lightning stroke currents were based on recent recordings in the eastern United States. The effects of corona attenuation and distortion were accounted for using a shunt linear model approach. Turn-up effects of both line insulator flashover voltages and surge arrester protective characteristics were based on manufacturer's volt-time curves. Wave-shaping effects of substation capacitances were modeling details in determining the overvoltages inside the GIS due to close backflashovers, which are caused by lightning strokes with varying intensity. These results are aimed at better evaluation of lighting protection requirements for GIS protected by metal-oxide surge arresters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Advanced observations of lightning induced voltage on power distribution lines. II

The authors discuss observations of induced voltages on the experimental overhead distribution line at a power plant facing the Japan Sea from October 1984 through March 1988. Waveforms of induced voltage from lightning strokes to a high stack of the power plant were measured simultaneously with the current waveforms of the lightning stroke to the stack. The polarity of lightning-induced voltage is opposite to that of lightning stroke current, regardless of the season. Except for unusual conditions, lightning induced voltages have a unipolar waveform. The lightning-induced voltage on the closest point of a distribution line to the lightning striking point is the maximum. The induced voltage waveforms generated on a distribution line were calculated by means of improved numerical analysis which took the height of the stack into consideration. The calculated results agree better with the measured waveforms than made those made by means of an earlier analysis method. It is clarified that bipolar induced voltages are not produced by usual lightning stroke currents.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Advanced Observations of Lightning Induced Voltage on Power Distribution Lines (II)

The authors discuss observations of induced voltages on the experimental overhead distribution line at a power plant facing the Japan Sea from October 1984 through March 1988. Waveforms of induced voltage from lightning strokes to a high stack of the power plant were measured simultaneously with the current waveforms of the lightning stroke to the stack. The polarity of lightning-induced voltage is opposite to that of lightning stroke current, regardless of the season. Except for unusual conditions, lightning induced voltages have a unipolar waveform. The lightning-induced voltage on the closest point of a distribution line to the lightning striking point is the maximum. The induced voltage waveforms generated on a distribution line were calculated by means of improved numerical analysis which took the height of the stack into consideration. The calculated results agree better with the measured waveforms than made those made by means of an earlier analysis method. It is clarified that bipolar induced voltages are not produced by usual lightning stroke currents. >

Advanced Observations of Lightning Induced Voltage on Power Distribution Lines

Waveforms of induced voltage from lightning strokes to a high stack of the power plant have been measured simultaneously with the current waveforms of lighting stroke to the stack since December 1980. This paper shows the lightning stroke current waveforms and the lightning induced voltage waveforms over a 3 year period from December 1981 through March 1984. The combination of polarities for waveforms of lightning induced voltage and lightning stroke current is indicated below: (1) Seven cases of positive induced voltage in response to negative lightning stroke current were observed. (2) Four cases of negative induced voltage in response to positive lightning stroke current were observed. Distribution of lightning induced voltages along the distribution line length was also demonstrated.

A method to estimate the lightning multiline flashover on transmission line towers

Most transmission line faults are caused by lightning. In Japan under ordinary circumstances, two circuits of transmission lines are strung on one tower due to the limited right of way. Therefore it is not rare that the two circuits break down simultaneously. Since the simultaneous two-circuit fault has a very serious effect on the security of power systems, it is very important to predict accurately the probability of multiline flashover. Much useful data have already been accumulated about the potential distribution of the transmission tower subject to lightning stroke. These data are used to analyze the mechanism of multiline flashover, and a tower potential rise method (abbreviated as TPR method) for the analysis of multiline flashover phenomena is proposed. In this method, it is possible to take into account the surge impedances of the transmission line and transmission tower and the coupling factor between the power line and ground wire, as well as the potential distribution of the transmission tower. In the proposed method, the conventional formulas for lightning stroke current and the frequency distribution curve of lightning stroke current, which have been used widely so far in designing the insulation level of the transmission line, are used. Hence, itmore » is possible to calculate the multiline flashover probability without modifying the basic principle of conventional insulation design procedures.« less

Determination of Lightning Response of Transmission Lines by Means or Geometrical Models

The voltages produced across the tower insulators of transmission lines struck by lightning can be determined both by measurements on geometrical models and by calculations. Measurements which have been made on geometrical models of the Ohio Valley Electric Corporation's (OVEC) 345-kv transmission towers agree well with the calculations of Lundholm, Finn, and Price.1 A simplified theory has been developed, using electromagnetic field concepts and the distributed constants of transmission lines, which explains the relationships between insulator voltages and lightning voltages and lightning stroke currents. This theory includes the effects of the magnetic field produced by the return stroke and the changing electric fields produced by neutralization of the charged column of the leader.

Lightning currents in field and laboratory

A review of available data on the magnitude and effects of lightning stroke currents, supplemented by laboratory experiments to check these effects, is presented herewith. Maximum currents of 150,000 to 200,000 amperes having durations of from 40 to 100 microseconds are indicated.

Lightning Currents in Field and Laboratory

A review of available data on the magnitude and effects of lightning stroke currents, supplemented by laboratory experiments to check these effects, is presented here-with. Maximum currents of 150,000 to 200,000 amperes having durations of from 40 to 100 microseconds are indicated.

Lightning Investigation on Transmission Lines---III

The field data for 1931 and 1932 are reviewed, with especial reference to lightning stroke currents. When direct strokes take place to towers or ground wires, flashover occurs if the product of current and tower footing resistance is higher than the fiashover strength of the insulators. Flashover seldom occurs if ground wires are present and the towers have low footing resistance. Three years' records on four systems indicate tower currents varying from 1,000 to 150,000 amperes. Tripouts correlate almost exclusively with high tower leg currents of negative polarity, that is, the tower top is negative with respect to the base. This indicates that the severe lightning strokes come from negatively charged clouds. A great amount of experimental data, relating to flashover between electrodes of dissimilar shapes, are shown to be in accord with these field observations.