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The detection system in substation of medium voltage overhead line can mostly detect only low impedance fault, neither broken conductor on the source side with high impedance, nor broken conductor on the load side with even direct to ground. This paper presents novel method to characterize such faults using time shifting in 3 phase line current. It can be applied, however, in parallel with the conventional...
Analysis of induced voltages on transmission tower and conductors has been performed when a high voltage line is subjected to propagation of lightning transient. PSCAD/EMTDC software program is used to carry out the modelling and simulation works. Lightning strikes on the tower top or conductors result in large overvoltages appearing between the tower and the conductors. Two cases considered for these...
This paper analyzes the lightning performance of 22 kV, ChiangMai substation 4 to Doi-Suthep, overhead distribution line with covered conductors. The performance of line which related to the insulator flashover has been modeled and analyzed using EMTP. The backflashover rate (BFOR), shielding failure flashover rate (SFFOR) and induced voltage flashover rate (IVFOR) of line have been determined. The...
The paper makes an analysis of the eighteen 220 and 400 kV overhead electric lines belonging to C.N. Transelectrica - Sibiu Branch (TSO) on the basis of a unitary methodology for assessing their technical state and taking into consideration the different types of expertise conducted until now, including the multispectral analysis from the helicopter of seven lines. Performance criteria for insulators,...
Because of the necessity to perform maintenance on one of the circuits of the high and very high tension double circuit lines that have one of the circuits operational, a case that lately becomes more frequent, the calculation of the currents and induced tensions in the circuit's conductors that is under induction is required to establish safety working conditions. This paper does not intend to modify...
Having been learned a lot from the previous work , this paper proposed a new medium-frequency current ice-melting method employing skin effect and proximity effect phenomena to overcome the weaknesses of existing de-icing method of overhead line. By the interaction of the two phenomenon, the transmission line unit resistance is expected to increase, compared with the working frequency current, the...
This paper describes shielding method for lightning protection on high voltage transmission line and also how to protect lightning effects on the line. If the fault is present, additional power system will be damaged and minimizing system reliability. This shielding method used in transmission line bases the unequal lightning ground flash density all over the country. This paper is tend to specialize...
Lightning has been one of the important problems for insulation design of power systems and it is still the main cause of outages of transmission and distribution lines. The lightning return-stroke current and the charge delivered by the stroke are the most important parameters to assess the severity of lightning strokes to power lines and apparatus. This paper presents the effects of tower, grounding...
Lightning flash is one of the natural causes of faults in overhead transmission lines. The critical stroke current which causes flashover is a basic parameter characterizing the lightning performance of transmission lines. In recent times, there has not been any mature experience to be referred to either in China or other foreign countries of the study on lightning withstand level of UHVDC transmission...
Distribution analysis power-flow and short-circuit studies typically model overhead and underground lines assuming that the neutrals are solidly grounded. That assumption has come under question since grounded wye lines will not actually have zero resistance between the neutral conduction and ground. Without a solid ground there will be a voltage between the neutral and ground. In order to determine...
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