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The limitation of switching overvoltage during EHV transmission line re/energization can be achieved traditionally through usage of circuit breakers equipped with pre-insertion resistors as well as the use of MOV surge arresters at both line ends and along the line. A recent and novel technique to reduce the switching transients is controlled switching. In this paper the results of comparative analysis...
In recent years, uprating of existing overhead power line has become a popular option for electric utilities to address increasing demand for power. Uprating overhead line by increasing voltage allows considerable increase in power transfer capability. This paper initially examines technical issues and conventional methods of uprating the voltage of overhead transmission lines. It then considers a...
While uprating an overhead line to a higher voltage level, it is often difficult to achieve the required clearance level for the uprated structure. Use of Transmission Line Arresters (TLAs) is an effective technique in controlling overvoltages and thereby, achieving the required clearance margin. In this paper, suitability of this technique in reducing the clearance margin is discussed. A case study...
In this paper a novel method of ATP (alternative transients program) simulation for single-pole auto-reclosing is introduced. This paper presents an investigation of single-pole auto-reclosing on HV transmission lines. By simulating real trapped charge, overvoltage profile is monitored. Most of the faults on HV transmission lines are single-pole to ground. In order to have a general overview of single-pole...
The development of an electromagnetic transient model to assess potential transient switching issues on a proposed three-ended 400 kV cable circuit is described. The key features of the PSCAD-EMTDC simulation tool and the methodology of model development and testing are discussed. Typical study results and the overall conclusions drawn from these are presented. The paper demonstrates how analysis...
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...
With the known greenhouse effect of SF6-insulated substations, the aim now is to reduce the size of transmission substations using air-insulated designs. In this work, a 400 kV compact substation layout is proposed adopting the lower IEC basic insulation level and switching impulse level, and consequently reduced clearances. Simulation studies using EMTP are performed to evaluate the lightning and...
The voltage rating of overhead lines is determined by a combined consideration of the stress applied to the line and its electrical strength. In this investigation, the voltage uprating of an existing `L3' 275 kV transmission line to 400 kV is explored. Minimum air clearances for 275 kV and 400 kV lines are first reviewed and the IEC recommendations for insulation coordination were considered. The...
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