EXPERIENCE WITH NEW METHODS FOR LIVE-LINE CONDUCTOR REPLACEMENT

摘要

A continuing disparity in the rate of construction of transmission capacity and the growth in electrical load have stretched the loading on many US transmission corridors to the point where new means must be found to supplement capacity gains already realized through supplementary system equipment and by dynamic rating technology. Energy price differentials across congested paths are high enough and of sufficient duration to produce a very high economic incentive for increasing thermal capacity of existing circuits. The reconductoring of critical circuits, an obvious solution which can increase thermal capacity by a factor of two or more, is beset with two major obstacles. (1) The structures involved are often already beyond their intended service life and therefore in need of repair or partial reconstruction; particularly if they are to support conductors larger than those already in place and (2) The circuits most in need of reconductoring are usually those which are most difficult to remove from service. A procedure has been developed for safe, efficient, and non-disruptive reconductoring of most HV and EHV lines. That procedure essentially creates a "spare" phase position alongside the section of line being restrung. [1] Each phase, in turn, is then relieved by that outboard position while it is re-conductored. The process requires careful prediction and accommodation of induced currents and voltages, switching provisions which recognize both, and a carefully designed equipotential grounding system at both pulling and tensioning terminals. While the above method can be implemented with conventional equipment technology, it can be achieved faster, more safely, and within much narrower right-of-way constraints by the use of recently developed robotic technology. [2] That technology not only expedites the live-line reconductoring process, but makes for efficient reinforcement or reconstruction of existing towers by lifting all three phases comprising a complete ac circuit off the tower during the tower's rebuild or replacement.