Research On Choosing Cables Of 220kV YongQing-Xinghua Transformer Substation Transmission Project

With the gradual deepening of the urbanization process, urban area is full of electric load. High voltage overhead transmission lines are limited by city planning, also with increasing high voltage cable manufacturing technology, the power cables are widely used in high voltage transmission line construction of the cities.Generally, the cost of power cable lines construction is 10 times higher than that of overhead lines, and the cable material cost occupies roughly 45% of the whole project cost. Therefore, the selection of cable type and cross section is significant for reducing the project investment and saving social resources.In this paper, power cable selection method was studied in terms of structure, and current-carrying capacity, and the main contents were given below.Firstly, the dependency structure of oil-filled cable and XLPE cable are discussed, and comparison of two kinds of cables in the engineering application of their respective advantages and disadvantages were introduced.After that, the basic parameters of cable, including induction voltage and grounding resistance parameters were theoretically analyzed. Three methods were put forward to reduce the induction voltage:(1) Reducing the three-phase distance of the same circuit. (2) Increasing the distance between the cables of different circuits can also play the same effect. (3) Change the relative position of cable.At last,220kV YongQing-Xinghua transmission project was taken as an example for cable selection analysis. The XLPE cable was chosen in the study of this case. Based on the real local topography, directly buried and exhaust pipe installation of cable laying scheme were selected in the general region, and crane span structure was selected in pedestrian bridge. Then, considering the calculation of current-carrying capacity, overvoltage analysis and cable type choosing, the problems in relation to cable selection were analysed in detail for the project. Finally, considering the difference of temperature differences of environment, the single core XLPE insulation wrinkles aluminum sheathed power cable YJLW03 (02)-127/220kV is most suitable for h directly buried installation、cable dust bank, while YJLW03(02)-127/220kV 1 X 1600mm2 cross-linked polyethylene insulated cable were used for crane span structure.