On reliability characteristics and service time limits of 500 kV overhead lines

Abstract

The results are given of statistical analysis of the values of the failure rate (failure frequency) and its structure for overhead lines (OHL) 500 kV of the European part of the country over a long time period. The age structure of the 500 kV OHL is presented, according to which about 40% of the OHL have developed a normative service time of more than 50 years. It is shown, that an increase in the duration of the OHL operation from about 30 to 60 years leads to a doubling of their accident rate. The maximum possible service time period of 500 kV ОНL was estimated. For this purpose, instrumental surveys of the strength property of reinforced-concrete foundations and the degree of corrosive deterioration rate of 500 kV OHL steel transmission tower in three regions of the country were carried out: Vologda, Moscow and Volgograd regions. It is shown that the most critical element of 500 kV OHL affecting the service time limit is their transmission towers. Moreover, the degree of wear condition of the metal of the transmission towers depends on natural-climatic and man-made factors and decreases from the southern to the northern regions of the country. At the same time, the maximum possible service time limit of 500 OHL, put into operation in the middle of the last century, can be increased from 50 to 70-80 years. After that, the main structural elements of the 500 kV OHL should be completely replaced, which will be a large scientific and technical problem from the standpoint of reliability of the operating modes of the country’s united power system.