Method for calculating partial discharge fault probability of cable

Abstract

The invention provides a method for calculating the partial discharge fault probability of a cable. The method comprises the following steps: 1) carrying out partial discharge and temperature detection on a to-be-detected cable, and continuously measuring partial discharge capacity and temperature data of the cable in n delta t time intervals; 2) calculating the increment delta Xi (i = 1, 2, ...,n) of the micropore of the electric tree in the ith delta t time period, solving a nonlinear equation set, and obtaining an estimated value L2i (i = 1, 2, ..., n) of the length l of the electric treeof the to-be-measured cable; 3) repeating the step (2) for n times to obtain estimated values L21 to L2n of the length of the electrical tree in n time periods, and carrying out non-parametric statistics on the estimated values L21 to L2n to obtain a probability density distribution function hFD (1) of the length l of the electrical tree of the cable to be measured; 4) counting the electric branchlength of the cable when the cable is close to the fault to obtain the probability density distribution fFD (L) of the electric branch length of the fault cable; and 5) solving the partial dischargefault probability FFD of the cable by integrating the hFD (1) and the fFD (L). The method has the beneficial effect that the purpose of quantitatively evaluating the fault probability of the XLPE cable by utilizing the partial discharge signal and the temperature data is achieved.

Description

technical field [0001] The invention relates to a calculation method of failure probability, in particular to a calculation method of cable partial discharge failure probability, and belongs to the technical field of electric equipment failure detection and diagnosis. Background technique [0002] In recent years, China's economic development and urban construction have become faster and faster. As a channel for transmitting electric energy, power cables are an important part of the power grid, and their usage is increasing year by year. In the urban power transmission system, cross-linked polyethylene (XLPE) power cables have become the mainstream equipment for power transmission. Some XLPE cables currently in operation are about to reach the end of their service life, and their insulation problems are becoming more and more significant. At the same time, the harsh laying environment and local defects of the cable itself greatly shorten the life of the cable, resulting in ...

AI Technical Summary

Problems solved by technology

Partial discharge defects in the cable body and accessories have complex randomness. At present, it is difficult to grasp the relatively accurate correspondence between the partial discharge signal and the length of the electrical branch in the cable insulation, so it is difficult to determine and predict the remaining power of the cable based on the partial discharge detection data. In the end, only a rough qualitative judgment of the cable status can be given

Moreover, the existing guidelines separate the partial discharge and temperature parameters of the cable for judgment, which cannot reflect the essential problem of material degradation

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