Method for the continuous monitoring and diagnosis of sources of partial discharges (PDs) in high voltage cables during connection to, and operation in the power grid, and physical system for carrying out same

摘要

A method specially designed for detecting events associated with partial discharges (PDs) in high voltage cables includes the identification of the location and the evaluation of the amplitude and rate of repetition per period of the grid voltage, with the possibility of identifying different sources producing PD signals as a function of the location thereof and recognising the type of defect associated with PDs in the same location. Generated electric signals are measured and the discriminated in relation to the background noise. A system for carrying out the method includes devices for discriminating the noise in relation to the transient waveform of the PD, determining the parameters associated therewith, determining the map of sources of PDs along the length of the cable, graphically representing the sources, and identifying the patterns of the sources of PDs separated as a function of the location thereof along the length of the cable.

主权项

1. A method for monitoring partial discharges in a high voltage cable, the method comprising:
measuring electric signals of the cable for a time interval of at least one grid voltage period with a plurality of partial discharge sensors; filtering noise of the measured signal by calculating a Wavelet transform and identifying a partial discharge as a function of a statistical dispersion of components of said transform; determining in the filtered signal a start time of a pulse and at least one of the following parameters: phase angle over time in relation to the zero-crossing of a grid voltage, amplitude and an integral of the pulse of the partial discharge at the sensing point, identifying the cable where the partial discharge originates as a function of a highest amplitude of the signals detected by each trio of sensors positioned in accessories, and determining the parameter associated with a location of the partial discharge, taking into account differences of arrival times to the different sensors that have detected the partial discharge.