The Study Of Partial Discharge Location In Cable Line

For recent years, high-voltage power system develops quickly in both China and other countries with largely increased service amount of high-voltage transmission cable. Technologies concerning detection on high-voltage transmission cable attract many attractions from specialists and scholars of different countries to guarantee stable, sustained and reliable operation of power cables. While studies online positioning of power cable partial discharges is one of the study focuses.This paper briefly introduces causes and mechanism of partial discharge on high-voltage transmission cables. By analyzing and comparing existing online methods for partial discharge of high-voltage cables in China and other countries, merits and demerits of these methods were summarized. A new cable impedance method-based partial discharge positioning method was then adopted and learned. Firstly,a corresponding cable model was selected according to its transmission characteristics. Theoretical derivation was performed for transmission rules of electrical signals in high-voltage transmission cables. It was suggested by the spread of electrical signals in cable line. And the results showed that major factors influencing the transmission of electric signals in power cable include cable length, cable unit resistance, unit inductance and unit capacitance. The higher these parameter values are, the severer signal attenuation is. It was also found by the signal transmission that signal attenuation is severe with higher electrical signal frequency.To verify the effectiveness of the method.An overall flow chart was designed according to the method and principle adopted by this topic, based on which a system simulation model was constructed. Simulation experiments were performed by selecting distances of 1km, 2km, 3km and 4 km from the position of partial discharge to cable input point. The simulation results show that the computer simulation results and are quite similar to practical values, it was found that the method raised by this paper was feasible. It was also suggested by comparing data accuracy of the method in this paper with positional accuracies of other methods that the former, with favorable accuracy, showed great superiorities of timeliness and simplicity over the later.Finally, the on-line partial discharge positioning system has carried on the design and implementation, A signal generator of 50 kHz, A capacitive coupler, a brand filter of 50 kHz, A/D conversion and the realize of FFT algorithm by DSP are designed in this paper. A complete system model can be built by combining these designed devices together.