Research on combined traveling wave fault location method of overhead line-cable hybrid line and influencing factors

Fault transient traveling wave of cable and overhead line hybrid transmission line has the characteristics of complex and variable propagation. To this end, this paper uses theoretical analysis and simulation verification to do the research of the mechanism of production and propagation characteristics of fault transient traveling wave of cable and overhead line hybrid line in depth. On this basis, the principle of single line traveling wave distance measuring principle for hybrid line is expounded and the influence of transition resistance, fault inception angle, fault type, fault position on the fault voltage traveling wave, current traveling wave propagation characteristics and combined traveling wave fault location precision is explored in detail. At the same time, the relationship between the fault current and the fault distance of cable-metal shielding layer single-terminal grounded line is calculated and analyzed. The transition resistance, initial phase angle, fault type have a significant impact on fault voltage traveling wave and current traveling wave amplitude of 220 kV cable-overhead-line hybrid line, but they have no effect on the time required to reach the first wave of the traveling wave; under different fault location, the time that the amplitude of fault traveling wave of hybrid line and initial row wave surge reach both sides of the line is different; the current traveling wave amplitude of the single end ground wire of the cable metal shield decreases with the increase of the cable part fault distance, that is nonlinear monotone decreasing characteristic.