DISTANCE RANGING-TYPE POWER TRANSMISSION LINE-BASED SINGLE PHASE GROUND FAULT DISTANCE PROTECTION METHOD

摘要

The present invention relates to the technical field of power system distance protection. Disclosed is a distance ranging-type power transmission line-based single phase ground fault distance protection method. The method: first, measured at where a power transmission line protection is installed are a fault phase voltage U_ϕ, a fault phase currentI_ϕ, a fault phase negative sequence currentI_ϕ2, and a zero sequence current I₀, where Φ = A, B, and C phases, to serve as an input quantity; calculated on the basis of the input quantity is a fault distance running from a single phase ground fault point to where the protection is installed; and finally, determined on the basis of the distance from the protection is whether or not |xz₁ - 0.5Ζ_set| |0.5Ζ_set| is satisfied to activate the protection. The method of the present invention has the fault distance and a fault impedance calculated on the basis of a linear relationship between a voltage drop from where the protection is installed to the single phase ground fault point and the fault distance, and utilizes the fault impedance and an impedance tuning to constitute a distance protection criterion. The fault distance measurement accuracy of the method of the present invention is not affected by factors such as transition resistance and load current; therefore, the method of the present invention is provided with enhanced capabilities for tolerance of a high resistance and resistance from being affected by a load current, and the method for the present invention can act reliably and correctly when a fault is found in proximity to a distance protection tuning range.