Zero-sequence parameter on-line identification method for 200 kV or more single-circuit power transmission lines

Abstract

The invention discloses a zero-sequence parameter on-line identification method for 200 kV or more single-circuit power transmission lines. The zero-sequence parameter on-line identification method comprises the steps of 1 saving three-phase asymmetric voltage phasor data and three-phase asymmetric current phasor data of two ends of a single-circuit power transmission line measured by a phasor measuring unit; 2 extracting three-phase asymmetric voltage phasors and three-phase asymmetric current phasors of the two ends of the single-circuit power transmission line from the saved data in a period from fault phase clearing to single-phase reclosure completion; 3 performing symmetrical component transformation and calculation to obtain zero-sequence voltage component data and zero-sequence current component data of the two ends of the single-circuit power transmission line; 4 solving positive sequences, negative sequence and zero-sequence voltage-current equations of the two ends of the single-circuit power transmission line by means of a least square method so as to obtain zero-sequence parameters of the single-circuit power transmission line. The zero-sequence parameter on-line identification method can complete zero-sequence parameter identification on the single-circuit power transmission line under the situation of the online power grid and has the advantages of being accurate in identification result and high in parameter identification reliability and identifiability.

Description

technical field [0001] The invention relates to an online identification method for zero-sequence parameters of single-circuit transmission lines of 220kV and above power grids. Background technique [0002] The zero-sequence parameters of transmission lines are an important basis for the calculation of relay protection settings in power systems. Inaccurate line zero-sequence parameters will cause deviations in protection setting values ​​and affect the safety, stability and economic operation of power systems. [0003] Zero-sequence parameters are affected by many external factors, such as grounding resistivity, equivalent depth, wire layout, etc. It is difficult to obtain accurate zero-sequence parameters through theoretical calculations. Therefore, my country's relay protection regulations stipulate that zero-sequence parameters must be measured. However, with the increasing scale of the transmission network and the continuous improvement of the voltage level, it is time...

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Problems solved by technology

[0005] However, during the normal operation of the power system, the zero-sequence component of the line is very small, and the zero-sequence parameters are not identifiable; only when a fault occurs can a larger zero-sequence component be obtained, but the fault lasts for a short time and the PMU is not sensitive to The processing effect of the periodic component is not good, making the identification result unreliable

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