On-line identification method of zero-sequence parameters of single-circuit transmission lines in 220kv and above power grids

Abstract

The invention discloses an online identification method for zero-sequence parameters of a single-circuit transmission line of a 220kV and above power grid, comprising: step 1, saving the three-phase asymmetrical voltage phasor and the three-phase Asymmetrical current phasor data; step 2, from the data saved in step 1, extract the three-phase asymmetrical voltage phasor and three-phase asymmetrical voltage phasor and three-phase asymmetrical Current phasor data; step 3, the symmetrical component transformation calculation to obtain the zero-sequence voltage component and zero-sequence current component data at both ends of the single-circuit transmission line; step 4, the positive-sequence and negative-sequence components at both ends of the single-circuit transmission line Solve the zero-sequence voltage-current equation to obtain the zero-sequence parameters of the single-circuit transmission line. The invention can complete the identification of zero-sequence parameters of a single-circuit transmission line when the power grid is online, and has the advantages of accurate identification results, high identification reliability and high identifiability of parameters.

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...

AI Technical Summary

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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