Online measurement method for impedance parameter of three-phase asymmetric power transmission line

Abstract

The invention discloses an online measurement method for impedance parameter of a three-phase asymmetric power transmission line, which comprises the steps of: a first step, mounting synchronous measurement devices at two ends of a measured three-phase asymmetric power transmission line, and synchronously measuring the three-phase voltage and current signals at two ends of the measured three-phase asymmetric power transmission line through the synchronous measurement devices at n times; a second step, perform quick Fourier transform on n sets of three-phase voltages and current signals which are acquired in the first step, thereby calculating n sets of three-phase voltage industrial frequency vectors at two ends of the measured three-phase asymmetric power transmission line and n sets of three-phase current industrial frequency vectors at the first end of the measured three-phase asymmetric power transmission line; a third step, calculating the self impedance parameter of each phase and mutual impedance parameters among different phases; and a fourth step, calculating a positive sequence impedance, a negative sequence parameter, a zero sequence parameter and coupling impedance parameters among the phases. The online measurement method realizes online measurement for the impedance parameter of the three-phase asymmetric power transmission line, and furthermore has a relatively high measurement precision.

Description

technical field [0001] The invention relates to an on-line measurement method for impedance parameters of a three-phase asymmetric transmission line. Background technique [0002] The power frequency parameters of transmission lines are necessary parameters for power system calculation of power flow, short-circuit current calculation, relay protection setting calculation and formulation of operation mode, and its accuracy is directly related to the accuracy of these calculation results. If the transmission line parameters used in the calculation are inaccurate, it may have a great impact on the power system, and even cause major power accidents. [0003] There are mainly theoretical calculation methods and measurement methods to obtain transmission line parameters. The theoretical calculation method is to calculate the resistance, inductance, conductance and capacitance parameters of the transmission line by using the physical parameters such as the self-geometric mean dist...

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Problems solved by technology

This method is more accurate in calculating the distribution parameters of single-circuit lines, but for multi-circuit transmission lines on the same tower with strong electromagnetic induction, the number of parameters to be identified is more than the number of electrical equations obtained from one measurement, so it is impossible to calculate Distribution parameters of multi-circuit transmission lines

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