T-shaped transmission line zero-sequence resistance parameter live measurement method

Abstract

The live measurement method of the zero-sequence impedance parameter of the T-shaped transmission line is to disconnect the single-phase switch on a certain branch of the T-shaped line to cause a lack of phase operation, and the zero-sequence current for measurement is provided by the load current. The method to restore the normal operation of the line to obtain the zero-sequence current and zero-sequence voltage of each branch of the T-shaped line; use GPS technology to realize the synchronous sampling of the multi-terminal zero-sequence voltage signal and zero-sequence current signal of the T-shaped line; use modem or Ethernet Summarize the data of each measurement point into the central computer; then use the least square method to solve the algebraic equations, differential equations or integral equations to obtain the zero-sequence impedance parameters of the T-shaped transmission line. The device of the present invention is composed of GPS antenna and OEM board, signal input terminal, signal transmitter, embedded DSP synchronous data acquisition card, output card, relay group, relay output interface, embedded PC card, power supply card, power supply signal Bus backplane and so on.

Description

technical field [0001] The invention belongs to the technical field of parameter measurement of power system transmission lines, and in particular relates to a method for measuring zero-sequence parameters of a T-shaped transmission line with electricity. Background technique [0002] With the development of the scale of the power system, there are more and more outgoing lines of power plants (substations), and more and more T-connection transmission lines; [0003] The zero-sequence impedance of the T-type transmission line will affect the fault state of the line, especially the magnitude of the zero-sequence current, which has a great impact on the zero-sequence current protection; because the zero-sequence impedance of the T-type transmission line is affected by many factors, the direction of the line , the grounding resistivity of the zero-sequence current flow area, etc.; the theoretical calculation value cannot meet the accuracy requirements for the calculation of the ...

AI Technical Summary

Problems solved by technology

[0003] The zero-sequence impedance of the T-type transmission line will affect the fault state of the line, especially the magnitude of the zero-sequence current, which has a great impact on the zero-sequence current protection; because the zero-sequence impedance of the T-type transmission line is affected by many factors, the direction of the line , the grounding resistivity of the zero-sequence current flow area, etc.; the theoretical calculation value cannot meet the accuracy requirements for the calculation of the relay protection setting value. If the calculated value is used as the basis for the setting calculation, the protection will refuse to operate or malfunction when the system fails. This directly threatens the safe and stable operation of the system; therefore, in the electric power industry standard of the People's Republic of China, "220kV-500kV Power Grid Relay Protection Operation Regulations (DL / T559-94, implemented in 1995-05-01)" The regulations on relay protection setting point out that: the zero-sequence impedance of overhead lines and cables, and other parameters that have a greater impact on relay protection should use measured values.

[0004] The traditional methods for determining the zero-sequence parameters of transmission lines include formula calculation method and blackout measurement method; because the calculation formula involves inaccurate parameters such as earth resistivity, the calculation result of the formula is inaccurate

[0005] The method of measuring T-type line parameters by blackout measurement method requires power failure of the tested line; it is often impossible to measure the power failure of the T-type line; in addition, according to the traditional blackout method, in a wider area, the amount of equipment, work The amount is too large to bear, and the simultaneity of measurement cannot be guaranteed; therefore, it is urgently needed by the power system operation department to seek a new live measurement method for T-shaped line parameters and to develop a corresponding test system, which not only has important theoretical value, and has great economic and social benefits

Images