A line disconnection protection method based on line parameter identification

Abstract

The invention discloses a line disconnection protection method based on line parameter identification, which belongs to the field of electric power system relay protection. The line disconnection protection method includes the following steps: obtaining voltage waveform sampling values, current waveform sampling values, current phasors and switch positions of the three phases at both ends of the line; The voltage waveform sampling value and current waveform sampling value of the three phases at the end, using the line differential equation to solve the resistance and inductance parameters of the line; compare the solved line resistance and inductance parameters with the preset measured line resistance and inductance parameters to calculate the difference; Whether the calculated difference between the line phases exceeds the set threshold value determines the location of the disconnection; according to the location of the disconnection, the corresponding disconnection protection scheme is implemented. The invention is helpful for quickly locating the disconnection fault, and can judge the disconnection fault more accurately under the condition of low load of the line.

Description

technical field [0001] The invention relates to a line disconnection protection method based on line parameter identification, which belongs to the field of electric power system relay protection. Background technique [0002] Disconnection fault is a relatively rare type of fault in transmission lines. The main causes of disconnection faults are the decline in the tension resistance level of transmission lines due to aging, arc combustion caused by lightning strikes, strong winds or external force impacts. Disconnection faults belong to longitudinal faults, which occur along the direction of electric energy propagation, including single-phase disconnection and two-phase (multi-phase) disconnection. When a disconnection fault occurs, it will not cause a large short-circuit current and a sharp drop in voltage, but when the system is in non-full-phase operation, a large negative-sequence and zero-sequence current will be generated. The negative-sequence current will cause the ...

AI Technical Summary

Problems solved by technology

[0003] It is easy to judge the disconnection fault of the system, but it is more difficult to distinguish whether the disconnection fault occurs in the area or outside the area, because when the disconnection fault occurs in the area or outside the area, the characteristics of the power frequency electrical quantity on both sides of the line There is not much difference, especially in the case of low load, which directly affects the selectivity of the protection action. If the judgment is not accurate, it may cause the expansion of the fault isolation range and affect the reliability of power supply.

Images