A Novel Protection Method for HVDC Transmission Lines

Abstract

The present invention relates to the field of high-voltage direct current transmission, in particular to a novel high-voltage direct current transmission line protection method, specifically establishing an electromagnetic transient simulation model of a direct current transmission line, performing single-pole grounding fault simulation calculations, and obtaining the current at the line boundary protection device Fault component: extract the second-order differential component of the current fault component, and use it as the characteristic quantity to identify the fault information, and set the protection setting value of the line boundary protection device, according to the position of the line boundary protection device and the current fault extracted under the fault condition Whether the second-order differential of the component is greater than the protection setting value is used to determine whether the fault is an external fault of the local line or a fault of the local line; according to the direction of the sudden change of the fault current, it is judged whether it is an external fault of the local line or the fault of the local line Fault. The invention takes into account the sensitivity problems caused by long line faults and high-resistance grounding faults, and effectively improves the sensitivity and rapidity of line protection.

Description

technical field [0001] The invention relates to the field of high-voltage direct current transmission, in particular to a novel protection method for high-voltage direct current transmission lines. Background technique [0002] The UHV DC transmission system has the characteristics of long transmission distance and complex terrain along the way, which greatly increases the probability of accidents such as short circuit and lightning strikes on the line, which seriously threatens the safe operation of the DC system itself. At present, the traveling wave protection widely used in DC transmission lines is susceptible to interference from transient phenomena such as lightning, commutation failure, and AC side faults, and its reliability is not high. It has the disadvantage of insufficient sensitivity when high-impedance grounding is required. Further research on new UHV DC transmission line protection with superior performance. [0003] At present, the main protection of the li...

AI Technical Summary

Problems solved by technology

It can be seen that when the line is long enough, the attenuation of the high frequency by the line will be much greater than that of the boundary. If the influence of the transition resistance is considered, it will be difficult to see the attenuation of the high frequency by the line alone and the double attenuation of the line and the boundary. obvious difference

[0006] The research contents of the above literatures all involve the study of the fault transient signal after considering the double attenuation of the electric quantity by the DC line and the boundary, and do not consider the sensitivity problems caused by long line faults and high-impedance grounding faults

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