Method and system for protecting zero-sequence current of power transmission line by superconducting current limiter

Abstract

The invention discloses a method and a system for protecting zero-sequence current of a power transmission line by a superconducting current limiter, and belongs to the technical field of high-voltagepower transmission lines, the power transmission line is a double-circuit power transmission line provided with a superconducting current limiter, and single-phase reclosing is adopted for a first circuit and a second circuit. The method is characterized in that when a loop line is overlapped with a permanent fault, a fault line is disconnected again, a superconducting current limiter of a non-fault line enters the current limiting state again due to the fact that a reclosure coincides with the permanent fault, the current limiting impedance is increased, the transmission power of the non-fault line is very large due to the current operation condition, the three-phase current limiting impedance of the non-fault line is asymmetric, and when zero sequence protection maloperation is caused,the action delay time of zero-sequence current protection is prolonged. By the adoption of the technical scheme, detailed analysis is conducted on the simulation research and setting cooperation principle of the superconducting current limiter on zero-sequence current protection of the power transmission line, and corresponding control measures are provided for misoperation of the superconductingcurrent limiter.

Description

technical field [0001] The invention belongs to the technical field of high-voltage transmission lines, and in particular relates to a zero-sequence current protection method and protection system of a transmission line by a superconducting current limiter. Background technique [0002] With the continuous expansion of power grid scale, the problem of excessive short-circuit current has become one of the prominent factors restricting the growth of power grid load and the development of power grid. In recent years, with the rapid development of the installed capacity of the power grid and the construction of grids of various voltage levels, the grid structure has been greatly strengthened, and a double-circuit inner and outer ring network structure has basically been formed in many areas. The power grid meets the needs of grid load growth and reliable power supply, but at the same time it also makes the short-circuit capacity of the grid continue to increase. Although the po...

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Problems solved by technology

[0004] However, the connection of the superconducting current limiter to the power grid will inevitably have an impact on the traditional zero-sequence current protection strategy.

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