State Grid Corporation of China

China Electric Power Research Institute

China Electric Power Research Institute Company Limited

Central China Branch of State Grid Corporation of China

State Grid Central China Grid Company Ltd.

China Electric Power Research Inst. Co. Limited

Huanzhang Liu

Dingxiang Du

Zexin Zhou

Xingguo Wang

Xiao Dong Li

Delin Wang

Yarong Guo

Xuming Liang

Hong Cao

Jing Li

Zhongqing Li

Pengfei Lv

Yong Li

Guosheng Yang

Siye Ruan

Huixin Li

Mingliang Jin

Lianhai Li

Xiangwen Chen

A line current i(k) of an M side of a first direct-current transmission line is collected at a moment k. A line current i(k−t) thereof is collected at k−t. At a moment k, a differential value di(k) of a current of the side of the first direct-current transmission line is calculated according to the line current i(k) and the line current i(k−t). It is determined whether the differential value di(k) of the current meets a protection enabling criteria. If so, direct-current protection for the M side of the first direct-current transmission line is enabled. A line current i(j) of the M side of the first direct-current transmission line is collected at a moment j. A line current i(j−t) thereof is collected at a moment j−t. A differential value di(j) of the current of the M side of the first direct-current transmission line at the moment j is calculated according to the line current i(j) and the line current i(j−t).

Direct-current transmission line protection method and system based on pure current characteristics

A method and device for starting direct-current (DC) transmission line protection, and a storage medium. The method includes: determining whether a sudden change of a DC line current at a present moment is greater than a sum of a memory start threshold and a maximum value in sudden changes of the DC line current within a time period preceding the present moment that is multiplied by a preset proportional coefficient, the time period being a time period between a moment preceding the present moment by a first duration and a moment preceding the present moment by a second duration; and starting DC transmission line protection in response to determining that the sudden change of the DC line current at the present moment is greater than the sum.

Method and device for starting direct-current (DC) transmission line protection, and storage medium

A current differential protection method for a self-adaptive half-wavelength line based on a time-difference method. Since an electrical distance of half-wavelength power transmission is long, after a fault occurs, there is an obvious time difference between the actuation times for protecting starting elements at two sides of a line. According to the principles of wave propagation, the position of a fault point can be determined by means of a difference between the actuation times for protecting the starting elements at the two sides of the line. By means of taking the fault point as a differential point, a current value at the differential point can be obtained according to a long line equation by means of the voltage and current at protection-mounted positions at the two sides of the line, and a differential current is then calculated.

Current differential protection method for self-adaptive half-wavelength line based on time-difference method

A method of free wave energy protection for a half-wavelength line based on a one-sided current includes: performing sampling and calculation on a current at protection measuring points to obtain variations in current sampling values; and activating a protective element to determine an occurrence time of a fault in a half-wavelength line. A free wave energy protection section includes a quick-action section, a basic section and a sensitive section, wherein the quick-action section, the basic section and the sensitive section serve as action criteria for performing protection with respect to the free wave energy of the half-wavelength line.

Method of free wave energy protection for half-wavelength line based on one sided current

A concomitant impedance protection method for a half-wavelength power transmission line includes that: three-phase currents and three-phase voltages of a relay protection device mounting position at an M side and a relay protection device mounting position at an N side of the half-wavelength power transmission line are acquired respectively; it is judged whether starting amounts of an M side and an N side meet starting conditions or not; a failure point F is determined according to a time difference when the starting amounts of the M side and the N side meet the starting conditions; and a relay protection action of the half-wavelength power transmission line is started according to concomitant impedance of the half-wavelength power transmission line. According to the method, a failure may be located by a time-difference method according to a characteristic of the failure, by compensating the voltages and currents on two sides of the line to construct concomitant impedance, and failures in the region of line can be correctly reflected. Since concomitant impedance protection effectively utilizes two-terminal electrical information, the fault can be quickly and reliably operated in the line region, misoperation on the failures out of the line region can be avoided, and the protection has relatively higher sensitivity.

Concomitant impedance protection method for half-wavelength transmission line

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Wuhan, China

Huanzhang Liu