CN-115333058-B - Transmission line differential protection method, device and system

Abstract

The invention discloses a differential protection method, a device and a system for a power transmission line, wherein the method comprises the steps of obtaining positive sequence current, negative sequence current and zero sequence current of two differential protection devices on two sides of the power transmission line; and calculating the complex sequence current of each differential protection device according to the positive sequence current, the negative sequence current and the zero sequence current of each differential protection device, and performing differential protection on the power transmission line according to the complex sequence currents of the two differential protection devices. The invention adopts longitudinal differential protection based on complex sequence current quantity, reduces data transmission quantity and improves the sensitivity of the current relay during fault.

Inventors

• ZHAO TONGHAN
• FU QIANG
• HOU WEI
• SHA YING
• XUE YIPENG
• XU SHU
• SU YUZHONG
• CHEN JUN
• MA HAIJUN
• WU BO
• LU GANGGANG

Assignees

• 国网宁夏电力有限公司固原供电公司

Dates

Publication Date

20260508

Application Date

20220810

Claims (7)

1. 1. A differential protection method for a power transmission line, comprising: acquiring positive sequence current, negative sequence current and zero sequence current of two differential protection devices on two sides of a power transmission line; Calculating the complex sequence current of each differential protection device according to the positive sequence current, the negative sequence current and the zero sequence current of each differential protection device; Performing differential protection on the power transmission line according to the complex current of the two differential protection devices; The complex sequence current has the following calculation formula: ; Wherein, the The current of the complex sequence is represented by the current, The positive sequence current is represented by the sign, Which represents the negative-sequence current and, Representing zero sequence current; The step of performing differential protection of the power transmission line according to the complex sequence currents of the two differential protection devices includes: calculating according to the complex sequence currents of the two differential protection devices to obtain differential protection discrimination values; comparing the magnitude relation between the differential protection discrimination value and a preset threshold value; determining a fault position according to the magnitude relation obtained by comparison; The differential protection discrimination value is calculated as follows: ; Wherein, the The differential protection discrimination value is indicated, Representing the complex sequence current of the differential protection device located on one side of the transmission line, Representing the complex sequence current of the differential protection device on the other side of the transmission line.
2. 2. The method of claim 1, wherein the predetermined threshold is , wherein, Indicating the rated current.
3. 3. The transmission line differential protection method according to claim 1, wherein the step of determining the fault location based on the magnitude relation obtained by the comparison includes: if the differential protection discrimination value is larger than the preset threshold value, determining that the fault position is positioned in the two differential protection device areas; And if the differential protection discrimination value is not greater than the preset threshold value, determining that the fault position is located outside the two differential protection device areas.
4. 4. A transmission line differential protection method according to claim 3, wherein after the step of determining the fault location based on the magnitude relation obtained by the comparison, the method further comprises: And according to the fault position, enabling the two differential protection devices to execute differential protection actions.
5. 5. The method according to claim 4, wherein the step of causing two differential protection devices to perform differential protection operation according to the fault location includes: If the fault position is located in the two differential protection device areas, the two differential protection devices execute tripping action; And if the fault position is located outside the areas of the two differential protection devices, the two differential protection devices do not execute tripping action.
6. 6. An embedded microcomputer protection device is characterized in that an embedded microcomputer program instruction is stored on a readable storage medium of the embedded microcomputer protection device, and the embedded microcomputer program instruction is executed by a processor to realize the transmission line differential protection method according to any one of claims 1-5.
7. 7. The differential protection system for the power transmission line is characterized by comprising the embedded microcomputer protection device as claimed in claim 6 and a power carrier information transmission channel, wherein the power carrier information transmission channel comprises a power cable, a coupler and a communication terminal.

Description

Transmission line differential protection method, device and system Technical Field The present invention relates to the field of power transmission line protection technologies, and in particular, to a method, an apparatus, and a system for differential protection of a power transmission line. Background The bandwidth resources of the carrier channel are limited, typically below 300kB/s. The protection based on the carrier channel generally adopts the pilot protection based on switching value transmission. If split-phase current differential protection, especially multi-terminal differential protection is adopted, data of each phase current is transmitted, and a higher requirement is put on channel bandwidth, if multiple sets of protection devices use carrier channels at the same time, channel resources become more intense, and even the usability of differential protection is affected. Disclosure of Invention The embodiment of the invention provides a power transmission line differential protection method, device and system, which are used for solving the contradiction between higher channel resource requirements and limited carrier channel bandwidth of the conventional power transmission line differential protection technology and improving the protection sensitivity to a certain extent. In a first aspect, a differential protection method for a power transmission line is provided, including: acquiring positive sequence current, negative sequence current and zero sequence current of two differential protection devices on two sides of a power transmission line; Calculating the complex sequence current of each differential protection device according to the positive sequence current, the negative sequence current and the zero sequence current of each differential protection device; and carrying out differential protection on the power transmission line according to the complex sequence currents of the two differential protection devices. In a second aspect, an embedded microcomputer protection device is provided, wherein an embedded microcomputer program instruction is stored on a readable storage medium of the embedded microcomputer protection device, and when the embedded microcomputer program instruction is executed by a processor, the differential protection method of the power transmission line is realized. In a third aspect, a differential protection system for a power transmission line is provided, which includes the embedded microcomputer protection device according to the embodiment of the second aspect and a power carrier information transmission channel, where the power carrier information transmission channel includes a power cable, a coupler, and a communication terminal. In this way, the embodiment of the invention adopts the longitudinal differential protection based on the complex-sequence current quantity, reduces the data transmission quantity and improves the sensitivity of the current relay during fault. Drawings In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Fig. 1 is a flowchart of a transmission line differential protection method according to an embodiment of the present invention. Detailed Description The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The embodiment of the invention discloses a differential protection method for a power transmission line. The transmission line is positioned between the two differential protection devices, and the differential protection is carried out by the two differential protection devices. As shown in fig. 1, the method comprises the steps of: Step S101, positive sequence current, negative sequence current and zero sequence current of two differential protection devices on two sides of a power transmission line are obtained. The positive sequence current, the negative sequence current and the zero sequence current can be obtained by a symmetrical component method, and the method is concretely as follows: Positive sequence current: negative sequence current: zero sequence current: Wherein, the The current of the a-phase is represented,The current of the B-phase is represented,Representing a C-phase current, α and α 2 each represent a