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Line protection method and system suitable for flexible direct access

A line protection, direct technology, applied in the field of power system, can solve the problems of insufficient protection sensitivity, differential current drop, braking current rise, etc., achieve high reliability, solve the effect of draining current, and improve sensitivity

Active Publication Date: 2020-06-05
STATE GRID CORP OF CHINA +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The short-circuit current provided by the flexible DC is greatly affected by the control strategy, which may cause the current angle on both sides of the line to be an obtuse angle, resulting in the situation of draining the current, causing the differential current to drop and the braking current to rise. Under the weak AC system, there is protection sensitivity insufficient risk

Method used

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  • Line protection method and system suitable for flexible direct access
  • Line protection method and system suitable for flexible direct access
  • Line protection method and system suitable for flexible direct access

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Such as figure 1 , figure 2 As shown, the main idea of ​​the line protection method for adapting to flexible direct access provided by this embodiment is: the operating characteristics of the operating element are the OR logic of the existing differential protection operating area and the extended operating area, and the "adaptive flexible" is set in the distance protection. The extended action area of ​​direct entry" control word, the extended action area adopts different action characteristic equations and protection criteria to realize adaptive protection according to the throwing and withdrawing conditions of the control word of "extended action area adapted to flexible direct entry". The specific process is as follows:

[0054] S1. Collect the secondary current of the current transformer (CT) where the line protection device is installed, including the A-phase current, B-phase current and C-phase current;

[0055] S2. According to the secondary current, calculate...

Embodiment 2

[0092] This embodiment provides a line protection system adaptable to flexible direct access, which includes:

[0093] The current calculation module is used to collect the secondary current of the current transformer where the line protection device is installed, and calculate the differential current and braking current of the line according to the secondary current of the current transformer;

[0094] The control word judging module is used to judge whether the control word of "expanded action area adapting to soft direct entry" is the set cut-in value, if the control word is the set cut-in value, the function of the extended action area is put into operation, otherwise the function of the extended action area is exited;

[0095] Extended action area line protection module, used to judge whether the function input of the extended action area is sufficient, and perform line protection for the extended action area with sufficient conditions;

[0096] The line protection modul...

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Abstract

The invention relates to a line protection method and system suitable for flexible direct access, and the method comprises the steps: S1, collecting the secondary current of a current transformer at an installation position of a line protection device, and calculating the differential current and braking current of a line according to the secondary current of the current transformer; S2, judging whether a control word of the extended action area adapting to flexible direct access is a set cut-in value or not, if the control word is the set cut-in value, inputting the function of the extended action area, and entering S3; otherwise, quitting the function of the extended action area, and entering S4; S3, judging whether the function input condition of the extended action area is sufficient or not according to a set condition, if so, determining that the fault is an in-area fault, tripping a protection action, and removing the fault; if the function input condition of the extended actionarea is insufficient, entering S4; and S4, if the extended action area function exits or the extended action area function input condition is insufficient, judging whether the differential current andthe brake current on the two sides of the line meet the current differential action condition or not, if so, determining that the fault is an in-area fault, removing fault by protectingaction trips,otherwise, returning protection.

Description

technical field [0001] The invention relates to a line protection method and system adapted to flexible direct access, and relates to the technical field of power systems. Background technique [0002] In order to solve the increasingly severe fossil energy crisis and environmental problems, wind power, photovoltaic and other new energy power generation technologies have developed rapidly. As of the end of 2017, the cumulative installed capacity of wind power and photovoltaics in my country reached 164 million kW and 130 million kW, respectively, most of which were collected through stations and then connected to the grid through high-voltage transmission lines. The correct action of the relay protection of the sending line is very important for the safety and efficient utilization of large-scale new energy power. [0003] The short-circuit current provided by the flexible DC is greatly affected by the control strategy, which may cause the current angle on both sides of the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26H02H3/28H02J3/36
CPCH02H7/268H02H3/28H02J3/36Y02E60/60
Inventor 刘颖肖智宏宋璇坤高旭申洪明李铁臣苏毅王紫琪张祥龙陈炜杜娜杜兆强范登博
Owner STATE GRID CORP OF CHINA