Circuit weak feedback side protection self-adapting start distinguishing method

Abstract

The invention discloses a circuit weak feedback side protection self-adapting start distinguishing method, which judges whether the weak feedback side protection can be started or not and opens a lockout relay of the weak feedback side protection according to weak feedback starting elements such as a zero sequence current variation starting element, a zero sequence voltage variation starting element, a phase-to-phase current decrement judgment starting element, a phase-to-phase voltage decrement judgment starting element and the like through the weak feedback features in circuit fault; when any one of the four elements meets starting conditions, the starting conditions of the circuit weak feedback side protection can be considered to be met. The starting elements can be started repeatedly, can overcome the problem that the existing protective device can only judge weak feedback once, and can the lead weakfeed back criterion to overcome the defects of incapability of being arranged at two sides, low sensitivity, inadaptation of dynamic weak feedback and the like by being matched with other criterions.

Description

technical field [0001] The invention relates to the field of electric power systems, and more particularly relates to a method for reliable start-up of power system relay protection weak feeder line protection on the weak feeder side adaptive to various problems. Background technique [0002] With the expansion of the scale of my country's power grid and the construction of various large-scale power projects, 500kV lines have been widely used. The power network has gradually become the main network with 500kV transmission lines. With the de-loop operation of 500kV and 220kV electromagnetic ring network, the operation mode of some 220kV substations has undergone great changes. The 220kV line often changes between the tie line and the terminal line. When the line is the terminal line, one end of the line becomes the load side, and the load side is no power or has a smaller weak power. For line protection, at this point, the line becomes a weak feeder line. When a fault occu...

AI Technical Summary

Problems solved by technology

When a fault occurs inside the line, the directional element on the weak power supply side, especially the distance element, is likely to fail to start due to too small short-circuit current. For the line protection on this side, the trip signal that allows the opposite side cannot be issued, and the line cannot be quickly cut off. full line failure

Moreover, after the line protection is started, if a fault occurs on the weak feeder line again, the protection needs to judge again that it is a weak feeder start. However, traditional algorithms such as abrupt amount start can only be judged at the initial stage of the first fault. After the protection starts, no more start discrimination

Images