Method and system for protecting ring main unit of power distribution network

Abstract

The invention provides a method for protecting the ring main unit of a power distribution network. The method comprises the following steps: (1) collecting measuring currents and current directions at protective installation positions in the ring main unit; (2) adopting different protection configuration schemes according to the difference of protective positions inside the ring main unit, and forming protective startup information and action information; (3) forming a logic criterion according to the protective startup information and the action information to carry out fault location and determining a failure circuit breaker; and (4) accelerating protective actions according to the result of the failure location and the failure information of the circuit breaker, and quickly clearing faults. Different protection configuration methods are adopted according to different protections, and the logic criterion is formed by using the protective startup information so as to accelerate backup protective actions, so that the power failure range is effectively reduced.

Description

technical field [0001] The invention relates to a protection method and system for a ring network cabinet, in particular to a protection method and system for a distribution network ring network cabinet. Background technique [0002] In the distribution network, the cable ring network wiring mode formed by the ring network cabinet is flexible. Since the short-circuit current protection of the incoming and outgoing lines of the ring network cabinet is close, even if the microcomputer protection is used, the selectivity is poor, and leapfrog tripping often occurs and the scope of fault influence is expanded. Especially when there is a fault in the line of the cascaded switch station, due to the short power supply radius of the distribution network, the large cross-section of the wire, and the accuracy of the protection TA, the short-circuit current experienced by the protection in the cascaded switch station is not very different, and it cannot be based on the short-circuit cur...

AI Technical Summary

Problems solved by technology

[0002] In the distribution network, the connection mode of the cable ring network composed of the ring network cabinet is flexible. Because the short-circuit current of the protection of the incoming and outgoing lines of the ring network cabinet is close, even if the protection selectivity of the computer is used, the protection selectivity is very poor, and leapfrog tripping often occurs to expand the scope of fault influence.

Especially when there is a fault in the line of the cascaded switch station, due to the short power supply radius of the distribution network, the large cross-section of the wire, and the accuracy of the protection TA, the difference in the short-circuit current experienced by the protection in the cascaded switch station is not large, and it cannot be based on the short-circuit current difference. achieve selectivity

In addition, the access of distributed generation (Distributed generation-DG) makes the distribution network change from traditional radial to ring network operation, and the current direction inside the ring network cabinet is more complicated.

The power supply line of the distribution network with the ring main unit as a segment cannot accurately locate the fault location, and the selectivity is poor, etc.

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