CN102347599A

CN102347599A - Protecting method for internal short-circuit current of generator

Info

Publication number: CN102347599A
Application number: CN2011102789418A
Authority: CN
Inventors: 郭振清
Original assignee: GUANGDONG TENFO ELECTRICAL GROUP CO Ltd
Current assignee: GUANGDONG TENFO ELECTRICAL GROUP CO Ltd
Priority date: 2011-09-20
Filing date: 2011-09-20
Publication date: 2012-02-08

Abstract

The invention relates to a protecting method for an internal short-circuit current of a generator. A differential relay, which is adopted to find out internal short circuit, has the following operating principles that: a current transformer (CTG) and a current transformer (CTL) are respectively arranged in the generator; currents (IG and IL) flowing through the current transformers (CTG and CTL) are equal to secondary currents (IG2 and IL2) thereof under normal condition, and the differential relay does not operate; if a short-circuit accident is occurred in the generator, the secondary currents of the two current transformers (CTG and CTL) are different, and the difference of the secondary currents has the following formula of (IG2-IL2)/IG2 in proportion to the secondary currents of the current transformers of the generator; and when the difference value exceeds a setting value, the differential relay operates, so that a universal circuit breaker can be tripped, the excitation field of the generator is cut off, and the flowing of the short-circuit current is stopped. According to the protecting method provided by the invention, the safety of the generator can be ensured, and compared with the prior art, the generator can be effectively protected and can not be further damaged, and the unnecessary maintenance cost is reduced.

Description

The guard method of generator internal short-circuit electric current

Technical field

The present invention relates to a kind of guard method of generator internal short-circuit electric current.

Background technology

If existing two generator G1 and G2 parallel running; The present G1 inside accident that is short-circuited; Or common bus is short-circuited; Add that the motor cluster of other generators and load flows into the electric current of short dot; The short time delay or the instantaneous release of omnipotent breaker are threaded off; Fault generator is excised from system, and system continues power supply by other trouble-free generators, has recovered the stable state of system.But prime mover of fault generator still continues to supply to give power, and generator G1 is short circuit current flow still, so the damage of fault generator or failure cable has the danger of further expansion.

Consider from generator, if be in the individual operation state, because of not from other generators offset component (phasor of electric current with), omnipotent breaker can't move, system is instability just.Necessity protection that the generator internal short-circuit is adopted can not be depended merely on the overcurrent trip mode, must and use with other effective ways.

Summary of the invention

The technical problem that the present invention will solve provides a kind ofly can effectively protect generator, can further not damage the guard method of the generator internal short-circuit electric current of generator.

For solving the problems of the technologies described above, the present invention adopts following technical scheme: adopt differential relay to find internal short-circuit, and rely on its action to make omnipotent breaker cut off the energized circuit of generator; The operating principle of differential relay is following: in star stator armature coil one side that generator is inner and the outside main electroplax current transformer CTG, CTL are housed respectively; Electric current I G, IL and the secondary current IG2 thereof, the IL2 that cross instrument transformer in normal state equate that differential relay is failure to actuate; The accident if generator inside is short-circuited; Then the electric current I G of generator all flows into short circuit place; The outside electric current I L that flows through is zero; The secondary current of two current transformer CTG, CTL is just variant, and its difference between current is that IG2 subtracts IL2 again divided by IG2 with respect to the ratio of the instrument transformer secondary current of generator; Surpass setting value when this is worth, differential relay is action just, thereby omnipotent breaker is threaded off, and the excitation field of cut-out generator stops the circulation of short circuit current.

The guard method of generator internal short-circuit electric current of the present invention; Find internal short-circuit owing to adopt differential relay; And the action that relies on it makes omnipotent breaker cut off the energized circuit of generator; It can guarantee the safety of generator; Relative to existing technologies; It can effectively protect generator, can further not damage generator, has reduced unnecessary maintenance cost.

Embodiment

In the present embodiment, the guard method of generator internal short-circuit electric current adopts differential relay to find internal short-circuit, and relies on its action to make omnipotent breaker cut off the energized circuit of generator; The operating principle of differential relay is following: in star stator armature coil one side that generator is inner and the outside main electroplax current transformer CTG, CTL are housed respectively; Electric current I G, IL and the secondary current IG2 thereof, the IL2 that cross instrument transformer in normal state equate that differential relay is failure to actuate; The accident if generator inside is short-circuited; Then the electric current I G of generator all flows into short circuit place; The outside electric current I L that flows through is zero; The secondary current of two current transformer CTG, CTL is just variant, and its difference between current is that IG2 subtracts IL2 again divided by IG2 with respect to the ratio of the instrument transformer secondary current of generator; Surpass setting value when this is worth, differential relay is action just, thereby omnipotent breaker is threaded off, and the excitation field of cut-out generator stops the circulation of short circuit current.

Below the present invention has been done a detailed description, the above only is the present invention's preferred embodiment, when can not limiting practical range of the present invention, promptly allly does impartially to change and modify according to the application's scope, all should still belong in the covering scope of the present invention.

Claims

1. the guard method of a generator internal short-circuit electric current is characterized in that: adopt differential relay to find internal short-circuit, and rely on its action to make omnipotent breaker cut off the energized circuit of generator; The operating principle of differential relay is following: in star stator armature coil one side that generator is inner and the outside main electroplax current transformer CTG, CTL are housed respectively; Electric current I G, IL and the secondary current IG2 thereof, the IL2 that cross instrument transformer in normal state equate that differential relay is failure to actuate; The accident if generator inside is short-circuited; Then the electric current I G of generator all flows into short circuit place; The outside electric current I L that flows through is zero; The secondary current of two current transformer CTG, CTL is just variant, and its difference between current is that IG2 subtracts IL2 again divided by IG2 with respect to the ratio of the instrument transformer secondary current of generator; Surpass setting value when this is worth, differential relay is action just, thereby omnipotent breaker is threaded off, and the excitation field of cut-out generator stops the circulation of short circuit current.