Protection function of circuit breaker
1. Configuration of circuit breaker protection device
Generally, in the double-bus and single-bus wiring mode, when the transmission line protection wants to send a trip command, only one circuit breaker
at the local end of the line will be tripped. Naturally, the reclosing will only reclose this circuit breaker, so it is reasonable to configure the reclosing according to the protection configuration. In the 3/2 wiring mode, failure protection, automatic reclosing, three-phase inconsistency protection, dead zone protection and charging protection are integrated into one device. This device is called circuit breaker protection.
2. Breaker failure protection
Breaker failure protection means that when the relay protection action of the faulty electrical equipment issues a trip command and the circuit breaker refuses to operate, the protection action information of the faulty equipment and the current information of the refusal circuit breaker are used to determine the failure of the circuit breaker
. Cut off other related circuit breakers in the same plant in a short time limit, so that the scope of power outage is limited to a minimum, thereby ensuring the stable operation of the entire power grid, and avoiding serious burning of faulty components such as generators and transformers and the collapse of the power grid.
The collapse of the accident. Generally, circuit breaker failure protection function is configured on 220kV and above circuit breakers
, and some important 110kV circuit breakers will also be equipped with failure function. Therefore, after the failure protection action of the side circuit breaker, all circuit breakers and the middle circuit breaker on the bus of the side circuit breaker should be tripped and the remote trip function should be activated to trip the circuit breaker on the opposite side of the line connected to the side circuit breaker.
If the failure protection does not activate the remote trip function, although the line's backup protection can cut off the circuit breaker on the opposite side, it will lengthen the fault removal time. Moreover, the failure protection of the middle circuit breaker basically has the function of remote tripping initiated by the failure action. The action process of the circuit breaker
failure in the double bus connection mode will not be repeated, and it is simpler than the 3/2 connection mode.
3. About automatic reclosing
There are two ways to start reclosing: position-incompatible start and external trip start. External trip start means that the line protection action sends a trip command and starts reclosing at the same time.
The position does not correspond to the start is divided into: single-phase stealth jump start and three-phase stealth jump start.
Protection trip start is divided into: single-phase trip start and three-phase trip start.
Regarding the setting method of reclosing, it can be selected according to needs: single-phase reclosing, three-phase reclosing, comprehensive reclosing and reclosing deactivation.
kind. Either the switch on the screen or the control word in the setting list can be used to select the reclosing mode.
Reclosing inspection method: The following three methods can be used when three-phase reclosure is required for line three-phase tripping.
Synchronization mode: line and synchronization voltage are greater than 40V, and then the phase difference between the line voltage and the phase voltage of the same name in the synchronization voltage is within the range of fixed value setting
No-voltage detection method: Check that the line or the voltage of the same period is less than 30V, and the corresponding TV is not disconnected.
No verification method: No inspection is performed, and the closing command is issued when the time is up.
Regarding the first closing and then closing reclosing: the first closing breaker is closed in the fault, the latter closing the breaker is no longer closed. In the 3/2 wiring mode, there is a problem of closing first and closing after the reclosing of the side circuit breaker and the middle circuit breaker
Reclosing first can send out a closing pulse after a short time delay. When the first closing and reclosing starts, the output digital contact is used as the "blocking first closing" digital input of the latter closing and reclosing. When the post-closing recloser receives the information that the "Latching first close" input contact is closed, its reclosing will send a closing pulse after a longer delay. The post-closing reclosing only sends the closing pulse with a longer delay when the input of the "locking first closing" input is input.
"Investment first"-soft pressing plate, hard pressing plate
Short time delay (reclosing setting time, about 0.7s)
Reclosing after closing:
"Latch first close" open entry
"Post-closing fixed" control word
Long time delay (reclosing setting time after reclosing time delay, about 1.4s)