Configuration principle of breaker failure protection_Starting condition of breaker failure protection
The so-called breaker failure protection is the protection action of the faulty component when the system fails. Because the breaker operating mechanism fails to trip, the breaker of the adjacent component of the same substation is made to be protected by the faulty component. Trip protection.
In the 220kV and above power grids, as well as the important parts of the 110kV power grid, the power transmission line generally has a large power transmission distance and a long transmission distance. When the line fails and the circuit breaker refuses to move, it will bring great threat to the power grid. The circuit breaker failure protection is generally installed, and the remaining operating circuit breakers on the busbar connected to the circuit breaker that is malfunctioning and rejected are selectively disconnected to reduce equipment damage, reduce the power failure range, and improve the safety and stability of the system.
1. Conditions for installing breaker failure protection
Since the breaker failure protection is protection in the case of a double fault in which the breaker fails while the line is faulty, it is allowed to appropriately reduce the requirement for it, that is, only the fault can be finally cut off. Conditions for installing breaker failure protection:
(1) When the sensitivity of the remote backup protection of the adjacent component protection is insufficient, the breaker failure protection shall be installed. For phase-separated circuit breakers, it is allowed to verify the sensitivity only by single-phase ground faults.
(2) According to the importance of the substation and the size of the installation failure protection, it is decided to install the breaker failure protection. For example, 220kV and above substations operated by multiple busbars should be equipped with failure protection when the failure protection can reduce the power failure range caused by the circuit breaker's refusal.
2. Requirements for breaker failure protection
(1) Misoperation of failure protection is the same as the misoperation of busbar protection. The scope of influence is wide and must have high reliability (safety).
(2) Failure protection first acts on the bus-coupled circuit breaker and the segmented circuit breaker. After the adjacent component protection has been able to remove the fault in successive actions, the failure protection acts on the bus-coupled circuit breaker and the segmented circuit breaker.
(3) Under the premise of ensuring no misoperation, the relevant circuit breaker should be selectively removed with a short delay.
(4) Failure signing components and trip blocking components of failure protection shall have sufficient sensitivity to the fault of the circuit or equipment end of the circuit breaker.
Breaker failure protection start conditionThe starting condition of the fault phase failure : after the corresponding line protection trip contact and the fault overcurrent high setting action, the three-phase trip command jumper breaker is sent through the settable timeout delay setting value. Then, the tunable jump jump adjacent switch delay setting value sends a failure protection action to jump adjacent circuit breakers.
Starting condition of non-fault phase failure : The three-phase trip input contact maintains the malfunctioning overcurrent high-value action component, and the malfunctioning over-current low-valued action component continuously operates. At this time, the output action logic is first adjustable by the tunable jumper. The switch time delay setting value sends a three-phase trip command to jump the circuit breaker, and then the tunable jump jump adjacent switch delay setting value sends a failure protection action to jump adjacent circuit breakers.
The starting condition of the three-hop starting failure circuit : The failure protection from the start and the start of the three-hop can be opened by three auxiliary criteria of low power factor, negative sequence overcurrent and zero sequence overcurrent. The three auxiliary criteria can be retired by the tuning control word. The output action logic first sends a three-phase trip command jump circuit breaker through the tunable failure jump switch time delay setting value, and then can be set by the configurable failure jump adjacent switch delay setting value failure protection action jump adjacent circuit breaker Device.
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