On March 21

2018

a large-area blackout occurred in Brazilian power grid because of a series of chain reactions caused by a circuit breaker overload protection. As sequence

the northern and northeastern power grids were disconnected from the main power grid in Brazil

14 states in north and northeast area came to blackout

and 9 states in south

southeast and midwest area were also affected. The operation status of Brazilian power grid before the accident and the cause

process and recovery of the blackout are introduced. It is pointed out that the main causes of the accident are the lack of necessary stability analysis before the accident

the defects in security control

the misoperation of protection and the unreasonable configuration of the third line of defense. Combined with the actual situation of power grid in China

some recommendations are put forward to ensure the safe and stable operation of the power grid and to prevent blackouts. For example

attention should be paid to the setting and operation of protection and control devices.