Method for prewarning safety of electric network operation fourth-order gradient

The invention relates to an early warning method at four-grads of power network operation, and belongs to the automation field of electric power system management. The method includes the following steps: a safe, stable and comprehensive evaluation is carried out at four-grads according to time scales; the first level is to carry out security evaluation to the real time situation of the power network, and to identify the safety level of the power network operation; the second level is to carry out security collation to the power network forecast operation situation in the next 15 minutes (before the power network operation), and to send a security alarm; the third level is to carry out security collation to a power-generating plan and a servicing plan of the next day; and to send an alarm; the fourth level is to carry out security collation to a power-generating plan and a servicing plan of the next week. The early warning method ensures that the power network can run safely and stably through the safety earl