Introduction-why we need state estimation Contingency Normal preventive Alert State State control Contingencies Multiple Contingency control control control Emergency State Loss of load Restorative Sate Power Systemn Security↓eves量多控制四川省童点实验蜜 家电电力系统广域测量与控制四川省重点实验室 Introduction-why we need state estimation Normal State Alert State Emergency State Restorative Sate control control control preventive Contingency Loss of load Power System Security Levels