With the development of electric technology

diversify of power system emergency control approaches is becoming remarkably obvious. Their advantages and disadvantages among the approaches have aroused significant concern. On the basis of the extended equal area criterion (EEAC)

this paper focuses on the analysis of different power system emergency control approaches

and points out the mechanism how different approaches improve the transient angle stability. Moreover

the evaluation index of emergency control is proposed with quick and effective features in the control approach determined beforehand. The accuracy and effectiveness of the proposed calculation method and evaluation index has been demonstrated through various simulation cases

a simple power system and the actual system. This work is supported by State Grid Corporation of China

Major Projects on Planning and Operation Control of Large Scale Grid (No. SGCC-MPLG003-2012) and State Grid Corporation of China.