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To prevent power system blackout following a severe contingency, an emergency control action may be needed. The underfrequency and undervoltage load shedding (UFLS/UVLS) schemes are usually in use in real-world power systems without coordination. This chapter emphasizes the necessity of using both voltage and frequency data, specifically in the presence of high wind power penetration, to develop an effective LS scheme. After a background on the LS problem, the chapter talks about an LS scheme using both voltage and frequency information with the described graphical tool. Then, the application of electromechanical wave propagation for the emergency control issue in a wide-area power system is emphasized. The chapter shows that the voltage and frequency responses may behave in opposite directions following many contingencies.