The most load shedding (LS) schemas proposed so far used voltage and frequency parameters via under-frequency (UFLS) and under-voltage (UVLS) LS schemes, separately. The under-frequency and under-voltage relays are working in the power system without any coordination. In this paper, the necessity of considering both of voltage and frequency indices to achieve a more effective/adaptive and comprehensive LS strategy is illustrated. It is also clarified that this problem will be more dominated in the presence of wind turbines. Finally, an effective LS scheme considering both system frequency and voltage characteristics is addressed.
