Voltage Sag Planning of Industry power system using hybrid differential evolution considering CBEMA curve

This paper is used to investigate the voltage sag planning of a radial industrial power system using the hybrid differential evolution (HDE) method. The analysis considers the CBEMA curve and coordination of over-current relays. Firstly, the analytical equations for direct calculation of voltage sag are investigated to obtain the sag severity of the system after single or three-phase faults. The equations are useful in the planning procedures using HDE. Then, the effect of over-current relay setting on the sag duration is evaluated. Finally, the HDE is used to obtain the impedance values of transformers considering the CBEMA curves. The relay time multiplier factor is also a variable. The test on a radial industrial power system with three △/Y-g connected transformers is chosen to reveal the effectiveness of this method. The study results show that the voltage sag severity can be controlled by the structure of the power system, the transformer impedances, and the relay setting.