Distortion of the supply voltage waveform with loadshedding and the effects on domestic appliances

This paper investigates the effects of loadshedding on domestic appliances and the shortening of their lifespan. The study involved monitoring the supply waveform during two distinct load shedding events, the beginning and the end of loadshedding on a domestic low voltage feeder with a 2-hour power interruption. The results show that loadshedding results in power quality issues such as voltage notching and sagging on the supply waveform without any overvoltages. The effects due voltage notching observed after loadshedding results in high rate of change of voltage (dV/dt) which contributes to the shortening of the lifespan of domestic appliances. A sub-grid system model is developed, including a Medium Voltage Vacuum Circuit Breaker, 11kV-400V step-down transformer, Low Voltage cable, and the load (domestic appliances). The Alternative Transients Program - Electromagnetic Transient Program software is used to model loadshedding transients and their impacts on different types of loads.