Economic Assessment of Voltage Sags Based on Quality Engineering Theory

Voltage sag, one of the modern power quality problems, may cause tremendous economic loss, which needs scientific method to evaluate. This paper proposes an approach using quality loss function and signal-to-noise ratio (SNR) in quality engineering theory to make economic assessment to voltage sag. The inverted normal probability loss function is used to describe losses of single-type sags, where SNR method is applied to integrate different types together. The index of sag-caused loss is proposed, which is an important parameter for PQ evaluation. A five-node 35 kV distribution system is used to verify the proposed approach. The result shows that the proposed method could effectively assess financial losses caused by sags and be a reasonable instruction for PQ evaluation, improvement and pricing.