Customer Satisfaction Degree Based Analytical Interval Assessment of Voltage Sag

To meet the power customer´s satisfaction is the essential responsibility of the utilities. Considering the property of customer´s satisfaction degree, an analytical interval assessment method of voltage sag frequency is proposed. The customer satisfaction degree is presented by an interval data corresponding to the voltage tolerance of tested equipment installed at the customer side. Based on the determination function derived from the relationship between the voltage magnitude and the length of fault line in the power supply system, the critical fault positions are determined using analytical iterative algorithm. By the variation of satisfaction degree within a given interval range, the interval sag frequency is calculated. Moreover, the quantitative sag frequency is determined by the help of the interval sag frequency. After plentiful theory analysis, the proposed method is applied to a five-bus system and IEEE 30-bus RTS test system. The experimental results are compared with those from existing methods. It has been proved that the proposed method is so credible and simple that it is suitable for the practical application.