Economic Evaluation of Voltage Sag under Uncertain Conditions Based on Beta Distribution Parameter Correction

The large investment of sensitive equipment seriously threatens the power quality. As an important factor affecting power quality, voltage sag has caused serious economic losses. Uncertainty is one of the difficulties in sag assessment. How to overcome this problem and further complete the accurate assessment of voltage sag loss has important practical significance and theoretical value. Firstly, by using the linearization method to correct the initial power flow distribution and establishing the iterative calculation model of voltage sag under load fluctuation, the simulation and evaluation of voltage sag probability under uncertain conditions are realized. Then, a method is proposed to describe the probability value of outage fault by using the function of the deviation degree of quality characteristics from the target value. The empirical data of the converted outage probability under different amplitudes are introduced as a priori expectation. Through the voltage sag density index obtained in simulation and evaluation, the function expression of voltage deviation under the expected characteristics is calculated. Fully combining empirical data and measured data, Beta distribution is used to optimize the mapping of voltage sag amplitude to outage loss. Based on this, the calculation of continuous voltage sag loss is completed. Taking the IEEE 39-bus test system as a test example, the results show that the method can effectively evaluate the economic loss level of voltage sags of the target system under uncertain conditions. The evaluation results can provide useful theoretical guidance for the assessment, improvement and pricing of the power quality.