Connection Number Assessment of Voltage Sag Frequency Considering the Influence of the Reliability Parameters

Considering the complexities of influencing factors on voltage sag assessment,such as the reliability parameters of system components and protection devices,the notion of connection number comprised of certain number and uncertain number was proposed to depict the uncertainty of reliability parameters for satisfying the requirements of the practical engineering. The connection number analysis method on the failure rate of system components and protection devices was studied. Based on the traditional fault location method,a new connection number assessment model and an approach were presented to assess the occurrence frequency due to voltage sags. The proposed method had been applied to the IEEE 30-bus test system. Compared with the current deterministic and interval number methods,the simulation results have shown that this method is the expanding of existing methods and it meets the practical application better.