Voltage Sag Assessment Considering Time Characteristic of Distance Protection in Meshed Network

Depicting the operation of protection coordination in a scientific way is one of the key points to objectively evaluate characteristic of voltage sag. In order to evaluate the operation of distance protection on voltage sag characteristic in meshed network, a novel voltage sag stochastic evaluation method is proposed. According to the operation time of distance protection and modification of node impedance matrix, duration and magnitude of multistage voltage sag can be determined. Nonrectangular voltage sag is converted to rectangular voltage sag based on the loss of voltage concept, and stochastic assessment model of voltage sag considering time characteristic of distance protection is established. The proposed method had been applied to IEEE 30-bus test system and process control system consists of several sensitive devices, simulation results showed that the proposed method is reasonable, adaptive and can meet the practical application better.