Method of critical distances for stochastic assessment of voltage sags in a meshed distribution system

This paper is concerned with the method of critical distances for stochastic assessment of voltage sags in a large complicated distribution system. As the system is meshed, the method of critical distances is extended. Critical percentage of the feeders is developed from the critical distance in convenience to use the data provided by the industrial customer. The three phase short circuit faults in different locations, i.e. in the distribution system and in the public transmission system, are investigated detailed. The critical percentage of the feeders for each PCC is calculated. The results show that short circuit faults in the distribution system at 110 kV level will cause serious voltage sags, the spurious equipment trips are mainly due to the faults in the onsite system, not in the public utility system.