Evaluation of the variations of short-circuit capacities along a feeder due to distribution system-type upgrading
The variations of short-circuit capacities (SCCs) along a feeder while a primary network is upgraded from original radial to normally closed loop arrangement is essential for examining the protection system of the network after upgraded. The increments of SCCs along a feeder may cause the existing protection devices installed at the original network and its customers distribution systems becoming inadequate. Hence, a simple, systematic and straightforward evaluation method is required, especially in the planning stage. To meet these requirements the short-circuit MVA method was adopted in this paper. Based on the adopted method, the variations of SCCs along a primary feeder before and after the network upgraded were represented by simple formulas and illustrated by figures that make the variations more easily be recognized. The results not only are useful for engineers of utilities to better realizing the impact on the SCCs along feeder during the planning stage of network upgrading, but also confirm that the short-circuit MVA method is quite suitable for evaluating the variations of SCCs along a feeder.
short-circuit capacity distribution system radial normally closed loop short-circuit mva method primary feeder