Reliability analysis of the isolation and restoration procedures of distribution feeders

The report [1] on the US-Canada blackout on August 14, 2003 revealed that the duration of restoring the Eastern Interconnect to a normal operating configuration was lengthy and complicated. One of the difficulties in modeling a power system is to represent the significant changes in loading patterns that present themselves during the restoration process following a major outage. The capacity of equipment may be adequate during normal operating conditions, however, severely compromised during restoration procedures particularly the restoration of thousands of distribution system feeder circuits. This paper will present a new restoration methodology for distribution system configurations that maximizes the amount of load that can be restored after a grid blackout, substation outage and distribution feeder line section outages and evaluates the cost of load point interruptions considering feeder islanding and substation capacity constraints. Several case studies with restoration procedures will be presented and discussed to clearly reveal the impact of distribution system capacity constraints on load point reliability indices and the cost of load point interruptions.