Parallel Feeder Operation Scheme Based on Distributed Automation Logic

Conventional distribution system supplies loads radially, and often relies on tied adjacent feeders to provide alternative supply during outage. This results in customer outages of varying duration while the fault is located and isolated and restored, which can be very costly to the impacted customers. This paper describes one unique distribution automation scheme implemented in BC Hydro which provides uninterruptable power service to connected customers. With the implemented networked feeder DA scheme based on distributed automation logic, the critical customer loads are supplied from two parallel feeders from neighbouring substations with the two feeders are normally tied together and operated in parallel continuously. Based on sophisticated protection and telecommunications scheme, when either of the feeders experiences a fault, fault interrupters quickly isolate the critical customers from the fault based on preset automation logic and the load remains continuously supplied from the alternate feeder. Instead of experiencing an outage, the customers’ service will be maintained uninterrupted but only experience a momentary voltage dip while the fault is cleared in 3 to 5 cycles. The DA system configuration, telecommunication and SCADA functionalities and detail protection logics are described in this paper. Practical considerations for voltage control to minimize the distribution tie current are introduced as well.