The existing 60-kVsystem supplying Park substation and the future Blue Oak substation is an open-loop network. Customers will loose power during single-circuit outages. Restoration of power will be done by manual switching. Load transfer is required. The proposed closed-loop system can maintain the power supply to the customers during single 60-kV circuit outages. It will also provide reliable power to the existing electrically sensitive customers in North Central area, such as the Galleria Mall, the hotel and conference center and the major commercial customers.
Also, the existing Park Substation was planned to supply 72MVA at peak. Due to the additional load growth in the North Central areas (the mall expansion, the addition of the hotel and conference center and certain site re-zoning), the revised ultimate peak demand is 82MVA. A new transformer and a new section of 12-kV switchgear will be needed to serve the additional load.
The Park substation expansion will add a 46MVA transformer, a new section of 12-kV switchgear with six feeder panels, seven 60-kV circuit breakers and three 60-kV bus sections. A new control house with high speed protection equipment will be installed to protect the four incoming lines. The project will need to upgrade the Berry Street 601 and Industrial 6040 with high speed protection for the closed-loop operation.
The closed-loop system will provide the following improvements:
- Improve the overall system reliability to cater for a minimum of single pole line failure.
- The ability to cater to system load growth and customer expansions. We need to extend our system to provide a reliable power supply to the existing customer expansions.
- The closed-loop system will allow the system to be operated in parallel for sharing the loads between Berry Street and Fiddyment substations with automatic backup.
- Protection improvement to reduce the fault clearance time and limit the damages to the equipment.
- Another outlet for the new Roseville Energy Park to the load center at Berry Street substation.
The additional transformer and 12-kV switchgear will support the load growth in North Central & HRN areas.