2009 Scenario Reliability Assessment - NERC

Scenario Reliability Self-AssessmentsTransmissionFor the Scenario Case, individual transmission owners may need to construct approximately 14miles of additional 230 kV transmission lines and network upgrades of approximately 132 milesof 230 kV transmission lines during the 2008—2017 planning horizon. In addition, one 230/138kV transformer may need to be upgraded.The table below summarizes, by voltage class, the number of additional new transmission linemiles attributed to the Scenario Case as well as the number of transmission line miles that mayrequire upgrades in order to integrate these renewable resources. Additional transmissionfacilities may be required in order to interconnect the proposed renewable resources. Theamount and type of interconnection facilities that may be required can be extensive depending onsiting locations relative to the existing transmission network. In addition, any changes to theassumed siting locations of these renewable resources used to assess the Scenario Case, can alsohave an impact on the amount and type of required facilities to integrate these resources.Transmission LinesVoltage (Miles)(kV) Upgrade New69 10 5115 7 0138 28 13230 132 14Total 178 31Operational IssuesAdditional operating guides are expected to be developed in order to mitigate potential operatingissues that may develop with the potential penetration of solar resources as modeled in theScenario Case. For example, a Solar PV installation does not involve a rotating mass andtherefore does not have inertia. Therefore, operating Solar PV systems have the potential forsubstantial ramps during partially cloudy days typical of the Florida weather patterns. Solar PVsystems can experience variations in output of +/- 50 percent in a 30 to 90 second time frame and+/- 70 percent in a five to ten minute time frame. 36 These type of ramps in the output of SolarPV plants can be experienced many times in a single day during certain weather conditions.Operating guides would likely include requirements to address the challenges of sudden changesin ramp rates throughout the day. These guides may need to limit the amount of Solar PVgeneration that can be online in a given area, based on the projected demand, to account forreactive requirements as well as frequency response requirements. Presently, high penetrationlevels of Solar PV within the FRCC Region are not expected to occur until more experience isgained in the operating arena to ensure the power system remains reliable.36 NERC Special Report: Accommodating High Levels of Variable Generation (Page 27).2009 Scenario Reliability Assessment Page 35