Interconnection Study

T&D Engineers conducts full interconnection studies to analyze the impact of generation facilities interconnecting to the transmission system at the location indicated and with the specified in-service date.

A. Short circuit analysis: Identifies increased level of fault duty in the study area as a result of this generation addition. The study will be conducted using a modified short circuit case created by adding the short circuit model for new generation to the latest available short circuit case model for the time frame associated with the projected in-service date.

B. Stability Study: The most current load flow cases will be used for this analysis. The transmission configuration for this analysis shall be consistent with that used for the steady state study. The stability study will also include improvements determined by the provider to be necessary to facilitate this interconnection request. Stability models of the proposed generation and any other future generation that is located near the proposed plant that already has a signed interconnected agreement will be added to the DWG load flow case and dynamic database. Voltage stability simulations will be conducted for close in three-phase faults at the adjacent transmission stations. Normal transmission three-phase fault clearing times of 9 cycles will be used for the study. Plots will be provided to show proof of stability or instability as a result of adding the proposed generation to the transmission grid.

C. Facility Study: T&D Engineers will perform a facility study to determine the required modifications and additions to the transmission system, including a detail of costs and the scheduled completion date for such modifications. This facility study will include determining the facilities required to accommodate any new facilities for interconnection to the generation addition. This facility study does not include any other ERCOT utility's transmission system upgrades that may be necessary.

T&D Engineers will deliver as part of this Facility Study the following:

• Switchyard electrical layout and electrical one-line for proposed interconnection.
• Switchyard relay one-line for proposed interconnection and remote substations.
• Description of transmission line facilities (if any) necessary for proposed interconnection.
• Conceptual design document for proposed interconnection.
• Detailed cost estimate for the transmission facilities for proposed interconnection and an estimate of the contribution in aid of construction to be charged (if any).
• Schedule for completion of proposed interconnection facilities.