AG1-363 System Impact Study Report

This project is eligible for the Expedited Study process per PJM Tariff Part VII, Subpart B, section 304 and will follow the Expedited Study Process rules outlined in PJM Manual 14H, Attachment I.3.4.

Projects in the Expedited Process will receive a retooled System Impact Study report with the Transition Cycle #1 projects (AE1-AG1) removed from the base case model used for their study. This System Impact Study (SIS) report has been prepared for the AG1-363 project using the updated case model. PJM performed reliability analysis for the project based on the serial study approach using the legacy Generator Deliverability Study method outlined in Manual 14B, Attachment C.3 (Revision 51 of M14B). Summer peak and light load load flow analysis was performed. Short circuit and dynamic stability impacts were also analyzed.

The interconnected Transmission Owner (TO) for this project is The Potomac Edison Company. The TO has provided their updated TO analysis results on the lower voltage system based on their own criteria.

This System Impact Study report summarizes both the PJM and TO analysis results for your project.

Note: This updated SIS report does not include any Physical Interconnection Facilities scope or cost estimates from the TO. As this project is in the Expedited Process, a Facilities Study will be conducted by the TO (and any affected Transmission Owner(s)) for updated Physical Interconnection Facilities and System Reinforcement (Network Upgrade) costs. The Facilities Study will be issued to the Project Developers along with the Generator Interconnection Agreement (GIA) as part of the Expedited Process.

The developer has proposed a Solar; Storage generating facility located in the The Potomac Edison Company zone — Garrett County, Maryland. The installed facilities will have a total capability of 300.0 MW with 220.0 MW of this output being recognized by PJM as Capacity.

AG1-363 will interconnect with the Potomac Edison Company transmission system by connecting to the Black Oak – Hatfield 500 kV line with a three-breaker ring bus interconnection substation and looping the Black Oak – Hatfield 500 kV Line into the new substation. The transmission line tap will be located approximately 5.3 miles from Black Oak Substation and 56 miles from Hatfield Substation. The project developer will be responsible for acquiring all easements, properties, and permits that may be required to construct both the new interconnection line tap and the associated interconnection facilities.

Attachment 1 shows a one-line diagram of the proposed interconnection facilities for the AG1-363 project to connect to the transmission system.

FE performed an analysis of its underlying transmission <100 kV system. The AG1-363 project did not contribute to any overloads on the FE transmission <100 kV system.

PJM Short Circuit Analysis did not identify any new overduty breakers or >3% contribution to previously identified overduty breakers.

Generator Interconnection Request AG1-363 is for a 300 MW Maximum Facility Output (MFO), solar and storage facility, located at Garrett, Maryland. AG1-363 will consist of 96 Power Electronics FS3430 3.55 MVA inverters and 34 Power Electronics FP3430 3.55 MVA inverters connecting to the Potomac Edison Company transmission system by tapping the Black Oak- Hatfield 500 kV line (8.2 miles from Black Oak and 53.2 miles from Hatfield) via a 500 kV transmission line.

This report describes a dynamic simulation analysis of AG1-363 as part of the overall system impact study. The load flow scenario for the analysis was based on the 2024 peak load case, modified to include applicable queue projects. AG1-363 has been dispatched online at maximum power output, with approximately unity power factor at the high side of the GSU, 1.02 pu voltage at the generator terminal, and 1.02 pu voltage at the POI bus.  AG1-363 was tested for compliance with NERC, PJM, Transmission Owner, and other applicable criteria. 44 contingencies were studied, each with a 20 second simulation time period (with 1.0 second initial run prior to any events).

Studied faults included:

a)  Steady state operation (Category P0);

b)  Three phase faults with normal clearing time on the intact network (Category P1);

c)  Single phase to ground faults with delayed clearing due to a stuck breaker (Category P4);

d)  Single phase faults placed at 80% of the line with delayed (Zone 2) clearing at line end remote from the fault due to primary communications/relay failure (Category P5).

e)  Single phase to ground faults with normal clearing for common structure (Category P7).

For all 44 fault contingencies tested on the 2024 peak load case:

a)  AG1-363 was able to ride through the faults.

b)  Post-contingency oscillations were positively damped with a damping margin of at least 3%.

c)  Following fault clearing, all bus voltages recover to a minimum of 0.7 per unit after 2.5 seconds (except where protective action isolates that bus).

d)  No other transmission element trips, other than those either directly connected or designed to trip as a consequence of that fault.

No other mitigation was found to be required for project AG1-363.

 AG1-363 meets the PJM reactive power requirement maintaining a power factor of at least 0.95 leading to 0.95 lagging at the high side of the main transformer.

Steady State Voltage analysis is not required for this project at this time.

The Projects below are listed in one or more dispatch for the overloads identified in your report. These projects contribute to the loading of the overloaded facilities identified in your report. The percent overload of a facility and cost allocation you may have towards a particular reinforcement could vary depending on the action of these earlier projects. The status of each project at the time of the analysis is presented in the table. This list may change if any earlier projects withdraw. This table is valid for load flow analyses only.

The AG1-363 project may be responsible for a contribution to the following estimated System Reinforcement (Network Upgrade) costs as shown below. The Network Upgrades listed below are required to alleviate a reliability criteria violation identified in the Network Impact analysis that PJM has performed for this System Impact Study. No physical Interconnection Facilities costs are included in this cost table.

Note 1: PJM Open Access Transmission Tariff (OATT) Part VI, section 217.3A outlines cost allocation rules for the Expedited Process projects. These rules are further clarified in PJM Manual 14A, Attachment B.

Note 2: To Project Developers with System Reinforcements listed: If your present cost allocation to a System Reinforcement indicates $0, then please be aware that if a prior project in the Expedited Process withdraws from the cycle, the cost responsibilities can change and a cost allocation may be assigned to your project. In addition, although the cost allocation to a System Reinforcement is presently $0, your project may need this system reinforcement completed to be deliverable to the PJM system. If your project desires to possibly come into service prior to completion of the system reinforcement, you would need to request an interim deliverability study to determine if all or a portion of your project would be deliverable.

The one line included in this refreshed System Impact Study report was originally developed prior to the Transition Date. Therefore, not all verbiage on the one line may align with the current Tariff definitions. An updated one line diagram will be provided in the Facilities Study report for the Expedited Process projects.

One-Line Diagram

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