PSC: MTEP23 Transfer Capability Analysis Scope Development (20230315)

Feedback of the Mississippi Public Service Commission re: MTEP23 Transfer Capability Analysis Scope

In the March 15, 2023, Planning Subcommittee Meeting, MISO presented an overview of the Transfer Capability Analysis Scope to be used in MTEP23.  MISO asked Stakeholders to submit informal feedback on the six (6) proposed Linear Transfers described in the presentation by March 14.  

The stated purpose of the Transfer Capability Analysis described by MISO is to identify weaknesses and limiting facilities within the MISO system that limit the transfer of power from one area of the system to another. While the Commission agrees with the need to identify weakness and limiting facilities in the transmission system when operating under extreme circumstances, and takes no issue with the transfers identified by MISO, without the benefit of having thoroughly reviewed the Transfer Capability Methodology to be used by MISO, including the reasonableness of all associated assumptions, this Commission is unable to judge whether the projects identified based on the outcome of the analysis would be justified.

Our concern therefore lies, not with the transfers identified at this early stage of the analysis, but rather with the possibility that high cost projects identified as necessary to address poorly conceived low probability events underlying individual transfers, may be proposed by MISO Staff in the MTEP23 planning cycle, and subsequently justified by unfounded concerns of service interruptions to load and the application of Value of Lost Load in the name of system resiliency.

Of particular concern to this Commission are the potential outcomes of the analysis of four (4) of the six (6) transfer scenarios proposed by MISO, namely: the MISO East to SPP Region; the MISO North Region to MISO Central Region (Summer and Winter); and the MISO Central Region to MISO North Region. Depending on the assumptions made with regard to flows associated to the North/South constraint (Regional Directional Transfer) in the analysis of these transfers, there may be projects identified that, if justified on the basis of resiliency, may take a life of their own during the MTEP23 planning cycle.

Other than pointing out its current concerns, the Commission intends to request further clarification on MISO’s Transfer Capability Methodology and the assumptions regarding adjustments to Area Interchange Flows used in the transfer analysis, and subsequently submit any documented concerns with the methodology and assumptions to MISO.

Given that the April 14 deadline given by the Planning Subcommittee for submitting feedback falls beyond the deadline specified by Appendix N of BPM20 to modify the methodology in response to Stakeholder comments, this Commission requests a reasonable extension of time beyond the end of the first quarter for MISO to respond to the Commission’s instant comments and to apply the changes (if any) to the current year assessments.  

The Transmission Owners (TOs) appreciate MISO’s presentation at the March 15 2023 Planning Subcommittee (PSC) meeting regarding the MTEP23 Transfer Analysis Scope.

The TOs offer the following comments in response to the proposed Scope presented by MISO:

• The TOs would like to see very high transfers be studied for all of the interfaces presented in MISO’s presentation from that meeting. As an example, the TOs would like to see 15,000 MW or 20,000 MW studied for those interfaces to enable us to see the transmission requirements for very large transfer levels – the types of transfers needed for situations like the extreme conditions on the transmission systems during the recent winter storms.
• The TOs also recommend MISO develop a desired transfer test level (MW) across MISO regions & RTOs, either using historical numbers or potential future scenarios, rather than using a standard 5000 MW level which we know far exceeded the test level of 5000 MW during winter storm Uri.
• The TOs would like to see n-1-1 conditions studied on all interfaces. If there is an interface with n-1-1 contingencies not applied, the TOs would like to see an explanation for not studying n-1-1 (P3 & P6).
• The TOs also recommend MISO perform AC verification of the results and monitor Voltages to see any soft spots on the system, as Voltages will be a concern, especially when the transmission system is heavily loaded.